XLR to RCA interconnect. Does mixed connectors provide less noise compared RCA to RCA?

Hi Jim,

I’d suggest asking Ayre, as I suspect the most significant factor that would be involved is how the balanced and unbalanced output circuits of the CDP are implemented. But FWIW my guess is that changing to an XLR-to-RCA cable is unlikely to provide any benefit.

If you do go with an XLR-to-RCA cable, however, MAKE SURE that it does not ground either of the two signals in the balanced signal pair. My impression is that most such cables, and also most XLR-to-RCA adapters, connect pin 3 (which carries a signal) to pin 1 (ground). That would be appropriate when adapting an RCA output to an XLR input, but can cause problems or conceivably even damage in many cases when adapting an XLR output to an RCA input. This thread, which also involved a solid state CDP, being an example.

Good luck with the new preamp! Regards,
-- Al

A follow-up to my previous post: I took a look at the manual for the CDP. It states:

It is not normally recommended to use both sets of analog outputs simultaneously.

Also, Stereophile’s measurements of an earlier version of the player show output amplitudes and impedances that are exactly twice as much for the balanced outputs as for the unbalanced outputs.

The relevance of all of this is that it suggests that the signal provided to the RCA connector for each channel is not independently buffered relative to the signals provided to the XLR connector, and that the RCA connector is wired directly to XLR pin 2. Meaning that both XLR pin 2 and the RCA connector are being driven with the same signal from the same output circuit. Which would seem to confirm that changing to an XLR-to-RCA cable is unlikely to be helpful.

Best regards,
-- Al

One reason to go TO an XLR at the amp is when the XLR inputs have greater impedance than the RCA equivalents, often XLR inputs are double.

Usually, although not always, the reason for the doubled impedance on XLR interfaces (inputs or outputs) compared to RCA interfaces is simply that the XLR spec reflects the sum of the impedances of the two signal legs. And the impedances of the two legs are generally made equal, to optimize noise rejection. So driving a single-ended signal into one leg of a balanced input, with the other leg of the input grounded, will in most cases not improve impedance compatibility compared to an RCA-to-RCA connection of the same equipment. And for the same reason an XLR-to-XLR connection will often result in an impedance ratio between two components that is no different than an RCA-to-RCA connection between the same components.

Although in some designs, in which the XLR and RCA interfaces are handled by circuit stages that are separate and independent, the balanced and unbalanced impedances may differ by either more than or less than the factor of two that is commonly seen.

Using an XLR output to RCA may help isolate from ground loops as the RCA pin and shield will be actively driven, with very high impedance to ground and the shield only connected on one end.

Assuming a direct XLR to RCA connection is made (i.e., a transformer such as one of the Jensen models is not being used), obviously a return conductor must be provided between the two components, whether it be a shield or, alternatively, a conductor within a shield that is connected at just one end. Assuming the RCA input is unbalanced (a balanced RCA input would be very unusual), if that return conductor is actively driven the actively driven signal will usually end up being connected to the destination component’s circuit ground, which in turn will usually be connected to that component’s AC safety ground through some low impedance or in some cases even directly. Not good news either way, with hum or conceivably even damage very possibly resulting.

As suggested by some of the others a Jensen transformer (or at a considerably higher price point something like an SMc Audio Flex-Connect, which is also transformer based) is the ideal way of interconnecting XLR and RCA interfaces.

Best regards,
-- Al

Hi Steve (Williewonka),

In this particular case, per my second post in the thread it appears very likely that the RCA output of the CDP is provided with the same signal that is provided to XLR pin 2 (the non-inverted signal in the balanced signal pair). Assuming that is the case, there would of course be no difference in impedance or any other signal characteristics between those two points. And if an adapter cable is used, XLR pin 2 is what would be routed to the RCA input of the preamp.

A lot of components which provide both RCA and XLR outputs are designed that way. And likewise in many cases for components which provide RCA and XLR inputs. In many of those cases involving inputs the center pin of the RCA connector and pin 2 of the XLR connector are wired together, and a switch is provided to ground pin 3 of the XLR connector when the RCA input is being used.

In some other designs, though, separate and independent driver or receiver stages are provided for the RCA and XLR connectors. In those cases, of course, impedances as well as overall sonic performance can differ in either direction depending on the specific design.

Sunnyjim 11-21-2016
BTW, there is a toggle switch on the back of the Ayre CD player that offers either RCA or XLR connectors.

Are you sure about that, Jim? I’ve looked at the manual and at several rear panel photos and the only switches I see are one that turns the player’s digital output on or off (the digital output is provided on an XLR connector, as AES/EBU), and a switch that selects between "measure" and "listen" modes.

Best regards,
-- Al