SET amp owners thread

[Atmasphere]

You had some comments above about staying true to the source recording. And you mention it again here. That's part of my head scratch. I too have played a lot of instruments. Listened to plenty live. I know what they sound like. So I have distortions that make it sound more natural and real. But they are distortions. So I am suppose to listen to something that has less distortion, but does not create playback I perceive as natural?

Are we talking about the argument of accurate vs musical?

If you have a recording you made where you were not playing, or if you have a recording of a live recording where you were there, that's what I'm talking about. I play bass; in the orchestra you can imagine my perspective of what an orchestra sounds like is pretty skewed from the perspective of the center in front of the orchestra!

You asked:

What I have a hard time getting my head around with SET is how much more real it sounds. Why is that. And why do I feel people think thats bad.

FWIW it is possible to be both accurate and musical at the same time. As you know there's lots of stuff that is more 'accurate' than an SET but isn't particularly musical. I put 'accurate' in quotes because the unmasked higher ordered harmonics that usually cause certain equipment to be less musical isn't a lot of distortion. On paper. To our ears though its a much bigger deal. So what the eye is seeing on paper doesn't agree with what we hear, which leads to the myth that we can hear things we can't measure.

We can measure the things we hear. Its just not easy or convenient. So its often not published.

If its not obvious by now, the thing that makes an amplifier sound the way it does is mostly how it makes distortion- that's the 'sonic signature'. The trick is keeping the distortion that the amplifier makes innocuous, which is something SETs do very well. But they are not the only amps ever made that can do that and some of those other amps are considerably more neutral without sacrificing musicality, since the distortion is kept innocuous.

As mentioned here or in the flea-watt thread, we tried the 2.3 Watt Decware 25th Anniversary Zen Triode (and I'm really just mentioning the lowest-powered amp I own as an example) with a variety of speakers whose "nominal sensitivity" (note e.g. @christoph believes all speaker manufacturers are lying when it comes to sensitivity, and I'm starting to think he's right) range from 85-96dB - it didn't perform in order according to the respective sensitivity rating at all. I build (or used to) loudspeakers, and have always been under the impression that there are other factors that make loudspeakers more or less benign as a load to tube amplification (e.g. acute electrical phase angles/shifts), partly information no loudspeaker manufacturer or reviewer publishes (anymore - people don't know how to correlate measurements to sound quality anyways, despite their deplorable belief in numbers), so that sadly, there is no way of determining synergy without trying first-hand. Perhaps the closest one can get to an educated guess is when speakers are "know factors" (e.g. Infinity Kappa 9, just kidding…), i.e. someone whose ears you trust is using the same type of speakers with a flea watt SET, and even there I'd say it's far from a safe bet. And I do not mean to be negative about this at all: I've heard some surprising combinations one would be tempted to dismiss out of hand, so caveat emptor…

Greetings from Switzerland, David.

You might want to read this:
The voltage and power paradigms

Sensitivity is a voltage measurement; efficiency is a power measurement. This has a big effect when talking about tube amplifiers which cannot double power as the load impedance is cut in half!

 

[acousticsguru]

You had some comments above about staying true to the source recording. And you mention it again here. That's part of my head scratch. I too have played a lot of instruments. Listened to plenty live. I know what they sound like. So I have distortions that make it sound more natural and real. But they are distortions. So I am suppose to listen to something that has less distortion, but does not create playback I perceive as natural?

Are we talking about the argument of accurate vs musical?

Accurate and musical are the same thing - don't let anyone convince you what you hear is wrong. It's all that matters.

Greetings from Switzerland, David.

 

[bonzo75]

e "nominal sensitivity" (note e.g. @christoph believes all speaker manufacturers are lying when it comes to sensitivity, and I'm starting to think he's right) range from 85-96dB - it didn't perform in order according to the respective sensitivity rating at all. I build (or used to) loudspeakers, and have always been under the impression that there are other factors that make loudspeakers more or less benign as a load to tube amplification (e.g. acute electrical phase angles/shifts),

Yes sensitivity is just loudness, and when you have multiple drivers, as you said things get lost in the grip required for the woofer and the complexity of the crossover. The Altec 817 that I like is 2-way 8 ohm top and bottom with both around 105 db, first order crossover, phase coherent, all drivers firing the same way, and because only 2 way, time aligned. That is why it gives so much resolution even with a Garrard 301 and SPU, going through a simple signal path. The General did the same running his original LPs through Mayer electronics with no crossover in the speaker, iirc no capacitor in the signal path.

 

[acousticsguru]

Yes sensitivity is just loudness, and when you have multiple drivers, as you said things get lost in the grip required for the woofer and the complexity of the crossover. The Altec 817 that I like is 2-way 8 ohm top and bottom with bot around 105 db, first order crossover, phase coherent, all drivers firing the same way, and because only 2 way, time aligned. That is why it gives so much resolution even with a Garrard 301 and SPU, going through a simple signal path. The General did the same running his original LPs through Mayer electronics with no crossover in the speaker, iirc no capacitor in the signal path.

