Years back, the company I worked for, designed and manufactured toroidal transformers. I personally wound thousands of them. All of the ones we built, were wound on compressed ferrite cores. Different mixes of core material for different properties of operation.
When I hear Toledo, I think of the famous Toledo Sword. 3:11 Yes they can rattle, but that's why manufacturers put them in a metal casing with damping on the inside. The damping prevents rattling and the metal can is a shield to keep the radiated EM noise in.
Thank you for the explanation. I came to YT looking for expert advise on toroidal transformers and when I saw your video, I know I could count on just that!
Paul mentioned in passing an attribute of toroidal transformers that is the primary reason they are used in balanced power isolation transformers. i.e. efficiency. I have two of those products. The toroidal transformer in each is about twice the size of the largest one Paul picked up the the video. One, a Furman IT-1210, is used to power all equipment in my electronic music studio and is totally silent. The other, made by Equi=Tech, makes a slightly audible hum. It is used to power the home theater electronics and is in a cabinet so the noise is not detectable from a theater seating position. In the early 1970's I worked as a technician trainee at the Pasadena Naval Warfare Center. One one assignment in an electronics lab I had the opportunity to fabricate some small toroidal coils. The process is interesting. A split bobbin is located through the core hole and then wound with the amount of wire required for the final part. The winding machine then rotates the bobbin to unwind the wire around the core while simultaneously slowly rotating the core to distribute the windings around the circumference. An interesting phenomenon that occurs when powering up such a large transformer is the reason I keep them powered on all the time. When first turned on the inrush current needed to saturate the magnetic core is so large that it has a tendency to trip the 20A breaker supplying the wall outlet. If that happens I quickly reset the breaker, which is fortunately nearby, and again flip the switch before the magnetic field can completely dissipate.
You can also build a slow start circuit. Just a big resistor in series so the in rush is lower amperage. A second switch to bypass the resistor after the first few seconds. It will save your breakers.
Like all good salesmen Paul is only telling you what puts him in an advantage. There are actually 3 types of transformers, EI, toroidal and R core. In the past, toroidal were very expensive because they had to be hand wound. Today we have machines that do it automatically so the price of toroidal transformers came way down. Generally but not as a rule, for a set price (low to mid) you get a better toroidal transformer than EI. This is due to the fact that EI transformers hum, vibrate and radiate large electromagnetic fields which wreak havoc for low signal components like preamps and dacs. But if cost is not an issue you can get better EI transformers. As for R-core, these are the best as they combine the advantages of EI and toroidal but none of the disadvantages but are even more expensive so they are very rare. To conclude, never pick equipment based on transformer type. Today toroidals are the bandwagon that everyone hops on.
I live in Lisbon-Portugal and Toledo is a fantastic Citadel.love it!! I have Been there 3 times.amazing!! In USA there are cities also called Lisbon or New Lisbon.
Isn't a toroidal transformer capable of about twice the output power for about the same weight as an EI transformer. Also, isn't an R-core the best for audio, at least for lower power devices, like a DAC?
Paul forgot to mention regulation, which is generally much better with a toroid - which will affect the sound, as there is less voltage droop at greater loads, especially important in high power amps.
@Dave Micolichek Hellop Mine Goods frends! Is this the title yu wer lookin for... Deregulation, Reagan-Style Jefferson Decker President Reagans was a get rid of REGULATORS. thanks yoiu, and are the good frends! THUMBBS UIPS!
Paul, I worked for a company that built power conditioning equipment for the computer industry. I wound transformers (all sizes) for 7 years and stacked quite a few along the way too. EI transformers are simple to make and are tunable. If you did them yourself you would have better luck with them. We soaked the finished transformers in resin and baked them in an oven after they were tuned. They did not buzz.
I worked at a stereo company that used a lot of EI transformers.The power Transformers were vacuume impregnated with some kind of varnish and then potted with 450 degree roofing tar. Worked pretty good.No transformer hum...
When the Dutch took over the land in 1624 we now call NYC , it was called New Amsterdam (fort Amsterdam). In 1664 the British took over, so there are a lot of Dutch and English names to be found. Many streetnames in Brooklyn are named after the farmers who used to own the land.
Thanks to this video a lot man. I play guitar and my toan is built around an awesome Hughes and Kettener Valve three channel pedal (NOS 1994)... The stock wallwart IE Transformer was noisy as hell, even when volume down that b... made noise in the line. So I got a toroid, stuck it a computer PSU with three prong ground and it sounds more even (bass, mids, highs). Yesterday I was testing both against each other and the stock wallwart being just in the same powerstrip and the toroid feeding the valve pedal, when I took out it made an annoying pop, whereas wallwart feeding the valve and taking out the toroid didn't make any noise. A friend told me that a guy that works with him (both are doctors at a research centre) told him "Your pedalboard is as good as your powersupply is" and I found this to be true. Yet need to finish my AC PSU with a soft start (check that out if you're using toroids), and enclose it roadworthly so that I can get it far away from my main DC PSU (yes some expensive musician makers sell stupid wallwarts in 2023). Thanks again man, you don't know how much you've helped me. Wish the audiophile world came more into guitar world which still seems doing some thing brainless. By the way still is a question why guitar valve amps use IE transformers (tough Laney has some toroid based amps), is it out of lazyness, not taking risks?
I have a Denon DRA 500 and a Yamaha RN 803 stereo/network receivers. They both use EI transformers. EI on Denon constantly hums the moment u turn it on whereas EI on Yamaha is literally silent.
Toroid transformers, they certainly have their issues too. Some very serious. Small electrical issues with an offset, they no longer work very well. I've heard of people that switched over to LED lights within their home, their toroid transformers would get hot to the touch and make a ton of noise within the secondary. I use them too. But it should be noted they have their issues.
Toledo Spain played a crucial role in Western history as that is where the Moors left behind a huge library filled with Ancient Greek texts which had been lost to the West, including Aristotle. When these works were translated, they formed the basis for the founding of European universities and thereafter the Enlightenment.
The most popular transformers used in audio are C-core or EI and they cost about the same to produce. There are two main reasons why the C-core is better. Firstly the C-core is made from grain-oriented steel which can be used for higher magnetic flux (lower distortion at low frequency). Secondly there is more space for windings (the more sections the lower leakage inductance). However, for lower output power amplifiers say 50w the EI transformer is a better choice because of lower stray capacitance (better high frequency)
@Lloyd Stout and your point is...dont just agree, add to the conversation. Paul was talking more about toroidal vs EL transformers . How about comparing R-core with toroidal
I don't think you mentioned toroids weigh significantly less. There is something to be said about less magnetic field leakage being less, thus less electrical noise in high gain circuits.
Great reply and I also prefer to see toroidal transformers inside my audio gear. For a particular application considering target BOM cost, physical layout, EMI concerns, operating frequency etc., either way can be optimum. BTW, you probably got your mains power through several transformers on the grid that aren't audiophile toroidal ones, but you better not worry about that :-)
@Fat Rat Well, not really saying that, but have you ever heard of oil in transformers? Those large ones that feed your audio gear somewhere outside can be full of oil and if they are older ones, nasty toxic PCB, worse than snake oil.
@@ilovecops6255 Dangerous (worse than snake oil) used in old transformers...PCB is very dangerous as it accumulated in our environment...th-cam.com/video/NKiIM6WJZfQ/w-d-xo.html
There is a measuremen of the quality of an inductor, the Q value, which compares the inductance to the resistance. Resistance is loss of power, and a toroidal transformer has a higher Q value. I am sure there are some special kinds of other transformers made, but the classic one is pretty crappy. When you need a lot of inductance a big beefy toroidal is quite incredible. It can hold a lot of Joules of energy.
If I use a toroidal transformer for sine wave inverter, do I need to install an inductor or choke as well? How to calculate the value of the inductor for each capacity like 750VA & 1250VA sine wave inverter?
Howdy. Also there is a lot more winding space available with toroids. One may use thicker winding wires to minimize winding losses. I should think this is essential in High End gear. The power supply needs to provide current fast without the voltage to buckle. Regards.
Does anyone have any information, pros or cons on R-Core transformers for audio components eg: cd players, DACs, etc? I remember Sony using them in some of their ES: Cd, DVD, and Blu-ray , players. Thanks
James Plotkin that might take some of the warmth away. In vintage guitar amplifiers, for instance, many of the old Marshall output transformers get ripped off by dubious repair shops, because it is often “the iron” that is so desirable. Also, you may find that much of the “warmth” and “fat bass” attributed to tube amplifiers is really coming from the transformers, hence why the early McIntosh solid state amps sound so “Tubie.” As this reflects a form of desirable distortion in both cases, I don’t think going for less of it would be desirable, but maybe...still the noise and distortion about which he speaks of eliminating with toroidal transformers is on the input power side and related the 50/60 hz A/C hum which is constant and otherwise mixes into the audio signal whereas the output transformers only color positively accentuate certain frequency ranges of the intense “pure” signal, so I doubt they would desire to clean up that stage too much. I could be wrong.
@@Diaphanic1 I don't know but I am sure you can find some opinions online. With most high end audio, it's probably more like "We use toroidal output transformers and they don't"
@@gordthor5351 Yes, in this power range E-I core designs are typically a good 50% heavier. It would probably add another 5Kg or so, to the amplifier weight.
@@petermartin9494 I dont think that's what he's trying to convey with "affects". You are speking specifically about residual noise that variates per power demand and can be mitigated but is not totally avoidable. Affectation in the other hand is how the transformer introduces EM noise to the circuitry which is avoidable with good design. Toroidal is just easier to control but not flawless.
