How does it sound with complex full orchestral music at a decent volume?
It may not sound quite as good, and here's why Pass LabsAudio distortion and feedback - Pass Labs
May be, that the few parts - compared with more complex circuits, like a many-stage-complementary-transes-amplifier - sound well.
Each single part modulates the signal, with e. g. the noise pattern of the material.
And also: complementary transistors do sound very different. A two-half-wave-amplifier...-)
And: Most people do not distinguish: show-measurement method and hearing-measurement method;-))
Yes, that’s what I’m trying to say. Correct me if I’m wrong….you’re taking a SE amp (stereo mode) and turning it into a PP driving one channel with the + and the other with its out of phase counterpart (-), but is it only the difference between H2 dominant over H3 dominant that makes me prefer the “single endedness “?
Hello... apologies if this has been addressed before, but I'm troubleshooting a 1.8 build and I'm at my wits end. This is the second of 2 monoblocks... first has no issues, and they were built exactly the same way.
This one has significant distortion, as evidenced by the attached image which should be a perfect 1kHz sine wave... any thoughts? Thanks in advance!
This one has significant distortion, as evidenced by the attached image which should be a perfect 1kHz sine wave... any thoughts? Thanks in advance!
Attachments
Try turning up the bias a solid 200mV regardless of what the meter says and see if this disappears. Diagnosis trick.
Edit: You do need to put a load on the output to set the bias reliably because without that, the natural environme ntal impact on the impedance is going to throw you off. Loading it down with a speaker gives it a "much stronger impedance to load"; it eliminates the fact that it gets more sensitive to changes in the bias voltage measurement when not loaded.
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I know you're not old enough to remember, but Bob Carver did this exact thing many years ago.
The outcome was the "Transfer Function" series of amps.
The Carver Challenge | Stereophile.com
Just sayin'...
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origin of your JFets?
SE or bridge?
done regular checkout - soldering, values and part positioning?
Thanks... the bias (originally set with no load) was ~12.1V. When I rechecked with 8ohm dummy load, it measured 12.34V. I dialed it back in to 12V... no change in distortion. I then turned it up .2V per your first suggestion; also no change.
The 12v setting is really the 'midpoint' adjustment and tbh even several volts away from the optimum will make little subjective difference to the point audible distortion sets in.
Bias (as in standing or quiescent current) is a critical value for the ACA but it is also non adjustable.
If the midpoint is OK and the bias current OK which is checked by measuring the volt drop across R1 and R3 and also making sure these four low value resistors (R1 to R4) are correct in value then it should work.
Are you sure you haven't a construction error shorting the output to ground????
Bias (as in standing or quiescent current) is a critical value for the ACA but it is also non adjustable.
If the midpoint is OK and the bias current OK which is checked by measuring the volt drop across R1 and R3 and also making sure these four low value resistors (R1 to R4) are correct in value then it should work.
Are you sure you haven't a construction error shorting the output to ground????
If you do bridge two ACAs, to balance, then unite the both psus. In general: use ONE psu, do not use "monoblocks" with separate psus.
To loose the 2nd harmonics is not as relevant as the outcrossing of the psu-character.
Our hearing loves, needs, distortions. Like psu-characters. And some 2nd harmonics too;-)
My experience;-)
To loose the 2nd harmonics is not as relevant as the outcrossing of the psu-character.
Our hearing loves, needs, distortions. Like psu-characters. And some 2nd harmonics too;-)
My experience;-)