Mastersound PF100 PSET Amplifier

Audiohertz2 · Jul 8, 2023

bazelio said:
Stereophile used to (and maybe still does) consider clipping to be 1% THD, which some might say was never "fair" to SET amps because without exceeding 1% you can't get anywhere near the max power output spec of any SET tubes without feedbavk. Max power output is 5% THD in many or most DHT datasheets for example. I've seen some pentodes specify max power at 10% THD. Now Ralph keeps saying most SET amps don't use feedback. I don't have any idea when that survey was taken, but I do know several that do. What is the topology of your SET amp that generates 35W at 1% THD. Which tubes does it use?

They used 1% basically as a reference for all amps has nothing to do with testing to clipping . In the real days of testing all amps were driven to actual clipping and observed measured performance as to even clipping , clip recovery etc , unfortunately those not surviving, ie. By letting the magic smoke out, well , led to alot of tears and political issues ..

So hence forth , the obligatory 1% thd rule , lower the bar because all amp lives matters .. !

Regards

Audiohertz2 · Jul 8, 2023

morricab said:
Tubes Do Something Special

Most people who now listen to tube amplifiers began with a transistor amp, and know from experience that a tube amp of a given measured power output sounds louder than its nominally identical transistorized equivalent. The unofficial consensus is that you need two to four times the transistor...

www.stereophile.com

Easily explained away fallacy ..!

Ron Resnick · Jul 8, 2023

morricab said:
Tubes Do Something Special

Most people who now listen to tube amplifiers began with a transistor amp, and know from experience that a tube amp of a given measured power output sounds louder than its nominally identical transistorized equivalent. The unofficial consensus is that you need two to four times the transistor...

www.stereophile.com

The unofficial consensus is that you need two to four times the transistor power to achieve the same loudness as you would using tubes. In other words, given the (subjectively) undistorted sound level a 25W (footnote 1) tube amplifier can provide, if you want the same loudness from solid-state technology you would have to replace it with at least a 50W transistor amp.

I am totally a tube person, but I think this is bogus. I have no idea what this guy is talking about.

In my personal experience I have never witnessed a tube amplifier magically gain 3dB or more of perceived SPL versus a twice as powerful solid-state amplifier.

Kcin · Jul 8, 2023

When I went to school a watt was watt regardless of the mechanism of generation.

Propensity to deal with reactive loads is a different story.

bonzo75 · Jul 8, 2023

Kcin said:
When I went to school a watt was watt.

Long time ago, things change. There is artificial intelligence now

bazelio · Jul 8, 2023

morricab said:
Read the papers from Earl Geddes. There is no correlation between THD or IMD and subjective sound quality...at least over the wide range they evaluated. This is what I mean by "means nothing". It's just a number... not a threshold for sonic quality. It's also why your statement about audiophile preference is questionable. If nearly all audiophiles really preferred ultra low distortion electronics, not only would SETs NOT have made a comeback, Ralph would not have been able to sell OTLs for over 30 years. Ralph's "explanation" is simplistic and almost certainly wrong. SS amps often have much higher distortion of high order harmonics with increasing frequency...this doesn't make them sound more dynamic... Usually they just sound annoying.

Who said nearly all audiophiles? I said many audiophiles. Let's face it, SET is a religion for you. And you run around the interwebs looking for "studies" and random tidbits to support your religion. Meanwhile, other common sense viewpoints are "almost certainly wrong" without lifting a finger. Not too unlike religious zealots of other bents. Ralph's explanation is simply common sense. I'd have said mostly the same thing had he not. I'm sure the paper is interesting, maybe even somewhat factual. But I also already know first hand that 1% vs 2%, even if contained in majority to 2nd harmonics, presents as an easily audible difference. Also, don't go too far in using SS for direct comparison, as THD is already orders of magnitude different - making correlation to SET a fool's errand.

bazelio · Jul 8, 2023

Audiohertz2 said:
They used 1% basically as a reference for all amps has nothing to do with testing to clipping . In the real days of testing all amps were driven to actual clipping and observed measured performance as to even clipping , clip recovery etc , unfortunately those not surviving, ie. By letting the magic smoke out, well , led to alot of tears and political issues ..