Now there is a can of worms: Are toroidal transformers better than laminated iron core ones? May I repeat the question but this time it is about the output transformer of a valve amplifier. I am really curious what Paul has to say about that one.
What challenges would I face if I wanted to swap a EI transformer with a Toroidal one? I'm having an issue with overheating in a PSU and am thinking this produces less heat than EI frame.
Power transformers cannot sound better. They simply provide ac voltages. If they are wound with proper wire gauges to provide enough current at rated voltages that's all that matters. Yes, toroids have more contained magnetic field so they can be placed closer to the preamp section. If you are using external PSU then it makes no difference what so ever. And transformers don't rattle if they are assembled properly and potted as they should be not in super glue but in epoxy resin or wax. Your output transformers are EI and they don't buzz at low frequencies, right?
You pretty much contradicted yourself. Basically in order to get a quiet EI transformer and in a way that it doesn't influence the preamp section you'd have to have it dipped in resin and incased away in yet another box (external PSU). That's just stupid. You slap a simple toroid and you're done with. For the most prts EI's are used in supercheap amps like Marantz's and Denon's 400$ amps (Made in Malaysia).
@@SpaghettiKillah That's not what I said, potting of transformers is a standard part of manufacturing process. It doesn't have to be in a separate box I was making a point since many high end products use both external boxes and toroids in them which makes no sense. There are no noise issues or quality issues with McIntosh and Dynaco amplifiers that have both power and output transformers on the chassis one next to the other and relatively close to the preamp section. Paying a premium to simply SLAP a toroid to an amplifier is closer to stupid than using a well designed and built EI transformer for a fraction of the price.
@G Guest Again, that's a completely bogus article, containing many glaring falsehoods and numerous mis-statements based on the author's complete misunderstanding of his sources.
Both transformers produce the same AC, that then leads to the same DC out, how is the DC is different in EIs and in toroids? I have one mono amp with a 970 VA cubic transformer that does not make any noise,any hum; it feeds a dual 15 inch woofer speaker box,2 Ohm, would a toroid do better for the sound?
Transformers only work with AC in (the primary winding) and AC out (the secondary winding). The AC secondary is then rectified into rough DC which is then “smoothed” in the L/C/R filter portion of a DC power supply to make useable DC current
Toroids tend to have lower secondary impedance which provides more peak current capability which is highly desired in audio power amplifiers. But EI types can be built that way as well. I don't think it's worth any effort to replace your factory transformer.
Can any of you good people, or infact paul, tell me how I can change the speed of the magnetic flux rotation? Is it as simple as increasing or decrease either primary or secondary windings?
I don't have any audio equipment with tordial transformers. I remember an old audio guru friend of mine telling me..."put the tip of a long insulated (wood, plastic, etc.) screw driver to the top plate of a EI transformer with power on. Place your ear to the butt end of screw driver. He said if you don't hear/feel anything then your transformer is good physically. If your hear/feel buzzing or hissing or maybe a radio broadcast then you may need a repair/replacement." I've honestly tried this before and have heard a local radio station through the screw driver from transformer. Crazy I know but true.
I was checking interconnect shield currents in my system the other day, and noticed a significant amount of RF energy from the local AM stations. But some of my cable runs are long, so most installations probably would not pick up so much RF.
I was playing with an old Crown D60 stereo amp the other day and man did that thing have a noisy transformer, sounding like a loud electric hair clipper. The transformer appeared to be pretty well saturated in some sort of varnish or glue, so inner rattling wasn't the main source of the noise. I ended up decoupling it mechanically so it floats in the chassis on o-rings and some dense foam. If toroids were an option, Crown probably would have used them as this amp has a super thin profile at 1-3/4" thick. I suppose it's possible to find an off-the-shelf toroid to replace this pancaked transformer. But I doubt it's worth the effort. Great little amp, otherwise.
Howdy again. Bandwidth Audio has a wonderful clip where it is explained how the unavoidable air gaps in EI cores help fight saturation. It is claimed that toroids saturate much easier when the mains has a DC component. Hopefully PS Audio uses toroids with say 2% more winding turns than what is calculated for laboratory clean 60 or 50 Hz. That will tolerate some redsidual DC in the mains. Regards again.
Great video. They are MUCH better because of how the magnetic Flux flows. They are quiet, run cooler, and are more efficient. Co$t is why manufacturers avoid them for the cheaper I an E type laminated type. A pre wound coil can be inserted into the "E" potion, then the "I" (which is always the base) can be weled on. Due to the torroids shape (one piece) it must be wound by CNC machine which takes more time and energy. You ARE, however, wrong about how the torrid is MADE. It is NOT donut shaped stampings ( Flux loss would still be high and magnet vibration within the core would result in heat and noise. They are 100% ceramic pressed and fired. I used to build and modify them for R&D.
Hi Paul! I got a pair B&W 805D2 I noticed 1 tweeter doesn't work(properly) I removed the cables and only put the cables in the tweeter terminals. The right tweeter plays fine. The left tweeter plays very very soft at high volume. I swapped the right cable to the left speakers and still the same problem. Is this the filter what is defect?(since I hear a little)
Does it matter/is it a problem that there is Very quiet hum from my sub that has one of these transformers? It performs ok and can’t hear unless my ear is next to it.
You talked about types of trans formers. Could you give an opinion of the marantz M7025 power amplifier sound quality? I believe it does not have a toroidal transformer. Tyty
I have Logitech Z-5500 speakers. They are more than 13 years old. Theres a toroidal transformer inside subwoofer. Can be this transformer the cause that the subwoofer makes thumping sound but only in the evening? Or maybe those two large capacitors inside? Thank you sir.
My favorite Marantz I've owned (and still keep as backup, separate power amp now) was my first torroidal with the SR8002. I always felt that had the cleanest and most headroom out of any others I've had...always made me wonder if the Torroidal transformer had anything to do with it or just better components then others for the gain sections. Now w Xbox One X and PS5 I need to replace my cheap SR5010...and noticed a SR8012 from 2 years back has a torroidal again. This is an interesting video to watch before I can make a choice.
Thanks for this one, great video...Only 1 question..In what year the did the first toroidal its entree in stereo equipment...somebody here who have the answer?
Not sure about performance, but one thing is for certain: Step-up transformers for tube equipment need a huge number of turns of fine wire, and would be extremely expensive to build in toroidal form.
My tube amp has 4 massive EI transformers, and 300Bs. Sounds awesome. My 2,500 dollar marantz uses torroidal. Supposed to be high end. Sounds terrible by comparison.
The transformer is only part of the equation. Bruce Rozenblit is a tube designer of some renown, and tends to use toroids in most of his power amp designs.
I suspect you are using these tubes single ended in which case there is constant DC in the output transformers. EI transformers are easier to make that can handle the DC.
@@MichelLinschoten im new to this audio stuff bought 2 years ago a pair of Dali Zensor Pico speakers, currently im searching the web because i want to DIY some speakers, and what i currently know that this audio-market is a lot of marketing besides that each ear is different so what might sound horrible to one might sound good for another
Hi paul, would it matter if we use EI transformer instead of toroid transformer in a CD transport. As I understood EI transformer produces noise, EMI more but does it matter in cd transport where only digital signal is transmitted to an external DAC
Hello Paul, can you or someone give me information about a place or shop where I can buy the material to make the core for toroidal transformers, thanks
I am writing to inquire about an issue of my Markbass CMD151P Jeff Berlin amplifier. I turned the amp on and practised for about 5-10 minutes. The sound was good, bright, full, nice. After that, the sound started to be weak, volume is little bit down, feeling is hard to play and not responsive. So, I stopped to play and wait for about 5 minutes (wait with turn the amp off or wait without turn the amp off), the sound became full and rich again but only for 2-3 minutes. Then again the same issueis appeared. Even though the offical service in my country (Turkey) couldn't reilize an issue, they accepted to replace my amplifier with a new one. The issuse pursued in the new amp and I decided to change other elemets; my guitar has also replaced other related parts such as socket etc. However, the issue is still exist. I started to belive the issue can be from a specific batch production. I would appeciate if you help me to solve this problem or give technical advice and check procedure that I can apply as an Electronic Technicihan.
My guess would be heat. As the amp warms up, a number of components could be heating up beyond their capabilities. A simple fix might just be to put a fan blowing on it. If I remember correctly, there is a built-in fan, but it is tiny, maybe replace that with one with more CFM. Bass player here.
You are a nice guy, you know a lot about audio, now it is time to go and see the world. Remember, not all your audience is from the USA... Ps: when ever you can, you are welcomed in Lisbon and I don't mean North Dakota.
If you want a much more thorough and objective answer to the question of "Are toroidal transformers really better and what are their electrical/magnetic disadvantages compared to regular run of the mill EI (i.e., box shaped) transformers, rather than they just "cost more and sound better...", do a Google search for the following: "EI and Toroidal Transformers" "ken stevens"
The problem is that Ken Stevens article is as flawed as this video. It was written to warm about the switch of a single component without tuning accordingly the rest of the circuit, not to properly answer the question. The First paragraph is the usual audiogourmet gibberish instead of proper measurements. The Second is true, as EI is way more resilient to DC but his examples can be easily fixed by cautiousness during the wiring and by using a rectifier in a single package instead of discrete diodes or by pairing them. Though, replacing the standard PN diodes with Schottky is a good idea as there is less Vdrop and less noise (but again, this have to be tuned). DC is even easier to fix in the primary. RF input noise is not that hard to effectively filter if you use common lab equipment. AC coupling is not an issue at all if the DC circuit is properly isolated inside a shielded compartiment. EI are even more noisier, especially in the audible spectrum. About ground and FM bandwidth : this is pure BS. If the ground paths and connections are correct inside the whole chain (the case, the cables the room and the building) this is enough to ensure proper shielding. Just have to be careful with ground loops as well as digital circuits or SMPS in the ground line. Same thing with main wiring: ideally using a line dedicated for audio from the electrical panel and filtering it. Finally the LC filter/resonator created in the secondary is not an issue when the circuit is properly tuned and measured. Just like putting decoupling caps in a design.
