keele line array, bad start...

[adason]

hi Pano, yes, no problem, what are you trying to see?

[adason]

i thing that much more interesting overlay is this
this is 1ft infront of the cbt array, again, no eq, in the middle of array, directly in on axis, (blue) than 20 degrees of axis (magenta), and 45 degree (green) of axis...
i thing it nicely shows cbt behaviour
(i took more angles, 5, 10, 30...but the measurement just fits righ in beween shown)

[adason]

since the 3" auras rolled of after 10k, I had to put tweeters on those
I added 18 tweeters, wired as 16 ohm to match midranges
crossover is single cap only
attached are two pictures for those who are interested
also the fr response with tweeters (no sub attached, just an array)
measures well, sounds good

[adason]

this is how whole system measures with active crossover, biamplified, with sub adjusted to match line arrays

[adason]

now, when I was adjusting the subwoofer level, something strange happened...
(this is old ugly sub which I use as stand mostly, but this time I had to put electronics off the sub, since it was shaking the cd player quite a bit
its a closed box of unknown volume, pretty big, with two 15" woofers
yes, there are two woofers, one on each side
the woofers are BOSS unknown model)
anyway, long story short, I tested the subwoofers configured as dipol or bipol
simply by switching the polarity on one woofer
subwoofer sounded much better in di-polar configuration, the bass was cleaner, deeper...
so I wanted to verify what I was hearing, so I did more detailed measurement
what measurement showed was that not only there was no cancelation or loss in di-polar woofers arrangement, there was gain ~5-6 dB!
I recommend to experiment with di-polar subwoofers, it seems to me that when woofers are not fighting against each other, creating big ups and downs in preasure inside the box, they move more air in the room
that's what my measument shows anyway, and I am sure many will not believe
I have no special theory about it, just that in di-polar arrangement the membranes move in unisono, so they move more freely, when in bi-polar configuration one is preventing the other to move

[18Hurts]

Thank you for the RTA readings,

I'm still breaking in my box of NS3-16's, 31 of them completed and will start building the new bezels in two weeks. Such is the slow progress in the winter as I have an affinity to breaking in speakers when the temps drop below freezing.

After listening to my 2-way line arrays, I've come to the conclusion that in the upper treble range, they hit a "wall" and the output of the line hit's it max at the higher frequencies and any additional drivers adds sound output to lower frequencies.

My wild guess is by using 21 drivers, the output should increase below 2KHz but not above it, maybe smooth the response even flatter? I'm crossing the NS3's at 400 and 6,000 Hz to woofer and tweeter lines so on paper--it is looking better all the time.

Thanks again for the results--I'll have mine in about a month and hope I can get close to your readings.

[Bill F.]

You may have already passed over the idea of shading, but I thought I'd bring up the idea of using multi-tap transformers instead of resistor networks.

For example, on my shelf I have a number of Tannoy THP-60 and THP-30 transformers out of ceiling speakers. They have taps for -3, -6, and -9dB, which correspond to Keele's shading steps, IIRC. It would raise the array efficiency somewhat, and might even be less expensive depending on on the resistors it replaces.

[rogozhin]

Hi, adason! Tell me, in your opinion: what's the principial difference between Keele's radial arrays with electrical shading and J-arrays, wide used in professional sound reinforcement, where the question of having of equal levels on each vertical direction and distance is solved by different number of drivers in each vertical direction. Sorry for bad english! Thanks!

[adason]

Hi guys, sorry for the delay in reply...I was not expecting any posts in this old thread.

Bill, thanks for good suggestion, as a matter of fact, I do have similar transformers...the ones from 70 volt distrubution boxes...I might experiment with those, but for now the arrays are sounding superbly.

rogozhin, I know nothing about J-arrays, I only gathered info about Don's CBTs