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Grounding issue or normal?


Super_Coo

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Hi guys I installed an RS Kit quite a while back and still had a lot of noise when using my Boss Metalzone. The noise MOSTLY stops when I touch a metal part of the guitar. It's fine when on clean. Is this normal for a pedal with such high gain?... or do I blame the pickups??? It was like this before the RS Kit but I thought the kit would help. It definitely made it sound better.

 

I checked and re-checked all my wiring and even had someone else look it over. The wiring diagram from RS was great and I solder and repair electronics for a living so it was easy for me to do.

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I'd say that is it pretty much normal. Any time you kick on distortion or overdrive pedals they will add some noise. Is it pretty quiet without the pedal(s) on? Try it without any pedals on and see how quiet it is.

 

I use a compressor, 2 overdrives and a GE-7, to name a few. Each unit that I kick on adds noise. If I kick all of them off my guitar sounds pretty quiet.

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Can't hear it long distance, so no way to tell -- BUT! Some noise is normal for any a/c powered item, and that normal noise level varies from item to item. Often, touching a metal part will reduce the noise. It may be because your body becomes at least a part of the system ground - which includes you, all the metal in the guitar, the cable, the amp, the plug/socket. (Note: this is why so many performers have been shocked by a microphone - or their amp - as I'm sure you know, but others may not, which is why this response is at this level.) It MAY mean you have a bad ground. Check to make sure the wire from the bridge is grounded into the circuit. Sometimes we forget that one. Its also possible for the wood around the mounting thimbles of the bridge to shrink a bit in winter weather/forced air heat and no longer make a perfect electrical connection with the bridge. Check with multimeter, your eyes lie - even the "tug" test won't do for this one. If the contact is poor, sporadic or non-existent, it means the bridge/stop, strings and tuners are acting like an antenna and that certainly can make more than normal noise.

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What jc said ;^)

If the "buzz" virtually disappears, or is much reduced, when you "earth" the guitar by touching the strings [or anything else connected to a ground]... then that's pretty normal. The high level of noise you'e experiencing is simply a function of the high gain in the signal path.

There are various souces of grounding related noise and interference when you introduce pedals or anything else with active electronics to the signal path. You end up with a relatively complex web of connections to ground with varying potentials. That's where much of the hum and noise comes from.

The better screened and the more effectively the guitar is grounded...the less noise of any kind you'll get. The problem is that even if you go to great lengths with "star earthing " techniques and the like, you won't get rid of it altogether.

I think we're happier if we accept that the old fashioned electric guitar does produce a certian amount of hum and noise... and we stop worrying too much about it ;^)

 

[Don't forget that recording studios typically use sophisticated active noise and hum supression. That's the only way to really submerge the noise in a complex high gain rig]

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You might want to add a noise gate to your signal chain if your amp doesn't have that feature. It will silence everything until you strike a note. You can probably buy a pedal noise gate and hook it up as the last pedal before the amp input. If you adjust it properly, there will be no tonal affect, just quiet when there's no signal.

 

The Vox AD50VT has a built-in, adjustable noise gate. So does the Roland Cube 60. I'm sure there are other amps that have it also.

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The Vox AD50VT has a built-in' date=' adjustable noise gate. So does the Roland Cube 60. I'm sure there are other amps that have it also.[/quote']

 

The Cube 30s have it too. Kind of stupid, actually, since you don't get the option to turn it off and it will cut your signal before it fully dies of its own accord which, under certain circumstances, may not be desired. Dunno about the smaller Cubes but I would bet that the new Cube 20X probably has it too.

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No you're not really grounding the guitar...but that's the perception and folks know what we mean by it ;^)

 

Ground loops and potentials are more complex issues than folks might think...but are seldom worth getting too involved in for most of us. At the end of the day, the electronics and circuitry employed in our favourite traditional guitars and amp designs is pretty crude by the standards of much modern technology. But that's how we still like it.

Not the most progressive of folks, we guitar players. ;^)

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I think we're happier if we accept that the old fashioned electric guitar does produce a certian amount of hum and noise... and we stop worrying too much about it ;^)

 

[Don't forget that recording studios typically use sophisticated active noise and hum supression. That's the only way to really submerge the noise in a complex high gain rig]

 

And that's the fundamental problem with high impedance circuits, Smoke.

If you consider 500K pots going into an amplifier ( with input impedance anywhere from

250k -350kohm for a transistor preamp stage and typically 1meg ohm for most tube

input stages, you are going to have some noise pickup from the "connection chain".

 

In the recording studio(where I used to work years ago), the recording condensor

mics (like Neuman) had double shielded cable, as well as transformer intermediate

stage/power supply to balance the output which was then plugged into a mic transformer

balanced input to remove common mode noise.

It was very critical from a noise to signal ratio inspite of the fact these recording mics had

either minature tubes or FETs to preamp the signal. Even then we had to run the signal through

Dolby noise suppressors because the noise thresholds.

 

 

A good quality guitar cable can make the difference.

<quote:Lemme>

Since different guitar cables have different amounts of capacitance, it is clear that using different

guitar cables with an unbuffered pickup will change the resonant frequency and hence the overall sound. <endquote>

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No you're not really

Ground loops and potentials are more complex issues than folks might think...but are seldom worth getting too involved in for most of us. At the end of the day' date=' the electronics and circuitry employed in our favourite traditional guitars and amp designs is pretty crude by the standards of much modern technology. But that's how we still like it.

Not the most progressive of folks, we guitar players. ;^)[/quote']

 

Well stated Smoke. Les Paul tried pushing his novel idea of a low impedance transformer balanced guitar output

through an XLR connector, but the it just didn't fly, even though the noise would have been virtually eliminated.

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Hi guys thanks for all of the info and advice.

 

Turns out we have 2 sets of 3 dimmer lights in our basement livingroom where I play near the computer usually.

When those lights are off I would guess roughly 80% of the noise drops. They seem to be my culprit as I was playing

last night louder volume than normal and WAYYYYY less noise. I tested this by turning those lights on and off. Those

lights are 50w bulbs (6 of them). I have another 13w fluorescent (twirly) bulb lamp on the desk that didn't seem to make

a difference and my monitor is LCD so that doesn't make much difference either.

 

I'm looking for a good deal on a used Boss GT-8 or something to that effect that would have a built

in noise gate rather than buy a seperate pedal.

 

I guess that's it.

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you're not really grounding the guitar when you touch it... better read this.. it might help

http://www.guitarnuts.com/technical/noisebucket.php

 

An excellent technical site. In his troubleshooting guide section using a GFI' date='[/b'] I got a kick

out of his statement.."If you ignore this advice, don't come crying to me if you get

killed....lol!

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