DIY Tube Amp sounds better than a normal Amp?!
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- เผยแพร่เมื่อ 12 พ.ค. 2024
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In this video I will not only show you how to build a proper vacuum tube amplifier, but I will also directly compare it to a transistor amp. You will hear the audio quality difference between them and I will also show you the difference between them by using an FFT and also by creating a Bode plot. Along the way you will learn all about tube amplifiers which come with a proper tube output stage as well as a transformer. Let's get started!
Thanks to Altium for sponsoring this video.
Music:
2011 Lookalike by Bartlebeats
0:00 I did injustice to tube amp lovers
1:15 Intro
1:54 Tube Theory (triode, pentode)
3:54 DIY Tube Amp schematic
5:51 Building the DIY Tube Amp
6:35 First Tube Amp audio test
7:45 Audio quality comparison
8:59 FFT & Bode plot comparison
9:34 Verdict - วิทยาศาสตร์และเทคโนโลยี
Fascinating! Enjoyed the video :^)
Thanks for the feedback :-) If you enjoyed the video then I think I did not make that many mistakes with the tube design. I mean, I often hear from my viewers that you are very familiar with the technology :-)
@@greatscottlab Well, I've worked on a tube circuit or two ;^) I'm all about encouragement, you did well!
@@MrCarlsonsLab Thank you very much :-)
Fancy seeing you here, Mr. Carlson. Love both of your guys' content, been watching both for ages now.
I see your facebook post i think you should change your style
Greatscott "I can't do it, it may blow up!"
Meanwhile ElectroBOOM "Let's plug it in!"
* explosion *
* profanity *
* more profanity *
Photonicinduction ... Lets give it some more volts
I was looking for this comment 😂
And more pain
Oh and I just remembered the UK hotel episode "Definitely shorted, let's plug it in and see what happens"
@@matthewday7565 naughty boy time ⚡️
It's rare to see greatScott getting into panic mode 👀
It happens from time to time. But not on camera. I thought it would be fun to include it here ;-)
@@greatscottlab 👀👀
@@greatscottlab please new old stock tube, and also complete amo with rectifier tube.
@@greatscottlab Gotta say I love seeing these reaction. Feeling the same way quite often when turning breakers on again after some repairs or renovations of buildings. Especially big fuses are always a little scary.
@@greatscottlab yes .it
I still remember going through an amplifier build with my father over 60 years ago using 6L6's in a Push-Pull Class B configuration. The more things change, the more they stay the same.
The added distortion is mostly 2nd order and even order harmonics. This happy coincidence gives a pleasing depth to the sound. Like having 2 or 3 talented back up guitarists. For other applications you’d have to filter all that out but for music it’s awesome.
That's true in class A, but most tube power amps are class AB and produce only odd harmonics, so use of a tube preamp with a solid state power amp hits the mark if you want even order tube distortion. That being said, there is some asymmetry in the class AB stage usually introduced by imbalance in the phase inverter tube or circuit, which adds some even harmonics back. A lot of what we associate with the tube sound though is actually interactions with the output transformer and, in older designs, the tube rectifier. Many tube power amps also have minimal negative feedback, giving a more gradual breakup than a typical solid state class AB design, even if the distortion is mostly odd-order still. The tube power amp built in this video is an exception because it is class A, but most of the cherished amps from Fender, Vox, Marshall, etc. are class AB.
@UCY--FesMnRbnw_0rpx954HA I agree. Douglas Self on power amps design says the same thing. If distortion in hifi systems is a desirable effects, then there must be a switch or a know to turn it on and off, just like tone controls on preamps. If distortion is purposely ingrained within the power amp circuit, that defies the point of hifi
ODD order harmonics are the pleasing harmonics that you get from, say, a wind instrument. Even order harmonics are a lot harder on the ear; steel and heavy metal.
Tubes are inherently nonlinear which creates intermodulation distortion but NOT usually the evil twin "clipping". Intermod is when you have say, a 200 Hz signal and a 300 Hz signal and after amplification, not only do you have the 200 and the 300, but sum and difference frequencies 100 Hz and 500 Hz at a much reduced level. Because the products are harmonically related it does make the sound a bit "warmer" and that's an effect that many people prefer to strict scienific accuracy and an amplifier with a damping factor of 1000 or more. Tubes have almost NO damping factor if I remember right; the ability to absorb and control the energy developed in the speaker itself as the voice coil moves through a magnetic field.
@@thomasmaughan4798 I dont think that damping factor has to do with intermodulation distortion. It is the ratio of the speaker's impedance to the output amplifier impedance.
