A/B Box not working properly

[DaSt]

Hi,

I have a weird issue with a simple A/B Box I just made using this schematic :



Here is the things I noticed :

- Using one 5/8Watts combo on each output everything is fine
- My friend tried if with two micro terror heads (with unknown to me cabinets behind) and when its on the A output we can still hear sound through the B speakers, and same thing the other way around. It's especially true at high gain

Any idea what have gone wrong with that setup ?

Thanks :)

[DaSt]

I think i got it finally.

No matter how good you isolate the jacks, the problem is that both amps fight over who is gonna ground the signal.

One solution would be to plug both in the same outlet, but it doesnt work for me. The other is to use a ground lifter (of make one - DIY FTW) on one of the amp. Then it's all OK.

If anyone encounters that issue, you'll know