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Since some people are trying XLR output systems into RCA input amps, might as well make an active converter instead of using an XLR to RCA using only pins #1 and #2. Active XLR outputs do not like being shorted like most XLR to RCA adapter do with tying pin #1 to pin #3. The passive cable version looses 6dB of output and 3dB worse SNR.

Using machine pin sockets for the opamps for listening trials. These are designed single opamps like NS LME49710, TI OPA134, TI OPA132, OPA627 and the discrete opamp versions like Sparkos Labs SS3601, Staccato OSH-S. The system is DC coupled with a gain of 1 and no more than 0.0001VDC offset from testing with the LME49710's. That will be opamp dependent.

Each channel has +/-12VDC linear regulators, metal film 0.1% resistors and bypass caps.

Works well from a dspNexus 2/8 and Douk A5 Class D amps with Sparkos Labs SS3602 opamps installed.

Just a question. Did you consider using a passive line level transformer instead of an active system. Granted, good transformers are expensive, but once you start talking about using discrete Op-amps and a decent power supply, the cost is comparable. Obviously no power required. Granted, proper shielding is make or break from a noise standpoint.

David

I do not like transformer limitations. No low or high frequency limitations with DC coupled systems. I hear it every time listening to systems with them.

Enough is already done in studios that use TX coupling to further limit the response for recordings.

There are proaudio versions of this available, but all I found use carbon film resistors, electrolytic coupling caps and single ended DC power supplies in this price range.

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Walt

Fair enough. I am always concerned about keeping circuits simple and to a minimum, since any additional active stage is going to have an influence on the overall sound. AND, considering my bias towards tube circuits, a transformer often is the simplest way of getting the job done (a lot simpler than a tube based alternative). Of course, I would rather accept a balanced input which would keep my amplifier circuit fully differential in a PP amp.

David

That would blow the XLR side active output stage as the RCA on the amp side is grounded. This is not an balanced input, it is the active output.

I have used the suggested 'conversion' cabling from RANE Sound System Interconnection for a number of years -- works well. Can you share the schematic?

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I had those cables made as 10ft for use with my system. You loose 6dB of voltage output and loose 3dB of SNR with that technique.

Here is the schematic. Very standard differential to single ended conversion circuit.

Duplicate.

Duplicate.