I have the Behringer A800 class D and it sounds like no other amp so clear so powerful there is no other class that can come close to that awesome clear sound
A800 and other pro-style class D amps are pretty good (a lot of the Behringer are based on IRS2092 chipset) but the Purifi amp is on another planet entirely. They sound like nothing at all, just the audio signal direct to the speaker; whatever you feed them they will put directly out without changing it.
I love the power and audio fidelity of these VTV amplifiers. I just wish they would put a couple VU meters in the front. What can I say, I'm a sucker for the old school amp look.
I recently bought one of the Fosi Audio TB10D amps (The updated version) and it changed my opinion on class D amps. It seemed to have clean power output at the volume levels I normally listen to and plenty of "punch" and that was listening to a Rush CD at genre appropriate levels through a pair of Infinity bookshelf speakers. Not bad for around $80 and it didn't get warm. Interesting that the Purify amp switching power supply was twice the size of both amp modules.
Purfi is another level, but I bought a crown xls drive cover to drive my diy subwoofer and I wanted to try it in stereo with my diy speakers and I have to tell you it sounds really good, very clear no coloration. I have some really nice speakers and they can handle a lot of power and this crown can deliver with no distortion and little heat. I'm thinking about building a class d kit or maybe get a ice amp off parts Express and make my own case
Nice review and I agree, Class D nowadays are fantastic amplifiers with amazing efficiency. If you want to experience it, try an ICE amplifier unit with built in switching power supply. For just 100 euro you can buys this with 250 watts output and really great quality
The IcePower Series is especially amazing! I have this in the 700€ Canton AS 650 SC Subwoofer, and tbh - that thing was the 2nd most expensive sub from Canton, but it was handmade over here in Germany and sounds so damn good, I will never want anything else! Linear down to 30Hz, and still absolutely pumping out in the 20‘s… I know, the Amplifier is only going to be equivalent to 1/3 of a good sounding sub especially, the other 2/3s is a serious quality Driver (Speaker) and the utmost attention to calculations for the enclosure and it’s vent measurements and placement.
Crazy to think that the toroidal transformer on my parasound a21 weighs like 2.5 complete amps. Sure can appreciate the electricity savings you get with an Amp like this compared to a class a ab amp.
That's a nice looking class-D amp, nice quality construction too. I am a big fan of class-D stuff, the only problem with them is when they go wrong, a lot of the time they take out the speakers with them aswell. But they are very efficient compared to class-A and others. Thanks for the videos. :-)
@@androidtvbox266 I'd take the vtv any day over old crown or sansewage garbage. I put this on my good speakers and I had to pick my jaw up from the floor.
I believe in you mr.12 volt that digital amp is good sounding and efficient ...i try it with a cheap module from china for my diy amp and even it was cheap i was very impressed for its clarity and efficiency compare to mid pricy class ab amp...
I use class D amps to drive my 3 subwoofers and they are smaller than the Analog ones and have plenty of power for the subs. I can fit like 12 of them into my Marantz receiver!
Yep these amps using the Purifi modules are great amplifiers. Glad you've gotten to experience one. If you don't need the power output, the class H Benchmark AHB2 delivers even better distortion but with still decent power output. Class D will always have more power output than Class H, but you'd be surprised how loud 100W really is. If you monoblock the AHB2, which a will give you even better performance, and a lot of people that buy this amp will buy two, you'll get 480 Watts into 6 ohms with 0.0003 % THD+N at full rated power, 20 Hz to 20 kHz. I know how you feel about specs, but this amp you reviewed here is solid state, not tubes, and is also an objectionably well measured amp too. I hope one day you'll get to experience an AHB2.
@@tyronenelson9124 That's RMS output of bridged mono at a 6 ohm load. They rate the output at 0.0003 % THD+N for that rated power, at 0.1% and 1% THD+N the output is much higher.
There are people who used to say "Any properly designed amp will have no sound of its own", using the nebulous qualifier 'properly', but we are not in that world anymore; the Purifi, NCoreX, and Starkrimson amplifiers sound just like the incoming signal - they are perfectly linear.
There’s a one man show in Ohio called Buckeye Amps run by a guy named Dylan. He assembles Class D amplifiers for sale. He has Purifi options in a higher power monoblock version and then also 2 and 3-channel versions using the same modules as the VTV in this video. He also offers Hypex amps using the NC252 and NC502 modules in 2, 4, 6 and 8-channel configurations. I am running my home theater with a 3-ch Purifi for the LCR array and 8-ch Hypex NC252 to run my surrounds. Great value for very capable amplifiers. Not exciting to look at but they are clean and powerful. Significant upgrade over my 7-ch ATI-built noisy amplifier. As far as I’m concerned the AVR industry needs to drop class AB and use a slightly smaller variant of Purifi or Hypex modules. Roughly 90% efficiency compared to 50-60% Class AB.
I agree class D is now the way to go. Very powerful and so clean these days. The perfect audio components to not add anything to the audio signal. SACD with a good dac and a class d amp is about as good as you will get followed by DAT then CD. Analog formats such as reel to reel next and then compressed digital cassette and vinyl the bottom. Of course people got used to analog artifacts and they think the sound is inferior when they are not present. And that's why people pay huge dollars for vintage equipment.
Those who are simply just making noise about Class D, just try to have a listen to Leema Acoustics Elements AMP with just 56Watts per channel with anything above (TRUE) 88db speakers and then you will understand you no longer needs that Class A or AB heater anymore on your room.
The people that dislike class D simply don't understand how it operates. These same people will argue till their are blue in the face that cassette tape and vinyl has better sound than cd and other digital formats. No point trying to educate them because you can't fix stupid
the little block of red caps are the filter caps the electrolytic capacitors and the 2 little inducters are on the power rails. you wouldn't use electrolytic caps for class D sine re-consatution at the output the power loss in the caps would be enormous and they would heat up and pop.
What does it sound like compared to your tube amp, Dave? If it can create the tube sound with instruments floating in mid air then it really is a winner!
It sounds transparant. If you want the tube sound plug in a tube buffer (preamp) àhead of it. The next model up has just that built in. PS audio has been doing this for years. Then you get the even order harmonics that makes. Instruments float. I use a tube buffer on my big crest amp to make it sound like my tube amp, with more punch.
@@12voltvids Thanks for the reply, Dave. I only listen at low most of the time, so the 32 watts I have is plenty, but if more power was ever needed the Purifi with tube buffer is definitely the way to go.
@@Markpab same here my tube amp is 40 per. The guy that loaned me this has the. Sonic frontiers i recently repaired. He's using his tube amplifier at the moment. I have my crest connected but will go back to my yaqin again when I do some serious listening. I have to clear out my living room. Wife inherited a bunch of furniture from a house clear out that I am slowly getting rid of and the moving truck put it all in my living room. As far as i an concerned they should have taken it to the dump. I wanted 1 piece out of the estate, ok 3, a giant special edition grandfather clock 1 of only 250 made. A commissioned copper art sculpture and a Robert Bateman painting. Unfortunately my wife was named in estate and since the old lady she cared for had no family she got everything including ugly really expensive furniture that I am finding it almost impossible to even give away.
@@12voltvids Oh dear - no good blocking the HiFi! Bet your cats love playing amongst all the furniture tho! I've had enough of spending money on HiFi, I like my set up now with my WAD tube amp, Rogers speakers from 1984 and Denafrips DAC with Cambridge CD transport, my loft is full of cassette decks, amps and tuners I've wasted money on.
Your multimeter isn't going to tell you much - the switching frequency of these amps is up in the range of 500kHz. You need a really good audio analyzer to see what these amps are doing.
Yes class D is a very unusual way to produce audio, i sort of remembered a pwm method with filtering at the end to remove the r.f, or something like that but i have forgotten all the details. Does it still have a kind of amplifier hiss?
No mouse at all. You can draw similarities between a class D amplifier and FM transmitter. They both do things similar ways. In both cases the audio is changed from an amplitude to a frequency or a pulse width. In FM as the signal goes positive the frequency rises as the signal goes negative the frequency drops. The amplitude of the incoming modulating signal affects how far the frequency shifts the higher the input the higher the frequency shifts on either side of the carrier that's called deviation. In a classy amplifier which is pwm the frequency remains constant the duty cycle shifts forward and backward of your time constant so as the voltage rises the on time of the positive transistor increases and the negative transistor decreases. As the voltage goes negative the positive transistor decreases its duty cycle and the negative transistor increases its duty cycle. The amount of shift is determined by the amount of voltage swing on the input. Filter out the carrier and the result is the audio signal. No noise added no distortion added no bumps or dips in the frequency response added just pure sound. They are bloody amazing and my next amplifier will definitely be a class D. Class H also have good Dynamics however there is that transition on a class h where they switch from the low to the high rail and that switch over point can be detected. Whether you actually hear it or not because by the time you're at that level of volume your ears are not quite as sensitive to transitions but they're still at transition point. at least they perform better than your conventional class A B where those transitions result in distortion because the power supply has no more reserve. That's what class H give you over a class A B which they are just a class A B just with a second power tap with charge capacitors on tap waiting to be switched in momentarily to handle that extra kick required to prevent clipping. Class D you don't need that you've got the reserve already there and you're not burning up extra energy keeping a second power supply in standby. When I showed my omt the other day, I forgot whether I showed the cooling fan in my communications closet but I have to have an exhaust fan in where my equipment is because the big Onkyo amplifier for my home theater produces so much heat that it would literally cook all of the equipment. I would go in the closet and it was like 35° C after an evening of the equipment running. I had to cut a vent hole in the wall and put an exhaust fan up at the ceiling or leave the door open to prevent all the equipment from overheating. Old class AB amplifiers are pretty inefficient especially the type that use dynamic bias. Dynamic bias amplifiers at low volume switch to a class A type output so they burn a lot of electricity doing nothing on the top of this Onkyo gets quite hot even when there's no sound going through it same with my Technics SUV 9. New class A as techniques called it. New class A my ass just a way to waste more energy turning it into heat doing absolutely nothing. As far as I'm concerned the old receivers that are collectible are only collectible for the same reason that old reel-to-reel recorders are collectible because they look cool and they make great display pieces like my old cameras but not really useful as far as sound quality goes or in the case of my old cameras they look impressive but my little cheap camera that I did this video on will run circles around them everyday and twice on Sunday
@@zx8401ztv haha. I was using voice dictation and that came across the tv just as I started speaking. Too funny. Was a home renovation show on and the people had a mouse problem. Lololol.
