Eye opener
"Often we find that audiophiles who prefer the low power Single-Ended Class A amplifiers listen to simpler sorts of musical material at modest volume levels." NP
Unfortunately, I missed Mr. Pass's talk because the only day I could attend CAS was Sunday. I went to experience ultra high end, cost is no object audio. I was especially looking forward to hearing Pass amps since I'm currently trying to decide between building an Aleph J or F6. My only audio shows previously were Burning Amp Festivals.
I found it educational in many respects. The most surprising thing I found was how mediocre many of the speakers sounded, some costing more than $20K! I was disappointed that few rooms I visited gave the visitor the opportunity to listen at "moderate volume levels." I was interested in finding a speaker that sounded great both at low to moderate levels and great at concert hall levels. Most of the exhibitors simply had the volume cranked!
"Often we find that audiophiles who prefer the low power Single-Ended Class A amplifiers listen to simpler sorts of musical material at modest volume levels." NP
Unfortunately, I missed Mr. Pass's talk because the only day I could attend CAS was Sunday. I went to experience ultra high end, cost is no object audio. I was especially looking forward to hearing Pass amps since I'm currently trying to decide between building an Aleph J or F6. My only audio shows previously were Burning Amp Festivals.
I found it educational in many respects. The most surprising thing I found was how mediocre many of the speakers sounded, some costing more than $20K! I was disappointed that few rooms I visited gave the visitor the opportunity to listen at "moderate volume levels." I was interested in finding a speaker that sounded great both at low to moderate levels and great at concert hall levels. Most of the exhibitors simply had the volume cranked!
In pro audio world, there is harmonics processor that generates 2nd and 3rd harmonics with frequency control, and it cost $7100! I tried the virtual plugin version of this unit (Free for 2 weeks, but UAD card required), and it sounds great.
Vertigo Sound VSM-2 Mix Satellite MK2 - Full Version - Vintage King Audio
Vertigo Sound VSM-2 Mix Satellite MK2 - Full Version - Vintage King Audio
Yes, VSM-3 (digital emulation) is the one I checked. There has been many harmonic generator plugins for music production, and Decapitator is one of most popular, but VSM-3 sounds best and most usable for me. It's too bad it requires UAD card.
In hardware world, it probably started with 2nd and 3rd harmonics button on the Distressor (one of the most popular drum compressor in the pro studio, and has been on the market for more more than 20 years). This buttons are intended to emulate tube and transistor sound.
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It would be nice if we could effectively get the same results by just dialing up
the harmonic distortion prior to the amplifier. We have noticed that it
seems to work best when the character is intrinsic to the output stage,
where at lower levels it is dominantly 2nd followed by declining third and
almost no higher orders. As the level goes up, third is allowed to increase
at a higher rate (2nd goes up as square root of power, 3rd proportional to
power) until the 3rd is dominant as you approach clipping.
Notice that this nominally corresponds to the GeddLee metric which includes
signal level and distribution of harmonic levels.
Probably the reason why the output stage is where it counts most is
related to the interaction between the relatively high distortion of the
output stage as compared with the rest of the amplifier and the loudspeaker
which is has the highest distortion of all.
😎
the harmonic distortion prior to the amplifier. We have noticed that it
seems to work best when the character is intrinsic to the output stage,
where at lower levels it is dominantly 2nd followed by declining third and
almost no higher orders. As the level goes up, third is allowed to increase
at a higher rate (2nd goes up as square root of power, 3rd proportional to
power) until the 3rd is dominant as you approach clipping.
Notice that this nominally corresponds to the GeddLee metric which includes
signal level and distribution of harmonic levels.
Probably the reason why the output stage is where it counts most is
related to the interaction between the relatively high distortion of the
output stage as compared with the rest of the amplifier and the loudspeaker
which is has the highest distortion of all.
😎
Papa Pass, does the description above approximate your output stage design of push-pull with single-ended bias for lower levels?
This makes sense . The last thing you want is the output stage turning that predialed 2nd and 3rd harmonic into higher order harmonics.
