Thank you Soundhappy for the link. Thank you Mr. Colburn for a clear, detailed and very informative presentation about yourself [relentless, highly detailed, skilled, broad minded ..] and the circuit under study. I am glad to see that you are using OpAmps in a high quality and demanding application. It complements the many discrete designs by Mr. Pass. More of such circuits will be a definite plus for diyaudio. The opto-coupled bias circuit for the output stage is interesting yet simple. Zen Mod is already working to adopt it to bias his DEF amp.
Thanks to the BAF team and its participants for enabling this high quality presentation for viewing and for its knowledge.
Thanks Soundhappy for the link. Thank you Mr. Pass for this highly enjoyable and informative presentation. It was like listening to my favorite music using my Threshold power amp.
Thank you BAF contributors, and participants for enabling the viewing of this knowledge-loaded and inspiring presenrtation.
Are you sure?
The greatest thing about DEF amp, is zero degeneration and simpler biasing.
Less is more.
If adding optocoupler means adding degeneration then that is a step backwards.
The biasing circuit in headphone amp is not significantly different from what is already in M2.
Wayne's presentation was very good, also there were many good questions that Wayne answered very well.
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I didn't had too much objectives .... just doing a favor to boyz interested in such amplifier
all that taking in account pcb screenshot Papa sometime posted and Soundhappy reposted few days ago , where is shown DEFiSIT amp with (as I see them ) optocouplers and source resistors
one of the ways to accommodate wakoo pair without too much hassle and endless search for perfect pair
in fact , to have proper stereo , one needs to pick two perfect pairs , for ideal DEF amp , be it SIT or not
anyone remembering in which thread exactly we were posting that ?
.....
anyone remembering in which thread exactly we were posting that ?
Silly Moi , as always
Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
These were mine. Happy to answer any questions about them, but RE the bass... did you notice the dipole subs on the floor? as Russ says, they were kind of a last minute thing. I put them together only during the couple of weeks leading up to the show.
Actually, a funny gotcha happened with the subs. I set up the filters wrong and they were not properly equalized. I thought it was just the room being boomy (which it was to some extent). Nope, it was a mistake on my part.
I still haven't unpacked these since the show. I liked their potential and wanted to redo them with a different woofer eventually, but I don't have a good place where I can set them up at the moment.
Anyway these were an attempt at a minimal-baffle OB for about 100Hz and up. The tweeter is the Peerless TG9, the 8 ohm version and the woofer is an old Focal 12" unit. I had a linux computer doing the crossover in software with a USB "preamp" interface connected to the computer that could control the volume, which input was being used, etc. That's also a project that I still have not unpacked since the show!
Drop me a line if you have questions about anything in particular.
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I was thinking about something, and while my thought is a bit distorted on that subject, I was wondering where is the apptopriate place on this forum to discuss that. Since I heard/watched Nelson Pass presentation on BAF 2017, and I have experienced some phenomena he mentioned there, maybe we could mention it here, or, maybe someone might point to the more appropriate thread.
So: Distortion. It is always there. Then, absolute phase. It is asways there, too. I noticed changes in the wuality of sound depending on the absolute phase (let's imagine that there is a single fullrange speaker playing), so it does not sound the same whether it is connected in phase or out of phase (but both speakers), although in theory it shouldn't be notticeable, and maybe some people don't notice the difference, but...
Second, the distortion spectra, second vs third, tjeir total quantity in the singnal and the relative amount of one vs the other (second and third harmonics). These depend on both the amp topology and the loudnness.
The result is: with certain amps, certain loudnes, cettain phase, the sound gets magical. Change something and the magic is gone. And no, I did not smoke!
Nelson mentioned something about this in his presentation, but I would like to discuss more.
Maybe that would explain why I enjoy Jfet Boz with J310 jfet with F3 amp more than some other combinations that should sound better on paper...
On one occasion I heard Hiraga le monstre amp, 8w, and liked it very much. Like tasting your favorite food:a certain amount of sugar, (second harmonic), salt (third harmonic), more baked (positive phase distortion), less baked (negative phase distrtortion)...
Now, Chef, how do you make it so tasty....
So: Distortion. It is always there. Then, absolute phase. It is asways there, too. I noticed changes in the wuality of sound depending on the absolute phase (let's imagine that there is a single fullrange speaker playing), so it does not sound the same whether it is connected in phase or out of phase (but both speakers), although in theory it shouldn't be notticeable, and maybe some people don't notice the difference, but...
Second, the distortion spectra, second vs third, tjeir total quantity in the singnal and the relative amount of one vs the other (second and third harmonics). These depend on both the amp topology and the loudnness.
The result is: with certain amps, certain loudnes, cettain phase, the sound gets magical. Change something and the magic is gone. And no, I did not smoke!
Nelson mentioned something about this in his presentation, but I would like to discuss more.
Maybe that would explain why I enjoy Jfet Boz with J310 jfet with F3 amp more than some other combinations that should sound better on paper...
On one occasion I heard Hiraga le monstre amp, 8w, and liked it very much. Like tasting your favorite food:a certain amount of sugar, (second harmonic), salt (third harmonic), more baked (positive phase distortion), less baked (negative phase distrtortion)...
Now, Chef, how do you make it so tasty....
BAF 2018 Burning Amp Festival 2018, DIY Audio’s Premiere International Festival, Set For September 30th in San Francisco - Dagogo
Burning Amp 2018!
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