Flex Your PCD Mettle:

[Pete Schumacher]

Re: Flex Your PCD Mettle:HP Power Pro

Hello Pete,
What is your final design on the crossover on this setup? I have the drivers and really want to make a pair of 'tribute' E-wave speakers honoring Evan. I have the badges ready to go (I fronted most of the $$ to have them made) He helped me more than a lot on my not so Econo JPL pro (2235H and 2452H-SL on PT-F95HF) speakers and I want to do this project right in honor of him.
Steve

If you check the very next post, Zilch commented on why it might not be so good to leave it at that setup, due to the vertical directivity.

The simplest thing to do would be to mount the woofer recessed so that acoustic centers line up.

But if I recall correctly, the nice plot was derived using the values in the previous post.

Woofer: 1.2mH, .2 Ohm ; 22uf shunt ; 1mH, .2 Ohm ; zobel 15uF, 8 Ohm

Tweeter: 1.5uF ; 1.2mH .2 Ohm ; 10uF in series with 3.3 Ohm to tweeter.

[gmannel]

Re: Flex Your PCD Mettle:

This is a detailed instruction set from 18sound with similar but older drivers - http://www.eighteensound.com/staticC...Sound_kit8.pdf
Same build and tweak/redo crossover or bi-amp w/ active(miniDSP)?

[gmannel]

Re: Flex Your PCD Mettle:

For an updated E-wave mini?
http://www.eighteensound.com/index.a...roduct&pid=262, plus either this -
http://www.parts-express.com/pe/show...number=290-507, this -
http://www.eighteensound.com/index.a...roduct&pid=256, or this -
http://www.eighteensound.com/index.a...roduct&pid=243??????
I have the above CD/WG and since neither that nor any of these 3 woofer choices were avail when the orig was developed, I was wondering if these 'model' well?

[dtruck]

Re: Flex Your PCD Mettle:

And finally, if I model the 2512 using TS parameters, etc, rec.box size is 2.37 cf. Manufac spec sheet says 0.8!! What do I believe? That's a huge difference!

[bwaslo]

Re: Flex Your PCD Mettle:

Sealed: some built-in protection if they are ever fed with very low frequency energy. Maybe a little easier to integrate with subs, though YMMV. Can stuff the daylights out of the box, to better absorb back wave midfrequencies.

Vented: less diaphram movement down near where the port contributes, so some more available output there. Less forgiving design if T&S parameters vary. Can't stuff box too much (as it will hurt port efficiency), so gotta be careful to somehow avoid midfrequency reflections back out the cone, or mids leaking out the port.

Passive: same as vented, except a little more versatile on adjustment (no big tubes inside box, just mess with weight on passive), and better blocking of leaking mids.

Use WinISD (or similar) and model it with different volumes/tunings. Sometimes the "ideal" box size is way bigger than one that works almost as well but is way smaller.

If you don't need output below where the sealed box works, I'd go with that. A lot more forgiving of parameters and stuffing.

[gmannel]

Re: Flex Your PCD Mettle:

Got my drivers! BC250, QSC, 2512, and my miniDSP.
Box will be scratch built. Size is not a consideration as will be behind a screen.
In general, for an Ewave, what would lead one to choose, or reject:
1) Sealed
Smaller size? Any acoustic advantage?
2) Vented
Better efficiency? Bass extension?(less important as already have TubaHT)
3) Passive radiator
Would this have a detrimental effect on the constant directivity goal?

And finally, if I model the 2512 using TS parameters, etc, rec.box size is 2.37 cf. Manufac spec sheet says 0.8!! What do I believe? That's a huge difference!

[Zvuchniak]

Re: Flex Your PCD Mettle:

@gmannel

Note that Edlafontaine and i had the same issues with mids using Deltalite II 2512. There is a solution but i haven't measured fr to se if it is linear enough, yet. That xover is done only by using PCD.

Please read this stuff:

http://www.audiokarma.org/forums/sho...ostcount=13885

[Mayhem13]

Re: Flex Your PCD Mettle:

So the lower resonant freq should steer me toward the Deltalite? As I said, price is essen the same, it was just the flatter FR that piqued my interest.
As to the baffle width, 17 is fine, I was just trying to learn if 17 was chosen for any acoustic reason, or just because the prebuilt box came that way. Since I'm building from scratch it matters not, so if it wasn't detrimental acoustically I thought to model the dimensions of the box to their most ideal config.

