Single ended to balanced connection
tmartin2 -- Fri, 03/10/2006 - 08:47
Is there a standard way of doing a single ended (RCA) to balanced (XLR) connection? I am running the single ended output of a preamp into a balanced only amp.
For example, there are adapters to do this. Do the adaters always short, say, pin 2 to pin 1 or something like that? Or are there different conventions?
I believe Balanced Audio Technology sells balanced-to-single-ended adapters. The adapters connect either pin 2 or pin 3 of the XLR jack to the signal pin on the RCA jack. The choice of pin 2 or pin 3 determines whether the signal is polarity inverted or not.
Robert Harley
Editor-in-Chief
The Absolute Sound
The Perfect Vision
And pin 1 is always ground?
If possible, I would buy the adaptors from the manufacturer of the amp (to be sure).
I've heard that not all adaptors follow the same conventions, but I can't back this up with any solid evidence.
Of course, in my case the manufacturer doesn't offer adaptors, nor any indication of how to apply a single ended input. Turns out, though, that adapters can be purchased for $5, so trial and error may work.
Here is how nuForce says that Cardas adaptors are wired:
RCA to XLR connector must have the correct wiring:
RCA center pin = XLR Pin-2
RCA ground = XLR Pin-1 and XLR Pin-3 (short Pin-1 to Pin-3).
There is no convention in balanced cables as to whether pin 2 or pin 3 is hot. Pin 1 is always ground. Choosing either pin 2 or pin 3 to ground will determine whether the adaptor is polarity-inverting or not.
Robert Harley
Editor-in-Chief
The Absolute Sound
The Perfect Vision
robert_harley6 wrote:There is no convention in balanced cables as to whether pin 2 or pin 3 is hot.
Actually there is, and it's pin 2 hot. This was first adopted by the IEC in 1975. SMPTE adopted it in 1986, the EBU in 1988 and the AES in 1992.
se
tmartin2 wrote:Is there a standard way of doing a single ended (RCA) to balanced (XLR) connection? I am running the single ended output of a preamp into a balanced only amp.
For example, there are adapters to do this. Do the adaters always short, say, pin 2 to pin 1 or something like that? Or are there different conventions?
There's no particular standard for adapting a single-ended output to a balanced input, but one of the better ways of doing it is to convert the single-ended output to a balanced output using a good quality line level output transformer. This will give you a true balanced output so that your balanced input can perform its job of rejecting common-mode noise.
se
Steve Eddy,
Can you recommend a good quality line level output transformer?
THX
Jensen makes one.
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