vinyl_junkie
active member
Joined: 24/06/03
Posts: 1436
Loc: Kent, UK
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Unbalancing digital output?
#1029381 - 19/01/13 06:54 PM
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Quick question
Some devices only have digital outputs on XLR connectors.
In my case these can be switched to either output the AES/EBU digital standard or the
"consumer" SPDIF standard.
Now I guess silly question but how can I wire this
up to go into a RCA plug so I can plug it into a consumer type device which has the
digital input only on RCA's?
I'm guessing the GND and Cold terminals will be
both going to the sleeve and the Hot pin to the center pin on the RCA?
Edited by vinyl_junkie (19/01/13 06:55 PM)
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Hugh Robjohns
SOS Technical Editor
Joined: 25/07/03
Posts: 18390
Loc: Worcestershire
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Re: Unbalancing digital output?
[Re: vinyl_junkie]
#1029382 - 19/01/13 07:07 PM
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Most digital inputs and outputs are via tiny 'pulse transformers' which means they are
'floating'. So the signal is presented on pins 2 and 3 on the XLR and you just need to
wire it to the pin and sleeve, respectively, of the RCA phono connector. Strictly speaking
the two interface formats have different impedances (110 vs 75 ohms) but provided you are
connecting one source directly to one destination over a shortish cable (a couple of
metres maximum) it will work just fine.
H
--------------------
Technical Editor, Sound On Sound
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ef37a
Joined: 29/05/06
Posts: 5627
Loc: northampton uk
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Re: Unbalancing digital output?
[Re: vinyl_junkie]
#1029409 - 19/01/13 10:53 PM
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Goddard
Joined: 04/04/12
Posts: 588
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Re: Unbalancing digital output?
[Re: Hugh Robjohns]
#1029416 - 20/01/13 03:11 AM
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Quote Hugh Robjohns:
Most digital
inputs and outputs are via tiny 'pulse transformers' which means they are 'floating'. So
the signal is presented on pins 2 and 3 on the XLR and you just need to wire it to the pin
and sleeve, respectively, of the RCA phono connector. Strictly speaking the two interface
formats have different impedances (110 vs 75 ohms) but provided you are connecting one
source directly to one destination over a shortish cable (a couple of metres maximum) it
will work just fine.
H
IME, the coax S/PDIF inputs on a lot of gear (esp. "consumer" and even "prosumer"
devices) are not transformer-isolated (even if the same device also has a coax S/PDIF
output which is itself galvanically isolated). This should not be a problem so long as the
coax S/PDIF source output being connected to is itself isolated, and Hugh's advice is
still valid even in such a case. But as a precaution, make the connections before powering
up.
Why I prefer running S/PDIF (or AES/EBU) over TOSlink optical when
possible... 
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Goddard
Joined: 04/04/12
Posts: 588
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Re: Unbalancing digital output?
[Re: ef37a]
#1029417 - 20/01/13 03:16 AM
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Hugh Robjohns
SOS Technical Editor
Joined: 25/07/03
Posts: 18390
Loc: Worcestershire
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Re: Unbalancing digital output?
[Re: Goddard]
#1029440 - 20/01/13 12:49 PM
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The midiman box is a powered format converter and is useful if you need to send an S/PDIF
signal a long way via AES3, but the expense is unnecessary for a short-length connection
in the back of a small equipment rack etc.
The Balan Dave linked to is a nice
and proper way of dealing with S/PDIF to AES interfacing, but again is significantly more
expensive than a simple 'bodeg cable' and -- in these examples, at least -- will need
BNC-RCA adapter cables anyway (since the balan is actually designed to convert from AES3
(on balanced XLR) to AES3-id (on unbalanced BNC cable) formats.
H
--------------------
Technical Editor, Sound On Sound
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vinyl_junkie
active member
Joined: 24/06/03
Posts: 1436
Loc: Kent, UK
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Re: Unbalancing digital output?
[Re: vinyl_junkie]
#1029441 - 20/01/13 01:05 PM
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Many thanks for all the helpful replies 
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