Polarity??

[mas]

"Another thing I might do is simply play around with it. I've taken a
setting on the Dx unit and copied it to another location with the
second location having the polarity reversed. Kind of easy to flip
around and see if I can tell any difference."

So that is what they are talking about when they refer to bi-polar behavior...

[DrWho]

You had the Jubilees outta phase with each other and didn't notice it? You're scaring me here Richard...[]

As far as the Dx38, I am not aware of any setting that inverts the system polarity....you can swap it individually on each channel though (which means flipping it in 4 places) - is this what you've been playing with?

As far as absolute polarity - I would claim to have heard some kind of difference, but honestly the magnitude is close to being within the window of placebo. It's definitely not one of the first things I'd concern myself with...

[johnyholiday]

The last time I used the auto setup on my Yamaha receiver, it declared that both La Scalas were "out of phase", while none of the other 5 speakers (center, surround and surround back) were. Since the cables were connected correctly, does this indicate a polarity mixup?

According to the manual, some speakers will show up as out of phase even if they're not. Is there something odd about horn speakers in this regard? When the program checked the distance (in order to set the delay), I was interested to notice that it measured the distance from the listening position to the diaphragm of the squawker horn, not to the front of the speaker (a difference of nearly 2 feet). Obvious when you think of it, but with typical speakers, I'd measure to the dust cap of the midrange driver.

The YPAO program seems best at measuring speaker distances from the listening position, while the other parameters like speaker size and level are better set manually, in my experience at least.

YPAO is good enough to catch a single driver miss wired ,johny had a Kg 2 with a out of phase woofer {wired backwards} in it, an YPAO caught it,.....might double check your drivers internal wiring ,for correctness

[Islander]

Thanks for the tip, Johny, but I checked the wiring pretty closely when I replaced the crossover caps and again when I recently replaced the speaker cables with longer ones. It would also be odd for both speakers to have a problem. I think it's just a quirk of the YPAO, since it gave the same result when I first got the speakers, before I changed anything. The manual mentions that it can be fooled sometimes.

As well, checking woofer wiring on La Scalas is a bit more of a project than I'm into at the moment...

[mikebse2a3]

Hey Mike...

Late getting back to this/you. I'll probably do that once our seminars are over and it quiets down a bit. (we're halfway through as of today)

Another thing I might do is simply play around with it. I've taken a setting on the Dx unit and copied it to another location with the second location having the polarity reversed. Kind of easy to flip around and see if I can tell any difference.

By the way, I PRESUME I would do that on the bass bins as opposed to the K-402?

-------------------------------------------------------------

I'm not sure what your asking here Richard.

If we assume that both your amps(High and Low freq. Amps) maintain absolute polarity(which is the most likely case but there can be rare exceptions) then if you want to experiment with hearing absolute polarity you would want to copy your current program with normal polarity on all outputs to exactly the same settings except you would choose inverted polarity for all the output channels (ie: Bass Bins and K402 also) to the new program location and then you can swap between in "absolute polarity" and "out of absolute polarity" by these two program locations to see if you can notice any difference in sound.

You must keep the Bass Bin and K402 in like polarity or you will alter the crossover frequency region shared by the Bass Bin and the K402. Again this is assuming both your high frequency amp and low frequency amp maintain absolute polarity in their design. The only way you would ever have the polarity of either Low Frequency or High Frequency Channels Output "inverted relative to the other" in the case of the Jubilee would be if one of your amps inverted polarity.

mike tn

[DrWho]

The reason the YPAO freaks out is because the bass bin has right around 90 degrees of phase shift on its output - in fact, if you're ever dialing in a sub with lascalas and you know they're time aligned (either colocated or you have the distances set correctly...don't forget to compensate for the extra 2.5 feet for the bass bin path), then you'll need to set the sub's phase at 90 degrees. You can see the interference at the crossover region go up and down as you adjust the phase and this has been consistent in every room I've measured...I have no doubt that this would throw off the algorithm calculating phase.

[mikebse2a3]

A question for mas or anyone who has used the ETF Program.

I have noticed an inconsistency with the polarity reading of the Impulse response when testing loudspeakers and I'm begining to believe the program can become confused under some conditions when it comes to multiple loudspeakers(ie: tweeter and woofer) reproducing the Impulse Test Signal. If I use the program to test an amplifier for example full range the impulse polarity readings are consistant but in the case of the loudspeaker I have had opposite indications of Impulse Polarity even though the test conditions stayed the same.

Thanks

mike tn

[johnyholiday]

The reason the YPAO freaks out is because the bass bin has right around 90 degrees of phase shift on its output - in fact, if you're ever dialing in a sub with lascalas and you know they're time aligned (either colocated or you have the distances set correctly...don't forget to compensate for the extra 2.5 feet for the bass bin path), then you'll need to set the sub's phase at 90 degrees. You can see the interference at the crossover region go up and down as you adjust the phase and this has been consistent in every room I've measured...I have no doubt that this would throw off the algorithm calculating phase.

correct thats why Kg2 was used as an example, just seen Who's on their toes,the real Doc Who..........the Khorn would give YPAO trouble too?

[Islander]

The reason the YPAO freaks out is because the bass bin has right around 90 degrees of phase shift on its output - in fact, if you're ever dialing in a sub with lascalas and you know they're time aligned (either colocated or you have the distances set correctly...don't forget to compensate for the extra 2.5 feet for the bass bin path), then you'll need to set the sub's phase at 90 degrees. You can see the interference at the crossover region go up and down as you adjust the phase and this has been consistent in every room I've measured...I have no doubt that this would throw off the algorithm calculating phase.

Well, that makes total sense! As it happens, I previously had the sub set at 180 degrees, but with the Scalas it gives the best readings at 90 degrees, so right on, Mike! However, I think the bass bin path is more like 3.5 feet, counting 2 feet to the back,1 foot to the center, then roughly six inches into the doghouse. Does that sound about right, or did you mean it's about 2.5 feet longer than the squawker? The squawker path is more like 20 inches, and the CT125 path is about 3 inches.

On a related note, is phase sort of the same as delay (or advance), within one wavelength at least?

[DrWho]

Well I said 2.5 feet because the time-arrival difference is 2.5ms between the bin and the tweeter....the recievers pretty much work on the premise that sound travels 1ft every 1ms.

If you're getting polarity issues with something like the KG, then it's probably a strong reflection or the speaker is actually outta polarity. I wouldn't go about reversing the polarity on the lascala.

Btw, don't some of the Heritage crossover invert the polarity to the squawker? Or is it the tweeter? It'd be nice to know what frequency range the YPAO is looking at for their phase information.

[mas]

Mike,

Look at figures 2 & 3 in the previously attached Polarity paper.

The properly oriented polarity will always be positive. (Assuming that there is no valid reason for having a driver's polarity inverted.)

Note, the display is for one driver. If you have more than one driver being fed you will most probably see several impulse responses offset in time. But all of the impulse responses will be positive for forward motion of the drivers.