@Douglas Blake I Saved the text ages ago, my vision goes out of focus when im getting tired. Ill leave the text untill tomorrow when im not crosseyed lol.
Class D are pulse with modulated amplifiers - a fully analog process. If it had been a digital amp it would be able to work on S/PDIF serial digital bit streams, or a parallel bit stream of some other kind. Nowhere in a class D amp you can work with digital signals. So don´t be one of the ignorant´s who keep spreading the message. SMPS are also not digital power supplies.
Actually it is a digital representation of an analog signal. The outputs are either on or off. There is no in between as in a linear amplifier. There are 2 states. On and off, or better represented as a 1 or 0. That is the definition of digital. You are thinking quantization where is waveform is aampled at a given rate and each value is driven a numerical value. The resulting serial pulse train is called pulse code modulation or PCM. When a CD is made the PCM is converted to a pwm signal in a conversion process called EFM, eight to fourteen modulation. This changes each 8 bit byte into a 14 bit word in such a way that the minimum pulse length is 3 bits wide in the resulting pwm that is modulating the laser. Trust me i do know what digital is and how it works. Class D convert analog signal into a digital representation that can be transmitted over a wire over a fiber optic link or operate a radio link. The amplitude is a result on the shift of the duty cycle. A simple filter to cancel out the carrier will return the original analog signal. Digital does not mean it has to be encoded in some way. It just has to be able to be represented as a 1 or 0 and class D amplifiers meet that criteria. So yes calling them digital amplifiers is accurate but if you like you can try to file a lawsuit claiming misrepresentation and see how far that goes. 😁
@@12voltvids This comes from Wikipedia: Please notice the sentence starting with **. "The letter D used to designate this amplifier class is simply the next letter after C and, although occasionally used as such, does not stand for digital. **Class-D and class-E amplifiers are sometimes mistakenly described as "digital" because the output waveform superficially resembles a pulse-train of digital symbols, but a class-D amplifier merely converts an input waveform into a continuously pulse-width modulated analog signal. (A digital waveform would be pulse-code modulated.)"
@@qddk9545 the D in class D has nothing to do with digital. Digital signaling is simply a binary way of signaling. Mores code is digital. It's an on or off state nothing else. You have 2 operational states, either on or off, no in between. Any analog signal can be represented as a pulse stream by mixing with a triangle waveform and a comparator that will switch high or low turning that analog waveform into a digital representation of the analog signal. I am sorry if you don't have the intelligence to understand that very basic form of communication. All the rest of us are laughing at you. You are confusing the very basics of digital technology which is a simple 1 or 0 state with coding. PCM Pulse CODE modulation. PWM, Pulse WIDTH modulation. You note both have the word pulse, that is the digital clue. The next one CODE indicates that the data train is a quantized numeric value. Pulse width modulation is a digital representation of an analog waveform. If you kept the duty cycle 50/50 and varies the frequency to follow the amplitude of the modulating you would have FM, frequency modulation. If you kept the frequency constant and rotated the phase of the oscillator using a varactor diode then you have creates phase modulation. These are purely analog modulations. However adding that comparator to turn the AC input into a duty cycle shift on a constant frequency square wave creates a binary waveform with only 2 states either on or off which is the basic definition of digital. Sorry you lose ! 😁😅😆😃😀😄🖕
Would you consider these to be somewhat disposable? How do you think the MTBF for a unit like this with the switching power supply would compare to Class A/B with a linear power supply?
@Douglas Blake Cold starting is literally a dead short till the caps charge. This is why good smps designs have soft start circuits. To prevent this from happening.
6:15 Is this aluminium plate all there is to the heat sink? Or does it come in contact with the case and use that as the main heat sink? The reason I am asking is that I am slightly sceptical about the power output. Can it actually output 250W continuous sine wave power per module? Because I would be inclined to expect each module to be half the size of the power supply module if it were. Granted, the power supply maybe over-specified and it also works at a much higher voltage, which necessitates larger components that bulk up the power supply, but even so the heat sink on the power supply is huge compared to that of the amplifier modules. Unless of course the power supply operates at around 70% efficiency and the power amplifier modules at around 90%. 12:45 The real question is whether it still sounded amazing in the main system, with high fidelity loudspeakers. Did it? 18:58 Not necessarily - we are not in the late nineties and digital amplifiers (well, to be precise, class D amplifiers) have come a long way since then so a lot of audiophiles now spend serious money on them. It is the audiophiles that are also retrophiliacs and that are into vintage components' sound that you are probably referring to. Either them or those very few that can afford to pay enough to buy a house or two with just to buy one component in their audio system. I am exaggerating a bit here. Make that a car or two. Now one should compare like with like. There are no class D amplifiers made that cost as much as a small flat or a new car currently. This is because: a) there is no need for them to be so expensive as they can generally achieve the same sound quality as class A or class AB amplifiers at 2 or 3 times their price and b) they still need to win their place in the market and for this to happen they need to remain 2 to 3 times cheaper than their A or AB class counterparts. Once they do dominate though (just wait for the last few valve factories to close down/go bankrupt - let's hope this does not happen by the way but suppose it does for the sake of the argument) we will for sure see class D amplifiers with gilded knobs and silver cables inside and anything else you can imagine that could drive their prices up to stratospheric levels. The reason for this is simple: there will always be a market for expensive stuff.
@@Douglas_Blake Yes, the same is true for SMPSs also but they still need a heat sink of some size... These modules here just have a small metal plate - hence my slight incredulity.
@@Douglas_Blake Yes, I'm aware of the benefits of class D operation. The reason I was insisting on continues sine wave power rating is that the output music signal contains nowhere near enough energy on average as a constant full amplitude sine wave. Re. the heat sink coupling, it does seem it couples to the case but it looks to me as if it stands on brass spacers - not quite the same as full contact over its entire surface. While on the subject of SMPS and Class D amplifiers, there are Class AB (or class AB genre) powered off an SMPS. I'm not sure whether Carver has done that (he'd be my primary suspect) but over in the UK, Chord does produce some super pricey amplifiers that operate this way. These were produced when Class D audio chips were already a mature enough technology. Even if they had not been, I would expect Chord to be in a position to develop them to their high standards. This is primarily a financial question of course. But they did go with this solution. I am not sure whether they still choose to make amplifiers this way or whether they have gone full class D as in this example.
@@Douglas_Blake The reason I mentioned the SMPS and class AB amplifier combination was because I am interested in the audio merits of class D vs. class AB - or even vs. class A. This is a technology that has been available since the end of the nineties but has not really caught on (in high end audio) until now. It had not received unanimous praise back then - even though the power consumption and power output figures were spectacular. I never found out why it did not catch on back then. I did read about poor implementations with undersized (?) output inductors being a possible cause but I did not quite believe that to be a sufficient reason having never seen (or heard) any such implementation. Since you have listened to both classes of amplifier powered off an SMPS, does the class D amplifier you have tried offer a wider dynamic range than a class AB amplifier of similar output power? Or is it quieter than the class AB at the same volume level? Re. the SMPS, were you able to notice its presence sonically? I only just noticed your response containing the analysis of power consumption. Like I mentioned earlier, I do not dispute the fundamental principles of operation of class D as its power consumption advantages are not disputable but we all know that it is the actual implementation that determines the real performance. This is why I was interested in finding out the actual specifications.
