Preamp with Inverse Polarity

[chessman]

I had myself about talked into a Conrad Johnson 17LS2 preamp when I noticed a comment that it output its signal in inverse polarity. Did some research and ended up not any more knowledgeable. Two channel reviewer just says reverse cables on speakers (which fails to account for HT bypass). Other discussion on the boards seems to fall into the "you cannot hear inverse polarity" camp or the "if you cannot hear it you are a moron" camp.

What has been your experience? Is this a big issue or much ado about nothing?

[NekoAudio]

The claim of inverse/absolute polarity is based on the idea that the rising edge of a frequency is different than the falling edge. In one case, the driver will initially push towards you while in the other the driver will pull away. Conceptually, you know the difference between wind blowing towards your face versus wind blowing from your back.

Since this polarity thing is all about voltage, if you reverse your speaker cables "ground" and "signal" are reversed and so positive voltage is now seen as negative voltage by your speaker. And vice versa. Of course you cannot do this with active speakers or feeding any active electronics, because ground needs to remain ground in those situations.

That being said, there's another group of absolute polarity aficionados who also say certain albums or individual songs on an album were created with absolute or inverse polarity. In which case you need to a) know if the song is of the correct polarity and b) switch your gear's polarity (usually with a switch/button) to account for it. And do this for every album or song as necessary.

Basically, if you start worrying about the polarity stuff, you're not going to enjoy your music much. :)

[dweekie]

Much ado about nothing. As Neko mentioned, even recordings can vary, so you can think of the preamp as a machine that fixes and breaks every other recording you play ..... :toilet:

(i'm probably statistically wrong, but you know what I mean)

I tried to find some samples. This is the only example I could find, which is quite a bit harder to discern than some other recordings. I only scored 8/10, oh well.

http://www.audiocheck.net/blindtests_abspolarity.php

[HAL]

When I hear the effects of signal polarity it is usually on simply mic'd recordings like RCA Living Stereo, Mercury Living Presence, Telarc and Pope Music. Most of those were done with reversed mic polarity, except Telarc.

Most modern multimic'd recordings from what I have tried are to varied to worry about.

My Dodd preamp inverts polarity. I just switch speaker leads on my known recordings. My P-T stack has polarity inversion on the P-3A DAC as do some of my other DAC's, so that makes it easy to try. Just wish the moded DAC-60 had polarity inversion, but easy enough to swap speaker leads.

[chessman]

Hal,

I have a P-3A as well, so I could also inverse the polarity for the two channel mains. If I did, would the HT bypass work ok?

[HAL]

The polarity switch on the P-3A will only affect the two channel feed from the source driving the P-3A. If the P-3A goes to the two channel preamp and the HT feed goes to the HT Bypass of that preamp it will not be affected.

If it is some other connection scheme then there might be.

[chessman]

Thanks, Hal! :salute: