Sunday 8 November 2015

A More Ambitious Upgrade - Part 7

Good progress made! I bit the bullet and added an effectively almost 100% bypass of the volume potentiometer, to make clear how much was being lost here; at maximum volume setting the level is set by a pair of series metal film resistors acting as voltage divider, the mechanism of the pot is almost completely invisible to the rest of the circuit. This I made a sensible, comfortable listening level well below the capability of the amplifier - and, I still retain the ability to attenuate the volume by adjusting the potentiometer back from fully clockwise.

This immediately showed a major benefit, the irritating buildup of low level distortion was now gone - a CD of 60's Jan and Dean surf music recorded by Brian Wilson showed tremendous depth, complexity and sparkle on tracks, quite spectacular to listen to!

The listening just a short time ago demonstrated a behaviour that happens over and over again when deliberately targeted tweaking to remove weaknesses is done: even though the sound had lost the unpleasant edge caused by the potentiometer part there was now a sense of loss of information in some disks, the sound wasn't as "big" as it should have been. Some experiments and thinking of what had been tried so far gave me the Ah-haaa! answer: so far I've been using rough, simple experimental manipulation of the power supply quality outside the component boxes to clean up interference; and I had doubled up the filtering on the amplifier side - this was in fact a mistake, the filters in action weren't combining in positive ways at all times. The cleaning up of the sound to a better level by improving the volume mechanism now made this much clearer; before, the masking by the dirt added from the potentiometer hid this effect.

So ... at all times be ready to step back and reassess where the sound is at, and be willing to undo an earlier change even though it made sense at the time, and appeared to be a positive. The flaws in a system causing the end sound to not be as good as it could be are a complex interaction of factors - the best, final results will always flow from a willingness to completely change one's approach in some area, on the basis of new evidence from ongoing, careful evaluation of the sound one is hearing.

Where's the sound at now? Very spacious, full - the ambience of the recording environment is getting mighty close to taking over the listening room - not quite at "invisible" speakers, it is still possible to pinpoint their location - but, there remains tonnes of things to be looked at, many aspects I normally do consider have yet to be addressed ... I'm sure I'll get there!

But ... what about, you know, 'conjuring'? Is it there yet? No. I'm getting more detail, a bigger sound ... but that is also making it easier to pick up where the remaining failings are ... possibly quite a few more rounds to go, c'est la vie ...

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