Quote:
Originally Posted by Robert Gribnau
Higher values for coupling capacitors make the -3dB point at the low frequency end shift to a lower point.
The coupling capacitors between the phase-splitter and power stage are inside the feedbackloop. Output transformers cause phase-shift at the low and the high end of the frequency spectrum. Higher values for these coupling capacitors could have a negative influence on the stability of the feedback loop. But you are using decent output transformers and the feedbackloop only contains one set of coupling capacitors (capacitors also cause phase shift) because the first stage and the phase-splitter are dc-coupled so probably the higher values are no problem.
Maybe the designers of this amplifier, meant for a record player, chose the values for the coupling capacitors so that the very low frequencies got a bit attenuated to prevent rumble being amplified (too much).
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Thank you for the info. Would you kindly elaborate on the -3dB point shift to a lower point? Does this mean more (louder) bass?
I have changed to these capacitors assuming they are better quality than the older ones, hoping the change will improve the sound. Despite lack of objective measurement, I think it sounds better: I mean stronger bass and better high frequency response.