@@rafgaming709 Correct - damping factor only really comes into play when phase shift is near zero in the driven system (resonance) or if your output impedance is grossly inadequate. In other conditions the negative feedback of the amplifier is incapable of correcting loudspeaker nonlinearity due to the phase shift in the loudspeaker. Damping factor is typically a worthless spec that is trumped up on hi-fi products to have another big number to brag about.
I have no idea what @Thomas Maughan is on about because intermodulation distortion is highly unmusical, resembling the sound of a ring modulator, and is generally to be avoided at all costs unless you want an unintelligible sound. You also can't produce intermodulation distortion separately from harmonic distortion in an amplifier circuit - they are always co-present. A great example of horrific intermodulation distortion can be had by running any loudspeaker past its linear excursion, especially with regard to the magnetic circuit. This is of course part of guitar sound in many cases because guitar speakers have very little Xmax, but for music reproduction it's never desirable.
Regarding odd vs even harmonics, that's backwards as well unless you want to get into the subjectivity of "pleasing". Low-order even harmonics, by definition, produce octave overtones and result in a coherent, "singing" sound on single notes, but typically the intermodulation distortion of a circuit that produces mostly even harmonics is more pronounced as well, souring chords. Odd harmonics provide the thick, hard-edged, brassy sound associated with crunchy distortion in the guitar/music production world because their relationship to the original sound is not a simple octave effect. Again though, intermodulation distortion is a huge part of traditional guitar tone, adding false bass notes that increase the perceived power and fullness of simple intervals like the fifth and octave, special cases where the sum and difference products are harmonically related to the original signal.
"Overdrive" style guitar distortion keeps chords from sounding unintelligible by applying a high-pass filter as pre-emphasis before/during clipping in order to prevent intermodulating the fundamental frequencies of the notes being processed, thereby maintaining enough information for your brain to determine what the original notes were. You'll also find a lot of high-pass filtering in high-gain guitar amplifiers for this reason.
The man is an electronics genius, a terrific educator, a good guitar player, and good looking to boot! What can't he do? Also, you should totally have a second channel where you play guitar and do covers.
Oh stop it :-) I am actually not that great with the guitar. Still lots of learning/practicing to do.
Terveisia Israilista
I agree so. He is my inspiration in electronics.
Nice handwriting too
I agree in everything expect being a good guitar player. He was mediocre at best.
I saw your community post today, so I figured I had to get in and watch this. I got the notification yesterday, but it was one of those "add to watch later" days, but that list only seems to get longer, so I'm glad the community post reminded me to come back to this.
You put so much into your videos, and it's very clear how much joy teaching electronics brings. Keep up the fight, the world needs to know this stuff!
Thank you for revisiting this! It would have been nice to see a bit more about the harmonic distortion on the scope, but I'm glad you gave this an honest try.
Thanks for the video. I have built many transistor and Tube amps. My overall preference is for the Single Ended (class A) tube amp. With modern capacitors and transformers and just a little feed-back, they sound great.
Using a non-gapped (ie. mains transformer) for a single ended output of the 6L6 will affect the output quality and frequency response significantly even if the the impedance ratio is correct. The flattening of the part of the sine wave and hence increased distortion are partly the result of this.
Ya and add a 10henry choke and better filter caps and test the ac after the filter capacitors I have built some very poor sounding tube amplifiers and some very good sounding ones
Also soild state amplifiers are great for low end bass but honestly if you own a 1950-1960 hi end stereo tube amplifier and play the music of that era it was recorded on it cannot be beat
But if you play something that was recorded today with digital and effects it just doesn’t sound right it’s all subjective in all accounts
And Celestion Greenback and a Hammond OT too :)
I appreciate your explanation about the pentode and how it's designed
I love your videos. They are well documented and explained. I hope TH-cam gives you credit for all you have done. Keep it up.
Love your videos! Thank you for putting in the time to do this comparison.
Thanks for watching!
Nice and soothing music you played in your guiter ❤️ and also the video is very informative..
Thanks a lot 😊
Love watching your videos. Keep up the fantastic work GreatScott
Amazing video, really intuitive description of tube amps helped me alot :)
You deserve more recognition! I hate not seeing when your videos come out because I always look forward to them. I wish you luck on this platform, thank you for always creating quality content for years
At 6:50 if it was electroboom he would plug it straight in mains 😁
:D
Yeah, and he would have put a capacitor or something backwards causing it to blow up.
First thought when he wanted to plug it in was about electroboom
Remember Electroboom has weak/safe 110v mains......but the joke still stands ;)
Awesome video! I'm an electronics engineering student and get very excited with your videos! This one does match the stuff I'm learning these days.
Nice Workshop! Thanks for this detailed analysis.
