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What is the Single Ended Triode thing?

There have been some great comments on this thread. In particular I appreciate the comments made by @RichardAusten above.

I have a few thoughts on this topic. I own and enjoy a modest 300B amplifier with 93dB efficient speakers. I also use well-maintained Quad 2805s, driven by a Quad 909 SS amp. I tend to listen at lower volume levels, typically much less than 80 dB. I have used my lowly 300B amp to drive my Quads. It can be done! I think the 909 sounds better with the 2805s. A bit fuller. More dynamic headroom. But the 300B on the Quads ain't bad, long as you don't ask it to tear the roof off the sucker, volume-wise.

My modified Audio Electronic Supply SE-1 has point to point wiring. The circuit is very simple. Low parts count. No negative feedback. I'm not using exotic or expensive 300Bs. It sounds great with the 93dB efficient JBL 4430s. With the 300B the JBLs often remind me of my Quads. Their tonal accuracy when reproducing the sound of a Fender Precision or Jazz Bass or stand-up bass is wonderful. They are capable of delicacy, nuance, finesse and gut-wrenching high powered FUNK, soul, blues, dub, reggae and whatever kind of electronica, hip-hop or guitar shredding rock you want to throw at them.

The criticisms often levied at 300Bs would, I think, be applicable if I were listening to small, inefficient box speakers with tiny woofers at high volume levels. That's not what I'm doing. When I listen, I don't hear distortion or weak, flabby bass. I hear rich, dynamic, live-sounding and feeling music with beautiful, accurate, rich tone. Would I like to hear them with super-high-efficiency speakers, like Altec VOTT? Sure. But for their studio monitors JBL always prioritized the ability to reproduce the lower frequencies over high efficiency, so instead of 100+ dB efficiency I have 93...Oh well.

Note - my wife and I had the good fortune to attend a live concert recently. Marty Stuart and the Fabulous Superlatives, at the Admiral Theater in Bremerton. Fabulous show. Fabulous sound. I used my decibel meter to check several times throughout the show and the VERY LOUD volume level was steady at ~95dB. We were sitting in the balcony. It was plenty loud. Check out his album "Way Out West".

My point is that I seldom drive my 300B that loud. At that volume it would be using about 2 watts and would still have some headroom. At my normal listening volume it is coasting. Personally, I love the sound of the 300B tube.
 
SET amplifiers do not have a singular sound so conversations about them can be difficult. I have lived in Hong Kong a mecca of audio gear. A dealer I often go to is an Audio Note dealer - arguably the king of SET amplifiers because they make more of them than anyone else. As such, I have been able to make direct comparisons. Audio Note uses various levels so level 3 amplifiers are Single Ended Triode and within that level are various SET amplifiers that use 2a3, 300B, 45, 211 output tubes. They all sound different from each other. So which you like will more or less depend on your taste and what you listen to and how sensitive your speakers are. The least of them I would probably take over any comparably priced Solid State amplifier. The Meishu Tonmeister 300B integrated I would take over any SS integrated from anyone. Albeit it's not cheap. Some other 300B SET amps have been described by dealers here as "Lady-Like" in that they soften the sound somewhat but this typically depends on the quality of the transformers. So 300B SET amps have a reputation for being good midrange amplifiers for singers and acoustics but not particularly good with rock and roll. Stereotypes like this get spread around on forums but again it's a lack of exposure IMO to better SET amplifiers. Audio Note at shows does try to ameliorate the stereotype by playing Nightwish, Rage Against the Machine, DIO, various Trance music at very stupid levels to illustrate what SET amps can really do with a decently efficient/sensitive speaker. The Meishu has a lot of Dynamic drive and bass depth and whack but a competing Cary or Line Magnetic 300B does not. They sound "Lady-like" and there are more soft SET amps out there than not.

As for the technology arguments - well SETs are not going to win - the measurements are geared for class A/B SS amplifiers - they test the amps at near full power - where SS measures their best and where SETs measure their worst - in other words, the tests are geared to make SS look better. SET amplifiers have linear distortion which means when you turn the volume up and up and up the distortion rises up and up and up. SS amplifiers often have distortion that is worse when the volume is in the tiny fractions of a watt and lower at 70-80% full power. So you often note that people say that they need to turn the system up for it to "come alive" and that is because the SS amp needs to be putting out some power - and combining them with low sensitive speakers that need power to also "come alive" you have certain systems that really only sound any good when played loud. The other thing to note is that a lot of measurements of amplifiers are actually never measuring a real input. They say see how good the distortion is 0.00001% but they are comparing the input only after the feedback loop has engaged. So the signal is not really the true unadulterated input but and sort of "fake input" with feedback to smooth out the actual input. Possibly why I was so shocked when I heard a Bryston Preamp and Power amp combination with phenomenal spec sheet numbers sound so muddy compared to a 10 watt SEP amplifier. I was there to buy the Bryston with the 20-year warranty and the bombproof measurements and 160 watts of power etc and I had to keep turning it UP to make things out and it sounded bass light and raggedy - the 10 Watt SEP amplifier (which only measures 4.2 watts per channel undistorted was clean and full bodies at low volumes not needing to be turned up to make things out and had better bass. Quiet in terms of noise floor as well. I gotta say back in 2003 it was a tough decision - a 10-watt amp with valves and a 2-year warranty from largely a no-name brand at the time over the 20-year warranty Bryston separates. I chose the SEP. And now in 2021, I can sell the amplifier for several hundred dollars more than I paid for it which can not be said about the Brystons.

