Many people like the single ended vacuum tube triode amplifier without negative feedback. For whatever reason it is very popular with some audiophiles. This is the most primitive design that exists. "Lee De Forest invented the audion, a vacuum tube device that could take a weak electrical signal and amplify it into a larger one. The audion helped AT&T set up coast-to-coast phone service, and it was also used in everything from radios to televisions to the first computers." The 300B vacuum tube which is also very popular was I think invented by Western Electric division of AT&T. The triode was an improvement to the vacuum tube diode which consisted of two plates, a cathode that emitted electrons when heated and a plate that attracted electrons. Forming a complete circuit it only allowed current to pass in one direction. Placing a third element, a control grid that is like a screen between them allows a small change in voltage between the cathode and screen to effect a large change in the current passing between the cathode and plate. This is how all vacuum tube amplifiers work. The amplifier is invariably low power because there is always current passing between the cathode and plate regardless of the control grid voltage. This is called class A operation. There are problems with this design besides its low power output. A small change in the temperature of the cathode results in a much larger change in its electron emissions. The characteristics of the amplifier are therefore highly dependent on temperature. This is why some users will allow their amplifiers to be on for an hour before it is "ripe" for listening to. (negative feedback can correct this problem.) Another problem is that the source impedance of the output circuit is very high so an impedance matching transformer is needed to lower the impedance to match the low impedance of the speaker. It also blocks the DC bias necessary to operate the tube from damaging the speaker. I've tried to be objective here but frankly it's not my choice and personally I don't like vacuum tube amplifiers at all. About 15 years ago I went to a trade show sponsored by Vacuum Tube Valley in Piscataway NJ. To my amazement, by sound alone I picked out the only solid state amplifier of all of the amplifiers at the show. To each his own.

Really enjoyed the video. Don`t think I`ve ever had tube amps explained in such a straight forward and easy to understand way. Ordered a small single ended tube amp for headphone listening a couple of weeks ago and looking forward to listening and tweaking. Thanks for all your other videos, always interesting and entertaining.

There is such a thing as too simple, SETs being an example. For instance: 1. The damping factor varies from low to zero as the signal varies and maximum power is achieved. This means the amplifier has little to no control of the speaker drivers/cones. 2. The intermodulation distortion (IMD) is roughly 3 times that of harmonic distortion (HD). So at 5% HD, one can figure 15% IMD. At 10% HD, 30% IMD etc. PP has less problems, and can include even order distortion products if properly designed, just not as much as SETs. 3. Higher order harmonics are in order due to the preceding driver stages having to furnish the large signal to drive the output tubes, 300bs etc. (The harmonics are multiples of the fundamentals. For instance the 2nd harmonic of 1khz is 2khz, the 3rd harmonic is 3khz etc. 4. Distortion producer inductors/chokes are almost always used in the signal path which creates frequency distortion (RCA Radiotron Designers Handbook, by 26 engineers). 5. Interstage transformers are often used, which creates phase shift and limited frequency response (FR) problems, just as the NOS tubes of yesteryear do, with poor specs. The main problem with Push Pull amplifiers is they are extremely difficult to properly design, and be accurate, but it can be done. Otherwise, PP amplifiers pretty much eliminate the problems of SETs listed above. A PP amplifier can actually be designed to be more accurate than any SET amplifier by definition. Very very few PP amps are accurate. Cheers

Great video. Really enjoyed it.

I understand that a single-ended power amp will generate even harmonics. But it also generates odd harmonics, both due to the asymmetric clipping caused by saturation and cutoff in the tube. In a guitar amp, that actually results in more complex overtones that can sound more aggressive than just the odd order harmonics of a push-pull power amp. Then there's preamp vs power amp distortion, sag, and intermodulation distortion caused by heater hum and supply ripple. All these things make a guitar amp pretty complicated.

Thanks man. Best video on the topic on YT.

Good presentation! With just a basic knowledge of the various componets, the viewer should gain a basic theoretical insight into the circuits discussed. I particularly applaud the disclaimers regarding buyer expectations and vendor snake oil claims. These things bear repeating.

Well done. Accurate, simple to understand and common sense recommendations. Perhaps the best SE vs push pull explanation I have heard. Also touching on the topic of quality of parts and transformers as a key ingredient. Also love the switch and jack locations. I built my push pull triode monos using all these same concepts and they sound great. Form follows function and the power is at the back. Signal comes in at the front on one side and out at the front on the other side. So I built them as mirror images and set the source in the middle. Signal starts in the middle and gets amplified to the left and the right with the amp near each speaker. Looks great and is functional.

This has been the best video I've watched explaining this topic. Thank you so much :)

Thanks

Great video! I know a good bit about tube amplifiers myself and everything you said is spot on. Initially I mostly dealt with push pull amps coming from servicing guitar amps, but for hi-fi, I quickly found out that push pull tube amps really didn't sound much better than a push pull solid state amp. The magic with "that tube sound" extended from the fact that single ended amps have a strong second harmonic, which makes the amp more musical sounding. Also, single ended amps have little or no feedback, which also improves the sound. I raised an eyebrow when you mentioned Skunkie Designs as I religiously follow her page and designs. In fact, I want to build the new 12ax7 / el34 amp she just covered, and is also producing for sale. Her EAR phono preamp and the "color" preamp are also of interest to me. When I found you it was the video you did comparing a single ended el84 amp with push pull 6v6 amp, and even on my computer speakers, I could hear the tremendous sound quality difference the single ended amp had over the push pull one. I know the latter well as I also owned push pull 6v6 amp, but I could never get a hum problem solved with it. Even so, I noticed that is sounded only slightly better than a transistor amp. So I sold it and started a very long research path into single ended amps. Now, I am finally going to build one! A bit off topic, but I am curious to your experience with the Hood solid state amp. Thus is another amp type I am researching, as it supposed to be a warm sounding transistor amp. I would like to team up such an amp with skunkie's color preamp for the ultimate in a warm sounding hybrid integrated amp. Great video and keep up the great work!

i appreciate your teaching. good video.

Parts are more critical in a SET amp and differences are noticeable. It's work experimenting and trying various parts in the signal path.

Great video!

Timely. Skunkie Designs covers similar topics and you really provide some excellent tutorials to increase my understanding and knowledge..

Great Video, have you compared any First Watt Sit amps to tube amps?

I would love to see a video on hybrid amps. I just picked up a Dayton Audio unit to mess around with, and I really don't know what to think. I think I like the thing...LOL

No Iron for "best" amp? Output transformers are impedance matching devices and distort the waveform.

Great presentation. Very informative. Thanks. Probably from what im seeing “audiophiles” re-discovered the SET amp designs and then hyped them as oh so special because well thats what they do. Now every shill promotes class D hahaha.

Hi, i bought a tube end amplifier. How do i know it is singele end or push-pull? It sounds good. All i know the big tubes are KT88 and it is hand build by a musician. The seller told me it's 2 x 16 watt. Can provide you some pictures if you want?

I know a HiFi guy that’s all about using 200 dollar fancy RCA cables. Maybe I’m cheap but I just can’t fathom how a 200 dollar pair of RCA cables could sound a 100 times better than a 2 dollar pair of cables. I’m sure they carry a signal that is pure but I don’t think my ears could easily hear the difference but my wallet sure can

You sold the 🦫 Valley The one you had for $1,400 😢 Someone got really lucky. But are you going to sell the SET amp ? Thought you going to make soon That is the question ⁉️ I don't want to miss out again