The output transformer of a tube amp is very important. Size does matter as well as closely match impedance between tube and speaker. The bottom end will thank you. I've yet to hear a transistor amp sound as warm as a tube amp.
Tube amps are the normal amps. Solid state amps are the weird ones...
Amen
I truly enjoy your videos! I’m just a part time hobbyist and have learned so much. Please keep them coming !
theyre fun and interesting for me, but cant really recommending to others
Always love your videos @GreatScott 👌👌👌 its very informative for me
Great video man, as a guitarrist I think the point of tube amplification is in overdriven sounds, for clean guitar it doesn't matter so much, and in fact I think there are some legendary amps for clean guitar that are transistor based.
However the warm overdriven tones you get with tubes are irreproducible with transistors that have a very nasty sounding saturation.
yep I feel like this is the main distiction it should be made when saying which one "sounds better", does better = cooler effects or accurate reproduction?
Would love to see more of you playing the guitar. 😄
Diy is Win
Maybe I can include my guitar more often in future projects ;-)
@@greatscottlab diy wahwah pedal. Just guessing, it is a fancy tone knob. Lord knows you're a voodoo child 🙏😎
@@greatscottlab You could build a guitar amp and make a video on it, that would be awesome 😅
@@greatscottlab Maaaate, I would watch the shit out of guitar related content.
The photography of you writing is excellent
Although sometimes I don understand a thing, love your videos and it makes me study
Nice video and yes, everything has a chosen purpose. You are absolutely right that transistors will get you better efficiency and much lower total harmonic distortion (THD) which is important when you want to faithfully recreate a signal (say at the recording mixer in a studio). However, one of the reasons tube amps are so popular amongst guitarist, is that certain kinds of distortion modes are highly desirable, along with the needed amplification. You have a class A design here, likewise, class AB along with the effects of magnetic saturation and loudspeaker type/size and speaker cabinet all significantly affect/color the linear and non-linear responses of the sound. From an artist perspective the sum of all of this it is referred to as "tone" - which means more than adjusting the treble and bass knobs btw. Also, electric guitarist use lots of "petals" between their (carefully chosen) guitar and the input to the amp. Some of these are "over-drive" petals, and are specifically designed to drive excess signal levels into the preamp of a tube type amp (but not a transistor amp). Tubes have a softer (slower) distortion characteristic (compression) than transistor circuits which remain linear until they hit the supply rails and "clip" the signal. Transistor clipping is harsh and generally not considered musically pleasant, whereas, tube amps have a non-linear gain that allows a wider range of operation before hard clipping occurs. This allows the musician to adjust their rig so they can play softer or harder, and control the transition of clean to dirty sound. BTW, it is worth mentioning that DSP technology has come a long way in reproducing these characteristics, see the Kemper and Line6 product line. Lastly, when you used the variac to bring up the plate voltage, I couldn't help but think of Eddie Van Halen, as he made this famous by using a variac to lower the plate voltage of a Marshall Plexi amp to achieve a seriously iconic sound (along with a lot of other things to go along with this too). FWIW, I grew up in a TV / Radio repair shop as a kid and it encouraged me to get a MSEE - additionally I am also a guitarist (since early teen years). Now, my oldest son is halfway through his EE degree... my how time flies! Love your channel - keep up the great work!
Also it looks like the most popular guitar speakers no mater what brand have really "low-fidelity " deformed spike in response in frequency around some popular guitar solos range done by famous guitarists and that makes everybody so subjective... tubes were the hippest amps made during famous 60-70 world rock stars and that's why they are still so popular...to design a very good tube amp has to be with driver transformer pushpool tube and very good transformer with special simetrical sections.. also the core laminate should be less than 0.2mm and silicon or permaloy, mumetal etc...there will be very good rezults but very expensive and very heavy...
This is also a good example of radio amplifiers for ham radio operators. The larger size amps still use tubes for amplification for the money spent, it’s sad to see that there will probably be a lot of distortion from higher harmonics.
Yes, but it is even order. This is pleasant.
1000 Watts for a Ham should be a good build its the maximum ands there should be lots of good parts and designs like the classic WW 2 American 5 coming at you mean and clean I thing the radio set on Apollo was 25 Watts if Im not mistaken cheaper better faster good tech always keeps hanging around careful pushing the power :)
RF power amps are usually class-C anyway. So there will be plenty of harmonics regardless of output device. However, only the fundamental frequency is required so the load (output matching and antenna) resonates at that frequency and also enough filtering is used to keep the FCC, or equivalent, happy.
Another great video from Great Scott!
Great video, well explained👍
I hope the thumbnail swap helped a little bit, I watched the video twice😉
Continue doing these kinds of videos, they are really informative!
