Flex Your PCD Mettle:

[figure8]

Re: Flex Your PCD Mettle:

"If you run the two LE14a's in parallel you'll gain 6db of sensitivity , which is a good thing. You will want to build it as a 2.5 way though , to avoid comb filtering effects which will result from the bottom woofer being too far from the tweeter for the 1.6k crossover frequency. This can be implemented with the addition of a single coil added between the two woofers."
Could you avoid the comb filter effect by putting one woofer on top of the waveguide and the other below. a/k/a MTM? Would this screw up the crossover designed for only one woofer. Phil

[mike price]

Re: Flex Your PCD Mettle:

"If you run the two LE14a's in parallel you'll gain 6db of sensitivity , which is a good thing. You will want to build it as a 2.5 way though , to avoid comb filtering effects which will result from the bottom woofer being too far from the tweeter for the 1.6k crossover frequency. This can be implemented with the addition of a single coil added between the two woofers."
Could you avoid the comb filter effect by putting one woofer on top of the waveguide and the other below. a/k/a MTM? Would this screw up the crossover designed for only one woofer. Phil

That would work as well , drawback being that the top woofer will be pretty high up to still keep the tweeter on axis at listening height.

[Skywave-Rider]

Re: Flex Your PCD Mettle:

Is there an advantage to offsetting a small waveguide like the JBL 6x6 in a baffle, in the way many dome tweeters are, to help minimize baffle effects? Or is this not needed since there is directivity control?

Does PCD model this?

[Skywave-Rider]

Re: Flex Your PCD Mettle:

Finally got PCD running, halleluiah!

[greywarden]

Re: Flex Your PCD Mettle:

You'd really need to take measurements and put them into PCD...

[Skywave-Rider]

Re: Flex Your PCD Mettle:

Yes. Right now I am going through the manual and seeing how things work. I suppose I have to make FR measurements with drivers mounted on baffle. I will go back and review this thread to see if I understand the process.

I will have questions. : )

[dtruck]

Re: Flex Your PCD Mettle:

EDIT: I managed to locate the incredibly dumb issue with my measurement setup on my own, but I will leave this link to my build thread in its place in case anyone wants to get involved there: http://www.audiokarma.org/forums/sho...=387079&page=4

[travisg]

Re: Flex Your PCD Mettle:

Has anyone done a Ewave using 18" woofers? If not, any reason not to?
And is there any reason to use the Eminence Kappalite series vs. the Delta or Sigma series?

Reason I ask is I'm interested in doing a 2.5 with 2 18" Eminence Sigmas.

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Has anyone done a Ewave using 18" woofers? If not, any reason not to?
And is there any reason to use the Eminence Kappalite series vs. the Delta or Sigma series?

Reason I ask is I'm interested in doing a 2.5 with 2 18" Eminence Sigmas.

There is no reason you couldn't use an 18" woofer, but to keep in the spirit of the econowave series, you'd need a much larger horn, so that you could cross at 700Hz or less. The impetus behind this series of systems is to seamlessly blend the woofer's loss of directivity, so that as you move off axis, the response drops uniformly across the band. If you try to push an 18" woofer to 1KHz, or higher, the off axis response will be dropped off quite a bit compared to the on axis response. A tweeter will have a much more broad dispersion, so what happens is that as you move off axis, there will be a suckout at 1KHz, and a peak above that as the tweeter response isn't rolled off. By choosing a lower XO point and a larger horn for the tweeter, you can better control the off axis character of the tweeter, to better match the woofer.

Were I you, I'd build an econowave variant, and turn it into a 3way with the 18" on the bottom, and forget the 2.5-way approach.

The Kappalites used in the Deluxe and Deluxe HO are top-tier performers, with exceptional linearity and extremely low distortion. They're just really well designed drivers, with plenty of copper in the motors. I think that's the main reason they would be chosen. They're very tough to beat.

[travisg]

Re: Flex Your PCD Mettle:

So what you're getting at is to use one 18", a midrange for around 700hz to 1200hz, and then one of the large horns and modify the crossover to accomodate?

How much modification would that require in the crossover?

[greywarden]

Re: Flex Your PCD Mettle:

You can find CD's that will reach down to 700Hz in the correct horn no problem. You could even try the BMS 4592D coax CD... a couple of the Faital Pro CDs can go to 500Hz, the more expensive ones.

https://www.usspeaker.com/homepage.htm

[Pete Schumacher]

Re: Flex Your PCD Mettle:

So what you're getting at is to use one 18", a midrange for around 700hz to 1200hz, and then one of the large horns and modify the crossover to accomodate?

How much modification would that require in the crossover?

Not quite. I'm talking about a 10" or 12" Econowave variant, with the 18" woofer on the bottom, and the 10 or 12 as the mid. Otherwise, you need to find a large horn and a very robust mid/tweet to be able to reliably reach 700Hz, or lower.

[Mayhem13]

Re: Flex Your PCD Mettle:

You can find CD's that will reach down to 700Hz in the correct horn no problem. You could even try the BMS 4592D coax CD... a couple of the Faital Pro CDs can go to 500Hz, the more expensive ones.

www.usspeaker.com/homepage.htm

Yeah but it's long been my contention that you need a 1.4" CD or larger to play to 700hz nicely and now the +10hz content suffers on both FR and directivity still leaning towards a three way only now with a super tweeter of sorts. Not a bad thing, but still a 3way. Better to fatten up the bottom IMO.

[travisg]

Re: Flex Your PCD Mettle:

Not quite. I'm talking about a 10" or 12" Econowave variant, with the 18" woofer on the bottom, and the 10 or 12 as the mid. Otherwise, you need to find a large horn and a very robust mid/tweet to be able to reliably reach 700Hz, or lower.

So how would I wire up the woofers? Simply parallel the 10 and 18, or is it not that simple? I expect it's not that simple...

Back to my question about Kappalite series vs. Sigma. Are the differences in drivers worth the extra cost given that I'm looking for a very high SPL and somewhat SQL speaker system? Plus the SPL of the Kappalite is rather lower, but the Sigma has lower Xmax so less bass extension. But I intend to add subs anyway...

Does anyone know anyone near Wilmington, NC that is a Pro Audio DIY hobbyist/expert?

Edit: I'm thinking a Sigma Pro-18A-2, a Kappa-12A, and a DE250-8. Any criticism with driver selections? I picked the woofers because of the 99dB SPL, good power handling, xmax, low Le, lower cost, and reviews.

[djg]

Re: Flex Your PCD Mettle:

Very OT, family vacation with parents at Carolina Beach. What a beautiful spot.

Travis, have you been to AVSforum DIY speaker subforum? Very many people there with similar interests. Check it out.