Slightly OT - balanced to unbalanced cables?

[Fraser, Colin J]

> -----Original Message-----
> From: Jezz Brookes [mailto:jbrookes at bluebear.freeserve.co.uk]
> Sent: 22 January 1999 12:51
> To: Synth DIY
> Subject: Slightly OT - balanced to unbalanced cables?
> 
> 
> Apologies if this is slightly off-topic but does anybody know 
> how to wire a
> balanced to unbalanced cable. I've just bought a compressor 
> with balanced
> XLRs and need to patch it into my system which is all 1/4" mono jacks.
> Somebody said to bridge pins 1 & 3 together, but I'm not sure 
> if this forms
> the Gnd or Signal. I remember seeing some design that 
> included a small (200
> ohm?) resistor as well. Any clues?

XLR connections are: pin 1 - shield, pin 2 - hot, or positive signal, pin 3
- cold, or negative signal.
Wiring pin 1 & 3 together wil give you gnd (by fixing the -ve signal at
earth), and pin 2 will be the signal, but (IIRC) you will end up with twice
the signal level at pin 2 and may overdrive input stages.
The 200ohm resistor is possibly used to prevent any ground loops when the
signal is referenced to the shield.

Have you considered adding balanced i/o to your other gear ?
I did this on my modular (with SSM balanced line driver ICs, but there are
cheaper ways), after I bought a Yamaha desk with balanced inputs on every
channel, and it makes a noticeable difference.

My favourite thing about XLRs is that inputs are female, and outputs are
male, so you can extend any cable directly with another cable.
Also, I have a Behringer Multicom compressor with balanced I/O that I can
patch in to any channel on my desk at the input, just by taking the male XLR
from the instrument cable out of the desk input and connecting it to the
female input cable to the compressor, then plugging the male output cable
from the compressor back into the female desk input - saves the cost of a
balanced patchbay.

XLRs are so nice and chunky too, much cooler than scrawny quarter inch
jacks...

Colin f