Time-aligned and phase-coherent are the terms I used when I first asked Steve Deckert if his 2.3 Watt Anniversary amp would drive my 91.5dB speakers, and the reason he gave a thumbs up, and because he knew I measured myself at 2.83V, not some sales blurb “nominal sensitivity” rating (about as accurate on average as “nominal impedance”?). Of course he was right.

Greetings from Switzerland, David.

 

[Solypsa]

Do you think a Parallel Single Ended 45 with about 12 watts will drive the PAP Trio 15 coax?

Is 12w for a 45 PSET realistic? I would have thought 3w.... Whats the amp?

 

[Solypsa]

Btw I used a 46 set into some old 'made in france' 3A Serie Master speakers I have, which are low 90s efficiency but woofer direct connected ( no crossover on woofer ) and it wasn't the worst. Not the best either

 

[bonzo75]

Btw I used a 46 set into some old 'made in france' 3A Serie Master speakers I have, which are low 90s efficiency but woofer direct connected ( no crossover on woofer ) and it wasn't the worst. Not the best either

the valve itself won’t make the set, or drive the woofer even if no crossover, as you know.

 

[bonzo75]

Is 12w for a 45 PSET realistic? I would have thought 3w....

Think he said it is a push pull.

 

[acousticsguru]

Yes sensitivity is just loudness, and when you have multiple drivers, as you said things get lost in the grip required for the woofer and the complexity of the crossover. The Altec 817 that I like is 2-way 8 ohm top and bottom with both around 105 db, first order crossover, phase coherent, all drivers firing the same way, and because only 2 way, time aligned. That is why it gives so much resolution even with a Garrard 301 and SPU, going through a simple signal path. The General did the same running his original LPs through Mayer electronics with no crossover in the speaker, iirc no capacitor in the signal path.

Another factor I believe is of paramount importance is the moving mass and mechanical Q factor of the bass drivers, as well as the series resistance of a passive filter (air coil or foil) inductor (if any - AFAIK there's none in e.g. some DeVORE speakers). While this may seem to directly translate into a higher sensitivity rating, it's not automatic, and such low-mass/high Qms/low damping drivers still tend to be more tube friendly - on average (again, all bets based on educated guess are off in the search real-world speaker/amp synergy).

Greetings from Switzerland, David.

 

[bonzo75]

Another factor I believe is of paramount importance is the moving mass and mechanical Q factor of the bass drivers,

Greetings from Switzerland, David.

The dual woofer FLHs I like have a very low QTS for such woofers (powerful magnet with light cone structure and voice coil) allow them to be driven by low watt valve amps with low grip, and with very quick but brief excursion allowing for agility. Keeping impedance match with the upper drivers keeps crossover simple

 

[DasguteOhr]

Another factor I believe is of paramount importance is the moving mass and mechanical Q factor of the bass drivers, as well as the series resistance of a passive filter (air coil or foil) inductor (if any - AFAIK there's none in e.g. some DeVORE speakers). While this may seem to directly translate into a higher sensitivity rating, it's not automatic, and such low-mass/high Qms/low damping drivers still tend to be more tube friendly - on average (again, all bets based on educated guess are off in the search real-world speaker/amp synergy).

Greetings from Switzerland, David.

very well I see the same. one more thing to keep the resistance of the loudspeaker cable low is included in the calculation of the damping factor of the amplifier, such as the air coil or foil coil. each lower the more control from the amp. my 15" woofers have a mass of 60 grams they don't need a strong drive. it always depends on what kind of speaker is built: horn, bass reflex or open baffle. many ways lead to rome.. proverb

 

[morricab]

What I have a hard time getting my head around with SET is how much more real it sounds. Why is that. And why do I feel people think thats bad. I definitely hear frequency issues and lots of noise with SET. Hum and such. But there is no denying, a piano, violin, saxophone etc sound much more like the real instrument in the room than with other amp topology I have had in my system. Why is this a bad coloration? Why do I want less natural and real with better specifications? I thought the goal, ir at least for me, is the recreation of the actual event. SET has gotten me much closer than any other topology.

Again, there are several SETs that don’t have significant noise, even with very sensitive speakers, and don’t have frequency issues or hum. Sounding more real is not a coloration. Why people don’t believe is because they trust more what they read and are told by “experts” than their own ears.

 

[Fishfood]

You had some comments above about staying true to the source recording. And you mention it again here. That's part of my head scratch. I too have played a lot of instruments. Listened to plenty live. I know what they sound like. So I have distortions that make it sound more natural and real. But they are distortions. So I am suppose to listen to something that has less distortion, but does not create playback I perceive as natural?

Are we talking about the argument of accurate vs musical?

