Effects Loop Selector

[Rowbi1]

Hi

I've made an effects loop switch box and it's got a few problems (I'll try and explain):

The box has 6 jack sockets, Main In, Main Out, Send 1, Receive 1, Send 2, Receive 2.
There are 2 DPDT foot switches, one switches between loop 1 or loop 2 and the other selects to use a loop or master bypass.

I've got it in a metal case, and all jack sockets are earthed to the chassis.  all the cable inside is microphone screened cable.

THE PROBLEM:  The box works fine for switching (there's a small pop when switching but I'll add a 1M resistor to the Main Out jack eventually to cure it) but when I'm using a distortion pedal where the gain is set high there's a high pitched squeal.  If I rotate the tone knob on my guitar or the distortion pedal the squeal changes pitch depending on which way I turn the knob.

Any ideas?

Regards

Andy

[zpyder]

hmm... this is interesting.  I have a similar setup but have not had this problem.  I actually have just a single DPDT loop selector, exactly as you described (just no master bypass) and I am planning on building another soon that has a master bypass and incorporates 3 LED's.

Actually I think the only different may be that I'm not using any screened cable.  I wonder - did you leave the screen open, or did you ground it in some way?

cheers
zpyder

[Rowbi1]

The Screen of each piece of cable is connected to a jack plug at one end and then it's earthed by the jack touching the chassis.  at the other end the screen isn't connected it's cut off and insulated with tape.

Any more thoughts?

I'm going to try taking it all out of the case tonight and if that doesn't work I may try using non screened cable, as no one else seems to use screened.

[Bernardduur]

Build a splitter blend; I have the same and no problems whatsoever