Just a small heads up for if you are ever going to revisit this again, but the thing that's most likely holding you back is the output transformer. For single ended tube amps the OT is normally air gapped to prevent saturation from high idle currents. Regular center tapped power transformers or ELA line transformers work for push pull designs but purpose made OTs generally offer much better linearity. There are also special ultra linear OTs with an extra windings that feed the screen grids and through some magic make the response even better. Good sources in germany are tubetown, tubeampdoctor (both more towards guitar amps) and "Frag Jan zuerst"
Very informative and detailed
Glad you think so!
Learnt a lot over the last few years, keep it up!
great video
Thanks for taking the time to make the video and share it
I learnt it bro and always like you diy or buy episode.👍🔥😎
Glad to hear that
Great video, but I thought I'd point out something important that seems to have been missed.
When you have a single ended amp like this, the output transformer has to have an air gap in it for it to work properly in this situation. A repurposed power transformer isn't going to have one.
As otherwise you are going to saturate the core with DC.
@@thomasmaughan4798 look at the bode plot section. That thing is just waiting to go into self-oscillation.
Yup, that distortion is core saturation. Also, altough only for hifi, feedback is very commonly used and brings distortion way down.
Also, there are other factors that sum up for a good output transformer, like the material of the core, interleaving, inductance and auto capacitance.
With a power transformer instead of a proper output transformer, he's basically hijacking the results.
@@joseislanio8910 yeah, this whole build is extremely amateurish. if you're going for a diy tube amp, there are plenty of legendary schematics that you can even modify to your taste for an amazing result; going for the right components, especially the output transformer (old guitar builders say the OT is 70% of the tone) is critical. also, without a guitar speaker it will always sound like shit.
the SS tone in this video sounds like shit, the tube one also sounds like shit. as someone that built and modded a few tube guitar amps, if a diy guitar tube amp doesn't make you jizz your pants, especially a class A one, you're doing it wrong.
Your explanation of triode / tetrode / pentode was very informative, thanks :)
My pleasure!
So so much talk about vacuum tubes but I have not seen anyone explain what speakers are needed for them. Speakers also play an important role, but we are not talking about specific models for this. Thanks for the invested and beautiful video.
I tried building class A and AB amp circuits with no success , I had to surrender and use discrete ICs , the results were spectacular with the TDA2030 but I think that my response wasn't flat , great subject though ! Please make more videos on amps !
Would be neat to see him follow up with a Class D design...that just blows all others away.
dig into it's internal schematic to figure out how it works
@@toddmarshall7573 from an efficiency stand point sure , but if you want max quality class a and ab are better , class d basically you're listening to a filtered square wave .
@@1900OP too complicated and too many components inside those ICs , you even have to match transistor gain across transistors . That's too much work !
@@piiumlkj6497 That's the limit you put on yourself.
It's not really 'tube sound' it's 'transformer sound'. The output transformer being a reactive component, has the biggest effect on the sound. Transistor amps don't use transformers so you don't get the same effect.
I believe your videos are getting better and better! Rob
If you want multiple harmonics in music, you can shift the Q bias point of a BJT to get the desired distortion. Great video!
As far as I know tube amps are only really useful when you want to get tube overdriven sound (and it is quite remarkable), which basically leaves only guitar amps, since for a normal amp you want no distortion of sound
I'm sorry , I beg to differ tube amplifiers have much more use than just to get over driven sound, a very well designed tube amplifier can sound more pleasing than most transistor amplifiers , at least to my ears , and in fact many audiophiles or music enthusiasts prefer tube amplifiers... although solid state can sound very good as well. Audio lovers that have auditioned many kinds of amplifier designs usually have a preference for one or the other, although the actual sound quality of and amplifier design whether tube or solid state is most influenced by the actual design and implementation, both can sound very good and both can sound bad. - My choice was governed by having a fairly complex and power hunger set of speakers NHT 3.3's, they were a 4 way design that needed some serious power to reach their full potential , my choice after listening to dozens of some of the best tube amplifiers and solid state amplifiers at that time - (this was in the mid 90's) - was a pair of Monoblock Tube amplifiers - a VTL MB300 DELUXE tube amplifiers that put out 300 watts , and they sounded So Good together , made you grin from ear to ear. When it comes to sound quality the only thing that matters in the end is how an amplifier or any other piece of audio equipment sound to you personally.
@@deanhalleck5738 "very well designed tube amplifier can sound more pleasing than most transistor amplifiers"
Or in short - a highend, very expensive setup CAN sound better than a dirt cheap one - what a wonder.
For the same complexity or cost a transistor-amplifier simply is superior.
