John Curl's Blowtorch preamplifier part II

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A prime example of added complexity affecting the "personality" of the
semiconductors is the Baxandall (super-pair)/Hawksford VAS on my last
"attempt".
The Hawksford nearly eliminates the early effect "personality"... and the
Baxandall eliminates load , saturation , reduces Cbb.
All this for just a benign added pole. GOOD tradeoff.
My (limited) experience with super-pair was some instability of this "compound" at very HF. Like the diamond. How do-you address-it ?
Did-you compared *in listening* with a simple VAS to see if nothing lost in micro dynamic and if the added complexity is worth the effort?
 
My (limited) experience with super-pair was some instability of this "compound" at very HF. Like the diamond. How do-you address-it ?
Did-you compared *in listening* with a simple VAS to see if nothing lost in micro dynamic and if the added complexity is worth the effort?

- In listening , both a more "airy" ,and transparent nature.

-in Abuse , tubelike clipping - low in "nasties". :D

-electrically , no load on preceding stage , Baxandall "self clamps" -
stays cool ... but with those
extra leds/ BC550/560 , more traces -pads. :eek:

price of glory = 4 leds + 4 15 cent BCxxx's .

OS

OS
 
Increase the FFT parameter by 2 or 3.


OK ... I crippled this line-stage.

Rser= 2R and FFT= 65536 (X4) , load = 33R.

THD went up a bit , still real low (below).

Residual "hash" became finer >100K , tried all of LT's 5$+
low noise FET input op-amps ... all below 1ppm any frequency.
Only allowing the buffer into class B could get me "normal"
distortion readings.

OS
 

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OK ... I crippled this line-stage.

Rser= 2R and FFT= 65536 (X4) , load = 33R.

THD went up a bit , still real low (below).

Residual "hash" became finer >100K , tried all of LT's 5$+
low noise FET input op-amps ... all below 1ppm any frequency.
Only allowing the buffer into class B could get me "normal"
distortion readings.

OS

OS
2R are emitter resistors on the output?
 
diyAudio Member RIP
Joined 2005
Which is as good a reason as any to dabble in audio electronics. Even if you think all amps sound the same (which I don't) I really like to try out new circuits, new concepts, doing thinks different that I think are better. Still fascinates me after decades of tinkering.

Jan
Also, as I frequently rationalize, techniques that may spring from audio investigations may find application in other fields, like scientific instrumentation.
 
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