cd player - xlr output buzzing

My guess would be that your adapter cable already shorts pin 3 to pin 1 (most xlr-to-rca adapter cables and adapters do that). And I would further guess that the reason for the problem is that the cd player, which has a low 22 ohm output impedance, cannot tolerate having its "cold" output signal (xlr pin 3) shorted to ground, with the only current limiting being provided by that output impedance.

Using an adapter plus an rca-to-rca cable would be no different, electrically.

I would suggest asking the cdp manufacturer if the player can tolerate having xlr pin 3 shorted to ground.

Shorting one side of a balanced input to ground via an adapter would not be a problem, but I would avoid doing so with any output unless the manufacturer confirms that it is ok, and/or the output impedance is known to be considerably higher.

To answer the question in your preceding post, the wiring configuration could be checked with a multimeter or ohmmeter.

Regards,
-- Al

Thanks Al - the difficulty I'm having in finding any consistency to testing the problem is that when it is connected to the preamp, the buzzing is only at low volumes and sometimes even disappears after a minute or two.

When I use the exact same connection/cable to a Vincent KHV-1 headphone amp, there is no buzzing detectable at all. This would indicate that the cable is possibly fine, but there is something the preamp is disagreeing with?

I can't explain that with any kind of certainty, but realize that when the adapter cable is in place you are most likely connecting one of the two outputs of the driver stage in the cdp (the output which drives xlr pin 3) to the chassis of both the cdp and the component to which it is connected (the preamp or headphone amp). That will expose both the signal return current flowing through the cable, and the output driver device, to noise voltages that may exist on or between the two chassis, as a result of leakage paths between ac hot or neutral and the chassis, and/or as a result of the fact that chassis and ac safety ground are common.

Those noise voltages would figure to be different between the headphone amp and the preamp.

And all of this will be happening while the output driver device is most probably being forced to supply more current than it is designed to supply.

In any event, I would not operate the cdp with xlr pin 3 grounded without first receiving assurances from the manufacturer that that will not cause improper operation, and that it will not cause damage or degraded long-term reliability.

Regards,
-- Al

Yes, splitting the rca is perfectly safe, and the very low output impedance of the cdp will mean that any sonic effects of having two loads and two cables attached to each of the rca outputs should be negligible.

Ground loop issues might still be a possibility, along the lines of what Dave suggested. But if need be those could be addressed with cheater plugs, or connecting to different ac outlets, or isolation transformers or other measures that are commonly used to address ground loop problems.

Re your last question, if my theory is correct, then yes the buzzing would remain if you continued to use the adapter cable. It is conceivable, though, that it might be avoided with a specially constructed cable that left pin 3 unconnected.

Good luck!
-- Al

I suspect that Atmasphere was thinking xlr input when he wrote his post, rather than xlr output.

Heineken or Samuel Adams would be great as far as I'm concerned :)

-- Al

Good suggestion by Dave about the Jensen transformers. A number of Audiogon members have reported using them, with no perceivable sonic side-effects.

There is an excellent paper at Jensen's site about interfacing balanced and unbalanced equipment:

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

Note that among the various approaches it describes, the adapter cable approach is shown for rca to xlr input, but NOT for xlr output to rca input. Although it certainly can be done sometimes, if the output impedance and drive capability of the output circuit permits, or if pin 3 is left open.

Here is a lower priced alternative to the Jensen transformers:

http://www.bhphotovideo.com/c/product/381596-REG/ART_DTI_DTI_Transformer_Isolator.html

http://www.artproaudio.com/downloads/specsheet/dti.pdf

I've used this device in non-critical voice recording applications, and in that application it has seemed perfectly transparent sonically.

I'm inclined to think that the problem is not due to noise floor sensitivity, because it seems to be inversely related to volume control setting, it is intermittent, and it is not present on the rca output (where the output level is only 6db lower than on the xlr output).

Good luck!
-- Al

Outstanding! I'll let you know when I can come down for the Sam Adams.

-- Al :)