Unbalanced to Balanced Audio Converter

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EmoRiot

Active member
Joined
Mar 18, 2005
Messages
39
Location
Beautiful Downtown Burbank
I'm needing an unbalanced to balanced audio converter for 2 channels. Looking around online, these boxes are geared towards video guys and run around a couple hundred bucks.

I'm assuming these can't be that tough to build, though. Anyone got any thoughts or even have a schematic?
 
If you just need to go from unbalanced to balanced without a level change, it's hard to beat a good transformer. If you need gain as well, then a low-noise amplifier followed by a transformer works well, or use a balanced driver IC as Roger suggested.

If you're going from -8dBU (-10dBV) "consumer" level to +4dBU "pro" level, you'll need 12dB of gain, obviously. If the device on the receiving end has input gain to spare, your lowest-hassle balancing option is to use a transformer and just make up the level at the receiving end. If the cable run is short, you don't even really need to balance the signal. It's not mandatory to use balanced sources with balanced inputs; most balanced inputs will work with an unbalanced source if wired correctly.

Tell us what you want to connect to what and we can give you a more specific answer.
 
Yep,

Lots of options here, SSM2142 is easy to use. A handful of op-amps connected as a gain stage followed by inverting stage to give balanced output drive (e.g. output stage of Gyraf SSL schematic etc), single op-amp stage driving 1:1 transformer. Here's one ready to go- Kev's done the work for you!

http://www.celestial.com.au/~rosswood/diy/balancingbox/balance.htm

As NYDave says, with more specifics you may be able to be guided to a simpler solution.

Mark
 
From reading your posts, it might not be necessary.

I'm going out of a Pod XT into my Fireface 800 audio interface. The fireface's computer setup interface only allows for a global setting of balanced or unbalanced. Since my mics are all coming in balance, I've obviously opted for a global setting of balanced, making the Pod XT run in lower than all others.

I've heard it said that there are audible differences from -10 consumer unbalanced running into a +4 balanced jack. Can't remember the specifics, but the difference wasn't just 12db... I've heard about some top end loss, etc. Maybe it's just urban myth, though.

Thanks, a bunch, for all the info.
 
It's best just to try it and see.

A handy set of cables is an unbalanced 0.25" jack plug on a foot or two of cable going to two croc clips. Then get a TRS 0.25" jack plug wired balanced going to another 3 croc clips (and an XLR cable male and female if you need these) Then you can experiment with all the different connections as in the Rane Note 110, to find the optimum connection. Often the connection is dictated by a hum-free connection rather than signal level!

Mark
 
Thanks Mark,

As an unrelated item, I noticed you're in Liverpool where I lived for 3 years while I went to LIPA - which you might know of.

Oh the memories!

Say "hi" to the Bold Street shopping crowds for me. :grin:
 
Great!

There are a lot of "sons and daughters" of Liverpool out there- even if you only pass through this city tends to have an effect on you :wink:

LIPA- yes, I'v got a few friends who work there, and worked with a lot of the musicians who've passed through there.

Ah yes, busy Bold St on a Saturday.... :roll:

But at least you can buy unusual pickles from Matta's International Food Stores!!

:green:

Mark
 
[quote author="Mark Burnley"]Great!

But at least you can buy unusual pickles from Matta's International Food Stores!!

[/quote]

lol! Oh it all comes flooding back into memory!

Thanks, Roger. That's probably what I had been told about before. Sounds familiar.
 

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