RCA to XLR adapters?

Thinking a little further about my previous post, Ralph's point does indeed make perfect sense to me, assuming that the input stage within the amp is what is known as a long-tailed pair differential amplifier. That will produce a balanced output in response to a single-ended input, thereby realizing the benefits of fully balanced internal design in the subsequent stages of the amplifier, including the power stages where it matters most.

I assume that is the architecture used in Ralph's designs. So the question becomes whether or not the input stage of all or at least most other "fully balanced" amps can be expected to have been designed in an equivalent manner. I don't know the answer to that question.

Best regards,
-- Al

From my experience with Cardas XLR to RCA adapters, it greatly degrades the sound. If you have a very high end system, I suggest only use in an emergency or temporary.

The only time I tried SE into balanced, the amp did not respond well at all, and it was fully differential. It made sound, but badly.

Many find that they don't need expensive XLR cables because the effects (or is it affects) of the cable get reduced. You didn't mention if your preamp has XLR outs.

One note of caution: Not all Balanced amps are created equal.

I put this very question to ARC's tech team some years back and learned -

ARC's balanced amps (according to ARC) will perform "very poorly" if you try this scheme. I'm not particularly technically oriented, but my understanding is that the lack of noise cancellation in the single ended signal will trip the protection circuitry at less than half the rated output. My 122 WPC VT30SE will output +/- 50 WPC (IIRC) before the protection police shut down the party.

Disclaimer: This posting is based on my recollection of a coversation with ARC's tech guy many years back, so I hope I got it right and that this explanation makes sense to those more knowledgeable of the issues at hand.

Marty

If the amplifier is truly balanced, it will not care if the input signal is balanced or single ended, nor will it matter if you use the RCA or XLR for that input.

I can imagine an amplifier that is balanced but does not take advantage of all the possibilities that balanced operation offers, but the idea that using a single-ended source with it might set off the protection circuit seems weird. If that is really true then there is a problem in the amplifier that needs to be fixed; I can't think of a reason why a properly operating amp would behave that way.

Now when you attempt to run a balanced amp with a single-ended source, care must be taken that the hookup is correct. Often its a good idea to make sure pin 3 and pin 1 (ground) are tied together. If this is not done, pin 3 can float and inject noise into the amplifier. This might be why we see a few weird responses in the posts above (although I would have expected that this sort of nuance would have been dealt with, but maybe not...). The Cardas adaptors we have seen do not do anything with pin 3 so they usually need some sort of attention, depending on the setup.