Need help with Bal/Unbal connections!

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Edge13

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This is my first post here, so go easy on me. :-)

Actually, I've been reading this forum for a little while and have seen some great advice. Thanks!

My problem right now (and for a while) is that I can't find a straight answer as to how to connect balanced equipment to unbalanced equipment. If I'm going from a balanced output to an unbalanced input, what do I use, TS or TRS? And do I need to do anything specific to that cable (ie. disconnect shield, etc.)? Is that the same if I go from an unbalanced output to a balanced input?

I've gained pretty much all of my knowledge from reading everything I can get my hands on. But I just can't find the answer to this one!

Thanks in advance.


BTW, what is the actual difference between -10 and +4? Is it that your signal to noise ratio is so low you can run hotter signals? I can't quite get that one.
 
A good reference on how to connect this to that: http://www.rane.com/pdf/note110.pdf

-10 and +4 are simply two different reference levels. Semi-pro gear is usually -10dBV, primarily because consumer level inexpensive opamps like to run from fairly feeble power supplies (like +-12 to15v, and minimal current capabilities). Pro gear is typically +4dBu, because it often uses beefier power supplies (like +-24v).

That's a gross oversimplification, though. You'll notice that I used two different units (dBV and dBu): that's because the specs are completely different for the two, because their operating environments are different- especially with respect to load impedances. -10dBV should be read as "10dB below a reference level of 1V into 10Kohms". +4dBu should be read as "4dB above a reference power of 1milliwatt into 600ohms".

One specifies a voltage, one a power. If you drive the same load impedance with both, you'll find that they are actually *12dB* apart, due to the effect of the differing load impedances in the reference portion of the spec. That always causes some annoyance. Any measurement specified in dB is always a *relative* measurement (essentially, the ratio between the signal of interest and some fixed reference). Change the reference, and everything else changes as well.

Anyway, +4dBu gear is designed to drive a 600ohm load impedance- which means that the output buffers can drive relatively heavy loads quite hard, and do so with lots of headroom in both the voltage and power domains. -10dBV gear is usually designed to drive minimal loads, has a great deal less headroom, and will suffer in both noise and distortion if driven into low impedances (such as multiple parallel connections and so on).

+4dBu is arguably better (more headroom, more robustness, more ability to handle iffy loads like patchbays where 10 things can get multed onto a signal), but don't lose sleep over it. Anything balanced is better than anything unbalanced, for noise performance.

One last caveat: some wonderful vintage (and even not-so-vintage!) +4dBu gear actually can sound worse than some modern -10dBV gear in modern studio setups, if just indifferently plugged in. A lot of older gear with transformer outputs can only achieve its peak performance when it is properly loaded: i.e., actually terminated into the 600ohms that the spec calls for. Stick it into a modern high-impedance bridging input (say, 100Kohms) with no termination load, and the output transformer rings, or the frequency response suffers, or whatnot... Once size does not always fit all! Shoot, if this stuff was easy, _everybody_ would do it...

Hope that helps.
 
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