Running preamp through fx return-super noisy

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mr11

mr11

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Noob question. So I have been trying to run my preamp through the power-section of my mark IV and getting a ton of noise when I'm not playing. I have it running into fx return, then turn the mains and standby on and turn the channel volume of the head to zero and the master at 3-4. Am I missing something here? Neither the amp head or preamp are noisy alone.

Thanks
 
Could you be having grounding issues? You might try sticking a isolation transformer between the preamp and the FX return, like the Ebtech HE-2 or similar.
 
I'll look into that. It does seem like a grounding issue since it's like a super exaggerated version of the hum you get as normal noise with a head. It also seems I have zero low end through the loop, especially when compared to when I run it through my power amp. Same tubes though.

Hiss isn't the word I would use to describe it
 
Zero low end seems weird, you often associate that with phase (polarity) issues which I don´t think you would encounter when running one preamp into one power section. Have you used the head with the loop circuit in line? Seems like one dodgy tube in the return circuit could be the culprit, if it has a tube return.
 
Dave L":cebx3tss said:
Zero low end seems weird, you often associate that with phase (polarity) issues which I don´t think you would encounter when running one preamp into one power section. Have you used the head with the loop circuit in line? Seems like one dodgy tube in the return circuit could be the culprit, if it has a tube return.
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Yeah I don't think the Mesa uses a tube in the fx loop, could be wrong though. I regularly run a 2880 loop pedal in the loop and have no sound issues. I'm not missing anything am I? I don't need anything plugged into the FX send? Do I ned to do anything with the channel volumes on the head or have anything going into the input?
 
The V2 tube seems to be the loop return, but if you say that it works I suppose that´s not the case. You might try working the levels a bit, adjusting the send from the preamp and the return of the head (which is the output, per the manual). Too little or too much signal in various parts of the chain can screw up a lot of things.

As for the MK IV, I have no experience with it. I still think it might be the grounding, but the bit with zero bass doesn´t really fit.
 
I have run my pod hd500 into my IV's fx return without any noise issues.
 
Tried it through the loop of my 5153 too. Sounded like crap, but not noisy. I guess I'm sticking with my power-amp set up.
 
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