3in midrange buyout

[MisterTwister]

they are advertised to play up to 3khz.
with 0.09 mH inductance they should play much higher.
has anyone measured these drives?
I was thinking to get about 60 of them for line array.

http://www.partsexpress.com/pe/pshow...number=289-084

[Andersonix]

Might be interesting in an open baffle line array with that 0.53 Qts? But 60x$3 is a pricey experiment, and with PE being over-optimistic, 3kHz is probably right. Definitely a visual statement, though (and a chance to tweak with EQ and xover). Get 10 tiny tweeters to go along with your PE order....

[MisterTwister]

got a pair to test. here is frequency response, taken on ~11x17 baffle, 2in mic distance. not bad sounding woofers, my only complain is that pole piece and/or frame are not vented.

[planet10]

Originally posted by MisterTwister
my only complain is that pole piece and/or frame are not vented.

I would be complaining if they had vented pole pieces.

dave

[MisterTwister]

why? what is downside of vented pole? I'd imagine vent may create unwanted air turbulence...
There are venting holes in cone under dust cap, I had to put paper tape on them. Yes, I already removed dustcaps (measurements depict unmodified driver).

[y8s]

a 3/4" voice coil and .020 inch X-max is why. there's not really much air movement, let alone enough to warrant "venting" it.

[planet10]

Originally posted by MisterTwister
why? what is downside of vented pole? I'd imagine vent may create unwanted air turbulence...

vented pole pieces are noisy and will have a very specific resonance. The air trapped under the dustcap is bad enuff without adding insult to injury. Not so bad in a sub where there is a seriously opaque dustcap and the oil can resonance should be way above the pass band, but in a mid?

dave

[BHTX]

Originally posted by planet10
vented pole pieces are noisy and will have a very specific resonance. The air trapped under the dustcap is bad enuff without adding insult to injury. Not so bad in a sub where there is a seriously opaque dustcap and the oil can resonance should be way above the pass band, but in a mid?

Is it possible to add a phase plug to a driver with a vented pole piece? Would it not cover up the vent? If it did, what would be the result? Of course, the frequencies largely affected by the trapped air under a dust cap is probably dependent on the size of the dust cap etc.. but what area of the frequency range is it usually for say.. a 6.5", 8", 10", and 12" mid woofer with average size corresponding dustcaps?

I've been thinking about this a lot lately, as my buyout Eminence Delta Pro 12's sound to ME like.. big plastic cups.. if that makes any sense. As volume levels increase, it becomes more and more apparent. Just for the record, I've only played them by themselves, both free-air and in sealed boxes. Anyway, I'm guessing it's a combination of the kapton former, dustcap, and vented pole piece.. but I'm wondering which of those is contributing to it the most. If I can figure out something to improve upon the negative characteristics of these drivers, I'd most likely end up modifying them a bit.. if only I knew where to start, and the best ways to go about doing it.

[planet10]

An easy experiment would be to stuff the pole vent with some damping material (not a good long term solution as fibres might migrate into the gap).

A phase plug over the vent hole would seal it if secured appropriately, get rid of the vent's oil can resonance, the voice coil's oil can, and improve HF response.

dave

[MisterTwister]

ordered 40 pairs of these instead http://www.partsexpress.com/pe/showd...number=309-160
my plan is to tear them apart and glue drivers by magnets together(bipole), 20x20, no enclosure, just mounting rails.