@@PainterVierax Non-RF input noise is impossible to filter as is evidenced by the fact that exactly ZERO of the regenerators are effective and doing this. This is the noise that gets to the secondary. If the rebuttal to this is to introduce bypass caps and do proper filtering on the secondary, then there is no point in using a toroidal transformer vs a cheap EI transformer, in the first place.
Far less important than it is for E-I core transformers. Toroidal magnetic fields are better contained, and the symmetry of their shape tends to cancel induced current in nearby circuitry.
There is a caveat to toroidal transformer mounting BTW, you wouldn’t strap it down by anything that creates a magnetic loop through it as that would be a shorted turn.
@@Jenny_Digital That's why most have an insulated bolt in the center. But even with rubber pad on both ends, a stainless bolt, and a stainless plate and plastic bushing on the bottom, it still will hum and have a little loss due to the bolt. But when you are talking about 6KW it is far less loss in the toroidial.
@@gravelydon7072 And as I understand it, R wound transformers are nearly as good as toroidal with E.I’s being the poor relative in many HiFi applications. I don’t see why these toroidal transformers can’t be mounted using polymer structures to to further limit losses etc. I know of some excellent fully fluorinated high temperature engineering materials.
Good advice. Similar to RCA vs balanced. In a perfect setup cheaper RCA can sound good but over a broad population of various setups, balanced XLR always wins.
They rattle and make noise? wow, now I know why they sound so awefull. and im not thinking about my sound ampliefier, im thinking about my Xbox, my gaming console. Im currently thinking about modding it, it would involve adding ram, an ssd, custom kernel and HDMI. all to bring the old gaming console to the future. What still bothered me was the power supply. being close to a PC the powersupply is basicly a PC powersupply. replacing the 1 fan with realy nice quiet onces worked as a threat but the PSU... im gonna look into a nice silent powersupply for my xbox and maybe look into a more solidstate solution or if a Toroidal psu excists (it wont have a effect directly on the audio ofcourse, because its mostly digital, even up to the output. But this video did answered the sound questions :D
I wish that the Sprout 100 didn't have distortion at high volume with bass heavy music. Id like to have the freedom of max volume as clean as low volume. A new even better version of the Sprout needs to be made. Maybe at the 1000 dollar price point.
I disagree. Watts have never been less expensive. You can get dual mono 250 watts per channel class D Ncore module amplifiers for like $600. The Sprout is jammed with functionality in a tiny package, hence its niche. The market is saturated with $1000 integrated amplifiers with more watts, and it doesn’t make sense for PS Audio to compete in it.
Paul, I've repaired a faulty circa 2010 Subwoofer by replacing some caps. However the toroidal tx hums at 50hz harmonics (I'm in Australia) Is it old age causing this ? Not sure if replacing would solve it, and that's if I can even find a 41.7/17v output.
Doubtful it's age. Probably poor design in the first place. Sometimes lower cost torroids are made from cheap steel or they are not wound properly. Lots of reasons they can buzz.
@@Paulmcgowanpsaudio I have the same issue as Scott here. Paul, I got the complete opposite answer from the manufacturer. They said that age is an issue. The older they get, the more they hum. So your "doubtful it's age" doesn't match up.
@@rabarebra Other than the varnish sometimes used, I don't see any mechanism for the steel and copper changing. I have worked directly with transformer vendors for years and have never found this to be a problem. Perhaps send me their response of how that could happen. Thanks.
Like most things technical, there is never a one-fits-all answer. While Toroid transformer do offer many advantages over EI types, there are some disadvantages. They can saturate very easily and have no tolerance for DC voltage which is often found on AC power lines today from switch mode power supplies and other direct line connected rectifiers.
You need to stop reading soundstage.com articles. The one about toroidal versus E-I core transformers is mostly nonsense. It is NOT true that DC voltage is often found on AC power lines. There are transients which can disturb symmetry, but these are short enough that they will not have the same effect as steady DC. If two transformers - toroidal and E-I core - are equivalent, then they will have the same saturation current. Further, you are not going to saturate any power transformer, merely by transient asymmetries on the AC power, because the idle current due to normal operating voltage is very small compared to the transformer's rated current.
@@marianneoelund2940 I don't read soundstage.com. I do read the IEEE journal as I am an accredited EE. Toroids saturate must faster than EI, that is a known fact. DC components on AC power lines is quite common today, especially in larger distribution systems such as in commercial buildings. Are you trying to say half wave rectification does not reflect a DC component on an AC source voltage? I am not saying toroids are deficient. They are an excellent choice for audio components. I am just pointing out some well known engineering pitfalls.
@@andydelle4509 If a toroidal and an E-I core transformer have the same VA capacity, then they must have similar saturation current. If the toroidal has much lower primary series resistance, then conceivably it could draw more DC current if a DC component were present - but do they truly have that much less primary resistance? The only way I can see to impress a DC component on power, is to have an asymmetrical high-current load (such as your half-wave rectifier example) on the same utility transformer secondary as the audio equipment. When does that happen in a residential environment? I'm remaining skeptical until someone can offer a realistic, detailed example with specific numerical parameters, that show how, in a residential environment, a toroidal power transformer could reach saturation due to another load on the line that's meant for domestic use.
@@marianneoelund2940 I didn't say toroidal transformers automatically saturate. I said they are more prone to saturation. As for DC on the line, how many half wave voltage doubler rectifiers do you have directly across the AC line in a typical 120vac residence TODAY. Think about it and it's not just cell phone chargers either. My 2007 vintage washer, dryer and a 3ton HVAC condenser all have VFD motor drives. Again that does not mean your toroidal transformers WILL saturate. But there are plenty of examples where toroidal transformers have harmonics that are cured by AC or galvanic coupling. You seem to be hung up on VA capacity. You are forgetting DC winding resistance. You can have the same VA capacity but significantly different DC resistance in any transformer winding.
@@andydelle4509 I did mention winding resistance in my last comment. I don't believe any of the domestic examples you cited use half-wave rectification. Most devices like cell phone chargers use FW rectifier bridges (do low-power devices even matter?), and I am having great difficulty believing that washers, dryers and HVAC units will use the AC power asymmetrically. The worst offender I can think of, is a microwave oven over the first few cycles while the capacitor is charging - but that's a transient condition. Regarding saturation, toroidal designs do tend to have less headroom with a more abrupt flux separation than E-I cores, but high-end audio suppliers like PS audio probably use a slightly larger part anyhow, as they may believe it sounds better in their listening tests. I think the biggest problem related to saturation is inrush current, not the occasional saturation that may conceivably occur due to a momentary DC component of power.
I made my own amplifier using 2 old halogen power supply transformers but its only 10 volt rms I coupled then whit 2 0.5F capacitors no riple what so ever and if I unplug it it keeps going for 2-5 minutes Its a very very basic amplifiers 2x MJ2955 and 2x2n3055 transistors and 4 opamps one of wich has its feedback connected to the output of the amplifier and it has almost no difrence from input to output only problem is that I need a little more voltage to drive my speakers 20 volts ain't enoug and I get some overdrive and all the parts can handle more voltage I stil thinking of geting a big toroid but that woud break the symmetry in my case and so I want 2 one for the positive rail and 1 for the negative rail
It’s all about cost-benefit analysis. Toroidal transformers are more expensive, so using a different power supply is one way to cut costs to fit a package into a certain price category.
Well anthem, rotel, yamaha can use it 2 in their flagship. By not using toroidal they will save what 500$ ? It would be nice 2 compare they same receiver with and without toroidal transformer and what will the price difference be.
Toroids have the cool factor, the one in my amp is coated with red epoxy and has the Parasound logo stamped in gold on the top. Whenever someone asks whyI wasted my money on that "crap" I just let them look in the top, shuts them right up
@Dave Micolichek Sure, but the cool factor is what's important. Amp's sound better with one, why I thought it was a mistake for Emotiva to go with switching mode psu's, you can call it anything you want, but while switch mode's are great for a lot of applications, Amp's need current. Companies are pushing class D and switch mode for one reason, they're cheap. They want to charge class A prices for Blutooth speaker prices. Screw that.
@Dave Micolichek Switching from class A and A/B to class D and to smps seems to be happening at the same time is all I'm saying. As for current, I would rather have a steady flow than "instantaneous" bookoos of current. Main thing is the reason they are changing to these two methods is the same, to save money by making something cheaper but not reducing the price, which is fine if the new way is better. Not if it is not. SMPSU'S are more "efficient, switching to higher current rails as needed. What I have posted before is that this is higher end audio, "efficency" does not matter a tinkers damn. Who cares if you save a few bucks a year on electricity? After I just bought a 2,000 dollar pair of speakers?
@@musicman8270 my class D stereo power amplifier has a massive toroidal transformer with dual linear power supply's. Not all class D amplifiers use a SMPS switch mode power supply.
@@C--A Still class D, they call it pulse "width" instead of pulse "code" but it is still non analog. I hace a class D from Emotiva, an ice module based monoblock.for my center. Some great uses for Class D, I just think analog should stay analog is all. Why bother with vinyl when you're gonna convert it to digital anyway?
