Signal Chain Query - Help!!

[bassicinstinct]

Can I apologise in advance if this is something which has been covered in previous threads but I have been unable to find anything appropriate using the Search facility.

My signal chain, via my pedalboard, currently is:

Goodfellow GBIV Active Bass > Boss TU2 > Boss GEB7 > Boss DD3 > SABDDI > Ashdown Combo.

All cables checked and OK. Power Supply from 2.1 amp AC/DC adaptor.

My problem is that, if I take a lead from the 1/4" Effected Output of the SABDDI into the Input of my amp, I get a horrendous hum both through the amp and PA (when direct injected).

If, however, I put my board throught the Effects Loop, everything is totally silent with no hum at all.

Any ideas? I know that the obvious answer is "Just put it through your effects loop then", but it is really bugging me.

As always, all help and info gratefully received.

 

[judas jedermann]

Have you tried switching the ground lift from sansamp?

 

[bassicinstinct]

Yes - makes no difference.

Incidentally, if I take a lead straight from my bass to the amp, this is also totally silent/hum free.

 

[judas jedermann]

Does the hum excist if you take Sansamp away from your effects line and plug straight from DD3 to input? If your cables are ok then I guess it has to be Sansamp or some other one of your pedals. Or bass. or bad something...

 

[bassicinstinct]

Must confess, I have not tried that. I'll experiment by eliminating each pedal in turn and see what happens.

BUT, why no problem when I'm in the Effects Loop?

 

[niftydog]

the earth lift switch only affects the XLR output anyways...

bad hum = check ground connections and troubleshoot for ground loops.

It may be that the effects loop doesn't have a ground connection at either or both the send and return jacks, so that might be breaking the loop.

Clean plugs and sockets paying particular attention to the ground contacts. To check for ground loops, run everything from batterys and leave the power supply disconnected.

 

[bassicinstinct]

I've solved it!!

All it took was to replace the "spider" lead powering my board with a "daisy chain" lead and job done, hum gone and everything OK.

Sometimes it's the most obvious and simplest answer eh?

Thanks to all for your comments though.