The only technical arguments I have really seen for SET amplifiers are their simplicity and lack of error-correcting after the fact fixes (because the amps create errors in the first place and then need to be fixed). Logically that would affect the time domain.

From Audio Note (note they make SET amps so they have a bias here obviously)

"... all-transistor amplifiers sound poor for the simple reason that transistors are inferior amplifying devices. The word “semiconductor” really means what it says and it says it all, “half”-conductor, sonically this could be translated to mean half the signal! Which is really what it sounds like. Pure and simple, transistors are highly un-linear and need a lot of correction (feedback of some sort) to have a bandwidth wide enough to be able to reproduce any music signals, they are not natural voltage amplifiers. Likewise both the pentode or tetrode requires corrective feedback to lower the load sensitivity and improve bandwidth, they are less un-linear than transistors being high impedance devices that require matching from an output transformer. Thus they sound better when used well, especially when used single-ended or in pseudo triode mode by connecting the grids together. Pentodes and tetrodes are more efficient (give higher static power) and much cheaper than triodes, this price advantage is paid for in poorer linearity and therefore overall open loop power bandwidth and load stability, nature always gives with one hand and takes with the other!

Directly heated triodes on the other hand are highly linear amplifying devices, the directly heated triode is the original voltage amplifier, the first, only and still the best, it responds well to better circuits, components and materials, but they are less efficient and more expensive than pentodes and tetrodes. Thus they require efficient speakers, with power output being at a premium price."

There is more written about why Negative Feedback sounds poorer than amplifiers that eschew it.
https://d1b89e86-9572-4311-9f80-600...d/3e7c3b_fd90b2b629a145709f59efd9116c652c.pdf

Martin Colloms back when he was the measurements guru at Stereophile https://www.stereophile.com/reference/70/index.html

Peter van Willenswaard an engineer also writing for Stereophile Tubes do Something Special https://www.stereophile.com/features/357/index.html

I got into building set amps in the mid 90s, after using and building various solid-state and valve amps previously.
My single ended amps have used mostly English valves, px4,px25, det25, 2p, pp3521 etc
Looking back all the valves have have a very similar sound, but different output transformers do give slightly different 'tone to the sound. I've also learnt that a single power supply in an amplifier with minimal interstage smoothing causes a the amplifier to cancel out detail in the music output.
That applies to all amplifiers to some degree not just single ended. And can be clearly heard once you know what your listing for..

Push pull operation should be perfect ? But in practice is not..
I was chatting with Morgan Jones a few years ago and we both agreed push pull operation removes /cancels part of the signal.. and you can clearly hear it..


Feed back in most implementations mixes the amplifiers output and back emf from the loudspeaker with the input to the amplifier. Making the loudspeakers affect the accuracy of the amps output, how much depending on the kit and the volume.

Both of the above can actually change the music into something slightly different to what's on the recording.

We had an example of that at mine a few months ago, 3 very different but competent single ended amps (one mosfet) and a high quality push pull, with all 3 single ended amps, the background detail in the recording was consistent.
The push pull amp was like a different version of the tune was being played, it emphasised different aspects by cancelling others.. just as the conversation I had with Morgan.

My view is there are comprimises in all hi fi topology and you chose your poison.
But distortion is not what makes a well built single ended amp sound more lifelike.
I've proved that to myself regardless to what some may post.
 
I read an article a while back where the author proposed the idea (with measurements) that the distortion spectrum of DHT power amps could sometimes mirror a single driver's distortion, so connecting with phased reversed could actually cancel said distortions! And which could explain why DHTs and single drivers can sound so good. I wish I could find it again. If anyone else can find it, please let me know.
I do regret selling my 815 power amps, but now use DHT pre-amps, which can run in their ideal operating range, so are not struggling to power difficult loads. Power amps are indirectly heated triode.
https://www.bartola.co.uk/valves/dht-pre-amplifier/26-dht-pre-amplifier-gen2/
and
https://www.bartola.co.uk/valves/dht-pre-amplifier/01a-preamp-gen2/
 
The only technical arguments I have really seen for SET amplifiers are their simplicity and lack of error-correcting after the fact fixes (because the amps create errors in the first place and then need to be fixed). Logically that would affect the time domain.

As far as I'm concerned, when it comes to reproducing music the time domain is king (couldn't care less about a perfectly flat frequency response).

The less you mess with the signal, the better the sound.
 
As far as I'm concerned, when it comes to reproducing music the time domain is king (couldn't care less about a perfectly flat frequency response).

The less you mess with the signal, the better the sound.

Yeah. This, plus tonality, accuracy of timbre. IME SETs get this right. So do Quad ESLs.
 
