Alan H
Ex Member
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Chasing hum, what fun >:(
Fitted a temporary, grounded, screen the length of my input leads. No improvement - removed it (for now).
Rewired chasis ground to chassis / iec earth pin using various arrangements. No difference.
Shortened all transformer leads to minimum length. No difference.
At this point (blush) I disconnected my inputs and switched on again. Ah - a difference. Amp silent to half volume, then sudden onset of irregular valve noise - jittery, slightly whistling sound.
The reason I had not done this before is that my other valve amp, and my T-Amps were silent, and this was just a drop in. Seems they filter out the noise somehow.
OK - external problem. Disconnected most of the chain, leaving just input from the DAC straight into the Kit1. Sounds good - but the Kit1 volume very sensitive (must check the Beresford DAC output specs, but I'm pretty sure they weren't higher than 2). Maybe just my efficient giant horns with no power-sapping crossover. Volume levels seriously staggering for 1.8 watts (8ohms) what was I worried about. My daughter just in from other side of the house complaining it was disturbing her playing Guitar Hero!
Anyway, hum now acceptable, and not intrusive from listening position. But can't go on like this, because I need more inputs, and these are on the TVC ... so major tidyup of wiring. Reconnect chain. Run things with TVC volume high and Kit1 volume low. Much better.
Must look at house earth.
Amp still burning in ... listening impressions to follow, including A/B comparison with Charlize+Auricaps. Should be interesting.
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