@@Douglas_Blake It's interesting to find out that an SMPS can be quieter than a linear PS. I guess the fact that it offers a more tightly regulated output has to do with its instant power delivery? I would presume the voltage regulators on both linear and switching PSs would use the same kind of regulator chips, so it has to be what lies before that makes the difference (on dollar-for-dollar per watt output basis)? That would explain the better impulse response too, right? higher instantaneous current delivery? When you mention lack of crosstalk you are obviously referring to a single PS for both channels. Still, I find the lower noise baffling. How can this be achieved with the same regulator chips? Unless, the SMPS you are using is specifically made for audio use and thus is more carefully designed (and more expensive)? You got me wrong though: I don't dislike class D because I think it is sonically inferior. I cannot state that having never heard a class D amplifier. I just dislike it for two reasons: because I do not like it as a solution purely from an aesthetic standpoint and because I like older technology. Had class D been used first and class AB been the newer one (hypothetically speaking) I'd probably be a solid class D guy. But these are all choices made on aesthetic grounds. Were I to poke at its potential flaws, there would be two that would come to mind. One I've already mentioned: it is not a simple technology, it relies heavily on large scale circuit integration and these two combined make it a less repairable technology. I have issues with any technology that is not repairable, especially any technology that comes closer to throw-away technology. Not that you cannot implement a class D amplifier with more than one chip if you wish or even with totally discrete components but the reality is that single chip implementations do and will rule. The second reason would be related to the implementation details. Class D relies on high frequency operation and as such it needs a steady oscillator (or clock). This brings in the question of jitter. I would presume that today, super accurate low jitter clocks are not a problem (I haven't checked what's on offer lately, I'm just assuming this). I am fairly certain however that back in the nineties Class D implementations had no better clocks than what was standard clocks for audio usage back then. If the clock was part of the single chip amplifier then, again I would assume it to have been a weak point. If it was external, again I would expect it to have been of the run-of-the-mill variety. So perhaps there might have been some truth in the audiophiles' reservations towards adopting class D amplification then based on available examples. But it would be quite hard to find a class D amplifier from the nineties today in order to compare it against current offerings so this is all just conjecture on my part. At the same time do not think I like class AB amplifiers - I do not. I am a solid class A fan. Again purely for aesthetic reasons. Don't ask me to explain why I do not like solutions with comparators and sawtooth waves, whether in class D or in ADCs or elsewhere. I just don't find these to be elegant solutions. On the other hand I really like SMPSs. So I am not unreservedly against all new technology. By the way don't knock audiophiles in a general blanket statement. They are just like any other section of society: they come in all sorts. Some audiophiles are accomplished engineers. You cannot deny that - else we would not have high end audio companies today and we would all be using cheap midi systems. We would not have had any serious audio devices period - of any technology. But some audiophiles may be of the gullible/uninformed kind or just stuck in their irrational convictions. Not all are the same. Besides, internet is a big element in the audiophile phenomenon nowadays. A lot of them just pass on what they read/heard somewhere on the internet creating trends..I do not think this was something that existed before the nineties. A lot of information on the internet is just nonsense or just misinformation and not everyone can tell which is which.
And here we go again. Class D is binary. 2 states. On and off. That is what defines digital. Morse fucking code is digital. PWM Pulse width modulation is as digital as any other signaling. You are thinking PCM Pulse code modulation which is another way if conveying information in a base 2 binary world. There are plenty of digital modes that do not rely on PCM. Teletype, radio teletype, FSK, all are digital but do not require quantization and PCM but they are every bit as digital. Class D is just that. The analog waveform is "sampled" into 2 states, a 1 or a 0. The 1 follows the positive swing and the 0 the negative swing. The duration of no signal is a 50/50 duty cycle. The amplitude of the waveform determines the duty cycle. The higher the amplitude the greater the duty cycle of the digital carrier. You need to go back to school and learn the very basics of electronics and stop listening to internet idiots that never finished high school.
19:09 Just so you know, the VTV PURIFI is 1% distortion at rated power. That's literally 100 times worse than most 50-year-old class AB amps. That doesn't mean it sounds bad or is bad. I'm not not an audiophile, I'm probably worse, I'm one of those pro audio guys who knows stuff. I have no idea what a cork smells like though so don't worry. I do see a lot of class D amps stretching the truth on their spec sheets though and that's probably because there are a lot of spec sheet sniffers out there that simply would not buy a 400 watt amp with a 1% THD rating. Not gonna lie, I probably wouldn't either, 1% is pretty bad and is easily audible by even the most untrained of ears. That being said, who's actually going to listen to the amp at 400 watts? Well.. all the people who bought it because they need 400 watts of power, that's who. That's why it's important that all amps are tested the same. The Purifi, at a 1/4 of its rated power-where its advertised THD rating was measured- is super clean and I'm sure it sounds and performs great at 100 watts. So really, it should live somewhere around there because nobody else is taking measurements at 1/4 power. When a short basketball player gets drafted to the NBA they don't lower the net for him when he shoots. He's expected to perform at the same standard as everyone else.
most of those 50 year old apps won't come close to their advertising spec for distortion at full output power either because their power supply start to sag. I myself run a creat vs900 which is 450 per channel into 4 ohms 250 into 8. It's also rated 1% at full power but again they are not rub at full power. You might need the power for a momentary transient but that is about it. It's all about being clean at normal music power which is typically 6db below max power anyway. It's called power reserve. My crest for example rated 450 would be happy pushing 250 all day long without breaking a sweat and havr plenty of reserve. Into 8 ohms it will happily drive 120 with 250 reserve for the peaks as needed. At full power distortion is 1% at 3db down 0.013 which is inaudible
I wish one of these modern Class D amp module companies (Purifi/Hypex/Pascal/Icepower) would make a sub 150w amp module and something that can be powered between 12-20v so they can be used in lower power portable applications.
The only thing that "doesn't work well" in this amplifier, at least in my opinion, is the retail price: over $1,000. Having seen it disassembled, and knowing the value of the components used, 200/300 dollars at most, it must be said that the manufacturer's and dealer's markup is really high. There are no large and heavy linear power transformers, batteries of final transistors in symmetry and in parallel with each other, large dissipators, large filter electrolytics; so how do you justify the high cost?
@@Douglas_Blake didn't write that that amp should cost $200/300, but considering a fair markup from the manufacturer and the seller, it could cost 600/700, exaggerating.
Try for more like 2500 and up for a new one. Why, because people with money will buy this in a heartbeat, they see it as a bargain compared to the likes of PS audio which is 2 to 3x the price for identical performance. Cost of the parts has nothing to do with the price. Engineering costs, marketing costs and of course a dirty word to you PROFIT
Great value when you see what others try to mark them up to. I think the NAD M23 uses the same modules and they charge $3800 and it’s only stereo. I got Dylan @ Buckeye to build me a 3-ch Purifi in a rack mount case for $1900. Dylan deserves to be paid for providing such good amps that are so far above the bs the amps boutique labels are trying to sell for $$$$. 11-channels of amplification was just a little over $3k. I can’t think of many more options where you can get 11-channels with high power capabilities and extremely low noise performance. Class D is the future. Surprised AVR makers are still doing AB at this point.
The Purifi website price is $682.39 for a pair of modules that have relatively few components (no heatsink, no PSU and no case), at that price I think they're taking the p1ss regardless of how good it sounds.
That is very unfair and simplistic. This is very reasonably priced relative to watts, life cycle and quality. There is more than parts count: paying your engineers for their r&d, testing and retesting (and the equipment that requires), bespoke ic, tooling for scale production yet at a volume many times smaller than that efficiency of legacy behemoths (, Yamaha, Sony, etc) paying for quality parts for reliability, etc. Reducing components often requires better front end engineering. And the lack of heat sinks is a good: none are typically required. Because of how well they are engineered. The modules are made to go into components that have low failure rates and last likely decades with minor servicing, This is not a disposable cheap consumer AVR destined for obsolete in 3 years. Innovation at this level, state of the art, is not cheap. And those who worked on it deserve to be remunerated accordingly as every rigorous test shows these new purify modules are indeed state of the art in terms of transparency and power. The latest purify based amps are producing hundreds of watts effectively perfectly to human hearing. Moreover, ten years ago, getting such low distortion and the power these modules are capable would cost likely at least twice as much in traditional class AB amps even in adjusted for inflation and cost you many times more to run in terms of electricity use and loading your air conditioning. There is a reason you don’t need giant heatsinks on the purify modules: they are an order of magnitude more efficient that class AB amps or yore. And the amount of would be many times larger. And be more probe to failure due heat and the number of components. So in fact, the per hour cost of purify based amp, once one takes into count electricity use, lifespan and repair rates is likely quite low. A good purify based amp is the last amp you may ever need. $1500 to $3500 is good value given that. Next time try doing a bit of research and thought before posting.
@ManFromLaBamba If you read the spec sheet you'll see that heatsinks are required and how do you know what the failure rate is? Run it without a heatsink and you'll know that it's not low. I build class A amplifiers that typically require a 2 KW PSU so I know what goes into making quality audio equipment. Next time try NOT telling others what to do.
Another fool that just doesn't get it. Only 2 states in class d. On and off. That's digital in it's simplest format. Morse code is also digital, be it much slower. You are confusing PCM with pwm. The p and m mean the same thing. Pulse and modulation. The difference is the middle letter. C for code. That's right the information is coded as a binary number which can be stored and retrieved. The w in pwm is width. The width of the pulse veries by the amplitude of the modulating signal. Low amplitude have very little pulse width deviation and high amplitude have large deviations. If you were to deviate the frequency as opposed to the pulse width you would have FM. Digital means 2 state, 1 and 0. The way all class d amplifiers work definitely fall into this catagory and that's why they are called digital. They meet the criteria.
Class D puts out a lot of power, they can sound half-decent, but they don't reproduce as fast and clean bass as good transistor class A or A/B or OTL tube amp can do. Class D is like traditional tube amp with big output transformer - bass is soft and boomy.