In US there are 8 cities named Milan (after the one in Italy)....go figure 😂 I think the settlers tried and tried and tried to duplicate it until they gave up. Or they were lacking inspiration for new names.
looking at the transformers and seeing those standard electric cables ,i cant help but think theres a lot of money wasted on these very expensive interconnects ,speaker cables etc. having said that i do have good cables..
admittedly these are just for the power supply, and good cables really make more of a distance with long runs where external noise really matters, the box of most audio equipment should help protect it from that until it gets into the jack, like yeah you could use 12 gauge wire for the pcb to jack connections but it really wouldn't make that much of a difference in most cases
I beg to differ. I do agree that stray fields are much reduced with Toroidal vs. EI transformers, but to say that Toroidals are more immune to mechanical rattling, I've found to be, untrue. For me, I don't believe toroids sound better than EI. I can say that toroids have a benefit with their smaller, weaker, stray field that they can be placed closer to quiet high gain circuits and not induce/couple as much hum into those circuits. This is good for Phono stages and the like. This was good when CRT monitors were the common display, due to the much smaller magnetic field. No issues with flat screen monitors. Back to the rattle issue. Toroidal transformers are more efficient and have tighter/better magnetic coupling between primary and secondary windings. This can also cause problems if not designed around. An issue that can arise is if you have large supply capacitor values, the tight coupling of the windings and the large capacitance will cause large inrush current that are hard on power switches. Soft start components, such as a varistor (Glo-Bar) can be used to prevent this issue. Toroids are very sensitive to a net DC value on the mains lines. You maybe asking, "What DC on the mains?". Well, there's lot's of half wave rectification on the same power line your using. Things like hair dryers, etc can leave net DC offsets on the power line. Harmonics spit back on the power line also create 'dirt' that toroids don't like. Mechanical potting of the laminations help, but is not a cure all. If you want quiet toroids, it almost requires a 50/60 Hz, clean, high powered sine wave generator to provide the signal to keep toroids quiet and happy. There was an old Mark Levinson amp, ML-9 I believe, that had an "anti-Rattle" module in line with the AC to the toroid transformer. They used a bride rectifier and a cap to provide a ~1.2VDC gap, bridged by a capacitor to help eliminate it's toroidal transformer's rattle on dirty lines.
I knew a traditional square transformer is called an 'EI' but I just realised by the same naming convention a toroidal is basically an 'O'. Now I have that damn kid's song in my head...
@@jon4715 Yes - a toroid's core is flat on the top and bottom and has vertical inside and outside edges, because it's made from a strip of metal of constant thickness curled up into a ring. An O-core is rounded such that the cross section is more like a circle. For the purposes of my silly joke, though, a toroid is basically an O.
@@jon4715 oh, man - now you're asking... off the top of my head the main benefits are a shorter length of copper required to make each turn and I think the magnetic flux is better 'contained' due to the copper bending through a constant radius around the turns (rather than flat-corner-flat-corner like in a toroid). I think they look nicer too - I heard of a toroid before I saw one, pictured an O-core and was disappointed when I saw a real toroid and not a nice rounded donut. I guess that's right, though - an O-core really is a torus, and toroid only means _like_ a torus. Yes - harder to make, the core strip has to be thin-fat-thin and designed to take into account the growing size of each 'lap' as it is wound into a spiral.
@@HandbrakeBiscuit Hey that's a great answer. Thank you (and I agree). I know Holo Audio makes a big deal about using them. But I wonder why these companies aren't using R-cores? A bit more difficult to make the core again, but so much easier to spool.
Another element here is that it’s cleaner to construct a toroidal transformer then an “EI” transformer. In fact a lot of High End Audio companies ( used too? ) wind their own. Most people here probably wern’t around when there were factories here in the USA that constructed EI transformers. They polluted the air with stink and the ground with junk. I grew up near Chicago and there were a lot of TV manufacturing plants there so the stink from the resin to construct EI transformers was everywhere. Somehow I get the idea that Paul purchases those Toroidal transformers rather the winds them himself. I bet there’s not a single EI Transformer manufacturing plant left here in the USA because the air pollution is so bad.
@@marianneoelund2940 One of the largest power line transformer companies in the USA is/was GE in Pittsfield MA. Back in the 60's you could always kinda smell those transformers being built. I haven't been back there for decades so I can't tell you if that plant still exisits. None-the-less I suggest that the vast majority of EI transformers are built in China. They don't care about the stink and the junk in the ground. A huge percentage of Consumer electronics are now powered by a "wall wart" or things like an external power pack for a laptop or a computer game. All manufactured in China where they don't care about the pollution.
@@wilcalint I know about Chinese air pollution. We get it here on the west coast. Conspiracy-theory types think it comes from airplanes spraying chemtrails overhead. I think they need to look a bit further west across the Pacific, for the real source.
@@marianneoelund2940 Somewhat related, one of the engineering functions I’ve done is to take a consumer product through the necessary UL/CSA and FCC Certifications testing process before being released for sale. The product used an external Made in China power pack, a wall wart. Knowing how they perform I brought a selection of 5 with me and would get the product certified with the one(s) that passed . Of the 5 that I brought 3 of them failed the FCC testing even though they had an FCC Cert number on their label.
@@wilcalint That was certainly good foresight on your part. My "pet peeve" is the power supplies in LED bulbs. The LED's may be good for 25 years, but many of the power supplies aren't good for even 1 year.
in transformers with the EI core there is some magnetic flow leakage but in the toroidal transformers there isn't because of their shapes , in toroidal cores magnetic flow goes in a circular path and there is no corner so the shape of magnetic flow wave is better in a toroidal core than an EI core , good shape of magnetic flow wave generates good voltage wave shape. better voltage wave shape : better sound !
Used your video in my physics class today. Thank you for your wonderful explanation. This will help us future engineers.
Years back, the company I worked for, designed and manufactured toroidal transformers. I personally wound thousands of them. All of the ones we built, were wound on compressed ferrite cores. Different mixes of core material for different properties of operation.
When I hear Toledo, I think of the famous Toledo Sword.
3:11 Yes they can rattle, but that's why manufacturers put them in a metal casing with damping on the inside.
The damping prevents rattling and the metal can is a shield to keep the radiated EM noise in.
Thank you for the explanation. I came to YT looking for expert advise on toroidal transformers and when I saw your video, I know I could count on just that!
Paul mentioned in passing an attribute of toroidal transformers that is the primary reason they are used in balanced power isolation transformers. i.e. efficiency. I have two of those products. The toroidal transformer in each is about twice the size of the largest one Paul picked up the the video. One, a Furman IT-1210, is used to power all equipment in my electronic music studio and is totally silent. The other, made by Equi=Tech, makes a slightly audible hum. It is used to power the home theater electronics and is in a cabinet so the noise is not detectable from a theater seating position. In the early 1970's I worked as a technician trainee at the Pasadena Naval Warfare Center. One one assignment in an electronics lab I had the opportunity to fabricate some small toroidal coils. The process is interesting. A split bobbin is located through the core hole and then wound with the amount of wire required for the final part. The winding machine then rotates the bobbin to unwind the wire around the core while simultaneously slowly rotating the core to distribute the windings around the circumference. An interesting phenomenon that occurs when powering up such a large transformer is the reason I keep them powered on all the time. When first turned on the inrush current needed to saturate the magnetic core is so large that it has a tendency to trip the 20A breaker supplying the wall outlet. If that happens I quickly reset the breaker, which is fortunately nearby, and again flip the switch before the magnetic field can completely dissipate.
You can also build a slow start circuit. Just a big resistor in series so the in rush is lower amperage. A second switch to bypass the resistor after the first few seconds. It will save your breakers.
@@user-od9iz9cv1w What else can you add to this conversation of any other interesting point Sir W ???
Like all good salesmen Paul is only telling you what puts him in an advantage. There are actually 3 types of transformers, EI, toroidal and R core. In the past, toroidal were very expensive because they had to be hand wound. Today we have machines that do it automatically so the price of toroidal transformers came way down. Generally but not as a rule, for a set price (low to mid) you get a better toroidal transformer than EI. This is due to the fact that EI transformers hum, vibrate and radiate large electromagnetic fields which wreak havoc for low signal components like preamps and dacs. But if cost is not an issue you can get better EI transformers. As for R-core, these are the best as they combine the advantages of EI and toroidal but none of the disadvantages but are even more expensive so they are very rare.
To conclude, never pick equipment based on transformer type. Today toroidals are the bandwagon that everyone hops on.
Wreak, not reek, is the word for which you are reaching. Unless of course your transformers are stinking.
Macht Schnell cheers
@@machtschnell7452 , good spot. he edited...now, you could be polite & remove your comment.
can they be made as output transformer for tube amps?
I live in Lisbon-Portugal and Toledo is a fantastic Citadel.love it!! I have Been there 3 times.amazing!! In USA there are cities also called Lisbon or New Lisbon.
Hi Paul, are transformers actually robots in disguise?
logtothebase2 that would make a cool jingle for a show or movie
Then they would be more than meets the eye...
@@VOLKOV9 hey cool, they should also include that. Where do you come up with this? You should charge for that
No. We don't have the technology. -Tenacious D
More than meets the eye. 😁
Isn't a toroidal transformer capable of about twice the output power for about the same weight as an EI transformer. Also, isn't an R-core the best for audio, at least for lower power devices, like a DAC?
Yes
Paul forgot to mention regulation, which is generally much better with a toroid - which will affect the sound, as there is less voltage droop at greater loads, especially important in high power amps.
