Film-Tech Forum ARCHIVE: MS-100 wiring

This is topic MS-100 wiring in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Richard May (Member # 2627) on 03-13-2019, 04:58 PM:

Wiring up one of these. I forget one part of it. I wired up processor outputs to monitor inputs with one ground. The amps are bi-amped so I have HF and LF + go to respective HF and LF terminals on the monitor. Do I need a ground and, if I do, take it from - from the amp?

Posted by Dave Macaulay (Member # 813) on 03-14-2019, 05:45 AM:

Ground is common, so one ground is enough - just connect the "+" amp terminals to the MS100. Since the MS100's ground is the same as the amplifiers' ground, you shouldn't really need even the one amp ground connection but in rare cases the monitor can have a lot of hum without one.
Bridged amps use the two channels together: connect either speaker output wire to the monitor, do not connect the other to a ground terminal. If the unmonitored amp channel fails it will not be noticeable in the monitor... but I don't know of a way around that.

Posted by Richard May (Member # 2627) on 03-14-2019, 07:31 AM:

Thanks Dave.

Posted by Sam D. Chavez (Member # 1841) on 03-14-2019, 01:27 PM:

I've had situations where the amp audio - needed to be connected to keep the system from breaking into oscillation. Only needed one connection for all the amps. Don't recall why but I considered it a safety ground. Let's suppose the cinema processor is loose in the rack for purposes of this topic.

I don't know if it's still true but the amp audio input ground and the output ground as in the black banana or terminal strip are not the same. Connect them together effectively and you are in for a nasty surprise. I'm sure Guttag can explain it to us.