So hence forth , the obligatory 1% thd rule , lower the bar because all amp lives matters .. !

Regards

Yes, correct. It's not a true clipping measurement. It's a threshold beyond which they consider distortion to be audibly noticeable / objectionable, etc.

morricab · Jul 8, 2023

microstrip said:
Earl Geddes work in the early 2000's on distortions of electronics was just the start of a promising work that was never tested or proceeded. Very interesting read, but unfortunately nothing more than that.

Although there are no established firm rules of correlation between THD or IMD and subjective sound quality, we can't pretend that an amplifier having more than 10% of distortion at a few watts is accurate when used with medium efficiency speakers. IMO consumers should be delivered measurements of what they get - in this aspect Lamm is exemplary. Fortunately magazines such as Stereophile, Audio Critic, HiFi New's or the german Stereo still publish them in their reviews.

Maybe just a start but better than relying on THD and IMD. I think Cheever’s metric is more practical to use and takes SPL into account.

morricab · Jul 8, 2023

microstrip said:
Such metric still does not exist and I doubt that it can be established for stereo purposes. And no way we should put in the same bag the careful work of Earl Gueddes and the Cheever amateurish MSc thesis.

I would be surprised if the two metrics if treated correctly would yield significant differences.

morricab · Jul 8, 2023

bazelio said:
Who said nearly all audiophiles? I said many audiophiles. Let's face it, SET is a religion for you. And you run around the interwebs looking for "studies" and random tidbits to support your religion. Meanwhile, other common sense viewpoints are "almost certainly wrong" without lifting a finger. Not too unlike religious zealots of other bents. Ralph's explanation is simply common sense. I'd have said mostly the same thing had he not. I'm sure the paper is interesting, maybe even somewhat factual. But I also already know first hand that 1% vs 2%, even if contained in majority to 2nd harmonics, presents as an easily audible difference. Also, don't go too far in using SS for direct comparison, as THD is already orders of magnitude different - making correlation to SET a fool's errand.

No better way to kill a discussion than to brand the one you disagree with a religious zealot…

morricab · Jul 8, 2023

Audiohertz2 said:
Easily explained away fallacy ..!

Ok explain

bazelio · Jul 8, 2023

morricab said:
No better way to kill a discussion than to brand the one you disagree with a religious zealot…

Oh it's fine for that discussion to die as.it wasn't going anywhere anyhow. I don't even know if I disagree with you or not, though. The only thing you've offered is a paper and a few articles. I've mainly said that THD deltas in the 1-2% are audible because I've done the experimentation. Whether or not that agrees with your papers, I have no idea.

morricab · Jul 8, 2023

Ron Resnick said:
The unofficial consensus is that you need two to four times the transistor power to achieve the same loudness as you would using tubes. In other words, given the (subjectively) undistorted sound level a 25W (footnote 1) tube amplifier can provide, if you want the same loudness from solid-state technology you would have to replace it with at least a 50W transistor amp.

I am totally a tube person, but I think this is bogus. I have no idea what this guy is talking about.

In my personal experience I have never witnessed a tube amplifier magically gain 3dB or more of perceived SPL versus a twice as powerful solid-state amplifier.

I know exactly what he is talking about…and I agree with him.

morricab · Jul 8, 2023

bazelio said:
Oh it's fine for that discussion to die as.it wasn't going anywhere anyhow. I don't even know if I disagree with you or not, though. The only thing you've offered is a paper and a few articles. I've mainly said that THD deltas in the 1-2% are audible because I've done the experimentation. Whether or not that agrees with your papers, I have no idea.

Then why the personal attacks? The audibility has everything to do with the nature of the distortion and I will trust Geddes over your “experiments “, whatever those might be.

Fishfood · Jul 8, 2023

morricab said:
No better way to kill a discussion than to brand the one you disagree with a religious zealot…

Plus, don't I have ears? And aren't my ears different than your ears? So who could possibly care about measurements when we all hear differently?

bazelio · Jul 9, 2023

morricab said:
Then why the personal attacks? The audibility has everything to do with the nature of the distortion and I will trust Geddes over your “experiments “, whatever those might be.