PResident RONALD RAYGUN got riods of lots of RELUGATION but demoncratesa keep getitn in as more REGUL;TSION. thankes youe san dthum,bbs IPS!
@Dave Micolichek Hellop Mine Goods frends! Is this the title yu wer lookin for...
Deregulation, Reagan-Style
Jefferson Decker
President Reagans was a get rid of REGULATORS. thanks yoiu, and are the good frends! THUMBBS UIPS!
Coincidentally, there is a New York near to Boston in Lincolnshire. It takes about a minute to drive through it.
Toroids use the magnetic flux more efficiently than the E shaped transformers
E X A C T L Y
Paul, I worked for a company that built power conditioning equipment for the computer industry. I wound transformers (all sizes) for 7 years and stacked quite a few along the way too. EI transformers are simple to make and are tunable. If you did them yourself you would have better luck with them. We soaked the finished transformers in resin and baked them in an oven after they were tuned. They did not buzz.
Some of them are clamped and welded also.
I worked at a stereo company that used a lot of EI transformers.The power Transformers were vacuume impregnated with some kind of varnish and then potted with 450 degree roofing tar. Worked pretty good.No transformer hum...
How did you tune the units Christopher. Any other interesting bit of knowledge would be appreciated.
When the Dutch took over the land in 1624 we now call NYC , it was called New Amsterdam (fort Amsterdam). In 1664 the British took over, so there are a lot of Dutch and English names to be found. Many streetnames in Brooklyn are named after the farmers who used to own the land.
I would just love to have a time machine and visit these places before humanity just took over the plant.
So if toroidal is sounds better than the IE , its means that classic or vintage amp that using IE are not better sounding?
Thanks to this video a lot man. I play guitar and my toan is built around an awesome Hughes and Kettener Valve three channel pedal (NOS 1994)... The stock wallwart IE Transformer was noisy as hell, even when volume down that b... made noise in the line. So I got a toroid, stuck it a computer PSU with three prong ground and it sounds more even (bass, mids, highs). Yesterday I was testing both against each other and the stock wallwart being just in the same powerstrip and the toroid feeding the valve pedal, when I took out it made an annoying pop, whereas wallwart feeding the valve and taking out the toroid didn't make any noise. A friend told me that a guy that works with him (both are doctors at a research centre) told him "Your pedalboard is as good as your powersupply is" and I found this to be true. Yet need to finish my AC PSU with a soft start (check that out if you're using toroids), and enclose it roadworthly so that I can get it far away from my main DC PSU (yes some expensive musician makers sell stupid wallwarts in 2023). Thanks again man, you don't know how much you've helped me. Wish the audiophile world came more into guitar world which still seems doing some thing brainless. By the way still is a question why guitar valve amps use IE transformers (tough Laney has some toroid based amps), is it out of lazyness, not taking risks?
Toledo in Spain was legendary for swordsmiths. Btw.
I have a Denon DRA 500 and a Yamaha RN 803 stereo/network receivers. They both use EI transformers. EI on Denon constantly hums the moment u turn it on whereas EI on Yamaha is literally silent.
Toroid transformers, they certainly have their issues too. Some very serious. Small electrical issues with an offset, they no longer work very well.
I've heard of people that switched over to LED lights within their home, their toroid transformers would get hot to the touch and make a ton of noise within the secondary.
I use them too. But it should be noted they have their issues.
Toledo Spain played a crucial role in Western history as that is where the Moors left behind a huge library filled with Ancient Greek texts which had been lost to the West, including Aristotle. When these works were translated, they formed the basis for the founding of European universities and thereafter the Enlightenment.
The most popular transformers used in audio are C-core or EI and they cost about the same to produce.
There are two main reasons why the C-core is better. Firstly the C-core is made from grain-oriented steel which can be used for higher magnetic flux (lower distortion at low frequency). Secondly there is more space for windings (the more sections the lower leakage inductance).
However, for lower output power amplifiers say 50w the EI transformer is a better choice because of lower stray capacitance (better high frequency)
@Lloyd Stout and your point is...dont just agree, add to the conversation. Paul was talking more about toroidal vs EL transformers . How about comparing R-core with toroidal
Every time I hear "toroidal transformer" I get a little tear in my eye because of memories of my Concept 12.0D receiver. I sure wish I still had it.
That thing was bad-assed. The best that Pacific Stereo made.
I don't think you mentioned toroids weigh significantly less. There is something to be said about less magnetic field leakage being less, thus less electrical noise in high gain circuits.
Great reply and I also prefer to see toroidal transformers inside my audio gear. For a particular application considering target BOM cost, physical layout, EMI concerns, operating frequency etc., either way can be optimum. BTW, you probably got your mains power through several transformers on the grid that aren't audiophile toroidal ones, but you better not worry about that :-)
@Fat Rat Well, not really saying that, but have you ever heard of oil in transformers? Those large ones that feed your audio gear somewhere outside can be full of oil and if they are older ones, nasty toxic PCB, worse than snake oil.
@@ThinkingBetter The have liquid cooles flammables pad transformesr according to IEEE 979 to styaye far aw2at from thems. I tounf its....
Institute of Electrical and Electronic Engineers (IEEE) © Standard 979 - 1994, Section 4.4.5. 2002 National Electric Code® (NEC®) Section 450.27. Edison Electric Institute, Fire Protection for Transformers, Table 2.
thnakes you,l youi are again tyhe HONESTS FREINDS. The others are PRETEND FRENDDS rop make not FUNNY jopkes. My Lo-Fi garbage is funny and a TRAGEDY at the same times. THUMMBS UP!
@@ilovecops6255 Dangerous (worse than snake oil) used in old transformers...PCB is very dangerous as it accumulated in our environment...th-cam.com/video/NKiIM6WJZfQ/w-d-xo.html
Kevin explains(listen to 4:00 or all of it) Toroidal Transformers and validates Paul ...th-cam.com/video/W0U-RGu-s4Y/w-d-xo.html
There is a measuremen of the quality of an inductor, the Q value, which compares the inductance to the resistance. Resistance is loss of power, and a toroidal transformer has a higher Q value. I am sure there are some special kinds of other transformers made, but the classic one is pretty crappy. When you need a lot of inductance a big beefy toroidal is quite incredible. It can hold a lot of Joules of energy.
Holy Toledo is a beautiful citadel.
If I use a toroidal transformer for sine wave inverter, do I need to install an inductor or choke as well? How to calculate the value of the inductor for each capacity like 750VA & 1250VA sine wave inverter?
What do you think, whats your experience being, with R-Core transformers?
heavy and takes up space :)
Howdy.
Also there is a lot more winding space available with toroids. One may use thicker winding wires to minimize winding losses. I should think this is essential in High End gear. The power supply needs to provide current fast without the voltage to buckle.
Regards.
About the American towns name - I'm from near Boston in England. The original one.
bah humbug ;)
@@CJANegrcTtpX8HwbR2SBDd Oh we supply all sorts of people ;)
Hello from Newcastle, Washington!
Born and raised in Albuquerque, yes there is a history to our name.
@@scottyo64 , im guessing the Governor prohibits you sharing this history?
Does anyone have any information, pros or cons on R-Core transformers for audio components eg: cd players, DACs, etc? I remember Sony using them in some of their ES: Cd, DVD, and Blu-ray , players. Thanks
thanks for the video Sir.
please can toroidal transformers be used for high-frequency DC-DC converters?
I have a question about toroidal transformers... Have they ever been considered for the outputs of a tube amplifier?
James Plotkin that might take some of the warmth away. In vintage guitar amplifiers, for instance, many of the old Marshall output transformers get ripped off by dubious repair shops, because it is often “the iron” that is so desirable. Also, you may find that much of the “warmth” and “fat bass” attributed to tube amplifiers is really coming from the transformers, hence why the early McIntosh solid state amps sound so “Tubie.” As this reflects a form of desirable distortion in both cases, I don’t think going for less of it would be desirable, but maybe...still the noise and distortion about which he speaks of eliminating with toroidal transformers is on the input power side and related the 50/60 hz A/C hum which is constant and otherwise mixes into the audio signal whereas the output transformers only color positively accentuate certain frequency ranges of the intense “pure” signal, so I doubt they would desire to clean up that stage too much. I could be wrong.
@@Diaphanic1 Thanks!
Yes that has been done by some very niche tube amp manufactures.
Andy Delle I’m curious to what effect they got out of it vs traditional transformers. Just cleaner or what?
@@Diaphanic1 I don't know but I am sure you can find some opinions online. With most high end audio, it's probably more like "We use toroidal output transformers and they don't"
Interesting video, I’ve got a great big toroidal in my H360 which probably accounts for its hefty weight - Jonathan from Old York, England
The equivalent E-I core transformer would not be any lighter.
@@marianneoelund2940 Wouldn't the E-I core be much heavier for the same output?
@@gordthor5351
Yes, in this power range E-I core designs are typically a good 50% heavier. It would probably add another 5Kg or so, to the amplifier weight.
If it effects the sound there is a problem with the amp circuit.
So a humming transformer hums because of the amp circuit?
@@petermartin9494 I dont think that's what he's trying to convey with "affects". You are speking specifically about residual noise that variates per power demand and can be mitigated but is not totally avoidable. Affectation in the other hand is how the transformer introduces EM noise to the circuitry which is avoidable with good design. Toroidal is just easier to control but not flawless.
what about ofc wire vs cca wire using to speaker is there a difference can hear on ears?
Now there is a can of worms: Are toroidal transformers better than laminated iron core ones?
May I repeat the question but this time it is about the output transformer of a valve amplifier. I am really curious what Paul has to say about that one.