@@xprcloud I don't own class D exactly because reasons what I mentioned. I listened Hypex class D with MartinLogan hybrid electrostatic speakers. Only mid-range was ok, bass was quite boomy and lazy. Very low impedance at higer frequencies - typical to esl - didn't help hypex modules either.
BS. Class D amplifiers put out exactly what is put into them. No more no less (musically that is) some earlier designs had thin miss but that problem was solved eons ago. Anything made in the past 25 or so years is fantastic. Even these little cheap boards sound great.
Definition of digital. Any signal that is represented as a 1 or 0. The outputs switch on and off. There is no variable amplitude as in analog. Everything beyond the comparator right through to the output filter is a 1 or 0, which by definition is digital. You are confusing this with pulse code modulation which is a quantized sample of an analog waveform suited for storage in a memory medium. Pulse width modulation is a digital transmission method. Incidentally a compact disk is by your definition also not digital as the signal recorded by the laser is a pwm signal. The audio is sampled into PCM and then that is converted to a pwm signal in a conversion process known as EFM that changes the 8 bit byte to a 14 bit representation that can then be written to the disk as a pwm waveform. Glad i could help you understand that there is more to the definition of digital other than PCM. Anything that can be represented by a 1 or 0 is digital and class D amplifiers certainly fall into this category.
Beautiful D class amplifier... alright, where's my A class? I need an upgrade to triple A and 1000W radiating rheostat just to load up the lines. I don't believe any progress has been made in the class D amplifiers in the last 30 years... it's just that the expectations have gone lower and Lower and LOWER. With the current gen of portable speakers a class D is way too nice for the quality of the speakers... so be it. It's like MP3s... then AAC, the eAAC+... get me an eAAC+ that sounds better than a 44.1 kHz sampled 16 bit PCM: 1982 beating the FUTURE (WAS CD Audio). We like RUBBISH! I also do... so I speak for myself.
@Douglas Blake no class AB can tough a class D these days. The improvement have been so great in the last few years that i would take class D any day and my standards have not gone down.
19:15 I disagree with you there. We should be comparing apples to apples. You can still fix a Sansui for a relatively modest amount of money (compared to its value). You can fix any amplifier like the Sansui even if the company that made it has long gone under. This is the case for most amplifiers made before the eighties, i.e. those without exotic transistors or integrated circuits. Compare that with this class D amplifier. If the main integrated circuits (which are really small computers) in it are no longer made and become damaged for some reason, then this will be a pile of junk - or at least the amplifier module will be. On the Akai amplifier in question: you say you blew your tweeter when you operated the Akai at 40W output. Yes but that is the maximum this amplifier can put out (AM-2450) so it is either clipping at these levels or playing with very high distortion. You should expect your tweeters to be blown in these conditions regardless of which amplifier drives them. The AM-2450 is an inferior amplifier compared to its predecessor, the AM-2400 quality-wise. The AM-2400 sounds very nice indeed. In fact, it sounds nicer than the AM-2600 and the AM-2850 (neither of which will blow tweeters when playing at 40W). Because of the increasing prices of the AM-2400/2600/2800 series, their counterparts, the AM-2450/2650 have also gone up without deserving it. The AM-2850/2950 are a different story. The value these devices enjoy today is also in large part due to their near antique age and the fact that most of them still work without any need for service despite being near antiques. So, we go back to comparing apples with apples. If you were comparing this amplifier with a class D amplifier from the nineties or with a similarly priced class A or class AB amplifier made today, then we would be comparing apples with apples.
@@Douglas_Blake Ok, that's true strictly speaking but there are class D amplifiers which do all the signal processing in the digital domain, i.e. convert the analogue signal to digital. I do not know whether this example falls in this category or the pure analogue class D amplifier type. But this is a little bit besides the point I was making: the chips containing this circuitry are proprietary and not common across manufacturers. You may or may not be able to restore an amplifier should one of these chips fails if the chip used is no longer available. If you do succeed in finding a near equivalent, you will have succeeded in restoring the function but maybe not the sound (as the particular signal processing done in the chip may differ from that in the original - whether analogue or digital). I understand you are referring to the driver chip only but in some cases it is all one chip, driver and signal processing.
Class D are analog devices. The only "digital" part of them is the pwm carrier on the mosfet and the signal is more closely related to FM radio. The incoming audio is mixed with a triangle waveform into a comparator that changes the audio into a digital pulse train. This drives the mosfets that provide the gain. The carrier is filtered to reveal the original audio.
@Douglas Blake I was simplifying it. The ramp and audio is fed into the comparator in a form of mixing as one signal goes into the positive input and the other the negative of an op amp and the resulting output is then clipped to either a positive or negative output to drive the mosfets.
@@12voltvids For some reason I assumed that all high-end class D amplifiers sold today convert any analogue signal to digital and then do all the processing e.g. volume control, filtering, feedback and PWM waveform generation in the digital domain. That was the source of the confusion. I was not implying that class D amplification itself is a type of digital amplification - at least not intentionally Now, if we just stick to semantics, the word I used to describe the chip was "computer" not "digital" (there are analogue computers) and the purpose of using it was to convey the idea that this is a very complicated circuit housed in that chip. But yeah, other than that, I agree totally. How about the AM-2450? Have you done a video on it? Can you share what you don't like about it, especially in comparison to the previous generation(s)? Akai was not doing well in the eighties. I'm not sure when exactly they got bought off, but they started concentrating on cheaper home audio devices and dropped their quality. But then we had the AM-73/93, AM-75/95 series in the nineties - which for some is their favourite series of Akai amplifiers.
@@Stelios.Posantzis some low end class D also process in digital domain but this is a straight amplifier. No volume or tone controls. Put a signal in, get a bigger one out.
When a conventional big amps goes wrong they also go boom and blow many parts. Direct coupled especially. On these you plug in a new module and you are good to go.
@@tyronenelson9124 but you shouldn't have to because they are very reliable. Much more than a conventional amplifier due to the design. And when you plug in a new module you are not paying someone 200 to change a bunch of parts only to find out that the parts are counterfeit and blows up again a few months later.
Class A or AB for me. Yeah transparent, but dry with no meat on the bone. I'd only consider D for an active subwoofer amplifier. Interesting tunes for royalty free.
Time to go back to school. The modern class D blows the doors off ab. Why do you think all the big brands are behind the technology? They sound amazing and can drive pretty much anything. This one drives a pair of Maggie's
@@tacofortgens3471 This does true to source. Tube buffers are used by many for that tube sound which is even order harmonics. That is why tube gear sounds so full. I would buy the new model that has the tube buffer built in just like the 7000 ps audio bricks have. I run a tube buffer on my crest and it sounds incredible.
@@wyup you can buy many for about 100 bucks. There is nothing to them. Just a unity gain triode. If you buy a new amplifier with a built in tube buffet sure you will pay their price.
What's the most power you've ever used to drive apeakers? I remember once going to 10 watts (according to the amplifier's meters) and I thought the house was going to collapse from the vibrations. This was back in the 80s. At the time, I never understood why people would buy huge amps. If I'll never max out a 40W amp, why pay for an 80W? Of course, the tech back then was different, so maybe it all distorted.
Boring!, your typical high power Class-D amp n I've seen many but I've got a custom built one by me that's been tested long term on a dummy load of 4 ohms that does 625W RMS/ CH but I haven't played with it in a a few yrs, I use to do disco's / nightclubs.
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I have the Behringer A800 class D and it sounds like no other amp so clear so powerful there is no other class that can come close to that awesome clear sound
Nothing beats a/b
Class d is garbage
A800 and other pro-style class D amps are pretty good (a lot of the Behringer are based on IRS2092 chipset) but the Purifi amp is on another planet entirely. They sound like nothing at all, just the audio signal direct to the speaker; whatever you feed them they will put directly out without changing it.
I have a Class D AVR (Pioneer) and it drives up to 175W / channel in stereo. Sounds super crisp and clear provided you feed it a good signal!
I love the power and audio fidelity of these VTV amplifiers. I just wish they would put a couple VU meters in the front. What can I say, I'm a sucker for the old school amp look.
I recently bought one of the Fosi Audio TB10D amps (The updated version) and it changed my opinion on class D amps. It seemed to have clean power output at the volume levels I normally listen to and plenty of "punch" and that was listening to a Rush CD at genre appropriate levels through a pair of Infinity bookshelf speakers. Not bad for around $80 and it didn't get warm. Interesting that the Purify amp switching power supply was twice the size of both amp modules.
Wow amazing amplifier. Like that it's so light weight compared to the dinosaur amps that weigh tons.
Purfi is another level, but I bought a crown xls drive cover to drive my diy subwoofer and I wanted to try it in stereo with my diy speakers and I have to tell you it sounds really good, very clear no coloration. I have some really nice speakers and they can handle a lot of power and this crown can deliver with no distortion and little heat. I'm thinking about building a class d kit or maybe get a ice amp off parts Express and make my own case
Nice review and I agree, Class D nowadays are fantastic amplifiers with amazing efficiency. If you want to experience it, try an ICE amplifier unit with built in switching power supply. For just 100 euro you can buys this with 250 watts output and really great quality
The IcePower Series is especially amazing! I have this in the 700€ Canton AS 650 SC Subwoofer, and tbh - that thing was the 2nd most expensive sub from Canton, but it was handmade over here in Germany and sounds so damn good, I will never want anything else! Linear down to 30Hz, and still absolutely pumping out in the 20‘s… I know, the Amplifier is only going to be equivalent to 1/3 of a good sounding sub especially, the other 2/3s is a serious quality Driver (Speaker) and the utmost attention to calculations for the enclosure and it’s vent measurements and placement.