Observations, not attacks. Are you really surprised that folks might describe your demeanor and behavior as fanatical, biased, and defensive? In any event, I just read "The Perception Of Distortion" and it does not explicitly suggest a specific threshold where an audible difference between distortion levels becomes apparent. Instead it introduces a Gm metric as a better predictor of subjective perception of distortion versus THD and IMD. But my point has been that there is an audible difference between THD levels such as 1% and 2%. And the study doesn't address this one way or the other. It does suggest higher order distortion in low signal levels may be more perceptible. But my experimentation has been with DHTs recently and it's plenty audible in that context already. It's not too difficult to set up. A multi-tapped OPT allows you to effectively change the load the tube sees on the fly. Headphones allow you to really drive up that load value in order to affect THD. So adjust the load, listen, measure THD, repeat. There's also the inline THD generator boards that were given away as door prizes at a Burning Amp a few years ago. That's an educational gizmo to play with as well. I just prefer any hands-on approach to reading theories.

BTW that study is of very limited scope and specific test conditions - e.g. one song. And with no mention of who the 42 participants are other than randos having normal hearing sensitivity, I'd be very cautious about hanging my hat on the results. Did those randos have any musical background, are they even audiophiles or in any way calibrated to audio playback nuances (which the majority of the general public are not), etc. Major grain of salt. I think you're over-selling it.

DasguteOhr · Jul 9, 2023

bazelio said:
Who said nearly all audiophiles? I said many audiophiles. Let's face it, SET is a religion for you. And you run around the interwebs looking for "studies" and random tidbits to support your religion. Meanwhile, other common sense viewpoints are "almost certainly wrong" without lifting a finger. Not too unlike religious zealots of other bents. Ralph's explanation is simply common sense. I'd have said mostly the same thing had he not. I'm sure the paper is interesting, maybe even somewhat factual. But I also already know first hand that 1% vs 2%, even if contained in majority to 2nd harmonics, presents as an easily audible difference. Also, don't go too far in using SS for direct comparison, as THD is already orders of magnitude different - making correlation to SET a fool's errand.

Buy the article from linear audio vol6&8 from frank blöhbaum.

Multiplied Transconductance Amplifiers - part 2 - high power amplification | Linear Audio

linearaudio.net

The magic word is MTA: Due to the special circuit technology, the entire amplifier behaves like a single super part triode (hence Multiplied Transconductance Amplifier). This results in a very low source impedance at the anode. And this "forces" the transformer to follow the signal - of course only as long as its core is not saturated. If the transformer is designed accordingly, you also have the option of realizing a very linear amplifier over the entire frequency range AND up to the modulation limit.
Do you want set amp under 1% distorsion read the artice. shematics are include for some tubes too.
P.S
license is with linear audio, I will not publish this article

bazelio · Jul 9, 2023

morricab said:
Ok explain

Failure to correlate. The perceived loudness of a system depends on many factors beyond amplifier peak voltage outputs, including frequency response, harmonic distortion, and transient response. All of these contributing factors will differ between the tube and solid state amplifiers under test but are not considered by the author.

Al M. · Jul 9, 2023

bazelio said:
Failure to correlate. The perceived loudness of a system depends on many factors beyond amplifier peak voltage outputs, including frequency response, harmonic distortion, and transient response. All of these contributing factors will differ between the tube and solid state amplifiers under test but are not considered by the author.

The factors that you mention may also contribute to an explanation of a test result in a friend's house yesterday. We were comparing power cords on a DAC and found that on some material the music seemed louder with one power cord (we both independently thought the same thing).

Was there "better current delivery to the DAC" with one cord, which would have caused it to sound louder? Of course not. But the sound of the DAC was different depending on the power cord used, and one or more of the differences, like frequency and/or transient response, must have caused that difference in perception of loudness.

morricab · Jul 9, 2023

bazelio said:
Failure to correlate. The perceived loudness of a system depends on many factors beyond amplifier peak voltage outputs, including frequency response, harmonic distortion, and transient response. All of these contributing factors will differ between the tube and solid state amplifiers under test but are not considered by the author.

He measured SPL in the second installment…did you not read the whole article?

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