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Post subject: Humming in Pro Tube Twin with Pedals
Posted: Mon Mar 01, 2010 10:25 am
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My Pro tube Twin Amp has developed quite a hum when trying to use any drive pedals "barber dirty bomb", ts-808, Boss bd, it doesn't matter. When I connect my guitar straight into the amp I have no problem and modulation FX thru the Loop are all OK. Can't figure it out. Have tried new cables, etc. Just wondering if anyone has any suggestions? New tubes maybe? Dunno, would appreciate any comments.
Thanks


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Posted: Mon Mar 01, 2010 10:34 am
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how are you powering these pedals,what kind of pickups are you using


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Posted: Mon Mar 01, 2010 10:40 am
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joncarr1979 wrote:
how are you powering these pedals,what kind of pickups are you using


power with boss dc-power supply daisy chained to all pedals. Guitar is strat american deluxe with scn pickups


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Posted: Mon Mar 01, 2010 1:06 pm
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Seems like you might be having a ground loop problem. Will the amp hum with just a battery powered pedal? Art

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Posted: Mon Mar 01, 2010 1:31 pm
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aclempoppi wrote:
Seems like you might be having a ground loop problem. Will the amp hum with just a battery powered pedal? Art


Yep! I have tried with and without ANY power, and have tried each of the pedals together and seperately. Power was my first thought because the hum is similar to good ol' 50-60hz AC.

Steve


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Posted: Mon Mar 01, 2010 2:18 pm
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I think Art meant did you try using batteries instead of the power supply?


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Posted: Mon Mar 01, 2010 6:30 pm
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1. Start off again with guitar, cord, amp, which you said works, no hum.
2. Add one effects box with battery (no AC Adapter) and check for hum.
3. Add another effects box with battery and check for hum.
4. Repeat until you find the culprit.

Do you get hum on all 5 pickup positions?

You mentioned trying different cable - what kind are you using? What pedals and how many? You may also be overpowering the Boss supply depending on how many pedals are on it.

Silly, but was the amp and Boss power plugged into the same outlet, and were power/audio cables running next to each other?

Chances are it's a ground loop, bad patch cable, or an intermittent short in a pedal jack contact.

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Posted: Tue Mar 02, 2010 6:49 am
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Thanx Nedorama,

I'll give your suggestions a try. I hadn't thought about the power supply possibly being overloaded, I have four pedals and a tuner chained together. My band uses 'trip-lite' isobar surge protectors for all of our gear but, I had the pedals PS plugged into a nearby wall outlet. ??? Also, should the power supply for the "front of amp" pedals be separate from the "loop" pedals, or would it make a difference?

As far as the cables go, I ordered a Pedal Snake last week that should arrive soon and I would think that will eliminate any problems that may be present with my current cables.

steve

PS...Nice lookin' amp you have there!


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Posted: Tue Mar 02, 2010 7:19 am
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Thanks Steve - I rescued a 65 bandmaster head that was almost gone and now it's my #1 amp for live.

Pedal snake - is that the power/audio snake combo? It may help, but I'd figure out what your noise issue is before making a big purchase like that. A pedal power supply like the Voodoo Labs Pedal Power may help as each output is transformer isolated.

Everything should be plugged into same outlet or the tripplite - amp, pedals and mod fx. The steps I gave will help isolate any problem pieces of gear.

For me, I've found several things to get rid of noise:
George L's Cables - won a guitar player mag shootout for lowest noise and best sound. Plus you can cut to fit, no soldering. I've used these for over 10 years on my pedalboard and rack.

Power - the Voodoo Labs Pedal Power helped as well.

True bypass and effects loop switches - I have half my pedals on 2 true bypass loops - when the switch is off, they're completely out of the signal path.

Good luck; let us know what the culprit is.

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Posted: Tue Mar 02, 2010 8:37 am
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Thanks Nedorama,

I'm hoping to get time to track down the problem this afternoon.

I'll keep you posted.

Steve


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Posted: Wed Mar 24, 2010 7:06 am
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hey Nedorama,

Just thought I would let you know that I isolated the humming problem. Followed your suggestions and, sure enough, ended being a ground loop problem with powering ALL the effects with one power supply. Now, my 'front of amp' pedals are powered separately from the pedals that are routed through the effects loop and everything is REAL SWEET!

Thanks again for the assist....!

Steve


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Posted: Wed Mar 24, 2010 7:14 am
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glad to help.

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