Line isolation

[ChuckD]

I need to isolate a guitar signal coming from a Y splitter into two Tube amps on different grounds

I picked up a couple of 1:1 audio transformers at radio shack and can't figure out what the resistor and cap in series should be for the output.

The Transformer is:

Primary resistance : 51 ohms
Secondary resistance : 70 ohms
Impedance 600-900 ohms

I tried a 1K in series with a 0.002uF cap across the output but still has buzzy noise and volume is decreased.

Anyone have some experience with this?


Thanks

-ChuckD

 

[PRR]

> 1:1 audio transformers at radio shack ... Impedance 600-900 ohms

These are 600 ohm transformers. Guitar pickup is more like 5,000, preferably very-high load (100K or more).

Use two direct-boxes.

You could probably use one direct-box, and two of these transformers to split its Low-Z output. Termination really should not be critical.

 

[ChuckD]

Turns out I was wrong about the buzz.
The solder station was causing the buzz to be picked up by the guitar and amp in the room all along.

So now with just the transformers in the path it is quiet and the Impedance mismatch causes a loss of volume.

Also I can hear a Radio station very well through the amp. Is ther a way to get rid of that?

I figure I will just use these as a test the replace them with a Mouser 42TM018 which is a 1:1 10K Impedance transformer.

How do I get rid of the radio?

-ChuckD

 

[NewYorkDave]

Don't expect great results with those tiny telephone coupling transformers. By all means, try it, but you'll probably notice a severe lack of bass.

 

[Mark Burnley]

Wasn't there a post a while back with a simple op-amp splitter with transformer iso option?

I know it's a silicon solution, but a bit of sand can work pretty well in these situations w.r.t impedance matching and losses...guitars are pretty finicky about low-Z situations...

:grin:

Mark