XLR waste of time ?


would it be worth it to use a set of cardas adapters, rca to xlr , in order to run my simaudio lp3 into my ayre K5x-e balanced preamp xlr input instead of the rca input im currently using ? thanks .
jrw40

Showing 3 responses by almarg

JimJoyce25: It sounds as if the conclusions being voiced here are based more on philosophical creed, rather than on experimentation----at least not recent experimentation.

Since either type of connector can be used on either type of cable, the comparison should be pretty straightforward.

I've done the direct comparison of Eichmann silver vs copper RCAs. and in a good enough system, the superiority of the silver is quite clear.

I'd be interested in knowing if anyone has done a similarly direct comparison between the Eichmann silvers and high-quality XLR connectors.
Not sure how balanced cabling can be used with RCA connectors, at least in a way that preserves the benefits of a balanced interface. And vice versa as well -- what would be the point to making a comparison between connectors using unbalanced cabling terminated with XLR connectors? One or both of those alternatives seeming to be the experiment you are proposing, if I understand correctly.

And it seems to me that in any experimental comparison between RCA and XLR connectors the differences will be vastly overshadowed by other variables. As Nrenter aptly put it, "A great audio system is not a collection of optimized independent variables, but a collection of optimized dependent variables."

Variables in this situation that clearly, imo, would far outweigh differences between quality connectors of the two types include, for starters:

-- Interface circuit differences at both ends, including the fact that in designs that have XLR connectors but are not "fully balanced" there will likely be an extra active stage in the signal path to convert between balanced and unbalanced (or vice versa).

-- The fact that in most and perhaps all conventional designs the ground sleeve of an rca jack (and consequently the shield of the unbalanced cable that is normally connected to it), is common with both signal ground, chassis, and ac safety ground. Resulting in signal return currents flowing through that shield in common with extraneous ac-related currents and noise caused by leakage paths and parasitic capacitances in the power transformer and elsewhere, and also due to ground loops which are often present to some degree.

Basically, if it is not clear, connecting balanced cabling via RCA's, and connecting unbalanced cabling via XLR's, makes no sense. And the suggestion in your last post of comparing RCA tape outs with XLR main outs, in order to evaluate connector differences, is, well, simply unworthy of comment considering all of the circuitry that is present between those points, most probably including the volume control.

On the other hand, contrary to what was said in some of the earlier responses in this thread, it is conceivable (although not especially likely) that in some systems there may be significant reduction of noise pickup if an unbalanced output is connected to a balanced input via a properly implemented adapter arrangement. See figure 2.1 of this reference:

http://www.jensen-transformers.com/an/an003.pdf

Note carefully how the adapter cable is architected, with the "adapting" basically being done at the source component's output, and balanced cabling being used from that point forward. Note also that although its common mode rejection ratio is far lower than for the transformer-based interface arrangements shown in the subsequent figures, the 30db cmrr figure which is indicated as being typical at 60Hz is significant nevertheless.

With respect to the op's question, I believe that a Cardas RCAM/XLRM adapter (RCA male to XLR male), followed by a conventional balanced XLR female to XLR male cable, would amount essentially to this same arrangement. I also suspect that comparable but probably much less expensive pro-oriented adapters, available from B&H Photo Video and many other sources, would provide similar performance, at least from a noise rejection standpoint.

But whether the overall sonic result would be superior to, equal to, or inferior to the op's present single-ended connection scheme would pretty clearly have to be determined by trial and error.

Regards,
-- Al
Sam, you're very welcome.

And thanks very much for the link you provided to the Rane paper, in your post dated 11/24. It is indeed, as you said, very informative, and makes the point (among many other points) that a lot of balanced equipment is designed incorrectly in some of the respects we have been discussing here.

That perhaps being one of the reasons for the disagreements that tend to arise about balanced vs. unbalanced, and perhaps being an underlying reason for some cases of sensitivity to cable differences as well, as Shadorne has often pointed out.

Best regards,
-- Al
Ralph, thanks for the comprehensive and excellent summary.

In your list of "actual as opposed to theoretical" advantages of balanced operation, my feeling is that reduced likelihood of ground-loop issues is another advantage that merits explicit mention, although it is perhaps somewhat implicit in your mention of noise rejection.

As can be seen from some of the posts earlier in this thread, it is not uncommon for audiophiles to discount the importance of noise rejection in a home environment, due to the short cable lengths and simpler setups relative to a pro or studio environment. But as we've seen in many other threads here at Audiogon, home systems with single-ended interfaces often encounter ground-loop issues involving low frequency hum and/or high frequency buzz, that would most likely not occur if the signal interfaces between components were balanced (due to the separation in balanced interconnections of signal return currents from ac-related currents that flow through the cable shields).

That advantage would seem to be particularly pertinent to setups that have MULTIPLE dedicated ac lines powering the different components in the system.

Best regards,
-- Al