F6 Amplifier

I suspect that I will switch back to my balanced F5 after a few days. One idea would be to find an antique cabinet used for the best radios in the 30s and 40s and equip it with an F6 and a decent 12 inch speaker.

I have not really played around with the P3 adjustment on the F5 other than to null the 2nd harmonic. I wouldn't say that there is much "edginess" with the F5, other than perhaps needing a little high frequency rolloff.
lhquam: A 12 inch Cone Musical Instrument Speaker [Order# 55-1305] for ~$35 at www.MCMelectronics.com. It has a 40Hz to 8 KHz response and 90dB SPL. I listen to two 15 inch similars driven by a current source amp in a no-baffle set up. They sound great.
 
Another day listening to the Teaser-6 and I am growing more fond of it. I am now hearing the music, voices, and baseball game rather than the differences between this amplifier and the F5-balanced.

It would be interesting to do an A-B comparison between the Teaser-6 and a tube amp of similar configuration.
 
If you ever trek to Seattle I can assemble a number of tube and hybrid amps from the hands of competent people and some of Papa's favorite Lowther's to add. You could also get involved with Gary Pimm and his PP SS Tabor, with all transformer coupled circuitry in Portland. I can introduce you to him if you like.... and he has quit racing his car for the year.

Bud
 
Another day listening to the Teaser-6 and I am growing more fond of it. I am now hearing the music, voices, and baseball game rather than the differences between this amplifier and the F5-balanced.

It would be interesting to do an A-B comparison between the Teaser-6 and a tube amp of similar configuration.
SIT in output stage of Teaser-6 as an additional possibility.
 
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The SIT makes most sense in a non global-feedback design. I suspect that the F6 would not have the sound Pa was looking for with zero feedback.
lhquam: What is the probability that a bright Software Engineer can devise a DSP to imbibe any line-level audio signal with triode, SIT, H2 and H3 , Pass amp, etc characteristics? Why continue to depend on future power amps to achieve these properties which at times appear vague?
 
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In post #2249 http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-225.html#post3190416
For some reason, one channel is behaving as predicted by Spice, but the other channel is not behaving well. I have to carefully check the wiring and components. The R100s were fairly well matched, so I do not think their differences could explain the different THD spectra.

I am having the same issue with one channel of a (Mu Follower) amp with matched Semisouth R100.

In one channel I can adjust H2 vs. H3 to desired level by varying source resistors.
The other channel is totally off, also having high H4 distortion.

Could it be an issue with Gate Leakage of R100, as described by Nelson for the R085 in the 'SiC Puppy SE Amp" thread ?
 
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lhquam: What is the probability that a bright Software Engineer can devise a DSP to imbibe any line-level audio signal with triode, SIT, H2 and H3 , Pass amp, etc characteristics? Why continue to depend on future power amps to achieve these properties which at times appear vague?

It would seem logical but somehow the efforts in that direction have not
borne fruit. Similarly, simply introducing these elements on the front end
of the amplifier while using a highly linear output stage have not given the
same results.

:cool:
 
Apparently gm matching of the R100s isn't enough. In my case, I was able to obtain the desired results by swapping in a spare R100 and adjusting the Zen pots (effectively the source resistors). I haven't carefully checked the gm (or other) parameters of the R100s that are now in use.

I am having the same issue with one channel of a (Mu Follower) amp with matched Semisouth R100.

In one channel I can adjust H2 vs. H3 to desired level by varying source resistors.
The other channel is totally off, also having high H4 distortion.

Could it be an issue with Gate Leakage of R100, as described by Nelson for the R085 in the 'SiC Puppy SE Amp" thread ?
 
Could it be that factors like output impedance and other load dependent behaviour haven't been addressed by those attempts?

It would seem logical but somehow the efforts in that direction have not
borne fruit. Similarly, simply introducing these elements on the front end
of the amplifier while using a highly linear output stage have not given the
same results.

:cool:
 
It would seem logical but somehow the efforts in that direction have not
borne fruit. Similarly, simply introducing these elements on the front end
of the amplifier while using a highly linear output stage have not given the
same results.

:cool:
I envision a multi-disciplinary team including gurus like you of high-end audio [a key contributor] revisiting and laying the framework for a solution to this question. Matter of time!