Crazy to think that the toroidal transformer on my parasound a21 weighs like 2.5 complete amps. Sure can appreciate the electricity savings you get with an Amp like this compared to a class a ab amp.
Audiophile here. Class D can be great depending on the design. Those old recievers are nice for a nostalgia system for non critical listening.
I couldn't have said it better myself. Time to unload all my old receivers.
That's a nice looking class-D amp, nice quality construction too. I am a big fan of class-D stuff, the only problem with them is when they go wrong, a lot of the time they take out the speakers with them aswell. But they are very efficient compared to class-A and others. Thanks for the videos. :-)
Oh so no worse than a crown dc300!!!
@@12voltvids Not quite as bad as the capacitor-cooking dc-300 no, but they sound nice-ish enough! :-)
@@androidtvbox266 I'd take the vtv any day over old crown or sansewage garbage. I put this on my good speakers and I had to pick my jaw up from the floor.
I believe in you mr.12 volt that digital amp is good sounding and efficient ...i try it with a cheap module from china for my diy amp and even it was cheap i was very impressed for its clarity and efficiency compare to mid pricy class ab amp...
I use class D amps to drive my 3 subwoofers and they are smaller than the Analog ones and have plenty of power for the subs. I can fit like 12 of them into my Marantz receiver!
Yep these amps using the Purifi modules are great amplifiers. Glad you've gotten to experience one. If you don't need the power output, the class H Benchmark AHB2 delivers even better distortion but with still decent power output. Class D will always have more power output than Class H, but you'd be surprised how loud 100W really is. If you monoblock the AHB2, which a will give you even better performance, and a lot of people that buy this amp will buy two, you'll get 480 Watts into 6 ohms with 0.0003 % THD+N at full rated power, 20 Hz to 20 kHz. I know how you feel about specs, but this amp you reviewed here is solid state, not tubes, and is also an objectionably well measured amp too. I hope one day you'll get to experience an AHB2.
480 watts of what exactly?
@@tyronenelson9124 That's RMS output of bridged mono at a 6 ohm load. They rate the output at 0.0003 % THD+N for that rated power, at 0.1% and 1% THD+N the output is much higher.
There are people who used to say "Any properly designed amp will have no sound of its own", using the nebulous qualifier 'properly', but we are not in that world anymore; the Purifi, NCoreX, and Starkrimson amplifiers sound just like the incoming signal - they are perfectly linear.
There’s a one man show in Ohio called Buckeye Amps run by a guy named Dylan. He assembles Class D amplifiers for sale. He has Purifi options in a higher power monoblock version and then also 2 and 3-channel versions using the same modules as the VTV in this video. He also offers Hypex amps using the NC252 and NC502 modules in 2, 4, 6 and 8-channel configurations.
I am running my home theater with a 3-ch Purifi for the LCR array and 8-ch Hypex NC252 to run my surrounds. Great value for very capable amplifiers. Not exciting to look at but they are clean and powerful. Significant upgrade over my 7-ch ATI-built noisy amplifier.
As far as I’m concerned the AVR industry needs to drop class AB and use a slightly smaller variant of Purifi or Hypex modules. Roughly 90% efficiency compared to 50-60% Class AB.
I agree class D is now the way to go. Very powerful and so clean these days. The perfect audio components to not add anything to the audio signal. SACD with a good dac and a class d amp is about as good as you will get followed by DAT then CD. Analog formats such as reel to reel next and then compressed digital cassette and vinyl the bottom.
Of course people got used to analog artifacts and they think the sound is inferior when they are not present. And that's why people pay huge dollars for vintage equipment.
Those who are simply just making noise about Class D, just try to have a listen to Leema Acoustics Elements AMP with just 56Watts per channel with anything above (TRUE) 88db speakers and then you will understand you no longer needs that Class A or AB heater anymore on your room.
The people that dislike class D simply don't understand how it operates. These same people will argue till their are blue in the face that cassette tape and vinyl has better sound than cd and other digital formats. No point trying to educate them because you can't fix stupid
the little block of red caps are the filter caps the electrolytic capacitors and the 2 little inducters are on the power rails.
you wouldn't use electrolytic caps for class D sine re-consatution at the output the power loss in the caps would be enormous and they would heat up and pop.
good its got a use for it
In my opinion class D amplifiers exceptionally blends with large full range speakers that is above 12 inches.
I have a Pioneer SC-LX73 but its a big heavy amp and uses lots of energy to. even more than my other AVR - 550 this is a much cooler amp.
Class D is amazing, small, light, sounds good & can drive speakers really hard without even getting warm!
What does it sound like compared to your tube amp, Dave? If it can create the tube sound with instruments floating in mid air then it really is a winner!
It sounds transparant. If you want the tube sound plug in a tube buffer (preamp) àhead of it. The next model up has just that built in. PS audio has been doing this for years. Then you get the even order harmonics that makes. Instruments float. I use a tube buffer on my big crest amp to make it sound like my tube amp, with more punch.
@@12voltvids Thanks for the reply, Dave. I only listen at low most of the time, so the 32 watts I have is plenty, but if more power was ever needed the Purifi with tube buffer is definitely the way to go.
@@Markpab same here my tube amp is 40 per. The guy that loaned me this has the. Sonic frontiers i recently repaired. He's using his tube amplifier at the moment. I have my crest connected but will go back to my yaqin again when I do some serious listening. I have to clear out my living room. Wife inherited a bunch of furniture from a house clear out that I am slowly getting rid of and the moving truck put it all in my living room. As far as i an concerned they should have taken it to the dump. I wanted 1 piece out of the estate, ok 3, a giant special edition grandfather clock 1 of only 250 made. A commissioned copper art sculpture and a Robert Bateman painting. Unfortunately my wife was named in estate and since the old lady she cared for had no family she got everything including ugly really expensive furniture that I am finding it almost impossible to even give away.
@@12voltvids Oh dear - no good blocking the HiFi! Bet your cats love playing amongst all the furniture tho! I've had enough of spending money on HiFi, I like my set up now with my WAD tube amp, Rogers speakers from 1984 and Denafrips DAC with Cambridge CD transport, my loft is full of cassette decks, amps and tuners I've wasted money on.
Your multimeter isn't going to tell you much - the switching frequency of these amps is up in the range of 500kHz. You need a really good audio analyzer to see what these amps are doing.
I have an older Spectron musical MK lll class D amp designed by John Ulrich It weights 54 lbs!! It has a 7" dia x 5" thick toroidal power supply
Yes class D is a very unusual way to produce audio, i sort of remembered a pwm method with filtering at the end to remove the r.f, or something like that but i have forgotten all the details.
Does it still have a kind of amplifier hiss?
No mouse at all. You can draw similarities between a class D amplifier and FM transmitter. They both do things similar ways. In both cases the audio is changed from an amplitude to a frequency or a pulse width. In FM as the signal goes positive the frequency rises as the signal goes negative the frequency drops. The amplitude of the incoming modulating signal affects how far the frequency shifts the higher the input the higher the frequency shifts on either side of the carrier that's called deviation. In a classy amplifier which is pwm the frequency remains constant the duty cycle shifts forward and backward of your time constant so as the voltage rises the on time of the positive transistor increases and the negative transistor decreases. As the voltage goes negative the positive transistor decreases its duty cycle and the negative transistor increases its duty cycle. The amount of shift is determined by the amount of voltage swing on the input. Filter out the carrier and the result is the audio signal. No noise added no distortion added no bumps or dips in the frequency response added just pure sound. They are bloody amazing and my next amplifier will definitely be a class D. Class H also have good Dynamics however there is that transition on a class h where they switch from the low to the high rail and that switch over point can be detected. Whether you actually hear it or not because by the time you're at that level of volume your ears are not quite as sensitive to transitions but they're still at transition point. at least they perform better than your conventional class A B where those transitions result in distortion because the power supply has no more reserve. That's what class H give you over a class A B which they are just a class A B just with a second power tap with charge capacitors on tap waiting to be switched in momentarily to handle that extra kick required to prevent clipping. Class D you don't need that you've got the reserve already there and you're not burning up extra energy keeping a second power supply in standby. When I showed my omt the other day, I forgot whether I showed the cooling fan in my communications closet but I have to have an exhaust fan in where my equipment is because the big Onkyo amplifier for my home theater produces so much heat that it would literally cook all of the equipment. I would go in the closet and it was like 35° C after an evening of the equipment running. I had to cut a vent hole in the wall and put an exhaust fan up at the ceiling or leave the door open to prevent all the equipment from overheating. Old class AB amplifiers are pretty inefficient especially the type that use dynamic bias. Dynamic bias amplifiers at low volume switch to a class A type output so they burn a lot of electricity doing nothing on the top of this Onkyo gets quite hot even when there's no sound going through it same with my Technics SUV 9. New class A as techniques called it. New class A my ass just a way to waste more energy turning it into heat doing absolutely nothing. As far as I'm concerned the old receivers that are collectible are only collectible for the same reason that old reel-to-reel recorders are collectible because they look cool and they make great display pieces like my old cameras but not really useful as far as sound quality goes or in the case of my old cameras they look impressive but my little cheap camera that I did this video on will run circles around them everyday and twice on Sunday
@@12voltvids " No mouse at all " What are you talking about dave?
