solderdude
Grand Contributor
Yes, not just a claim either but math based on the spec sheet of the 3255.
It is because this amp was not designed to be driven from a 0.9V source.
He used a headphone amp between the source and his amp and that solved the problem but now he does not want that headphone amp in between any more so needs to increase the gain in this particular amp. (see post#11)
Gain of non PFFB 3255 = 16dB (but balanced so is 22dB) = 12.3x gain so 11.3V max regardless of power supply voltage (assuming standard application, it may even have less gain than that but certainly not more gain)
At 36V it can reach 27V so would require 2.2V in to reach that.
Only 0.9V is available so the amp needs to have more gain.
This is what the proposed mod will bring.
As this is used for a subbass I would recommend (because of the lower input imp) to increase the capacitor values 2x as well so would recommend to fit 22uF or 47uF instead of the fitted 10uF input caps.
It is because this amp was not designed to be driven from a 0.9V source.
He used a headphone amp between the source and his amp and that solved the problem but now he does not want that headphone amp in between any more so needs to increase the gain in this particular amp. (see post#11)
Gain of non PFFB 3255 = 16dB (but balanced so is 22dB) = 12.3x gain so 11.3V max regardless of power supply voltage (assuming standard application, it may even have less gain than that but certainly not more gain)
At 36V it can reach 27V so would require 2.2V in to reach that.
Only 0.9V is available so the amp needs to have more gain.
This is what the proposed mod will bring.
As this is used for a subbass I would recommend (because of the lower input imp) to increase the capacitor values 2x as well so would recommend to fit 22uF or 47uF instead of the fitted 10uF input caps.
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