RCA to XLR adapters?

12-16-10: Tmsorosk: I think most of the responders here have missed the Question. Bobheinatz wants to use a single ended ( 2 wire cable ) in a balanced set up , Which will require a 3 wire cable . You can use adapters or reterminate , but you won't get a balanced signal with a 2 wire cable.

The discussion has focused mainly on the EFFECTS of putting an unbalanced signal into a balanced amp, so I don't think the question has been missed.

12-15-10: Kirkus: A common example is this notion of a "balanced amplifier" being simply two amps stuck in a chassis wired to different pins of an XLR connector. In this instance (as you correctly postulated) any voltage imbalance between the two amplifier stages will disturb the necessary null for cancellation of even-order harmonic distortion products. And this voltage imbalance will be affected by any impedance OR voltage imbalances in the preceeding equipment, cables, or the input termination resistances . . . not to mention any differences in gain, distortion performance, or bandwidth between the two amplifier stages.

I think it's also worth noting that using an adapter to put an unbalanced signal into that kind of design would result in up to 75% of the amplifier's power capability being unable to be utilized, since the voltage swing capability between the two output terminals would be cut in half.

Best regards,
-- Al

Almarg ... I'm aware of where the discussion went , I just don't think we helped out the poster much , probably confused him as much as I .

Ralph,

The protection circuit issue with the ARC amp may be weird, but it doesn't mean the amp needds to be fixed, either. I learned of the issue not because I had a problem, but because I called ARC before I even tried the approach. They explained the issue to me as an inevitable result of the amp's design. Now, it may not be broken, but that doesn't mean you have to like the design.

Of course, it is possible that I "misremembered" the explanation, but I don't think so.

Marty

Martykl, its my guess its the latter rather than the former. I really doubt ARC would make an amplifier that could not manage a single-ended input!

Ralph,

I can only tell you what ARC told me.

They said that RCA to XLR adaptors would cause the VT-130SE to suffer "serious" (or words to that effect) performance deterioration including loss of more than half of the power output capability. They weren't talking about my amp, specifically, but rather every example of the VT 130SE. And ARC said that it wouldn't work properly for - as best as I can recall - the reason I cited, lack of noise rejection tripping the protection.

As a non-technical guy, it would be hard for (and silly of) me to try to defend their design decisions (much less try to justify the consequences of those decisions). I take it from your post (and several of the posts preceding yours) that the technically informed/design community types out there do not approve of this approach. I would never argue with you guys.

All I can say is that the amp sounds great - although I've never tried to use it with RCA to XLRs ;-}

Marty