Thursday 29 October 2015

A More Ambitious Upgrade - Part 5

Progress has been made, in improving the quality of the volume control, but there is still clearly audible degradation. As a first major reworking I altered the circuitry around the potentiometer to turn it into a shunt topology, with immediate, obvious, audible benefit - the series resistor in the top arm leg was a fairly large value with the intended result that much more of the pot travel would be used in normal listening. Very much a step upward in the sound, and at first I was very pleased, thinking that maybe enough had been done to offset the inherent flaws in the construction of the potentiometer part; but, being the sort of person I am I immediately started using more testing recordings to highlight details of behaviour, and - you know what's coming - finally tried a track where the losses were very clear: a 'dirty' quality could be heard, which temporarily went away when the volume setting was jiggled, cleaning the contact points momentarily.

So, more has to be done! I'm not keen on simply buying, installing a much more expensive, 'higher quality' pot - I suspect that I won't make the problem go away, based on previous experience, merely slightly lessen the audible degradation - what I want is a complete solution. Without spending silly money, or going through strenuous contortions to get a better mechanism in place ...

That said, the system is in a pretty good space - most recordings come across very well, much better than the typical standard of 'audiophile' rigs: solo piano, harpsichord, is intense, rich and vibrant; massed string section playing has that sweet, satisfying sheen to it ... but, "poorly recorded" tracks catch it out still.

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