The XO was originally created in that size box so there is a relationship to the final voicing and BSC.

Generally the lower Fs idicates that the driver will extend lower. My experience with the 2512 has shown it to be true in this case. Good luck with your build!

[gmannel]

Re: Flex Your PCD Mettle:

So the lower resonant freq should steer me toward the Deltalite? As I said, price is essen the same, it was just the flatter FR that piqued my interest.
As to the baffle width, 17 is fine, I was just trying to learn if 17 was chosen for any acoustic reason, or just because the prebuilt box came that way. Since I'm building from scratch it matters not, so if it wasn't detrimental acoustically I thought to model the dimensions of the box to their most ideal config.

[Mayhem13]

Re: Flex Your PCD Mettle:

Ordering my 12" driver for the Deltalite plan and came across this other Eminence driver - aside from weight is this not a better FR curve? Cost about the same.
http://www.parts-express.com/pdf/290-593s.pdf
http://www.parts-express.com/pdf/290-510s.pdf

And, I am aware that the baffle is 17" wide because that is how the Trap PA comes, but if one is building their own box is there an acoustic reason not to narrow that down to 15 and round over the edges? Sealed box, ~ 2cf.

Note the resonant freq of the Deltalight.....much lower than the pro and I wouldn't even think about trusting Eminence measurements. If you can find reliable 3rd party measurements of the Delta Pro to compare then they might be worth the effort.

As to the baffle width, reducing it will alter the original designs baffle step compensation slightly. I doubt you'll hear a difference but I don't understand why you can't maintain the designed width and still maintain the recommended box volume by simply altering the enclosure depth.

[gmannel]

Re: Flex Your PCD Mettle:

Yes, I will be measuring, have a NIB CS calibrated Dayton mic and a NIB Tascam 124MkII 'sound card'( with not a clue yet as what to do w/ them)

[bwaslo]

Re: Flex Your PCD Mettle:

You should be fine with that and the MiniDSP, provided you have a way to measure and see what you're getting. By ear alone you'll never know whether you have the match at the crossover region right. Delay in the MiniDSP helps out on that a lot, adding delay in a passive can be trouble.

[gmannel]

Re: Flex Your PCD Mettle:

I could do the already designed passive xover, but I was planning to bi-amp and use a miniDSP. I felt like since I was not using the exact cabinet in the plans the designed crossover might need some changes, and my newby understanding is that active is easier to tweak. The speaker(as a vertical center behind the screen) was maybe going to be taller as a sealed 2cf trap box to get to better listening height. Driver spacing as per plans. Do you see any issues?

[donprice]

Re: Flex Your PCD Mettle:

Ordering my 12" driver for the Deltalite plan and came across this other Eminence driver - aside from weight is this not a better FR curve? Cost about the same.
http://www.parts-express.com/pdf/290-593s.pdf
http://www.parts-express.com/pdf/290-510s.pdf

And, I am aware that the baffle is 17" wide because that is how the Trap PA comes, but if one is building their own box is there an acoustic reason not to narrow that down to 15 and round over the edges? Sealed box, ~ 2cf.

The 2512/DE250/QSC152i combo has the crossover already worked up. Change the woofer and you need to change the crossover. I would stick with the 2512 if the cost difference isn't an issue.

Changing the baffle width from 17" to 15" will have some effect on the system response. Will it be enough to matter? I don't know. I doubt it would be huge.

[gmannel]

Re: Flex Your PCD Mettle:

Ordering my 12" driver for the Deltalite plan and came across this other Eminence driver - aside from weight is this not a better FR curve? Cost about the same.
http://www.parts-express.com/pdf/290-593s.pdf
http://www.parts-express.com/pdf/290-510s.pdf

And, I am aware that the baffle is 17" wide because that is how the Trap PA comes, but if one is building their own box is there an acoustic reason not to narrow that down to 15 and round over the edges? Sealed box, ~ 2cf.