Wouldn't this relate mostly to common source output stages since common drain output stages are relatively distortion free in comparison.
The more I think about it Nelson, the more I think about the waveforms you presented ie it's not so much the harmonic but whether the harmonic is actually an accurate representation of the original note. If the guitar makes a perfect sine wave (it doesn't) you want the harmonics to be perfect sine waves, not messy waveforms that aren't representative of the original sound.
Having said that 5th and 7th Harmonics should be avoided like the plague
Having said that 5th and 7th Harmonics should be avoided like the plague
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Good observation. I spent some time thinking about that issue, but after a
while my brain hurt. 🙂
The phenomenon seems true with both CD and CS output stages.
The other item is that even a low distortion loudspeaker has very significant
phase shift between current and voltage, which will just complicate the
issue for the output stage, usually more so than in the front end.
The whole thing still begs the question of why the brain perceives this stuff
as it does. I have a pet hypothesis that the grouping mechanisms are
watching for these harmonics, and it provides a convenient trail of crumbs.
😎
I was fortunate to have attended....best was Nelson's talk, especially his tagging of different amp's to their respective distortion graphs by looking at the curves alone. The Tannoy Westminsters driven by Pass electronics weren't too shabby either😉
Mario
Mario
Predialing second harmonic seems to work on my bass amp though. My ear loves what it does to bass guitar. It's not in your face, it's subtle and it affects the soul, don't ask me why (no idea).
On that amp it has 2 separate preamps in parrallel, a triode preamp and jfet preamp (they could be both input buffers actually) then it has a pot that splits the signal to any pecentage of jfet preamp to tube preamp. The rest of the amp is virtually a copy of the old Hitachi whitepaper with two voltage gain stages using small signal transistors (2 x ltp) then Hitachi lateral mosfets (you know the ones) in common drain configuration. The amp has very nice low distortion (very neutral, looking a little similar to the B1 buffer distortion profile but a bit higher) with no high order harmonics according to simulation, so the predialing seems to work very well for that specific application. I've never played a cd recording through it so can't say it works at all on recorded music. That amp was sold many years ago to go to the USA on a holiday.
Generally speaking I think another part of the equation (possibly only a small part though) is likely due to the fact music is recorded in an anechoic chamber and overly engineered. This is a bad idea in my opinion, sounds nothing like real music. Maybe having these nice simple amps add back to music what normally is there in an average room when the instrument is played live.
Sounds like you are on the verge of making a big discovery. Don't worry it will come in a dream or when you're taking the trash out.
I get these downloads of ideas and I never know where they came from, it couldn't be from the brain (at least my brain). 🙂
Edit: Stupid idea coming up. I wonder if you put a single ended CD output stage in parrallel with a single ended CS output stage with a pot at the input to split the signal to any percentage between the 2 output stages what that would sound like.
I like stupid ideas. Sorry Nelson. 🙂
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I just realised that sounds very much like a version of PLH/JLH except I meant entirely independent output stages in parrallel, maybe that is even more dumb. I never know what to think.
you Dodo
he already made that with Aleph
(two OS in one , saving half of CD and one half of CS)
you Dodo
he already made that with Aleph
(two OS in one , saving half of CD and one half of CS)
The real secret is Nelson has built a time machine and stolen all my dumb ideas.
Hehehe
Hi Nelson
Why does F3 barely get a mention while SIT1 and SIT2 get all the limelight?
Is F3 too clean sounding (too neutral) or is it the output impedance, cascode, output caps, low power output?
For the record I like F3 but haven't heard SIT1 or SIT2.
It seems F3 barely gets a mention in comparative reviews against the other firstwatt amps.
Why does F3 barely get a mention while SIT1 and SIT2 get all the limelight?
Is F3 too clean sounding (too neutral) or is it the output impedance, cascode, output caps, low power output?
For the record I like F3 but haven't heard SIT1 or SIT2.
It seems F3 barely gets a mention in comparative reviews against the other firstwatt amps.
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