[Eeyore]

bg wrote:

wrote in message
...
Hello!
I use a transducer and preamp (from Schertler Corp.) for my double
bass. When I upgraded, the new preamp had only balanced out, but my
amp has only unbalanced in. A Radio Shack adapter works, but I don't
like the way it sticks out of the amp. I tried a cable connecting pin
2 of the XLR to the tip of the 1/4" jack. It sort of worked, but there
was huge attenuation which made S/N an issue . What I'd like to do is
mount a matching transformer inside the amp (Hartke) itself with a TRS
jack. Can anyone recommend a simple circuit using a transformer
commonly available from Mouser or the like? FR should be at least 30
to 10k Hz, and I'm hoping not to spend a princess's dowry.
Thanks,
Rob

If your output uses a transformer -
XLR pin 2 to the tip
XLR pin 3 and pin 1 to the sleeve

Fine.


If your output is an active (ie opamps) or Z balanced (resistor in the low
side) -
XLR pin 2 to the tip
XLR pin 1 to the sleeve
Leave XLR pin 3 disconnected

Not always completely true in the case of a (servoed) op-amp balanced stage.
May work acceptably but with minor defects like non-flat frequency response.

Those manufacturers who simply use an inverting op-amp driving pin 3 deserve
to be taken out and shot.

Graham