Neumann RSM 191 - bypassing the MTX and cabling direct to 702T

[Mike Peter Reed]

This should be possible, right? (Though may lose additional shielding?) My BP4029 (for example) is 5-pin through-and-through and I've never experienced interference.

Let me give you some context:

I picked up the RSM 191 as an eBay "bargain" (always a risk, but you don't see many 2nd hand in the UK)

The supplied cabling or MTX has an obvious earthing problem somewhere so there's a really bad hum (which goes away if you use your body as earth by touching the metal on the connector or the MTX box). The mic itself is fine.

Since I already have quite a bit of 5-pin XLR cabling and splitters around it makes sense to me to create a cable (perhaps just a tail) to take the 7-pin DIN down to 5-pin XLR. The 702T can handle the P48 and matrixing so the Neumann MTX box seems a little redundant anyway - the only reason I'd seem to need it is to patch into its 5-pin XLR output (and if doing single-system which I'm always looking for reasons not to do anyway).

Just looking for opinions on this approach, maybe someone's already done something similar?

[Christian Holm]

Transformerless circuitry... not always the best sellingpoint... :)

[Mike Peter Reed]

I'm somewhat embarrassed to say that I discovered I was trailing the cabling over a mains connected PSU which was causing the hum.

Question still stands though - is it possible (or even sensible) to bypass the MTX and wire a XLR-5 cable to the 702T and let that do the matrixing?

[Scott Smith]

Mike:

As I recall, the output of the RSM-191 at the seven pin connector consists of unbalanced audio on two leads, a +48 volt power lead, a -48 volt power lead (needed for the side capsule powering if I remember correctly), a +10 volt power lead, and ground. There is a transformer and other circuitry contained in the matrix to control the steering. As such, I don't think you are going to be able to connect this directly to a +48 phantom powered mike circuit with a fair amount of additional circuitry.

Either way, I would look at the schematic very closely before attempting any other powering schema,e as there is a good chance that you could blow the damage the mike circuit.

You might want to try posting a question on the Neumann message forum. They are always extremely helpful.

Good luck.

Scott D. Smith C.A.S.