Are there transformers that are better than triodal, spare no expense ??? Thanks fella
If you need some kind of tube output transformer with air gap, then it is easier with EI core, than cut toroid core on half.
What challenges would I face if I wanted to swap a EI transformer with a Toroidal one? I'm having an issue with overheating in a PSU and am thinking this produces less heat than EI frame.
Power transformers cannot sound better. They simply provide ac voltages. If they are wound with proper wire gauges to provide enough current at rated voltages that's all that matters. Yes, toroids have more contained magnetic field so they can be placed closer to the preamp section. If you are using external PSU then it makes no difference what so ever. And transformers don't rattle if they are assembled properly and potted as they should be not in super glue but in epoxy resin or wax. Your output transformers are EI and they don't buzz at low frequencies, right?
You pretty much contradicted yourself.
Basically in order to get a quiet EI transformer and in a way that it doesn't influence the preamp section you'd have to have it dipped in resin and incased away in yet another box (external PSU).
That's just stupid.
You slap a simple toroid and you're done with.
For the most prts EI's are used in supercheap amps like Marantz's and Denon's 400$ amps (Made in Malaysia).
@@SpaghettiKillah That's not what I said, potting of transformers is a standard part of manufacturing process. It doesn't have to be in a separate box I was making a point since many high end products use both external boxes and toroids in them which makes no sense. There are no noise issues or quality issues with McIntosh and Dynaco amplifiers that have both power and output transformers on the chassis one next to the other and relatively close to the preamp section. Paying a premium to simply SLAP a toroid to an amplifier is closer to stupid than using a well designed and built EI transformer for a fraction of the price.
I gave you the thumbs up but we both know that the first law of High-End Audio dictates that Nothing can make NO difference, never ever!!
@G Guest
Again, that's a completely bogus article, containing many glaring falsehoods and numerous mis-statements based on the author's complete misunderstanding of his sources.
Both transformers produce the same AC, that then leads to the same DC out, how is the DC is different in EIs and in toroids? I have one mono amp with a 970 VA cubic transformer that does not make any noise,any hum; it feeds a dual 15 inch woofer speaker box,2 Ohm, would a toroid do better for the sound?
Transformers only work with AC in (the primary winding) and AC out (the secondary winding). The AC secondary is then rectified into rough DC which is then “smoothed” in the L/C/R filter portion of a DC power supply to make useable DC current
Toroids tend to have lower secondary impedance which provides more peak current capability which is highly desired in audio power amplifiers. But EI types can be built that way as well. I don't think it's worth any effort to replace your factory transformer.
Why do they paper wrap transformers. Does that effect the noise that transformers make?
They dip the paper (the whole transformer in fact) in resin, that's why
Can any of you good people, or infact paul, tell me how I can change the speed of the magnetic flux rotation? Is it as simple as increasing or decrease either primary or secondary windings?
I don't have any audio equipment with tordial transformers. I remember an old audio guru friend of mine telling me..."put the tip of a long insulated (wood, plastic, etc.) screw driver to the top plate of a EI transformer with power on. Place your ear to the butt end of screw driver. He said if you don't hear/feel anything then your transformer is good physically. If your hear/feel buzzing or hissing or maybe a radio broadcast then you may need a repair/replacement."
I've honestly tried this before and have heard a local radio station through the screw driver from transformer. Crazy I know but true.
I was checking interconnect shield currents in my system the other day, and noticed a significant amount of RF energy from the local AM stations. But some of my cable runs are long, so most installations probably would not pick up so much RF.
Thanks Paul, Your clarification is helpful.
Yeah, those B&O modules work really well.
Hi Paul. You mentioned ice power modules. Do you prefer multi power amplifiers with toroidal for home theater, or ice power?
I was playing with an old Crown D60 stereo amp the other day and man did that thing have a noisy transformer, sounding like a loud electric hair clipper. The transformer appeared to be pretty well saturated in some sort of varnish or glue, so inner rattling wasn't the main source of the noise. I ended up decoupling it mechanically so it floats in the chassis on o-rings and some dense foam. If toroids were an option, Crown probably would have used them as this amp has a super thin profile at 1-3/4" thick. I suppose it's possible to find an off-the-shelf toroid to replace this pancaked transformer. But I doubt it's worth the effort. Great little amp, otherwise.
What about Venice?
Hey Paul! Why no mention or love for the R core transformers?
Howdy again.
Bandwidth Audio has a wonderful clip where it is explained how the unavoidable air gaps in EI cores help fight saturation. It is claimed that toroids saturate much easier when the mains has a DC component.
Hopefully PS Audio uses toroids with say 2% more winding turns than what is calculated for laboratory clean 60 or 50 Hz. That will tolerate some redsidual DC in the mains.
Regards again.
Great video. They are MUCH better because of how the magnetic Flux flows. They are quiet, run cooler, and are more efficient. Co$t is why manufacturers avoid them for the cheaper I an E type laminated type. A pre wound coil can be inserted into the "E" potion, then the "I" (which is always the base) can be weled on.
Due to the torroids shape (one piece) it must be wound by CNC machine which takes more time and energy.
You ARE, however, wrong about how the torrid is MADE. It is NOT donut shaped stampings ( Flux loss would still be high and magnet vibration within the core would result in heat and noise. They are 100% ceramic pressed and fired. I used to build and modify them for R&D.
Hi Paul!
I got a pair B&W 805D2
I noticed 1 tweeter doesn't work(properly)
I removed the cables and only put the cables in the tweeter terminals.
The right tweeter plays fine.
The left tweeter plays very very soft at high volume.
I swapped the right cable to the left speakers and still the same problem.
Is this the filter what is defect?(since I hear a little)
Probably a bad tweeter.
Does it matter/is it a problem that there is Very quiet hum from my sub that has one of these transformers? It performs ok and can’t hear unless my ear is next to it.
Dave Micolichek almost 2 years.
The Bogen Tpu 250 uses both styles of transformers (ei and toroidal) it's weird can someone explain why? Why use both when you can use just one
You talked about types of trans formers. Could you give an opinion of the marantz M7025 power amplifier sound quality?
I believe it does not have a toroidal transformer. Tyty
And how does a swithing psu commpire to a toroidal?
hey man.. love your educational videos. I'm learning al ot from other peoples questions!
I have Logitech Z-5500 speakers. They are more than 13 years old. Theres a toroidal transformer inside subwoofer. Can be this transformer the cause that the subwoofer makes thumping sound but only in the evening? Or maybe those two large capacitors inside? Thank you sir.
are used vintage tubes with half full power or gain better than russian made preamp tubes? from the 80's or 70's ?thanks mate.
My favorite Marantz I've owned (and still keep as backup, separate power amp now) was my first torroidal with the SR8002. I always felt that had the cleanest and most headroom out of any others I've had...always made me wonder if the Torroidal transformer had anything to do with it or just better components then others for the gain sections. Now w Xbox One X and PS5 I need to replace my cheap SR5010...and noticed a SR8012 from 2 years back has a torroidal again. This is an interesting video to watch before I can make a choice.
Thanks for this one, great video...Only 1 question..In what year the did the first toroidal its entree in stereo equipment...somebody here who have the answer?
I have a Musical Fidelity B200 Amplifier from 1990 which utilises a Toroidal transformer.
The cambridge p40 integrated amplifier 1969 was the first ever receiver that used a toroidal transformer.
y they didn't introduced earlier?
I was reading in an article about transformers (sorry don’t remember which website) that traditional transformers perform better in valve amplifiers.
Not sure about performance, but one thing is for certain: Step-up transformers for tube equipment need a huge number of turns of fine wire, and would be extremely expensive to build in toroidal form.
My tube amp has 4 massive EI transformers, and 300Bs. Sounds awesome. My 2,500 dollar marantz uses torroidal. Supposed to be high end. Sounds terrible by comparison.
The transformer is only part of the equation. Bruce Rozenblit is a tube designer of some renown, and tends to use toroids in most of his power amp designs.
I suspect you are using these tubes single ended in which case there is constant DC in the output transformers. EI transformers are easier to make that can handle the DC.
Gianna Giavelli and that has nothing to do with the transformer choice .. never seizes to amaze me how uninformed audiophiles are 😂
@@johnhodgson5313 y thats why u never see torroidals with sets
@@MichelLinschoten im new to this audio stuff bought 2 years ago a pair of Dali Zensor Pico speakers, currently im searching the web because i want to DIY some speakers, and what i currently know that this audio-market is a lot of marketing besides that each ear is different so what might sound horrible to one might sound good for another
My Technics SU-X301 buzzes but my AV-810 with a toroidal transformer is super quiet.
Hi paul, would it matter if we use EI transformer instead of toroid transformer in a CD transport. As I understood EI transformer produces noise, EMI more but does it matter in cd transport where only digital signal is transmitted to an external DAC
Torroids are noisier than EI. R-core are the best for source gear.
Hello Paul, can you or someone give me information about a place or shop where I can buy the material to make the core for toroidal transformers, thanks
Essex-furakawa for the wire feromagnetics for some of those toroids.
One area where toroids are inferior to EI and C core transformers is their cores saturate much more when DC is present on the mains supply.
Absolutely correct. Very few people understand this.
I am writing to inquire about an issue of my Markbass CMD151P Jeff Berlin amplifier.
I turned the amp on and practised for about 5-10 minutes. The sound was good, bright, full, nice. After that, the sound started to be weak, volume is little bit down, feeling is hard to play and not responsive. So, I stopped to play and wait for about 5 minutes (wait with turn the amp off or wait without turn the amp off), the sound became full and rich again but only for 2-3 minutes. Then again the same issueis appeared.
