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Topic: More ground loop buzz questions |
Richard Sinkler
From:
aka: Rusty Strings -- Missoula, Montana
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Posted 25 Sep 2012 8:47 am |
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I have a couple of places I use a Nashville 400 and a Webb together. I plug them both into the same power strip with a Hum-X on the NV400. I can get down to basically no hum at all. If I put the Hum-X on the Webb, I get a little noticeable buzz, but not enough to spoil things.
But, and here's the questions, at one gig, the guitar player also plugs his amp, PA and effects pedal (RP250) into the same strip as my amps. One time after I got the buzz out, he turns on his Fender Deluxe Reverb and my buzz is back, real bad. Flipping the ground switch on either the Webb or the 400 will kill the buzz. Then, this weekend, the bass player (who uses 2 small Ampeg bass amps) was getting a buzz and could reduce it by flipping the ground lift on the A/B/Y box he uses. My outlet strip (and everything else outlined in the previous paragraph) has to plug into his outlet strip along with his amps. We have to do it that way because the outlet on the side of the stage where the guitar player and I are has a bad ground, and the one on the bass players side is good (we always test for a good ground). Now, when he flips his ground lift switch, it caused my amps to hum until I flipped the ground switch on my Nashville 400 (or it may have been the Webb - I forget which one I changed).
The big question: If you are plugged into a strip that has other amps in them, do they become part of your ground loop? What else could cause that phenomenon? Is it just a finicky coincidence?
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting. |
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Richard Sinkler
From:
aka: Rusty Strings -- Missoula, Montana
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Posted 25 Sep 2012 8:56 am
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And another question: The Bass player is using 2 small Ampeg single 15 amps on some larger venues (not for volume increase, but like me using 2 amps, for better tone shaping. He has a Radial A/B/Y box he uses that has a ground lift switch which will get rid of his ground loop buzz. But now after seeing how well my Hum-X works, he wants to get one for his setup. Actually, he has expressed a desire to get one for each amp.
1. Does the ground lift on the A/B/Y box "safely" take care of the ground problem with 2 amps, as the Hum-X does?
2. I have always heard that you are not supposed to put a Hum-X on both amps, just one. Is that true?
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting. |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 25 Sep 2012 9:09 am
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When you're playing along on the same outlet strip with someone using an amp that still has the 'death cap' installed, and they don't have the center-off 'death cap lift' like the later Fenders, then you'll have hum injected onto your ground... that's what that little UL-listed cap does. Older Fenders don't have the center-off position on the ground switch... *all* amps with that cap in them need to have it removed and a three-wire cord installed. Most old Fenders also need the fuse moved to the hot lead (!).
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Too much junk to list... always getting more. |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 25 Sep 2012 9:26 am
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| Richard Sinkler wrote: |
1. Does the ground lift on the A/B/Y box "safely" take care of the ground problem with 2 amps, as the Hum-X does? |
Since the A/B/Y box is not inline with the mains lead yes, no problem... it's just a 1:1 transformer isolator for the signal. Whether to use 2 of them is another question... you're removing the earth ground from your guitar, which may actually introduce more noise. Have him check the manual.
| Richard Sinkler wrote: |
2. I have always heard that you are not supposed to put a Hum-X on both amps, just one. Is that true? |
If that were so I'd expect to read about that in their (very cheesy one-page) manual. Basically the HumX is a ground-lift that's limited to a small signal... if the signal gets big then the ground is reconnected (in effect). Here's the industry standard paper on the problem:
http://www.jensen-transformers.com/an/generic%20seminar.pdf
These guys know what they're doing, I'd tend to follow what they say.
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Too much junk to list... always getting more. |
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