Relax on the balanced output guys!

Posted by Chuck Swindoll, Jr. [IP: 199.174.241.122] on February 01, 1999 at 16:46:41:

In Reply to: Relax on the balanced output guys! posted by Andre Yew on February 01, 1999 at 11:44:46:

:Third, a balanced system is not what you think it is. It does not involve opamps nor 6 or 14 dB boosts.

Who said anything about op-amps, or boosts? All I said was that a balanced line in a pro piece of gear is 99% of the time a plus 4 level, and not minus 10 like in consumer equip. If you try to mix these two levels within a single system, problems will arise.

:That is overkill in the wrong direction, as many devices, like the Lexicon DC-1, generates much RF by itself already. A copper-lined room does not solve noise sources internal to itself like video signals, DACs, digital lines, TVs, etc. RF protection is gained by good design, and part of that good design is using balanced lines.

Yes, lining a room with copper may be overkill, but I have known a few studios that had to do this as RF was bombarding the studio recording rooms, and lining the inner walls with copper was the only cure...
Please explain to me how a unit that generates audible RF noise within itself will be cured of the problem with balanced lines? The noise will simply be passed through the cable balanced or not. Secondly, if the unit is that bad, it may be time to purchase a replacement. By the way - Good design is not limited to balanced lines. That statement is too limiting, and biased.

:hum in a system is caused by the non-zero impedance of ground lines, carrying return currents, which can be caused by using the shield of a cable as both shield and signal return.

Sometimes, but not always.

:A properly implemented balanced system with no "pin-1" problems will always be ground hum and buzz free.

Simply not true. Ask any house engineer or studio owner/designer with any experience, and they would flat laugh at that statement. You may note that a lot of the times to rid a system of hum or buzzing, a balanced line is the culprit, and by unbalancing the line, the hum/or bus is removed. I have used this cure myself.

Establishing a grounding stake does no good as the interchassis current will still be flowing through your shields which are shared as ground currents.

Interesting concept. Seems funny then that in every well designed studio, venue, or even a home, that a ground stake is used exclusively for the sound system to be isolated from the rest of the equipment/electricity. I guess all those thousands and thousands of people are just wasting their money...

Follow Ups:

• Relax on the balanced output guys! - Andre Yew 11:17:16 02/02/99 (1)
  • Relax on the balanced output guys! - Chuck Swindoll, Jr. 13:28:53 02/02/99 (0)

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