Even though the offical service in my country (Turkey) couldn't reilize an issue, they accepted to replace my amplifier with a new one. The issuse pursued in the new amp and I decided to change other elemets; my guitar has also replaced other related parts such as socket etc. However, the issue is still exist. I started to belive the issue can be from a specific batch production.
I would appeciate if you help me to solve this problem or give technical advice and check procedure that I can apply as an Electronic Technicihan.
My guess would be heat. As the amp warms up, a number of components could be heating up beyond their capabilities. A simple fix might just be to put a fan blowing on it. If I remember correctly, there is a built-in fan, but it is tiny, maybe replace that with one with more CFM. Bass player here.
You are a nice guy, you know a lot about audio, now it is time to go and see the world.
Remember, not all your audience is from the USA...
Ps: when ever you can, you are welcomed in Lisbon and I don't mean North Dakota.
I’m surprised you even knew there’s a Lisbon in North Dakota
Are there ANY people at all living in North Dakota?
If you want a much more thorough and objective answer to the question of "Are toroidal transformers really better and what are their electrical/magnetic disadvantages compared to regular run of the mill EI (i.e., box shaped) transformers, rather than they just "cost more and sound better...", do a Google search for the following: "EI and Toroidal Transformers" "ken stevens"
The problem is that Ken Stevens article is as flawed as this video. It was written to warm about the switch of a single component without tuning accordingly the rest of the circuit, not to properly answer the question.
The First paragraph is the usual audiogourmet gibberish instead of proper measurements.
The Second is true, as EI is way more resilient to DC but his examples can be easily fixed by cautiousness during the wiring and by using a rectifier in a single package instead of discrete diodes or by pairing them. Though, replacing the standard PN diodes with Schottky is a good idea as there is less Vdrop and less noise (but again, this have to be tuned). DC is even easier to fix in the primary.
RF input noise is not that hard to effectively filter if you use common lab equipment.
AC coupling is not an issue at all if the DC circuit is properly isolated inside a shielded compartiment. EI are even more noisier, especially in the audible spectrum.
About ground and FM bandwidth : this is pure BS. If the ground paths and connections are correct inside the whole chain (the case, the cables the room and the building) this is enough to ensure proper shielding. Just have to be careful with ground loops as well as digital circuits or SMPS in the ground line. Same thing with main wiring: ideally using a line dedicated for audio from the electrical panel and filtering it.
Finally the LC filter/resonator created in the secondary is not an issue when the circuit is properly tuned and measured. Just like putting decoupling caps in a design.
@@PainterVierax Non-RF input noise is impossible to filter as is evidenced by the fact that exactly ZERO of the regenerators are effective and doing this. This is the noise that gets to the secondary. If the rebuttal to this is to introduce bypass caps and do proper filtering on the secondary, then there is no point in using a toroidal transformer vs a cheap EI transformer, in the first place.
Paul- How important is it to shield those toroidal transformers to prevent noise? Love the shows!
Far less important than it is for E-I core transformers. Toroidal magnetic fields are better contained, and the symmetry of their shape tends to cancel induced current in nearby circuitry.
There is a caveat to toroidal transformer mounting BTW, you wouldn’t strap it down by anything that creates a magnetic loop through it as that would be a shorted turn.
@@Jenny_Digital That's why most have an insulated bolt in the center. But even with rubber pad on both ends, a stainless bolt, and a stainless plate and plastic bushing on the bottom, it still will hum and have a little loss due to the bolt. But when you are talking about 6KW it is far less loss in the toroidial.
@@gravelydon7072 And as I understand it, R wound transformers are nearly as good as toroidal with E.I’s being the poor relative in many HiFi applications.
I don’t see why these toroidal transformers can’t be mounted using polymer structures to to further limit losses etc. I know of some excellent fully fluorinated high temperature engineering materials.
I always learn something here. Excellent.
Good advice. Similar to RCA vs balanced. In a perfect setup cheaper RCA can sound good but over a broad population of various setups, balanced XLR always wins.
Just because something is more expensive does not always mean it is better.
WHAT??? Blasphemy!!!!
They rattle and make noise? wow, now I know why they sound so awefull. and im not thinking about my sound ampliefier, im thinking about my Xbox, my gaming console. Im currently thinking about modding it, it would involve adding ram, an ssd, custom kernel and HDMI. all to bring the old gaming console to the future. What still bothered me was the power supply. being close to a PC the powersupply is basicly a PC powersupply. replacing the 1 fan with realy nice quiet onces worked as a threat but the PSU... im gonna look into a nice silent powersupply for my xbox and maybe look into a more solidstate solution or if a Toroidal psu excists (it wont have a effect directly on the audio ofcourse, because its mostly digital, even up to the output. But this video did answered the sound questions :D
I have a modded xbox with ram upgrade and that 😂
I wish that the Sprout 100 didn't have distortion at high volume with bass heavy music. Id like to have the freedom of max volume as clean as low volume. A new even better version of the Sprout needs to be made. Maybe at the 1000 dollar price point.
It's a 50wpc amp (at 8 ohms)...
The days of affordable audio equipment having headroom appear to be over.
I disagree. Watts have never been less expensive. You can get dual mono 250 watts per channel class D Ncore module amplifiers for like $600. The Sprout is jammed with functionality in a tiny package, hence its niche. The market is saturated with $1000 integrated amplifiers with more watts, and it doesn’t make sense for PS Audio to compete in it.
The cambridge p40 integrated amplifier 1969 was the first ever receiver that used a toroidal transformer.
Paul, I've repaired a faulty circa 2010 Subwoofer by replacing some caps. However the toroidal tx hums at 50hz harmonics (I'm in Australia)
Is it old age causing this ? Not sure if replacing would solve it, and that's if I can even find a 41.7/17v output.
Doubtful it's age. Probably poor design in the first place. Sometimes lower cost torroids are made from cheap steel or they are not wound properly. Lots of reasons they can buzz.
@@Paulmcgowanpsaudio I have the same issue as Scott here. Paul, I got the complete opposite answer from the manufacturer. They said that age is an issue. The older they get, the more they hum. So your "doubtful it's age" doesn't match up.
@@rabarebra Other than the varnish sometimes used, I don't see any mechanism for the steel and copper changing. I have worked directly with transformer vendors for years and have never found this to be a problem. Perhaps send me their response of how that could happen. Thanks.
@@Paulmcgowanpsaudio So a toroidal transformer should work just fine as it did 30 years ago?
@@rabarebra Absolutely. The power supply capacitors it feeds are probably not ok, and these should be replaced.
Like most things technical, there is never a one-fits-all answer. While Toroid transformer do offer many advantages over EI types, there are some disadvantages. They can saturate very easily and have no tolerance for DC voltage which is often found on AC power lines today from switch mode power supplies and other direct line connected rectifiers.
You need to stop reading soundstage.com articles. The one about toroidal versus E-I core transformers is mostly nonsense. It is NOT true that DC voltage is often found on AC power lines. There are transients which can disturb symmetry, but these are short enough that they will not have the same effect as steady DC.
If two transformers - toroidal and E-I core - are equivalent, then they will have the same saturation current. Further, you are not going to saturate any power transformer, merely by transient asymmetries on the AC power, because the idle current due to normal operating voltage is very small compared to the transformer's rated current.
@@marianneoelund2940 I don't read soundstage.com. I do read the IEEE journal as I am an accredited EE. Toroids saturate must faster than EI, that is a known fact. DC components on AC power lines is quite common today, especially in larger distribution systems such as in commercial buildings. Are you trying to say half wave rectification does not reflect a DC component on an AC source voltage? I am not saying toroids are deficient. They are an excellent choice for audio components. I am just pointing out some well known engineering pitfalls.
@@andydelle4509
If a toroidal and an E-I core transformer have the same VA capacity, then they must have similar saturation current.
If the toroidal has much lower primary series resistance, then conceivably it could draw more DC current if a DC component were present - but do they truly have that much less primary resistance?
The only way I can see to impress a DC component on power, is to have an asymmetrical high-current load (such as your half-wave rectifier example) on the same utility transformer secondary as the audio equipment. When does that happen in a residential environment?
I'm remaining skeptical until someone can offer a realistic, detailed example with specific numerical parameters, that show how, in a residential environment, a toroidal power transformer could reach saturation due to another load on the line that's meant for domestic use.
@@marianneoelund2940 I didn't say toroidal transformers automatically saturate. I said they are more prone to saturation. As for DC on the line, how many half wave voltage doubler rectifiers do you have directly across the AC line in a typical 120vac residence TODAY. Think about it and it's not just cell phone chargers either. My 2007 vintage washer, dryer and a 3ton HVAC condenser all have VFD motor drives. Again that does not mean your toroidal transformers WILL saturate. But there are plenty of examples where toroidal transformers have harmonics that are cured by AC or galvanic coupling. You seem to be hung up on VA capacity. You are forgetting DC winding resistance. You can have the same VA capacity but significantly different DC resistance in any transformer winding.
@@andydelle4509
I did mention winding resistance in my last comment.
I don't believe any of the domestic examples you cited use half-wave rectification. Most devices like cell phone chargers use FW rectifier bridges (do low-power devices even matter?), and I am having great difficulty believing that washers, dryers and HVAC units will use the AC power asymmetrically. The worst offender I can think of, is a microwave oven over the first few cycles while the capacitor is charging - but that's a transient condition.
Regarding saturation, toroidal designs do tend to have less headroom with a more abrupt flux separation than E-I cores, but high-end audio suppliers like PS audio probably use a slightly larger part anyhow, as they may believe it sounds better in their listening tests.