@@deanhalleck5738 yeah the heavy tube amps I had a pair of multitones mono blocks 8 tubes each (8 times el34) they got really hot I used them for some live setting but decided I better use the class D amps. I sold them but good lord they were some heavy tube amps really awesome. They had the full 200/300 watts when I hooked them up to the AR3a's it was like some giant rubber hammer had landed in the room. that was some serious tube power :)
Hey, congratulations for getting sponsored by Altium! You deserve it, mate! 👌🏼
Thanks :-)
Something to consider are the types of tubed. Some are designed for a more clean sound and some are designed for distortion. That can also be a factor, along with tube bias and warming the tube up to get the ideal performance. But very informative and nice job as always. Ill always be a tube amp man, when set up properly they are warmer and less harsh.
Brilliant video, as per, my first job was a Saturday job at a local music store, one of my fellow Saturday workers was told to wire up 2 WEM 4 x 12 PA cabs, he did directly to the mains, it made the loudest sound and explosion I have ever witnessed. We were then all given a lecture on safety, as apparently when electric guitars first came on the scene some customers had cut off the jack plug and fitted a mains plug, "BANG"
i recommend doing a thing called bi-amping where you combine a tube amp and a transistor amp to get the "distorted" sound of a tube amp and the bass response of a transistor amp (can only be done on certain speakers)
Love Altium at work but too expensive for hobby projects. :(
Great project by the way!!
Yeah that’s what I don’t get about the Altium ads on several channels. Almost no viewer will be willing to pay 300 bucks per month for the industry standard PCB designer. I simply don’t get what the target audience is for these ads.
you know, you can go to "grey" zone and be a pirate. cracking Altium is not hard, but you have to do your own research, i cant tell you for obviously reason
@@ThePunischer1000 People who willing to install "non-legal" software. If you has searched about it, you will be surprised by how easy to bypass Altium security.
I think they are intended that way, to make more and more people using Altium, so that when those people apply for a job, they will tell their boss to buy Altium, since that what they are familiar with.
I believe this is also business model of Winrar
I doubt you will need the full Altium Designer for your hobby projects. CircuitMaker is free, and CircuitStudio is at least affordable. I agree that the Designer is a bit pricey for non-commercial use.
I don’t plan on using an illegal copy of Altium, since I have access to it through work anyways. I tend to use KiCad for simpler projects.
great review
great comparison
thanks for sharing your experience with all of us 👍😀
Hi Scott, another thing that’s known about tube amps is that they sound the best cranked up. I don’t know if in the audiophile world this holds true but in the guitar world it does. Due to the hysteresis of the output transformer, it starts to compress the sound. Speaking of transformers, many audio engineers pass the signal from the microphone through a Neve 1073 pre-amp sometimes without any filtering just to capture the sound of the transformer. So that being said, I think a part 3 is warranted where you can explore the effect a transformer has in an audio amplifier.
Bruh you really used a mains transformer as an output transformer on a SE amp? Without air gap the core just went into saturation...
I tried flyback transformers but none worked. The amp actually sounded pretty good with the transformer I used.
@@greatscottlab Yes, but from what I have seen at the oscilloscope there was something clipping, probably wasn't fault of the core saturation but was fault of the primary (mains voltage) winding DC resistance...you should have put the oscilloscope on the anode of the power tube and with a variable resistance instead of a fixed value one, you should have calibrated properly the mid-point... It would have sounded ways better!
Anyway, great video! Bye :)
@@fabriziobrutti1205 Thanks for the feedback :-)
As long as the transformer is big enough this should not be that big of a problem. I have used an oversized power transformer for output in a test before and it worked fine (but that was something like 250W transformer for maybe 1W output), not as good as a proper audio output transformer (it's not just the air gap, the windings on an audio output transformer are different to allow better HF response), but could be good enough.
There was visible clipping in the waveform though, maybe the amp was overdriven or the bias was wrong?
@@Pentium100MHz Not just different core material. On a proper output transformer the windings are split into several alternating layer for better coupling. But yea, the air gap and the alloy is more important.
Yes the tube amps sound great when overdriven. I play metal guitar and I love the tube amps for this. With a good tube amp though they can sound really nice and clear when not overdriven and produce a clean guitar sound. Transistor amps are fun too. Everything has its place.
I hate the sound of either amp being overdriven so I prefer the sound of a transistor amp.
