Polarity mystery: Can you help me solve it?

Jea48...Some driver manufacturers (JBL for example) use the oposite polarity definition (cone pulls in).

Some driver manufacturers (JBL for example) use the oposite polarity definition (cone pulls in).

Eldartford,

True..... My point was to verify the polarity was indeed reversed on the driver/s and with the test make sure both speaker box units are in phase with one another. http://recforums.prosoundweb.com/index.php/mv/msg/2661/29039/0#msg_29039

Thanks for the responses so far.

Gregm - Yes, the soundstage does seem a little deeper. But the more obvious improvement is that images are more focused. Your theory that the improvement is attributable to a room interaction was my first thought, but I don't know exactly what acoustical effect would account for it. Any idea?

Dopogue - I don't believe that the improvement is attributable to preserving the absolute phase of the recording, because the improvement is the same across a wide range of recordings.

Jea48 - Thanks for describing that method of checking the drivers. The fact that the tweeters and woofers are wired with opposite polarity is confirmed in Stereophile's measurements of the Focal 1007be, and from what I understand, that is common practice with a Linkwitz-Riley crossover with a 36 dB slope, as described here. Also, I am positive the two speakers are in phase with each other, as I have used a test disc with in-phase/out-of-phase tracks to confirm it.

Almarg - That is a very interesting theory, and certainly would never have occurred to me. In answer to your question, my friend with the same speakers does not have similar electronics. He is using an Ayre dac, a Vincent preamp, and a Parasound Halo amp. How would I know if my system had a DC offset?

How would I know if my system had a DC offset?

Hi Bryon,

You would need a good multimeter, preferably a digital one that can measure dc voltage with a resolution adequate to read say a few millivolts (mv), or ten's of mv at most.

You would power up the entire system, let it warm up for a few minutes, and set the multimeter to measure dc voltage. With no music playing you would then place the two leads of the multimeter between the red and black speaker terminals of one channel, or between the corresponding terminals on the amplifier. Repeat for the other channel.

I don't particularly have a feel for what the upper limit of acceptability would be for the reading. Perhaps someone else reading this will. But I would feel fairly comfortable with a reading of say 60db below the voltage that, were it ac, would result in the 88db spl that your speakers are rated to produce, at 1 meter, in response to an ac input of 2.83 volts. 60db below 2.83 volts is 2.83 millivolts.

Hope that helps,
-- Al

Al - I believe I have a digital multimeter around here somewhere. I will look for it and report back my findings. Thanks!