@@zx8401ztv haha. I was using voice dictation and that came across the tv just as I started speaking. Too funny. Was a home renovation show on and the people had a mouse problem. Lololol.
@@12voltvids ha ha i wondered if two men were coming to put you in a restraint jacket lol.
That voice dictation works really well :-D
@Douglas Blake I Saved the text ages ago, my vision goes out of focus when im getting tired.
Ill leave the text untill tomorrow when im not crosseyed lol.
Class D are pulse with modulated amplifiers - a fully analog process. If it had been a digital amp it would be able to work on S/PDIF serial digital bit streams, or a parallel bit stream of some
other kind. Nowhere in a class D amp you can work with digital signals. So don´t be one of the ignorant´s who keep spreading the message. SMPS are also not digital power supplies.
Actually it is a digital representation of an analog signal. The outputs are either on or off. There is no in between as in a linear amplifier. There are 2 states. On and off, or better represented as a 1 or 0.
That is the definition of digital.
You are thinking quantization where is waveform is aampled at a given rate and each value is driven a numerical value. The resulting serial pulse train is called pulse code modulation or PCM. When a CD is made the PCM is converted to a pwm signal in a conversion process called EFM, eight to fourteen modulation. This changes each 8 bit byte into a 14 bit word in such a way that the minimum pulse length is 3 bits wide in the resulting pwm that is modulating the laser. Trust me i do know what digital is and how it works.
Class D convert analog signal into a digital representation that can be transmitted over a wire over a fiber optic link or operate a radio link. The amplitude is a result on the shift of the duty cycle. A simple filter to cancel out the carrier will return the original analog signal.
Digital does not mean it has to be encoded in some way. It just has to be able to be represented as a 1 or 0 and class D amplifiers meet that criteria. So yes calling them digital amplifiers is accurate but if you like you can try to file a lawsuit claiming misrepresentation and see how far that goes. 😁
@@12voltvids This comes from Wikipedia: Please notice the sentence starting with **.
"The letter D used to designate this amplifier class is simply the next letter after C and, although occasionally used as such, does not stand for digital.
**Class-D and class-E amplifiers are sometimes mistakenly described as "digital" because the output waveform superficially resembles a pulse-train of digital symbols, but a class-D amplifier merely converts an input waveform into a continuously pulse-width modulated analog signal.
(A digital waveform would be pulse-code modulated.)"
@@qddk9545 the D in class D has nothing to do with digital.
Digital signaling is simply a binary way of signaling. Mores code is digital. It's an on or off state nothing else. You have 2 operational states, either on or off, no in between. Any analog signal can be represented as a pulse stream by mixing with a triangle waveform and a comparator that will switch high or low turning that analog waveform into a digital representation of the analog signal. I am sorry if you don't have the intelligence to understand that very basic form of communication. All the rest of us are laughing at you.
You are confusing the very basics of digital technology which is a simple 1 or 0 state with coding.
PCM Pulse CODE modulation.
PWM, Pulse WIDTH modulation.
You note both have the word pulse, that is the digital clue. The next one CODE indicates that the data train is a quantized numeric value.
Pulse width modulation is a digital representation of an analog waveform. If you kept the duty cycle 50/50 and varies the frequency to follow the amplitude of the modulating you would have FM, frequency modulation. If you kept the frequency constant and rotated the phase of the oscillator using a varactor diode then you have creates phase modulation. These are purely analog modulations. However adding that comparator to turn the AC input into a duty cycle shift on a constant frequency square wave creates a binary waveform with only 2 states either on or off which is the basic definition of digital. Sorry you lose !
😁😅😆😃😀😄🖕
From fixing crappy tape decks from the 90s to a purifi amp. At least i know your on the same planet as me now.
That pufifi amp sounded sweet.
Would you consider these to be somewhat disposable? How do you think the MTBF for a unit like this with the switching power supply would compare to Class A/B with a linear power supply?
Modular. When module fails just pop in another. Cheaper to replace module than repair an old big amp especially trying to source obsolete transistors.
@Douglas Blake that's why i leave monitors for security cameras running 24/7
@Douglas Blake
Cold starting is literally a dead short till the caps charge.
This is why good smps designs have soft start circuits. To prevent this from happening.
So it's nice to have classes A, B ... and D ☺ ; where is the real expression of natural sound - Live Music !
And just what do you think they use for sound reinforcement these days? Yup class D amps.
6:15 Is this aluminium plate all there is to the heat sink? Or does it come in contact with the case and use that as the main heat sink? The reason I am asking is that I am slightly sceptical about the power output. Can it actually output 250W continuous sine wave power per module? Because I would be inclined to expect each module to be half the size of the power supply module if it were. Granted, the power supply maybe over-specified and it also works at a much higher voltage, which necessitates larger components that bulk up the power supply, but even so the heat sink on the power supply is huge compared to that of the amplifier modules. Unless of course the power supply operates at around 70% efficiency and the power amplifier modules at around 90%.
12:45 The real question is whether it still sounded amazing in the main system, with high fidelity loudspeakers. Did it?
18:58 Not necessarily - we are not in the late nineties and digital amplifiers (well, to be precise, class D amplifiers) have come a long way since then so a lot of audiophiles now spend serious money on them. It is the audiophiles that are also retrophiliacs and that are into vintage components' sound that you are probably referring to. Either them or those very few that can afford to pay enough to buy a house or two with just to buy one component in their audio system. I am exaggerating a bit here. Make that a car or two. Now one should compare like with like. There are no class D amplifiers made that cost as much as a small flat or a new car currently. This is because:
a) there is no need for them to be so expensive as they can generally achieve the same sound quality as class A or class AB amplifiers at 2 or 3 times their price and
b) they still need to win their place in the market and for this to happen they need to remain 2 to 3 times cheaper than their A or AB class counterparts. Once they do dominate though (just wait for the last few valve factories to close down/go bankrupt - let's hope this does not happen by the way but suppose it does for the sake of the argument) we will for sure see class D amplifiers with gilded knobs and silver cables inside and anything else you can imagine that could drive their prices up to stratospheric levels. The reason for this is simple: there will always be a market for expensive stuff.
@@Douglas_Blake Yes, the same is true for SMPSs also but they still need a heat sink of some size... These modules here just have a small metal plate - hence my slight incredulity.
@@Douglas_Blake Yes, I'm aware of the benefits of class D operation. The reason I was insisting on continues sine wave power rating is that the output music signal contains nowhere near enough energy on average as a constant full amplitude sine wave.
Re. the heat sink coupling, it does seem it couples to the case but it looks to me as if it stands on brass spacers - not quite the same as full contact over its entire surface.
While on the subject of SMPS and Class D amplifiers, there are Class AB (or class AB genre) powered off an SMPS. I'm not sure whether Carver has done that (he'd be my primary suspect) but over in the UK, Chord does produce some super pricey amplifiers that operate this way. These were produced when Class D audio chips were already a mature enough technology. Even if they had not been, I would expect Chord to be in a position to develop them to their high standards. This is primarily a financial question of course. But they did go with this solution. I am not sure whether they still choose to make amplifiers this way or whether they have gone full class D as in this example.
@@Douglas_Blake The reason I mentioned the SMPS and class AB amplifier combination was because I am interested in the audio merits of class D vs. class AB - or even vs. class A. This is a technology that has been available since the end of the nineties but has not really caught on (in high end audio) until now. It had not received unanimous praise back then - even though the power consumption and power output figures were spectacular. I never found out why it did not catch on back then. I did read about poor implementations with undersized (?) output inductors being a possible cause but I did not quite believe that to be a sufficient reason having never seen (or heard) any such implementation.
Since you have listened to both classes of amplifier powered off an SMPS, does the class D amplifier you have tried offer a wider dynamic range than a class AB amplifier of similar output power? Or is it quieter than the class AB at the same volume level? Re. the SMPS, were you able to notice its presence sonically?
I only just noticed your response containing the analysis of power consumption. Like I mentioned earlier, I do not dispute the fundamental principles of operation of class D as its power consumption advantages are not disputable but we all know that it is the actual implementation that determines the real performance. This is why I was interested in finding out the actual specifications.
@@Douglas_Blake It's interesting to find out that an SMPS can be quieter than a linear PS. I guess the fact that it offers a more tightly regulated output has to do with its instant power delivery? I would presume the voltage regulators on both linear and switching PSs would use the same kind of regulator chips, so it has to be what lies before that makes the difference (on dollar-for-dollar per watt output basis)? That would explain the better impulse response too, right? higher instantaneous current delivery?
When you mention lack of crosstalk you are obviously referring to a single PS for both channels.
Still, I find the lower noise baffling. How can this be achieved with the same regulator chips? Unless, the SMPS you are using is specifically made for audio use and thus is more carefully designed (and more expensive)?
