SIGNALS & NOISE (Letters to Editor) Feb. 1984

CD Phase Relationships

Dear Editor:

I have enjoyed Leonard Feldman's concise equipment reviews in Audio and Ovation for some time. Mr. Burstein and Mr. Giovanelli have helped me with technical problems, also.

There are very few really knowledgeable people working in most of the audio houses here, and I've gotten 10 different solutions to the same question at 10 different shops! I have the Sony CDP-101 machine and haven't had any problems as yet--just two discs that skipped or stuck, which was the disc manufacturer's fault, not the player's. Mr. Turok's CD reviews, which appear in Ovation, mentioned a muting problem in three out of four of the discs he reviewed, which made me very leery of buying these discs. However, every CD that I bought which muted on his machine, did not mute on my Sony. (He is using the Sharp player.) My Sony dealer tells me that the machine is in reverse phase and the speaker wires should be reversed. I have tried this and cannot perceive any difference in the bass or performance. In switching the speaker wires normally, doesn't this put the speakers out of phase and reduce bass? If this technician is correct and the Sony is reverse phase, reversing the speaker leads should increase the bass, shouldn't it? Sony doesn't say anything in their manual about reversing speaker leads.

-Frank Fabian; San Francisco, Cal.

Leonard Feldman Replies:

Thank you for your letter concerning phase relationships in your Sony CDP-101 player. I'm afraid that the salesman is either confused himself or has confused you in describing what he perceives as a problem. First of all, the two outputs of this player are not out of phase with respect to each other. They may well both be out of phase with respect to the input signals. That being the case, what the salesman probably is suggesting is that you reverse the connections to both speakers. That is, connect the "hot" wire from each of your amplifier's output channels (usually marked "+" or colored red) to the "cold" or "ground" terminal on each speaker, and the "cold" wire (marked "-,' "Com," or "Ground") from each channel of the amplifier to the "hot" terminal on each speaker.

Doing this will hardly ever result in a major audible difference, though some critical listeners maintain that such absolute phase relationships are important and that they do hear a difference when both speakers are out of phase with respect to the way the microphones picked up the sound waves of the music in the first place. I would say that there's no harm in reversing the phase of both speakers, as described, and if you feel that you hear an improvement (however subtle), it's perfectly all right to leave the connections that way.

All of the above is not to be confused with the situation where one speaker is out of phase with respect to the other speaker. When that happens (inadvertently or otherwise), there is a clear loss of bass response in the system, and placement of instruments takes on a vagueness that is clearly perceived by just about any listener: Thanks again for the kind words about my work in Audio magazine and elsewhere.

-L.F.

Audio Once Again

Dear Editor:

Bravo, bravo, oh bravo! I applaud what appears to be the return from the grave of the "old" Audio magazine that I so sorely missed! Congratulations on your July and August 1983 issues, the construction articles therein and much other meaty content. I had all but given up, but will now gladly renew my subscription.

You are to be especially commended for your continuing in-depth coverage of the Compact Disc equipment, which is the greatest innovation in the audio field in at least 25 years. Also, of extremely great value is the reviewing of the CD software by Bert Whyte, who has the courage and integrity to call a spade a spade (as well as a dog). You are currently the only publication with the courage, honesty and integrity to honestly evaluate such things rather than the Delphic and Pollyanna-ish stance taken by the other rags. Keep up the outstanding work!

-Paul T. Kelly; Fort Wayne, Ind.

Separate But Equal

Dear Editor:

I really appreciate your reviews of Compact Discs under a separate heading. I am a new subscriber to Audio and a new owner of a Compact Disc player. I subscribed primarily due to your Compact Disc reviews; my small CD library is based heavily on them. CDs are expensive and I want the best buy for my money. I live in a small town and I must often buy "blind and deaf" except as guided by you. Your guidance has been excellent so far; please continue.

Having Compact Discs as a separate magazine department is good because CDs seem to require a different method of recording and mixing, and thus separate reviews from analog recordings. It necessitates listening to the CD, and not just saying, "We reviewed this work four years ago and the CD ought to sound the same." Telarc seems dominant in top-quality CDs. There is apparently a magic touch 'n making CDs that Telarc has in abundance. I hope you continue with reviews of mainly good CDs (like Telarc's). It's more important now, when choices are few, to know what to look for rather than what to avoid. I do enjoy the rest of Audio. Keep up the good work.

-Ron Charlton; Paducah, Ky.

(Source: Audio magazine, Feb. 1984)

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