View Full Version : from unbalanced to balanced...

10-03-2006, 03:08 AM
Hi all!
I recently bought an Audio Research LS7 with only one pair of single ended outputs. My previous preamp (Luxman C-3) had both single ended and balanced XLR outputs. Using my old preamp I had the single ended outputs connected to the amp driving my mid's and high's and the balanced output connected to a JBL M552 for my subs. Now I've got a couple of questions:

How do I connect the wires in the balanced cable to a RCA -contact to be able to connect the JBL M552 to the Audio Research?

I know it will no longer be a balanced signal, but the M552 shouldn't mind, or?

I suppose number one (shield) goes to earth on the RCA, but what about two and three, should I use only one of them?

What can be expected in signal strength? Will there be any loss/gain?

If I feed the crossover an unbalanced signal, should I modify the cables going from the crossover to the sub-amp in the same way as well?

Thank You for any info on this!

By the way: I love the Audio Research, tubes rules!!!

Best regards: Jakob

10-03-2006, 06:51 AM
there are options you can use something like the Rane BB22 to convert the signal from unbalance to balance or simply a stereo DI box (quality of the trasformers makes a big difference).

another option which will give you some loss in gain of 6db but you could make a cable to go from the RCA to the XLR. Some companies when they make the cable tie pin 3 to ground and other lift pin 3 completely.


the cable between the crossover and sub amp can remain balanced with no problems.

10-03-2006, 09:43 AM
These little device comes in pretty handy for such needs...

Radial (http://www.radialeng.com/re-products.htm) have great filters - I use their DI's all the time in the field. Radial have another JPC DI which requires +48v phantom power so is not so handy for home stereo apps.

I also use this Whirlwind (http://www.whirlwindusa.com/dirbox.html) PC DI, which is passive (no +48v required). Very handy...

10-04-2006, 12:24 PM
Hello jakob.

There is no problem, you can easy make your own cables with Rca->Xlr.
I recently made 3 to my Meridian processor, and you donīt have to do anything with the other cables to the crossover.

Regards Mats

10-05-2006, 06:07 AM
The sheild on the RCA goes to pin #1 and the center conductor goes to pin #2.

10-05-2006, 06:31 AM
Hi Jakob,

The JBL iput stage is an active differential amplifier referenced to 0V.

The best way to achieve you goal is to use transformer coupling. This isn't trivial and requires some thought about how to wire it and you also need to watch polarity.

Direct wiring without a transformer is also possible. If you wish to do this, take the balanced cable and cut the end that connected to your old preamp. Connect the wire that used to be attached to pin 2 of the XLR to the centre pin of the RCA connector. Connect the wire that used to connect to pin 3 to the outer ring of the RCA. Leave the shield unconnected at the RCA end. (it should only be connected at the M552 end)

http://www.rane.com/note110.html gives a drawing of the arrangement.
(drawing 17)

Cheers, Ralph

10-06-2006, 05:39 AM
Thanks to everyone!
It all worked out just fine, and it sounds great!

Regards: Jakob