Thanks, I wanted to see the comparison of FFTs of both amps and you did that well :)
Great video, but i was super interested in the Bode plot for both out to high frequencies
I think the transistor amp sounds better, but it's true, clipping on a tube amp sounds miles better than clipping on a transistor
An amp should never clip. Either buy more sensitive speakers or a more powerful amp
Xavier Monteballan I think he means when purposely overdriven like in a guitar amplifier
@@xanderguldie clipping is used on guitar amps all the time. Purposely overdriving and distorting signal is part of electric guitar music.
@@Valtra103 yeah, the other dude also pointed that out and you're correct. I was also aware of that fact, but since we're on the subject of high end audiophile gear in was only talking about those kind of amplifiers.
@@xanderguldie And you are right in case of recording reproduction. Clipping should never happen in that case. I Would even say, nearing to it is already bad, when distortion spikes.
Can you make a Tesla coil ( not the solid state one). By the way love your videos love from pakistan
I can put it on my to do list :-)
Great video! As a future electronics technician and a kinda musician myself, I think it would be awsome to see you make a video about electric guitars
Interesting video...keep doing this types of comparison videos
GreatScott knowing everything is ok:
"No, I can't do it, it may blow up" 😐
Meanwhile ElectroBOOM knowing something is shorted:
"Let's plug it in." 💥💥
Photonic:
"Let's OVERVOLT it" 😁
Dave Jones: don't turn on take it apart.
You dont solder directly to the tubes because quick thermal expansion creates micro-cracks in the glass causing slow air ingress and tube degradation when used.
didnt know that. thanks for sharing
Really interesting, informative and well made video, thank you.
Thanks for the great videos - Much appreciated.
Sir, thank you for this video. I hope you will permit some observations.
1 - Your valve amplifier has NO NEGATIVE FEEDBACK (NFB). The Fender amp to which you referred almost certainly had. Your semiconductor amp certainly is heavily fed back.
2 - You are comparing a low-level semiconductor circuit with a power valve circuit which is obviously unjust. It would be fairer if you compared it with the 12AX7 WITH NFB APPLIED.
3 - If you really wanted to compare like with like, you might take such a circuit as the Mullard 5-10 valve amp and compare it with one of their 10W transistor amplifiers.
4 - To apply simple NFB to your valve amp 12AX7 , I suggest omitting C2 and C4 (the cathode bypass Cs).
5 - Apply NFB to the output stage which includes the OP trans. Connect one side of the output transformer secondary to ground, and feedback through a high resistor - maybe 1M - to the cathode end of the now unbypassed R4. Start with high R to see whether the amp oscillates. If so, reverse the connections to the OP trans sec.
6 - For the OP stage feedback, first measure its gain (A) from grid of the OP valve to OP trans sec. Then arrange the feedback ratio to be between 1÷A and 2÷A (that's R4 ÷ new feedback R from OPT sec)
7 - To refine the circuit, insert a 100R resistor at the ground end of R4 and feedback onto its junction with R4. Reduce the feedback resistor in proportion with 100R to retain the same feedback ratio. For more info on OP stage NFB on single-ended valve amplifier, see www.r-type.org/articles/art-003h.htm which will include some phase correction for the OP transformer.
8 - Please note the suppressor grid's function. The low-energy electrons emitted by a warm anode are referred to as "Secondary emission". The suppressor grid's function is to creating a weak reverse electric field. This doesn't affect the higher energy electrons from the cathode, but serves to repel - or suppress - secondary emission. It doesn't conduct them to the cathode. Incidentally the 6L6 is a beam tetrode with beam-forming plates instead of a suppressor grid. They're connected to the cathode and suppress secondary emission by beam-forming the electron flow to the cathode.
9 - The absence of an OP transformer from semiconductor amplifiers removes two problems that exist in valve amplifiers: (i) the OP trans introduces distortion and limits the OP stage's bandwidth, both LF and HF. (ii) Because of (i), there is a severe limit to the level of NFB within the limits of amplifier stability. So the semiconductor amplifier can sustain a very high level of NFB whence a very low distortion.
10 - The wasted power in valve amps weighs against them also.
11 - There are some hifi addicts who still say valve amplifiers "listen better" than semiconductor amps. Where you and I listen to the music, they listen to the distortion. To each his own.
12 - Finally, I explain that as an 80 year old (retired) electronic engineer, I've designed with both thermionic and semiconductor technology. I remember lots of folk who claimed that they "Knew all about valve circuits but couldn't get on with transistors". A few penetrating questions usually showed that they didn't know all about valve circuits anyway. Now I encounter people who claim the reverse. And some of them actually do understand semiconductor circuits. Just some of them.
You didn’t cover the biasing of the tubes. That’s an important step to protect the tube and get the distortion correct.