You got me wrong though: I don't dislike class D because I think it is sonically inferior. I cannot state that having never heard a class D amplifier. I just dislike it for two reasons: because I do not like it as a solution purely from an aesthetic standpoint and because I like older technology. Had class D been used first and class AB been the newer one (hypothetically speaking) I'd probably be a solid class D guy. But these are all choices made on aesthetic grounds. Were I to poke at its potential flaws, there would be two that would come to mind. One I've already mentioned: it is not a simple technology, it relies heavily on large scale circuit integration and these two combined make it a less repairable technology. I have issues with any technology that is not repairable, especially any technology that comes closer to throw-away technology. Not that you cannot implement a class D amplifier with more than one chip if you wish or even with totally discrete components but the reality is that single chip implementations do and will rule. The second reason would be related to the implementation details. Class D relies on high frequency operation and as such it needs a steady oscillator (or clock). This brings in the question of jitter. I would presume that today, super accurate low jitter clocks are not a problem (I haven't checked what's on offer lately, I'm just assuming this). I am fairly certain however that back in the nineties Class D implementations had no better clocks than what was standard clocks for audio usage back then. If the clock was part of the single chip amplifier then, again I would assume it to have been a weak point. If it was external, again I would expect it to have been of the run-of-the-mill variety. So perhaps there might have been some truth in the audiophiles' reservations towards adopting class D amplification then based on available examples. But it would be quite hard to find a class D amplifier from the nineties today in order to compare it against current offerings so this is all just conjecture on my part.
At the same time do not think I like class AB amplifiers - I do not. I am a solid class A fan. Again purely for aesthetic reasons. Don't ask me to explain why I do not like solutions with comparators and sawtooth waves, whether in class D or in ADCs or elsewhere. I just don't find these to be elegant solutions.
On the other hand I really like SMPSs. So I am not unreservedly against all new technology.
By the way don't knock audiophiles in a general blanket statement. They are just like any other section of society: they come in all sorts. Some audiophiles are accomplished engineers. You cannot deny that - else we would not have high end audio companies today and we would all be using cheap midi systems. We would not have had any serious audio devices period - of any technology. But some audiophiles may be of the gullible/uninformed kind or just stuck in their irrational convictions. Not all are the same. Besides, internet is a big element in the audiophile phenomenon nowadays. A lot of them just pass on what they read/heard somewhere on the internet creating trends..I do not think this was something that existed before the nineties. A lot of information on the internet is just nonsense or just misinformation and not everyone can tell which is which.
@@Douglas_Blake Thanks for taking the time to share this information and your experience. Take care.
Purifi from Denmark, ICEpower also from Denmark.
Class D is not digital! Where did you go to school? Class D is pulse width modulated.
And here we go again. Class D is binary. 2 states. On and off. That is what defines digital. Morse fucking code is digital.
PWM Pulse width modulation is as digital as any other signaling.
You are thinking PCM Pulse code modulation which is another way if conveying information in a base 2 binary world. There are plenty of digital modes that do not rely on PCM. Teletype, radio teletype, FSK, all are digital but do not require quantization and PCM but they are every bit as digital.
Class D is just that. The analog waveform is "sampled" into 2 states, a 1 or a 0. The 1 follows the positive swing and the 0 the negative swing. The duration of no signal is a 50/50 duty cycle. The amplitude of the waveform determines the duty cycle. The higher the amplitude the greater the duty cycle of the digital carrier.
You need to go back to school and learn the very basics of electronics and stop listening to internet idiots that never finished high school.
Before you said the weight, I guessed 12 pounds (I was a little off, lol) . Nice looking amplifier!
Have you got a new set of probes ordered?
This meter is on its last legs. I have a new fluke i got on Facebook waiting in the wings.
Oh my god there is going to be anal probing
@@12voltvids So will you be if you keep using it with a taped up probe like that ☠, ask me how I know.
@@Kimble221 Yup
19:09 Just so you know, the VTV PURIFI is 1% distortion at rated power. That's literally 100 times worse than most 50-year-old class AB amps. That doesn't mean it sounds bad or is bad. I'm not not an audiophile, I'm probably worse, I'm one of those pro audio guys who knows stuff. I have no idea what a cork smells like though so don't worry. I do see a lot of class D amps stretching the truth on their spec sheets though and that's probably because there are a lot of spec sheet sniffers out there that simply would not buy a 400 watt amp with a 1% THD rating. Not gonna lie, I probably wouldn't either, 1% is pretty bad and is easily audible by even the most untrained of ears. That being said, who's actually going to listen to the amp at 400 watts? Well.. all the people who bought it because they need 400 watts of power, that's who. That's why it's important that all amps are tested the same. The Purifi, at a 1/4 of its rated power-where its advertised THD rating was measured- is super clean and I'm sure it sounds and performs great at 100 watts. So really, it should live somewhere around there because nobody else is taking measurements at 1/4 power. When a short basketball player gets drafted to the NBA they don't lower the net for him when he shoots. He's expected to perform at the same standard as everyone else.
most of those 50 year old apps won't come close to their advertising spec for distortion at full output power either because their power supply start to sag.
I myself run a creat vs900 which is 450 per channel into 4 ohms 250 into 8. It's also rated 1% at full power but again they are not rub at full power. You might need the power for a momentary transient but that is about it. It's all about being clean at normal music power which is typically 6db below max power anyway. It's called power reserve. My crest for example rated 450 would be happy pushing 250 all day long without breaking a sweat and havr plenty of reserve. Into 8 ohms it will happily drive 120 with 250 reserve for the peaks as needed.
At full power distortion is 1% at 3db down 0.013 which is inaudible
I wish one of these modern Class D amp module companies (Purifi/Hypex/Pascal/Icepower) would make a sub 150w amp module and something that can be powered between 12-20v so they can be used in lower power portable applications.
Infineon MA12070 is what you're looking for I think. Great sounding amps used in a lot of applications including active speakers.
What ever happened to the good old Bose 901 speakers?
For the price you pay it better sounds good lol
The only thing that "doesn't work well" in this amplifier, at least in my opinion, is the retail price: over $1,000.
Having seen it disassembled, and knowing the value of the components used, 200/300 dollars at most, it must be said that the manufacturer's and dealer's markup is really high. There are no large and heavy linear power transformers, batteries of final transistors in symmetry and in parallel with each other, large dissipators, large filter electrolytics; so how do you justify the high cost?
@@Douglas_Blake didn't write that that amp should cost $200/300, but considering a fair markup from the manufacturer and the seller, it could cost 600/700, exaggerating.
Try for more like 2500 and up for a new one. Why, because people with money will buy this in a heartbeat, they see it as a bargain compared to the likes of PS audio which is 2 to 3x the price for identical performance. Cost of the parts has nothing to do with the price. Engineering costs, marketing costs and of course a dirty word to you PROFIT
Great value when you see what others try to mark them up to. I think the NAD M23 uses the same modules and they charge $3800 and it’s only stereo. I got Dylan @ Buckeye to build me a 3-ch Purifi in a rack mount case for $1900. Dylan deserves to be paid for providing such good amps that are so far above the bs the amps boutique labels are trying to sell for $$$$. 11-channels of amplification was just a little over $3k. I can’t think of many more options where you can get 11-channels with high power capabilities and extremely low noise performance. Class D is the future. Surprised AVR makers are still doing AB at this point.
Tear down & no demo! 6 sec sound blast would suffice!? Don't trigger copyright police...
The Purifi website price is $682.39 for a pair of modules that have relatively few components (no heatsink, no PSU and no case), at that price I think they're taking the p1ss regardless of how good it sounds.
That is very unfair and simplistic. This is very reasonably priced relative to watts, life cycle and quality.
There is more than parts count: paying your engineers for their r&d, testing and retesting (and the equipment that requires), bespoke ic, tooling for scale production yet at a volume many times smaller than that efficiency of legacy behemoths (, Yamaha, Sony, etc) paying for quality parts for reliability, etc.
Reducing components often requires better front end engineering.
And the lack of heat sinks is a good: none are typically required. Because of how well they are engineered.
The modules are made to go into components that have low failure rates and last likely decades with minor servicing, This is not a disposable cheap consumer AVR destined for obsolete in 3 years.
Innovation at this level, state of the art, is not cheap. And those who worked on it deserve to be remunerated accordingly as every rigorous test shows these new purify modules are indeed state of the art in terms of transparency and power. The latest purify based amps are producing hundreds of watts effectively perfectly to human hearing.
Moreover, ten years ago, getting such low distortion and the power these modules are capable would cost likely at least twice as much in traditional class AB amps even in adjusted for inflation and cost you many times more to run in terms of electricity use and loading your air conditioning. There is a reason you don’t need giant heatsinks on the purify modules: they are an order of magnitude more efficient that class AB amps or yore. And the amount of would be many times larger. And be more probe to failure due heat and the number of components.
So in fact, the per hour cost of purify based amp, once one takes into count electricity use, lifespan and repair rates is likely quite low.
A good purify based amp is the last amp you may ever need. $1500 to $3500 is good value given that.
Next time try doing a bit of research and thought before posting.
@ManFromLaBamba If you read the spec sheet you'll see that heatsinks are required and how do you know what the failure rate is? Run it without a heatsink and you'll know that it's not low.
I build class A amplifiers that typically require a 2 KW PSU so I know what goes into making quality audio equipment.
Next time try NOT telling others what to do.
P W M ! Analog !
