[bubba966]

I'm currently wiring up some gear, and I need to go from balanced to unbalanced on the outputs.

I have seen it done before, but I'm not sure I'm remembering it correctly.

Do you just need to jumper the cold & ground on the balanced end?

[JoshK]

I've seen it done a number of different ways.  There is a white paper that explains a couple techniques and the ideas behind it but the way you mentioned should be quite adequate. You can of course experiment to figure out what sounds best but if you don't want to go through the trouble, then your idea is quite sound.

Edcor sells some transformers online and on ebay that take consumer to pro and visa versa as well as other applications.  You could do a search for those as well if you want to experiment with transformers for noise rejection. I think their raw trannies are $8 for this application. You can also go crazy and buy the Jensen tranformers which are ~$100/ea.  The Jensens are suppose to be the bomb.

[JoshK]

come to think of it.  An experiment that I have wanted to try from going from balanced to unbalanced is:  Take the two signal conductors in your wire and attach them to + & - on the XLR, take the shield and tie it to the ground on the XLR, on the other end, take the + and attach it to the center of the RCA and the - to the shield of the RCA, now take the shield of the wire and attach it to a small .15uf (or there abouts) cap and the other end of the cap to the shield of the RCA.  

This should have the advantage (theorectically) of rejecting RFI from the signals in the cable without giving a clear path for the EMI to transmit from case to case.  The type of cap shouldn't be important as it isn't part of the signal, so any ol' little ratshack cap should do.

[bubba966]

Thanks Josh.

Mike Galusha did a balanced to unbalanced conversion on a Behringer I bought from him some time ago. But I don't have it any longer, so I only had to go by my memory of how he'd wired it.

Experimenting would be fine if I had XLR's to do it with. But I'm taking the output of a Sony DFP-3000 SDDS cinema processor out to a Proceed AVP2. The Sony is commercial theater gear, the Proceed isn't. The Sony's output is through a DB25 connector. So I'm having to solder up IC's to the backside of a DB25 plug. Which is lots of little pins that are close enough together to make soldering, unsoldering, & re-soldering more hassle than it'd be worth.

Besides, film playback isn't so easy & instantaneous as say CD/DVD or even LP playback. Would make a/b'ing a bit of a bitch.

I think I'll just stick with trying the cold & ground together. If that works fine, then that's what'll be done.

[JoshK]

Yikes DB25, yeah that would be a pain.  Although that isn't the side I'd experiment with anyway, it would be the RCA side.  But I hear ya.

[bubba966]

Yeah, 18 connections on a DB25 connector....

The cable & RCA's have already been assembled & heatshrinked, which would make it easier to do any switching on the DB25 side.

[shokunin]

I've made a few balanced to single ended cables from a balanced Source to an unbalanced preamp.  In that instance I used the signal hot pin  (pin 2) from the balanced XLR as the hot on the RCA and ground (pin 1) to ground.  You could use either (pin 2 or 3)  of the balanced "hot" signals depending on which phase you want.   My equipment is electronically balanced, but if the source gear is transformer based then I believe you could use pin 3 as ground and pin 1 as shield.

[JoshK]

Then won't you be getting only half the voltage?

[shokunin]

Yes, you only get half the voltage of the balanced output.  If find this is purer than trying to use a transformer to sum the phases into a single ended output.  

Chris Venhaus was helpful in deciding which way to go, since I used some furutech XLR's and pulsar wires that I bought from him.