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Author
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Topic: Proper Monitor Input Wiring
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Steve Guttag
We forgot the crackers Gromit!!!
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Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 02-16-2003 01:16 PM
Ken touched on some good points...
In order to properly answer your question, one must know several things. Is the monitor balanced or unbalanced? Are you amplifier outputs balanced or unbalanced (most common). If if your amplifier outputs are unbalanced, if you "bridged" your amplifier then the output is now balanced.
If your monitor is of the balanced type, then you will need to run a separate pair of wires to each amplifier output to the + and - terminals on the monitor. Don't just use one amp's "-" for all...that would be very poor practice that can breed oscillations.
If your monitor is unbalanced...only connect the high-side of the amp's output and make sure the monitor has a good ground reference...connecting all of the amp's "-" terminals to a commong "E" buss is also very bad practice and practically defines ground loop. Many unbalanced monitors dont even connect, internally, the "E" terminals.
BTW...one error Ken made in his statement is that balanced connections are "not ground referenced". Unless they are isolated with a transformer, they are indeed ground referenced and often exactly in the middle of + and - voltage swing (henced balanced).
To shield or not to shield...certainly, shielding doesn't hurt. The amp side of the monitor is almost always a high-impedance input (often over 100K) so noise is easily impressed onto the lines...if you have a multi conductor shielded cable tie the shield to the monitor's "E" terminal and verify it is grounded or it won't do much. Most monitor manufacturers simply dont "get" grounding but then again, neither do most techs.
If you have rather long monitor lines, you will need to go to runing individually shielded lines if you don't want such horrible crosstalk that you might as well have bought a mono monitor.
Steve
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