Advice on mitigating noise

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stubby
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Advice on mitigating noise

Post by stubby »

Hello all,

I play in a little pub here regularly and, until I bought my Rick and my Vox, I've never had a significant problem in the place with noise interference (running mics and acoustic instruments straight into my PA). This place is well known to cause lots of noise/hiss in amps though, probably from old, poor wiring (it's an old converted house). Though I know I can't totally get rid of it, is there any advice on how I can maybe mitigate it somewhat? It helps a bit to run the amp independently (usually I line it into my PA board) and noise suppression and compression from the amp have helped too. The problem too, in fooling with these things is that I sacrificed a great, robust tone I had going. Are there any other steps I might take? Note that I'm using a Vox AD30VT and a 360/6.
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sharkboy
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Post by sharkboy »

The following things are items I'd look at, but the Valvetronix stuff is a bit of a mystery to me.

One thing that may increase noise is if you are using pedals that have wall warts. They may add hum on their own and if they are plugged in elsewhere from where the amp is, you may be complicating the grounding (ground loop.) Often, using batteries solves this sort of problem. You might want to see if you can affect the noise by amp placement (transformer in the wall behind the amp) or plugging into different circuits (may be less noise generated elsewhere- something like neon- in different circuits.)

Running line out causing noise levels to come down is a little baffling, since the chance of that adding a ground loop this way is increased, but, noise can be accentuated through a guitar speaker. If it was a ground loop problem between the amp and PA (that caused the amp to hum), it could be reduced by using a mic and not the direct out.

This may get back to the interaction of the single coils and the way the amp's internal grounding scheme works. At this point a 1:1 audio isolation transformer _might_ help between the guitar and the amp, but try before you buy. I have had good results sometimes with this method.

A thing to check is if the hum is reduced when you touch the metal amp chassis (there might be something your amp tech can do to make the ground work better inside the amp. For instance, I remember reading in one of Kevin O'Connor's books about tube amps that by just changing the grounding scheme in a Champ, one can accrue many db of noise reduction without any detriment to tone.)

If the noise comes in from the wall, there may be some level of filtering between the wall and the amp that you can use. Most line filters work outside of audible frequency. Some degree of isolation (power isolation transformer) may be really a good thing if they have things like neon lights or something on the circuit, but they are expensive, and you probably want to try somehow before you buy.
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triode
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Post by triode »

I have had similar problems playing in small clubs with old wiring and unshielded motors, refrigeration, etc. I found that using a Furman Power Factor Pro ($230-240 street price) cleans up the AC tremendously and makes your equipment more coherent and harmonically correct.
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