I share these exact thoughts. I play guitar, hear live music while being recorded for movies all the time both in the studio and on location in various places (quite a few churches, actually). I'm just trying to reproduce that sound and like you, I know what that is and I'm sure I have all the orders of harmonics working like mad in my house with my SET amp.

 

[AudioHR]

If you have a recording you made where you were not playing, or if you have a recording of a live recording where you were there, that's what I'm talking about. I play bass; in the orchestra you can imagine my perspective of what an orchestra sounds like is pretty skewed from the perspective of the center in front of the orchestra!

You asked:


FWIW it is possible to be both accurate and musical at the same time. As you know there's lots of stuff that is more 'accurate' than an SET but isn't particularly musical. I put 'accurate' in quotes because the unmasked higher ordered harmonics that usually cause certain equipment to be less musical isn't a lot of distortion. On paper. To our ears though its a much bigger deal. So what the eye is seeing on paper doesn't agree with what we hear, which leads to the myth that we can hear things we can't measure.

We can measure the things we hear. Its just not easy or convenient. So its often not published.

If its not obvious by now, the thing that makes an amplifier sound the way it does is mostly how it makes distortion- that's the 'sonic signature'. The trick is keeping the distortion that the amplifier makes innocuous, which is something SETs do very well. But they are not the only amps ever made that can do that and some of those other amps are considerably more neutral without sacrificing musicality, since the distortion is kept innocuous.

You might want to read this:
The voltage and power paradigms

Sensitivity is a voltage measurement; efficiency is a power measurement. This has a big effect when talking about tube amplifiers which cannot double power as the load impedance is cut in half!

I like the way you have phrased things!

I am a newbie in the SET world. My Shindo Monbrison and Cortese with Coherent Audio Neo 15 speakers sound very musical and the setup is dead quiet. Is it accurate? Probably not but I prefer it to what I hear from many hi end systems.

 

[DasguteOhr]

Owe god. I had my amp rebuilt 3 times. Its still a bucket of issues. I don't ever want to go down that road again. I have as much into it as a new amp, and still I have to use Ebtech HumX. Now a guy wants another $4k to $6k to rebuild the power supply. Rebuilding the Audion Black Shadow had been my single biggest waste and loss of money in audio so far. The only mistake I would say I have made.

Sorry to hear i look at the specs I find the values very optimistic in terms of distortion. Normally, at full load, they are between 3.0 and 10% with set amps. the low weight makes me suspicious, good main and outtransformer re heavy for 211/845 high voltage. it could be that one of the two is running at the limit and thus produces hum and noise. I don't want to badmouth this amplifier, I don't know the structure and components that are used. But the values are unrealistic

• Type: Zero feedback, single-ended triode mono power amplifier
• Tubes: 1× 845, 1× 6922/6H23N, 1× E182CC per channel
• Power output: 25W Class A into 8?
• Loading: four and eight ohm nominal
• Frequency Response: 13Hz–34kHz ±3dB
• Distortion: <?0.1%
• Noise: <?(CCIR) –90dB
• Sensitivity: Variable >?150mV full output
• Dimensions (W×H×D): 26×25×46cm (per channel, excl. tubes)
• Weight: 12kg per channel

 

[SVS]

Again, there are several SETs that don’t have significant noise, even with very sensitive speakers, and don’t have frequency issues or hum. Sounding more real is not a coloration. Why people don’t believe is because they trust more what they read and are told by “experts” than their own ears.

The noise and hum of SET amplifiers is not their property, but a designer's error. Or the user's religion.
When I made a SET amplifier for 6B4G for speakers with a sensitivity of 102 dB, I had to rectify and filter the voltage for powering the heaters well. But there are users who fundamentally want the heaters to be powered by alternating voltage. It sounds better to them regardless of the hum. I call it religion.

 

[SVS]

• Type: Zero feedback, single-ended triode mono power amplifier
• Distortion: <?0.1%

These are technically incompatible things.
0.1% distortion is impossible with zero fitback (perhaps distortion is measured at a power of 0.01 W, but the amplifier is not used at such a power).

 

[bonzo75]

I like the way you have phrased things!

I am a newbie in the SET world. My Shindo Monbrison and Cortese with Coherent Audio Neo 15 speakers sound very musical and the setup is dead quiet. Is it accurate? Probably not but I prefer it to what I hear from many hi end systems.

Shindo is quite coloured. The fact that some SETs are coloured does not mean colouration is a trait of SETs

 

[SVS]

An interesting paper on the topic of this debate: https://next-tube.com/articles/Cheever/cheever.pdf

 

[DasguteOhr]

Shindo is quite coloured. The fact that some SETs are coloured does not mean colouration is a trait of SETs

Shindo sounds good, the probem is in earlier models used carbon mass resistors that have not been painted, their values change depending on the humidity in the room. the device sounds different every day. can be exciting for the listener.they have to be baked dry afterwards varnished. then measured and matched. then there will never be coloured again. Exsample