Output A bleeding through Output B

H

haychess

Member
I've spent several days trying to work out why I've been having some apparent phasing issues between my amps, and finally figured out tonight that I'm getting Output A signal bleeding through Output B.

I have tried numerous cables, bypassed all Loops on the PBC and it is still there. What's even weirder is if I touch the outer housing of the cables together, it *almost* goes away, making me guess there is some sort of grounding issue going on.

Would you have any clues on how to fix this?

Right in the middle of a serious amount of guitar tracking so this is a real bummer.
 
Hard to say without knowing more details. I assume this is a PBC/10? If so, does anything change when you turn on the isolation transformer?
 
Yes it's a PBC/10. The ISO B switch does not do anything.

Both outputs have some bleed between each other, but the bleed from Output A to B is so considerable that it's causing some weird phase issues for some reason.
 
In loops 7-10, which pedals are mono and which are stereo? What kind of cables did you use for each loop? (did you follow our recommendations posted here in the forum and in the manual?) And, how do you have the switches set on the rear of the PBC?
 
7: Strymon El Cap (Send: mono 1/4" cable / Return: Stereo insert cable)
8-10: Strymon pedals all with Stereo insert cables for send and return

The issue is still present even when no loops are engaged. I also tried switching out the Loop 7 send cable for a "ring disconnect" cable but that didn't make any difference.
 
Mono/Stereo = Out (stereo)
Mono Output = Off
Iso B = Off (tried switching this On but did not fix the problem)
 
Are the PBC outputs connected directly to your amps, or is there a patch bay, interface, or anything else in between?
 
I'm not sure what's happening, then. Are you using effect loops on the amps, or are you only connecting to the amps' front inputs?

How do you know that it's signal bleed from one side to another? Have you investigated the possibility that the amps are out of phase with each other? What happens when you unplug the cable from one amp? If it's a bleed issue, the problem should continue even with one amp.
 
rjmmusic said:
I'm not sure what's happening, then. Are you using effect loops on the amps, or are you only connecting to the amps' front inputs?

How do you know that it's signal bleed from one side to another? Have you investigated the possibility that the amps are out of phase with each other? What happens when you unplug the cable from one amp? If it's a bleed issue, the problem should continue even with one amp.
Click to expand...
I have all loops bypassed, and no fx loop running.

My signal chain is:
PBC Output A > Amp 1 > Suhr Reactive Load IR #1 > SSL Pre #1 > Pro Tools I/O
PBC Output B > Amp 2 > Suhr Reactive Load IR #2 > SSL Pre #2 > Pro Tools I/O

When I mute Output A on the PBC, I still hear (and see) a low level of signal going to Amp 1, and vice versa. If Output A is off, then there should be no way for signal to show at the input of Amp 1.

Definitely has me stumped. The only thing I can put it down to is somehow there's some sort of signal bleed in the PBC.

Here is a dropbox link to a zip with two wav files. With both files, Amp 1 is the left channel and Amp 2 is the right channel. One recording is Output A Only, and the other is Output B only. You can see that there is much more bleed in the first recording, but both files have at least some bleed between outputs.

www.dropbox.com

HS PBC OUTPUT BLEED.zip

Shared with Dropbox
www.dropbox.com www.dropbox.com
 
I am officially losing my mind with this.

If I go directly from the PBC outputs A + B to Amps 1 + 2, there is no bleed.

If I go from the PBC Outputs A & B in to a stereo pedal (I've tried Big Sky, Space, Poly Beebo etc), I will get bleed between amps.

What's even weirder is if I turn Amp 1 (connected to Output A) on STANDBY, the bleed on AMP 2 goes away.

I have tried different amp configurations, cables, isolators... nothing seems to fix it.
Basically means I can't run in to a stereo out after my PBC or it all goes to crap.

I cannot figure it out.
 
Are the amps right on top of each other or next to each other? I'm wondering if the magnetic field from one is bleeding into the other. If they're close, try moving them apart and see if that changes things.
 
rjmmusic said:
Are the amps right on top of each other or next to each other? I'm wondering if the magnetic field from one is bleeding into the other. If they're close, try moving them apart and see if that changes things.
Click to expand...
They are a few feet away from each other. I cannot make sense of this.
 
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