Didn't cover many things. Layout being another critical item
@@kbkman7742 I totally agree ! Heater filaments wiring must be twisted and positioned in such a way that their magnetic field don't interfere with the signal. As such, perf board is really not adequate for tube amps circuitry and having components on both sides makes things even worst I imagine. But for someone who has never made a tube amp, he did pretty good nonetheless !
@@unboxedtravels there is so much to even a simple valve circuit.... you can spend years studying it and still not understand design nuances. To slap a little circuit like that together and suggest it's representative is profane
@@kbkman7742 what do you expect from someone that confuses octal and noval sockets? it's clear that he's an absolute amateur when it comes of tube amps and does not yet grasp basic concepts.
there's a reason why his "tube" amp sounds absolutely awful. (actually many many reasons, besides all you've said, appropriate speaker and lacking an adequate OT transformer are also big factors).
Vaccume tube amplifies well and sounds very nice
The reason why I love great Scott
He is a GENIUS
Hard to tell much of a difference with an acoustic/clean tone, but hit them with enough signal to drive the power amp into clipping and it'd be night and day. Solid state tends to hard clip and produce mainly odd order harmonics that sound "harsh" or "fizzy", while the tube amp will have a more musical or "singing" overdrive due to more even order harmonic content.
This is the very reason why
vt-amps with higher THD than transistorized-amps would still sound better and more pleasant to the ears.
You should definitely use an actual output transformer or at least a transformer with an air gap. This way your get way more power with way less distortion
Been waiting for a while on this one
It was either my dad, or my electronics teacher back in college who made the comment comparing vacuum tubes to transistors for audio of the fires. One of the other or both said that the clipping from transistors is what makes them sound harsh and not as nice sounding as vacuum tubes. So the residence/harmonics are what makes the Richard tones using vacuum tubes
All I work on is Heathkit Tube test equipment and Tube Radio's. Solid state is just not as fun!
the high voltages terrify me. How did you get started on tubes?
@@kentestes192 - When I was 9 years old in the 60's, I was repairing TV & Radio's for my neighbors. I also worked in a recording studio. Always loved electronics and grabbed every electronic magazine that I could get my hands on! In early 70's while in the Army I taught, HAM Radio, Telephone Systems, Basic Electronics & Microwave Propagation.
From 1976 to 1980 I worked for Heathkit. I then got into the Network industry for 35 years designing NoveII Server's, and Cisco Routers.
After retiring, in 2004, I was bored, and a light bulb came on one day, and I remembered how much I missed electronics, so I setup shop and the rest is history. I was hooked again and went back to restoring old tube gear. So now I'm 73 and love working with old tube gear once again in my 'Man Cave' !! :)
Hey Scott how is the weather in Germany
Very nice :-)
the weather enjoy and your longboard takeSo
3 years waiting this video LOTS OF THANKS
As always, a great, educational video!
Try the EM-84 [or other tube] magic eye tube vu meter. That would look match with your tube amp!
Edit: magic eye
It´s a magic band, not an eye.
EM11 is an magic eye.
@@MultiWirth I mean- the tube with little screen in them that display either a lines/circles/fan etc and its glowing blue or green
Which voltage regulator can i use which can handle 24v 5 amp input and can output 12 volts plz tell me 🙏
Use a switching one. There should be tons on Ebay.
@@greatscottlab thank you very much
This one for example: de.aliexpress.com/item/4001038505321.html But a 12V power supply might be better when it comes to switching noise.
You are a great engineer.i sub your channel because of your super easy explanation.
Awesome video, thank you! What were the specific distortions you were seeing with both amps? Could it have been due to the transformer or tubes specifically?
Don't wanna use high voltage? try VFD amp. Yes, using a display like a preamp
is it possible?
@@amd6474 yup, and it looks beautiful too, when in use
Personally, I hear your sample the transistor sounds more clear than the tube. Tube is as if there is a small background noise, same noise as when listening to a radio station with a weak signal
That is the mains voltage frequency.
Coming from a musician’s standpoint - nothing beats the warmth and grit of an overdriven tube amp. Before leaning about electricity, I wasn’t concerned about efficiency. Nowadays, I find it more interesting and amazed at how they engineer these circuits, but would still select a tube over transistor strictly due to the sound.
Amazing video!!! Would you be able to go over different capacitors inside an electric guitar and why it alters the sound? I think that would be another great video.
