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Old 22nd February 2005, 04:17 PM   #1
fuzzboy is offline fuzzboy  United States
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Default Transformer based audio isolators

I've got this guitar rack that is plagued by hum. I've heard that if i plugged into a trans. based ground isolator that my problem could be solved. Any info out there? Designs?
Thanks for all your help
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Old 23rd February 2005, 07:08 AM   #2
Enzo is offline Enzo  United States
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Transformer iso is one way to break a ground loop. Guitar has limited freq range, so I have used these in the past. Make sure not to mount jacks on a metal box for it. Or they ground together and the efect is lost. You need a shielded box, but use plastic jacks like Cliff jacks - "MArshall jacks" the ones with the black plastic nut.


Allied 967-2539 preferred choice

Mouser 42TM018 also consider
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Old 23rd February 2005, 03:28 PM   #3
fuzzboy is offline fuzzboy  United States
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i know the jacks you're talking about, but what about the trans. and other parts? do you know of any schematics?
thanks again.
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Old 23rd February 2005, 11:37 PM   #4
Enzo is offline Enzo  United States
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Go to the Allied Electronics web site and look up the stock number I listed. From there you can view the data sheet. it is just a transformer 1:1 so wire each winding to one of the jacks. Either end can be input or output. It will transfer the signal without direct connection. Mount it in a metal box and ground the box to ONE of the jacks. There is no schematic, just wire each jack across a winding on the tranny.
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Old 28th February 2005, 02:43 AM   #5
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Get a DI box. The good ones use transformers.
Or:
www.jensentransformers.com
They are about the best made. The studio guys gush over these.
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Old 3rd March 2005, 04:35 PM   #6
fuzzboy is offline fuzzboy  United States
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Thanks for all your help guys. Enzo, the trans your talking about, would it also be good to use one as an iso tran in a 2 guitar amp setup?
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Old 5th March 2005, 07:38 AM   #7
Enzo is offline Enzo  United States
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It can be used wherever you need 1:1 isolation. I would not try to mix with it, and putting two in parallel would probably load things down severely.

For ground loops, you have to determine which gear is offending, then make sure their grounds are not connected togehter. What I use this for is when I have two combo amps sitting side by side, and they hum when a Y cord connects the guitar to both. That Y cord is grounding them together through its shield. So after the Y cord, I insert a tranny in one leg, thus breaking the direct ground path bwteen the amps.
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Old 27th March 2005, 02:11 PM   #8
R.G. is offline R.G.  United States
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You might like to use the transformer isolated output of the hum free splitter at GEO (http://www.geofex.com). It uses a $2.50 transformer available from Mouser.com and drives it from an opamp to extend the frequency response to 60Hz-28Khz.
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