On the face of it, I would have expected that you could, and I have played
with several approaches which manipulate the harmonic character in the
front end, but none of them subjectively duplicate having that character in
the output stage itself.
I don't have a good answer why, but I believe it relates to the manner in
which the output stage interacts with a complex load.
😎
I personally thought that this is what you were doing on the .8 looking at the picture...I guess I was wrong.
I thought you had four wipers one each side and with that you would play with the harmonic distortion and then adjust bias and offset accordingly on the wipers on VAS stage.
😎
May be the four pots are used to make the distortion spectra even, means no k dominant, so the Frontend is neutral and the output gives the flavour.
You can do that, but the pots are necessary for adjusting bias and offset
anyway.
I didn't say that you can't adjust harmonic ratios in the earlier stages, only
that it doesn't seem to truly duplicate the effects of such things as current
sources in the output stage.
😎
after this we could suppose that the four inner pots regulate bias and offset similar to BBA-3,
and that the outer pots called bias and offset might be for the output stage.
🙂
and that the outer pots called bias and offset might be for the output stage.
🙂
I occupied a bit with the SE bias in Spice simulating an amp analog to X….
No matter if I added a passive or active solution I got at 1W always a bit higher distortion values than without the SE stage.
Is this because the SE stages adds in Spice always a bit more k2?
And is the distortion value with SE bias only smaller when there is an imperfect match in the PP stage and the SE stage compensates by adding the inverse amount of k2 needed to get only k3?
That is what I understand from Nelsons lines in "leaving class A" article
"By setting the value and direction of a single-ended bias current in a push pull power stage you can reduce the distortion by canceling the second harmonic nature of imperfectly matched Q1 and Q2 halves,….."
And when I follow the rest of the sentence…..
"or you can arbitrarily select a desired ratio of second to third harmonic, depending on subjective evaluation of the resulting sound"
I could do this in Spice only with different SE bias on both halves of the X stage.
🙂
No matter if I added a passive or active solution I got at 1W always a bit higher distortion values than without the SE stage.
Is this because the SE stages adds in Spice always a bit more k2?
And is the distortion value with SE bias only smaller when there is an imperfect match in the PP stage and the SE stage compensates by adding the inverse amount of k2 needed to get only k3?
That is what I understand from Nelsons lines in "leaving class A" article
"By setting the value and direction of a single-ended bias current in a push pull power stage you can reduce the distortion by canceling the second harmonic nature of imperfectly matched Q1 and Q2 halves,….."
And when I follow the rest of the sentence…..
"or you can arbitrarily select a desired ratio of second to third harmonic, depending on subjective evaluation of the resulting sound"
I could do this in Spice only with different SE bias on both halves of the X stage.
🙂
Now there's an amp. Has an attachment for the listener the self adjusts according to the reaction to the song. I am sure Nelson probably has some ideas.
So theoretically, a stereo XA.8 could have 8 SE CS's.
So theoretically, a stereo XA.8 could have 8 SE CS's.
What I thought was most interesting about 6moons review was how well he described the differences in the FW stuff vs the PL stuff. That Nelson has come close to bridging the gap with XA.8, is pretty ridiculous. You know it's good when the reviewer buys it for his personal collection
you're Dodossess
both
I suppose "Dodossess" is a kind of princely title----- 🙂
over all the jokes folks do not forget I had a severe topic….
http://www.diyaudio.com/forums/pass-labs/264094-xa-8-single-ended-current-sources-3.html#post4108641
🙂
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