I think the biggest problem related to saturation is inrush current, not the occasional saturation that may conceivably occur due to a momentary DC component of power.
I wish you would give making a electric Guitar pickup a try I think you would be good at it.
ANother Abigail Ybarra! THNAKESA YOUES AND THU,MBNBS UPS!
Provided an EI is shielded very well so as to not cause magnetic interference, why would a toroidal sound better?
Paul is the "Hickok 45" of the Audio World.
Thank you for the video, i learned something new today. 😊👍
I made my own amplifier using 2 old halogen power supply transformers but its only 10 volt rms I coupled then whit 2 0.5F capacitors no riple what so ever and if I unplug it it keeps going for 2-5 minutes Its a very very basic amplifiers 2x MJ2955 and 2x2n3055 transistors and 4 opamps one of wich has its feedback connected to the output of the amplifier and it has almost no difrence from input to output only problem is that I need a little more voltage to drive my speakers 20 volts ain't enoug and I get some overdrive and all the parts can handle more voltage I stil thinking of geting a big toroid but that woud break the symmetry in my case and so I want 2 one for the positive rail and 1 for the negative rail
Seat Toledo is popular car in Europe.
Marantz is using toroidal transformer, why dont other companies use it too?
Marantz uses Ei transformers in their SR, NR & MM units... they only use a toroidal in their $2500.00-$3000.00 flagship SR unit.
It’s all about cost-benefit analysis. Toroidal transformers are more expensive, so using a different power supply is one way to cut costs to fit a package into a certain price category.
Well anthem, rotel, yamaha can use it 2 in their flagship. By not using toroidal they will save what 500$ ? It would be nice 2 compare they same receiver with and without toroidal transformer and what will the price difference be.
Toroids have the cool factor, the one in my amp is coated with red epoxy and has the Parasound logo stamped in gold on the top. Whenever someone asks whyI wasted my money on that "crap" I just let them look in the top, shuts them right up
@Dave Micolichek Sure, but the cool factor is what's important. Amp's sound better with one, why I thought it was a mistake for Emotiva to go with switching mode psu's,
you can call it anything you want, but while switch mode's are great for a lot of applications, Amp's need current. Companies are pushing class D and switch mode for one reason, they're cheap. They want to charge class A prices for Blutooth speaker prices. Screw that.
@Dave Micolichek Switching from class A and A/B to class D and to smps seems to be happening at the same time is all I'm saying. As for current, I would rather have a steady flow than "instantaneous" bookoos of current. Main thing is the reason they are changing to these two methods is the same, to save money by making something cheaper but not reducing the price, which is fine if the new way is better. Not if it is not. SMPSU'S are more "efficient, switching to higher current rails as needed. What I have posted before is that this is higher end audio, "efficency" does not matter a tinkers damn. Who cares if you save a few bucks a year on electricity? After I just bought a 2,000 dollar pair of speakers?
@@musicman8270 my class D stereo power amplifier has a massive toroidal transformer with dual linear power supply's.
Not all class D amplifiers use a SMPS switch mode power supply.
@@C--A Still class D, they call it pulse "width" instead of pulse "code" but it is still non analog. I hace a class D from Emotiva, an ice module based monoblock.for my center. Some great uses for Class D, I just think analog should stay analog is all. Why bother with vinyl when you're gonna convert it to digital anyway?
@@musicman8270 Class D can be totally analogue.
Great video, as always, I also consider the toroid superior to the EI if used in power amplifier.
In US there are 8 cities named Milan (after the one in Italy)....go figure 😂
I think the settlers tried and tried and tried to duplicate it until they gave up.
Or they were lacking inspiration for new names.
We have one in michigan but we pronounce it with long I and short A
Actually a lot of the founders was from the places it was named after. Or they will name a town after themselves.
Most AVR use EI Transformers. Factor of sound quality not only depend on toroidal transformer.
cyrux has a scotish made round transformer
looking at the transformers and seeing those standard electric cables ,i cant help but think theres a lot of money wasted on these very expensive interconnects ,speaker cables etc. having said that i do have good cables..
admittedly these are just for the power supply, and good cables really make more of a distance with long runs where external noise really matters, the box of most audio equipment should help protect it from that until it gets into the jack, like yeah you could use 12 gauge wire for the pcb to jack connections but it really wouldn't make that much of a difference in most cases
I beg to differ. I do agree that stray fields are much reduced with Toroidal vs. EI transformers, but to say that Toroidals are more immune to mechanical rattling, I've found to be, untrue. For me, I don't believe toroids sound better than EI. I can say that toroids have a benefit with their smaller, weaker, stray field that they can be placed closer to quiet high gain circuits and not induce/couple as much hum into those circuits. This is good for Phono stages and the like. This was good when CRT monitors were the common display, due to the much smaller magnetic field. No issues with flat screen monitors. Back to the rattle issue. Toroidal transformers are more efficient and have tighter/better magnetic coupling between primary and secondary windings. This can also cause problems if not designed around. An issue that can arise is if you have large supply capacitor values, the tight coupling of the windings and the large capacitance will cause large inrush current that are hard on power switches. Soft start components, such as a varistor (Glo-Bar) can be used to prevent this issue. Toroids are very sensitive to a net DC value on the mains lines. You maybe asking, "What DC on the mains?". Well, there's lot's of half wave rectification on the same power line your using. Things like hair dryers, etc can leave net DC offsets on the power line. Harmonics spit back on the power line also create 'dirt' that toroids don't like. Mechanical potting of the laminations help, but is not a cure all. If you want quiet toroids, it almost requires a 50/60 Hz, clean, high powered sine wave generator to provide the signal to keep toroids quiet and happy. There was an old Mark Levinson amp, ML-9 I believe, that had an "anti-Rattle" module in line with the AC to the toroid transformer. They used a bride rectifier and a cap to provide a ~1.2VDC gap, bridged by a capacitor to help eliminate it's toroidal transformer's rattle on dirty lines.
I knew a traditional square transformer is called an 'EI' but I just realised by the same naming convention a toroidal is basically an 'O'.
Now I have that damn kid's song in my head...
O-core is considered different than a Torroid apparently.
@@jon4715 Yes - a toroid's core is flat on the top and bottom and has vertical inside and outside edges, because it's made from a strip of metal of constant thickness curled up into a ring. An O-core is rounded such that the cross section is more like a circle.
For the purposes of my silly joke, though, a toroid is basically an O.
@@HandbrakeBiscuit Thanks for the details. I guess the O-type core is a bit more difficult to make. Do you know what the benefits might be?
@@jon4715 oh, man - now you're asking... off the top of my head the main benefits are a shorter length of copper required to make each turn and I think the magnetic flux is better 'contained' due to the copper bending through a constant radius around the turns (rather than flat-corner-flat-corner like in a toroid). I think they look nicer too - I heard of a toroid before I saw one, pictured an O-core and was disappointed when I saw a real toroid and not a nice rounded donut. I guess that's right, though - an O-core really is a torus, and toroid only means _like_ a torus.
Yes - harder to make, the core strip has to be thin-fat-thin and designed to take into account the growing size of each 'lap' as it is wound into a spiral.
@@HandbrakeBiscuit Hey that's a great answer. Thank you (and I agree). I know Holo Audio makes a big deal
about using them. But I wonder why these companies aren't using R-cores? A bit more difficult to make the core again, but so much easier to spool.
New York formerly known as New Amsterdam
Another element here is that it’s cleaner to construct a toroidal transformer then an “EI” transformer. In fact a lot of High End Audio companies ( used too? ) wind their own. Most people here probably wern’t around when there were factories here in the USA that constructed EI transformers. They polluted the air with stink and the ground with junk. I grew up near Chicago and there were a lot of TV manufacturing plants there so the stink from the resin to construct EI transformers was everywhere. Somehow I get the idea that Paul purchases those Toroidal transformers rather the winds them himself.
I bet there’s not a single EI Transformer manufacturing plant left here in the USA because the air pollution is so bad.
What do you get your AC power from?
@@marianneoelund2940 One of the largest power line transformer companies in the USA is/was GE in Pittsfield MA. Back in the 60's you could always kinda smell those transformers being built. I haven't been back there for decades so I can't tell you if that plant still exisits.
None-the-less I suggest that the vast majority of EI transformers are built in China. They don't care about the stink and the junk in the ground.
A huge percentage of Consumer electronics are now powered by a "wall wart" or things like an external power pack for a laptop or a computer game. All manufactured in China where they don't care about the pollution.
@@wilcalint
I know about Chinese air pollution. We get it here on the west coast. Conspiracy-theory types think it comes from airplanes spraying chemtrails overhead. I think they need to look a bit further west across the Pacific, for the real source.
@@marianneoelund2940 Somewhat related, one of the engineering functions I’ve done is to take a consumer product through the necessary UL/CSA and FCC Certifications testing process before being released for sale. The product used an external Made in China power pack, a wall wart. Knowing how they perform I brought a selection of 5 with me and would get the product certified with the one(s) that passed . Of the 5 that I brought 3 of them failed the FCC testing even though they had an FCC Cert number on their label.
@@wilcalint
That was certainly good foresight on your part.
My "pet peeve" is the power supplies in LED bulbs. The LED's may be good for 25 years, but many of the power supplies aren't good for even 1 year.
in transformers with the EI core there is some magnetic flow leakage but in the toroidal transformers there isn't because of their shapes , in toroidal cores magnetic flow goes in a circular path and there is no corner so the shape of magnetic flow wave is better in a toroidal core than an EI core , good shape of magnetic flow wave generates good voltage wave shape. better voltage wave shape : better sound !