Just for fun I would remind people that the original Linsley hood class a amplifier is a single ended design, albeit with an active collector load.

It also sounds extremely good on ESL57s, despite only being 10 watts per channel.
 
SET amplifiers do not have a singular sound so conversations about them can be difficult. I have lived in Hong Kong a mecca of audio gear. A dealer I often go to is an Audio Note dealer - arguably the king of SET amplifiers because they make more of them than anyone else. As such, I have been able to make direct comparisons. Audio Note uses various levels so level 3 amplifiers are Single Ended Triode and within that level are various SET amplifiers that use 2a3, 300B, 45, 211 output tubes. They all sound different from each other. So which you like will more or less depend on your taste and what you listen to and how sensitive your speakers are. The least of them I would probably take over any comparably priced Solid State amplifier. The Meishu Tonmeister 300B integrated I would take over any SS integrated from anyone. Albeit it's not cheap. Some other 300B SET amps have been described by dealers here as "Lady-Like" in that they soften the sound somewhat but this typically depends on the quality of the transformers. So 300B SET amps have a reputation for being good midrange amplifiers for singers and acoustics but not particularly good with rock and roll. Stereotypes like this get spread around on forums but again it's a lack of exposure IMO to better SET amplifiers. Audio Note at shows does try to ameliorate the stereotype by playing Nightwish, Rage Against the Machine, DIO, various Trance music at very stupid levels to illustrate what SET amps can really do with a decently efficient/sensitive speaker. The Meishu has a lot of Dynamic drive and bass depth and whack but a competing Cary or Line Magnetic 300B does not. They sound "Lady-like" and there are more soft SET amps out there than not.

Sorry but this is absolute tosh. Now if you had said "In my opinion" that would be acceptable, we like what we like & no-one's opinion carries any more weight that the next. I have a Line Magnetic 845 & spent a lot of time with their 300b/805 amp, & they have all the dynamism & bass weight you could wish for. I can also say that at the recent show in Leamington I was very disappointed in the Audio Note room. A £28k turntable with a £11k amp couldn't follow a simple bass line with any authority at all, & I wasn't the only one with that opinion. If it floats your boat that's fine, but I couldn't live with that.
 
In my case, I am departing Quads and returning to Tannoys, after a gap of 47 years! They suit me more, I guess. YMMV.

IMHO you should make the switch to Tannoys, but keep your Quads. I kick myself for some of the equipment I've sold. It's easy to take things for granted and "the grass is always greener". Hence, my approach to having two systems.
 
Around 10 years ago I sold my quad 57s, another regret, but I do have a pair of quad corner ribbons, that suit my amps much better when they occasionally get an airing.
They are rare things with only a few being made. The ribbons are still exceptional quality reproducers, even compared to todays loudspeakers

My everyday loudspeakers are well over 100dbs, so less than a watt results in room filling volumes.
 
We don't all live in mansions! Or have the money.
The Quads + valves did sound good though! (All things considered).
There is a side issue here though isn't there: that neither Quads or valves are towards the low maintenance end of the audio spectrum, and that if we put the music first, then how much time (and money) we are happy to devote to ongoing maintenance cannot be ignored.
 
The Quads + valves did sound good though! (All things considered).
There is a side issue here though isn't there: that neither Quads or valves are towards the low maintenance end of the audio spectrum, and that if we put the music first, then how much time (and money) we are happy to devote to ongoing maintenance cannot be ignored.

A very valid point and one of the reasons I'm reluctant to move back to valve poweamps, especially SET designs, the expense of the amps to start with, the expense of replacement Valves, seemingly good quality valves are an arm and a leg, combined with the necessary 98db Horn loudspeakers (according to GT, and I'm inclined to take his word) which generally tend to be expensive and large.
 
, combined with the necessary 98db Horn loudspeakers (according to GT, and I'm inclined to take his word) which generally tend to be expensive and large.
I had a pair of these with 88dB speakers, and they worked fine. I still regret having to sell them.

mingda%20mc845.jpg
 
combined with the necessary 98db Horn loudspeakers (according to GT, and I'm inclined to take his word) which generally tend to be expensive and large.

Coda II has been exposed to those, all be it for a limited period of time, but I am sure if you ask him he will tell you what he heard...

Indeed, owning a valve amplifier is a little like owning a high performance sports car, in that the running costs are going to be higher, but then everything "high performance" comes at a price. Hopefully more Porsche and Mercedes than Ferrari or McLaren... :)
 
Coda II has been exposed to those, all be it for a limited period of time, but I am sure if you ask him he will tell you what he heard...

Indeed, owning a valve amplifier is a little like owning a high performance sports car, in that the running costs are going to be higher, but then everything "high performance" comes at a price. Hopefully more Porsche and Mercedes than Ferrari or McLaren... :)

Or.....Lotus.
 
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@Darren L : To me a stable and high impedance is more important than a very high sensitivity, especially with SET designs.
The thing is, many, if not most, manufacturers are lying with their specs. Especially with the sensitivity and the nominal impedance.
There are so many claimed 8 ohm speakers which in reality have only 4 or 5 ohm in reality.
 


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