Nice one
You voice is sooo relaxing
Amplifier please make video
Answer my chat
I will gona come Germany 🇩🇪 next month
Hope you meet scott
Ok
Answer my chat scoot
I did tons of amps videos before. Just search for "amp" on my channel. Not hard to do.
the tube amp is totally clipping at 9:07
It would be interesting to find out why the tubes are more prone to harmonics than the digital amp. There must be a reason for it. Other than the overdriven sound, I didn't hear much difference between the two in the short demo here. Further proof that preference is in the ear of the beholder. Thanks for sharing!
i love this videos please keep doing them
Unless you’re a musician who simply can’t deal with one of the millions of perfectly fine VST or stomp box modeled tube-overdrive options, then you really don’t have much of an argument for a tube anything outside of aesthetic value. Maybe musicians or sound engineers who are driving an all-analog signal path for a project, or picky guitarists who want a classic stack. But most audio tube thingys sold today are of the “tube-preamp” variety, and are targeted at audiophiles (audiophools, more accurately). They’ll insist a tube-pre is necessary to pair with their equally overpriced turntable, else they’ll spoil the vinyl experience. Of course, the tube-pres work fine usually, but you could easily replace the guts with a modern high quality pre and they’d never know the difference so long as they visually see a pair of glowing glass bobbins.
People seem to pretend we're still living in the dark ages of electronics. With 24bit/192kHz AD/DA converters and powerful DSPs being a mainstream thing, one can model any ideal (and non-ideal) filter and replicate anything that analog tube electronics from the past would have produced.
But as long as people buy oxygen-free copper cables, there will be a market for tube amps.
I’d have to disagree. To me, the appeal of a tube amplifier comes from the simple and easy to understand nature of how vacuum tubes work, and that you can visually see the individual parts that make it work (ie: heater, plate, grid &c.), which is something that neither software or solid-state components can achieve.
Your choice of output transformer is more than questionable. For single ended amplifier, like yours, you can't plug any transformer due to significant DC current flowing through primary winding, saturating the core, which results in distortion and loss of lower frequency capabilities of the amplifier. Output transformers for SE amplifiers have an air gap in their cores, which prevents the core from saturating.
Yep. Correct. I did not have a fitting flyback transformer though. The shown transformer however did an awesome job. I tried ordering a fitting transformer for this task but could not find one.
Rewatch 5:40 It also wouldn`t change anything about the comparison.
@@marvin1432 It would definitely change a lot, this core is saturated. Mains transformers are not designed for operation with DC current. This amplifier, judging by the FFT plot, is badly distorting and I suppose this is the main reason.
@@greatscottlab There are output transformers always available. You can either pay a lot for a new Hammond one from Mouser or buy an used one from eBay. There is plenty of old transformers pulled from radios, they are usually designed for EL84 though, so they won't match a 6L6 (too high DC current, too high output power - core will start clipping as the first component in the whole amplifier).
Also: you've omitted the negative feedback completely. One of the secondaries of output transformer should be connected to the circuit ground - I believe you've managed to do it the long way through earth connection of the scope? And lastly: Fender Champ is a guitar amp, it's... designed to distort, or at least its high distortion made it very popular among guitarists :)
If you plan to ever make yet another tube amp, I would be happy to help you build it properly. If I knew earlier I would save you some costs, as a ECL86 tube is enough to build a whole amplifier - containing a triode and pentode in one envelope, capable of producing few watts, and lots of radio pulloff transformers match it. And also measure it properly, for audio measurements line input of PC is better than an oscilloscope, Rightmark Audio Analyzer will do all the measurements for you.
Thank u Scott!
Great video, keep them coming
Tubes are great for adding "color"/"warmth" to a signal, which might desired for recording. Replication, adding "color"/"warmth", to me seems like an FU to the recording engineers effort to make the recording a certain way.
Also DSP technology for emulating tube instrument amps have come a long way, and way more efficient.
Exactly my thoughts: recorded and mastered music must be reproduced as precisely as possible! If harmonics are needed for this particular music, they were added by sound engineer already, don't touch recorded and mastered music with your dirty distortions.
Yes, these distortions can be good and desirable when you record your own music (think: guitar amp), but recorded music must be played as intended by authors.
You don't add new chapters to published novels and you don't cut and re-edit scenes from movies.
Why do you add your own sound to music?!
TLDR: everything you said in your first video holds up. Tube amps waste a lot of power, are bulkier and add distortion to the sound.
Some people like distortion on their sound equipment ;)
They use a lot of power not waste it and it's actually a sweet sounding distortion.
It's heat, that's called wasted power. Distortion is distortion. As I said, some people like distortion on their sound equipment 🤷
You are very talented !
Great video, very informative.
The answer is, and always has been: NEITHER
Neither "sounds better" than the other. They just sound "different". "Better" is entirely subjective
True
My friend how use Tube amp with a speaker set: it better it a "real" analogue sounds.
Me who use a USB head phones with a lot of features: go on
Thanks for your video, just posted my recently built tube amplifier.
Keep it coming!