I'm sure this has been covered before, but I couldn't find out for sure on through the "search" function.

So...are you supposed to lift the ground on one amp when playing with two?

I'm almost certain that this is the case, though it's something, as I'm sure you all understand a guy should be clear on.

Bzzzzow!!!

Now lifting the ground has nothing to do with a ground switch as found on most amps but means disabling the ground pin on the AC plug of the amp, usually by means of a ground lift adapter. Now this doesn't account for any other AC powered goodies (effects) you might be using but I would first try a 6-way power strip coming from the convenience outlet of the slave amp and improvise from there. You will probably find one way of wiring the AC for all your gear that yields a quiet, shock free situation for the majority of your gigs.

I would recommend having a 3 prong cord with a working ground pin on all your AC gear. I have found that occasionally certain pieces of gear are actually wired incorrectly from the factory. I used to play guitar thru 2 Fender Princeton Reverbs, silverface amps with factory stock 3 prong AC power cords. I could never get the rig recording-quiet and I would get occasional low level shocks. After getting fed up, I took it all apart and discovered factory incorrect wiring. Once properly corrected, everything worked perfectly and quietly. With a 3 prong AC cord, the hot and neutral must be wired correctly whereas older gear with a 2 prong cord (without the wide/narrow blade designation) can be wired any way because you can insert the plug into the outlet either way. If you have an older amp, for safety's sake, get a 3 prong AC cord put on by a competent tech. I don't recommend that anyone use an amp with a two prong cord; I've seen too many hellacious shocks to users of such equipped gear.

There are always reasons why ground loops occur but they can be be hard to find or track down. Having good procedure will carry you thru most situations.

Bob M.

[This message was edited by Bob Metzger on 28 February 2005 at 10:44 PM.]

That pretty much answers it; I wasn't concerned with a ground loop. It was the death thing I was concerned with.
Now, if I don't lift the ground on the "Slave" amp, is will I come across any problems, save an obnoxious hum?

Between now and April, I'm concern with the 'taxes thing'. After that, I'll revert to worrying about 'the death thing' again. One or the other will eventually get you. I guess musicians, long time members of the underground economy, could say, "There are two things for certain in life: Death and Ground Loops".

Why don't you try wiring your rig both ways (lifting/not lifting the ground on the slave amp) and see what works best in terms of hum/quiet. I bet the quietiest way will be the most safe way. The hum is a symptom/indication/warning that something horrible is gonna happen. It's a bit like a rattlesnake, giving you ample warning before putting a giant herpie on your lip when you go up to sing on the mic!

Be careful and have respect for electricity and live a long life (paying lots of taxes).

I'm not sure I can make any broader statements as I'm not really familiar with the electrical codes and standards in Canada. Ask a Canadian tech for greater detail on this.

Bob M.

[This message was edited by Bob Metzger on 28 February 2005 at 11:11 PM.]

Happy taxin'

You can never just feel you have the answer for every room..the wiring, the lighting,what else is on the lines etc...all that stuff..just be prepared to deal with whats in front of you.

I don't slave..I feed both amps from a stereo profex feed for the steel and AB the fender for the Steel and Tele'...

That's all I need to know.

You are then safely grounded. I see some guys who just lift the second amp, and the hum disappears, and they stop there!! NO, NO. The signal cables that are plugged into your setup are what is now providing the ground for the second amp to the primary amp. These signal cable wires are woefully inadequate to carry the large AC current that can result from a major fault in the second amp.

I had a close friend almost killed because he did this...the second amps power transformer had a meltdown and dumped the 120 volts onto the chassis and thru his guitar cables on it's way to the ground at his primary amp. The resulting current ran thru his signal cables looking for the shortest path to ground. The guitar cable to the primary amp melted instantly and blew like a fuse. He now had NO GROUND at all. At that point the shortest path to ground was from his lips to the microphone. He survived, but got a free ride to the hospital, and was layed up for a few days.

Sorry this is so long-winded...the point is that AC cabling can handle those high currents allowing fuses to do their job. Our bodies, and those little signal cables, can't. Please be safe, and please read responses like Bob's very carefully.

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Every day is a Great day,
Mike
(aka Sideman)

[This message was edited by Mike Wheeler on 05 March 2005 at 05:46 PM.]

Or could you feed power to the ground-lifted slave amp with a plain extension cord?

One more question: aside from the annoying ground loop noise, there is no safety concern if both amps are properly and separately grounded, right?

[This message was edited by Dwayne Martineau on 05 April 2005 at 02:37 PM.]

Again, use an Ebtech Hum-x and that will solve your noise issue and keep the amp safely grounded. You only need one Hum-x at the end of either amp's line cord! This also solved the ground loop problem associated with a Tubefex or Transtubefex.
http://www.musiciansfriend.com/srs7/fg=61/g=home/search/detail/base_id/113645

I just ordered another one and got it in yesterday. I will not play without one in my two amp set-up!

[This message was edited by Ken Fox on 05 April 2005 at 03:58 PM.]

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quote:

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Steel players do it without fretting

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$59.99 to prevent unwanted death.

Brad Sarno