Another fool that just doesn't get it. Only 2 states in class d. On and off. That's digital in it's simplest format. Morse code is also digital, be it much slower.
You are confusing PCM with pwm. The p and m mean the same thing. Pulse and modulation. The difference is the middle letter. C for code. That's right the information is coded as a binary number which can be stored and retrieved. The w in pwm is width. The width of the pulse veries by the amplitude of the modulating signal. Low amplitude have very little pulse width deviation and high amplitude have large deviations.
If you were to deviate the frequency as opposed to the pulse width you would have FM.
Digital means 2 state, 1 and 0. The way all class d amplifiers work definitely fall into this catagory and that's why they are called digital. They meet the criteria.
Class D puts out a lot of power, they can sound half-decent, but they don't reproduce as fast and clean bass as good transistor class A or A/B or OTL tube amp can do. Class D is like traditional tube amp with big output transformer - bass is soft and boomy.
BS from a guy who does not own class-D
@@xprcloud I don't own class D exactly because reasons what I mentioned. I listened Hypex class D with MartinLogan hybrid electrostatic speakers. Only mid-range was ok, bass was quite boomy and lazy. Very low impedance at higer frequencies - typical to esl - didn't help hypex modules either.
BS. Class D amplifiers put out exactly what is put into them. No more no less (musically that is) some earlier designs had thin miss but that problem was solved eons ago. Anything made in the past 25 or so years is fantastic. Even these little cheap boards sound great.
These amplifiers are not DIGITAL!
Definition of digital. Any signal that is represented as a 1 or 0. The outputs switch on and off. There is no variable amplitude as in analog. Everything beyond the comparator right through to the output filter is a 1 or 0, which by definition is digital. You are confusing this with pulse code modulation which is a quantized sample of an analog waveform suited for storage in a memory medium.
Pulse width modulation is a digital transmission method. Incidentally a compact disk is by your definition also not digital as the signal recorded by the laser is a pwm signal. The audio is sampled into PCM and then that is converted to a pwm signal in a conversion process known as EFM that changes the 8 bit byte to a 14 bit representation that can then be written to the disk as a pwm waveform.
Glad i could help you understand that there is more to the definition of digital other than PCM.
Anything that can be represented by a 1 or 0 is digital and class D amplifiers certainly fall into this category.
Class D is NOT digital.
Sure is. It's not PCM but the output is still a binary output so it meets the technical requirement is digital.
@@12voltvids OK, boomer.
@@Bob.martens that's the best you can come up with when you have been schooled. 🤪
Beautiful D class amplifier... alright, where's my A class?
I need an upgrade to triple A and 1000W radiating rheostat just to load up the lines.
I don't believe any progress has been made in the class D amplifiers in the last 30 years... it's just that the expectations have gone lower and Lower and LOWER.
With the current gen of portable speakers a class D is way too nice for the quality of the speakers... so be it. It's like MP3s... then AAC, the eAAC+... get me an eAAC+ that sounds better than a 44.1 kHz sampled 16 bit PCM: 1982 beating the FUTURE (WAS CD Audio).
We like RUBBISH! I also do... so I speak for myself.
@Douglas Blake no class AB can tough a class D these days. The improvement have been so great in the last few years that i would take class D any day and my standards have not gone down.
most bluetooth speaker's r class D
All tv amps, all cell phone amps, pretty much everything these days.
so empty inside.
Don't need much space. Old amps have big transformers which are not needed on class D
19:15 I disagree with you there. We should be comparing apples to apples. You can still fix a Sansui for a relatively modest amount of money (compared to its value). You can fix any amplifier like the Sansui even if the company that made it has long gone under. This is the case for most amplifiers made before the eighties, i.e. those without exotic transistors or integrated circuits. Compare that with this class D amplifier. If the main integrated circuits (which are really small computers) in it are no longer made and become damaged for some reason, then this will be a pile of junk - or at least the amplifier module will be.
On the Akai amplifier in question: you say you blew your tweeter when you operated the Akai at 40W output. Yes but that is the maximum this amplifier can put out (AM-2450) so it is either clipping at these levels or playing with very high distortion. You should expect your tweeters to be blown in these conditions regardless of which amplifier drives them. The AM-2450 is an inferior amplifier compared to its predecessor, the AM-2400 quality-wise. The AM-2400 sounds very nice indeed. In fact, it sounds nicer than the AM-2600 and the AM-2850 (neither of which will blow tweeters when playing at 40W). Because of the increasing prices of the AM-2400/2600/2800 series, their counterparts, the AM-2450/2650 have also gone up without deserving it. The AM-2850/2950 are a different story. The value these devices enjoy today is also in large part due to their near antique age and the fact that most of them still work without any need for service despite being near antiques. So, we go back to comparing apples with apples. If you were comparing this amplifier with a class D amplifier from the nineties or with a similarly priced class A or class AB amplifier made today, then we would be comparing apples with apples.
@@Douglas_Blake Ok, that's true strictly speaking but there are class D amplifiers which do all the signal processing in the digital domain, i.e. convert the analogue signal to digital. I do not know whether this example falls in this category or the pure analogue class D amplifier type. But this is a little bit besides the point I was making: the chips containing this circuitry are proprietary and not common across manufacturers. You may or may not be able to restore an amplifier should one of these chips fails if the chip used is no longer available. If you do succeed in finding a near equivalent, you will have succeeded in restoring the function but maybe not the sound (as the particular signal processing done in the chip may differ from that in the original - whether analogue or digital).
I understand you are referring to the driver chip only but in some cases it is all one chip, driver and signal processing.
Class D are analog devices. The only "digital" part of them is the pwm carrier on the mosfet and the signal is more closely related to FM radio. The incoming audio is mixed with a triangle waveform into a comparator that changes the audio into a digital pulse train. This drives the mosfets that provide the gain. The carrier is filtered to reveal the original audio.
@Douglas Blake I was simplifying it. The ramp and audio is fed into the comparator in a form of mixing as one signal goes into the positive input and the other the negative of an op amp and the resulting output is then clipped to either a positive or negative output to drive the mosfets.
@@12voltvids For some reason I assumed that all high-end class D amplifiers sold today convert any analogue signal to digital and then do all the processing e.g. volume control, filtering, feedback and PWM waveform generation in the digital domain. That was the source of the confusion. I was not implying that class D amplification itself is a type of digital amplification - at least not intentionally
Now, if we just stick to semantics, the word I used to describe the chip was "computer" not "digital" (there are analogue computers) and the purpose of using it was to convey the idea that this is a very complicated circuit housed in that chip.
But yeah, other than that, I agree totally.
How about the AM-2450? Have you done a video on it? Can you share what you don't like about it, especially in comparison to the previous generation(s)? Akai was not doing well in the eighties. I'm not sure when exactly they got bought off, but they started concentrating on cheaper home audio devices and dropped their quality. But then we had the AM-73/93, AM-75/95 series in the nineties - which for some is their favourite series of Akai amplifiers.
@@Stelios.Posantzis some low end class D also process in digital domain but this is a straight amplifier. No volume or tone controls. Put a signal in, get a bigger one out.
They may sound great and be very efficient but also somewhat unreliable because when they go wrong, they go wrong.
When a conventional big amps goes wrong they also go boom and blow many parts. Direct coupled especially. On these you plug in a new module and you are good to go.
@@12voltvids Yea you are right, you can plug in a new module that cost three times as much as whatever parts a conventional amp would need.
@@tyronenelson9124 but you shouldn't have to because they are very reliable. Much more than a conventional amplifier due to the design. And when you plug in a new module you are not paying someone 200 to change a bunch of parts only to find out that the parts are counterfeit and blows up again a few months later.
What’s THD? & freq. response?
Thd is 0.0007 frequency response 20 - 30khz
Class A or AB for me. Yeah transparent, but dry with no meat on the bone. I'd only consider D for an active subwoofer amplifier. Interesting tunes for royalty free.
Added harmonics.. yeah nice... I rather have true to source...
Time to go back to school. The modern class D blows the doors off ab. Why do you think all the big brands are behind the technology? They sound amazing and can drive pretty much anything. This one drives a pair of Maggie's
@@tacofortgens3471
This does true to source. Tube buffers are used by many for that tube sound which is even order harmonics. That is why tube gear sounds so full. I would buy the new model that has the tube buffer built in just like the 7000 ps audio bricks have. I run a tube buffer on my crest and it sounds incredible.
@@12voltvidswhich tube buffer? VTV ones are so expensive for adding a tube on the buffer board...
@@wyup you can buy many for about 100 bucks. There is nothing to them. Just a unity gain triode. If you buy a new amplifier with a built in tube buffet sure you will pay their price.
What is the source your using?
Cheap mp3 player
What's the most power you've ever used to drive apeakers? I remember once going to 10 watts (according to the amplifier's meters) and I thought the house was going to collapse from the vibrations. This was back in the 80s. At the time, I never understood why people would buy huge amps. If I'll never max out a 40W amp, why pay for an 80W? Of course, the tech back then was different, so maybe it all distorted.
Boring!, your typical high power Class-D amp n I've seen many but I've got a custom built one by me that's been tested long term on a dummy load of 4 ohms that does 625W RMS/ CH but I haven't played with it in a a few yrs, I use to do disco's / nightclubs.
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