Thump when I switch on.

[andrew ivimey]

Thanks for your advice John, I don't want to use a relay and will probably make up a switch box using a large resistor to soak up the thump.

I will look at white noise audio, later.

Here's something worse though. I have gotten my hands on an old Quad 33pre-amp. When I switch that off a large thump goes through to the power amp, which faithfully reproduces the sound using my cherished loudpeakers; nasty or what! I'll rip its heart out rather than let that happen again.

[Richard Higgins]

Hi Andrew
I had a similar problem with a Troughline, thumps through speakers on switching on and off. Richard and Will diagnosed failed main filter cap, in this case a triple cap. I changed it to 3 seperate caps and the problems disappeared.

Regards Richard Higgins

[andrew ivimey]

I think it may be the caps in the 33pre-amp.

I'm ripping the PSU right out, preferring my own regulated supply, the idea coming from Net-Audio.

[Global]

Hi Andrew

I did the complete set of Net Audio mods on my Quad 33 and found them excellent.

Of more relevence to what you are doing now is that prior to these mods, I did change out all the electrolytics in the 33 and found it was silent at switch-on and -off. So it looks as though the caps may well be noisy. Your own PSU will no doubt fix that but I think it's worth changing the electolytics on the other boards as well. I used Panansonic FCs.

(Did all the mods on a 303 as well - excellent!)

Mark