Fascinating! Enjoyed the video :^)

Greatscott "I can't do it, it may blow up!" Meanwhile ElectroBOOM "Let's plug it in!" * explosion * * profanity * * more profanity *

Tube amps are the normal amps. Solid state amps are the weird ones...

It's rare to see greatScott getting into panic mode 👀

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.

I appreciate your explanation about the pentode and how it's designed

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.

Love your videos! Thank you for putting in the time to do this comparison.

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.

I love your videos. They are well documented and explained. I hope KZfaq gives you credit for all you have done. Keep it up.

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.

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.

Another great video from Great Scott!

Been waiting for a while on this one

Nice and soothing music you played in your guiter ❤️ and also the video is very informative..

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

Amazing video, really intuitive description of tube amps helped me alot :)

Learnt a lot over the last few years, keep it up!

At 6:50 if it was electroboom he would plug it straight in mains 😁

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.

Nice Workshop! Thanks for this detailed analysis.

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!

Would love to see more of you playing the guitar. 😄

Very informative and detailed

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.

I believe your videos are getting better and better! Rob

I learnt it bro and always like you diy or buy episode.👍🔥😎

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.

The photography of you writing is excellent

Love watching your videos. Keep up the fantastic work GreatScott

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.

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.

great video Thanks for taking the time to make the video and share it

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!

Hey, congratulations for getting sponsored by Altium! You deserve it, mate! 👌🏼

I truly enjoy your videos! I’m just a part time hobbyist and have learned so much. Please keep them coming !

3 years waiting this video LOTS OF THANKS

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"

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.

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.

Adding distortion to the signal ? perfect ! that's exactly what we want.

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)

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" 😁

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"

The reason why I love great Scott He is a GENIUS

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.

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 !

As always, a great, educational video!

Always a great day when GreatScott uploads.

Love Altium at work but too expensive for hobby projects. :( Great project by the way!!

I think the transistor amp sounds better, but it's true, clipping on a tube amp sounds miles better than clipping on a transistor

If you want multiple harmonics in music, you can shift the Q bias point of a BJT to get the desired distortion. Great video!

This is so badass. It's my DREAM to build a tube amp from scratch. But I have about 1/1000th of your knowledge. Pretty fn awesome. 🤘

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

Can you make a Tesla coil ( not the solid state one). By the way love your videos love from pakistan

Your explanation of triode / tetrode / pentode was very informative, thanks :)

Interesting video...keep doing this types of comparison videos

Bruh you really used a mains transformer as an output transformer on a SE amp? Without air gap the core just went into saturation...

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

I discovered my tube amp at an estate sale and took it home to refurbish and sell. Only an inventory item that was worth more running than not and not too hard to fix. Both channels were down. By moving around tubes I got one channel up and decided to take a listen to that. I was moved by what I heard. Soon I had both channels up. I was utterly hooked on this thing we call tube sound. That was in 2012. Twelve years later I still have it and because it was hand wired I have made tasteful under chassis changes to bring this ST-70 even more to my liking. Six months ago I added a new source for it. Tube component FM stereo. Even better. When I traveled to the Audiofests in my area where amps started at say 5k$ and top out over 100k$, I noticed about half of the 25 to 30 systems auditioned were tubed and I could tell tubed from not tubed just by listening. It's all in the ear of the beholder.

Vaccume tube amplifies well and sounds very nice

All I work on is Heathkit Tube test equipment and Tube Radio's. Solid state is just not as fun!

Hey Scott how is the weather in Germany

Keep it coming!

I respect you Scott. You take feedback from every comment, even the rude ones. Not everyone can do that. Kudos to you.

Try the EM-84 [or other tube] magic eye tube vu meter. That would look match with your tube amp! Edit: magic eye

You didn’t cover the biasing of the tubes. That’s an important step to protect the tube and get the distortion correct.

i love this videos please keep doing them

Always love your videos @GreatScott 👌👌👌 its very informative for me

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.

Don't wanna use high voltage? try VFD amp. Yes, using a display like a preamp

Great video, keep them coming

Rewatching the video for you Scott ;)

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.

Which voltage regulator can i use which can handle 24v 5 amp input and can output 12 volts plz tell me 🙏

Love these kind of videos based on audio devices

Nice one You voice is sooo relaxing

Amplifier please make video Answer my chat

the tube amp is totally clipping at 9:07

Why does he have to look so good, I'm straight up simping for this guy

awesome, as always!

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.

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

Dude. I have to say your videos are great. I've forgotten how great electronics can be. Now going to build up a new lab.

You are very talented !

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 ;)

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.

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!

You are a great engineer.i sub your channel because of your super easy explanation.

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.

The answer is, and always has been: NEITHER Neither "sounds better" than the other. They just sound "different". "Better" is entirely subjective

That was a polite and educative way to make tube amp people put their pitchforks down. Awesome job as always.

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.

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

You used a power transformer for audio, this is not good. Audio transformers have air gaps to limit saturation of the iron core, limiting distortion cause by the transformer. I usually like your videos, but all you proved was that a sub-optimal tube design may not sound as good a a particular transistor design. No one can draw a reasonable conclusion from this video. All you can say is both tubes and transistors can make an audio signal stronger, which almost all of us knew beforehand.

Vielen dank furs video! Wilkommen bei Michigan.

Really interesting, informative and well made video, thank you.