Flex Your PCD Mettle:

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Not too shabby really......if used with a sub which is a given for HT use.

[ATTACH]10100[/ATTACH]

After you factor in baffle step, yeah, it's still pretty anemic. Better would be to make that response flatter, with a higher tuning frequency.

If you are using a sub, may as well get the low end sensitivity up at least even with the mid band, maybe even forget going vented altogether.

[edlafontaine]

Re: Flex Your PCD Mettle:

Mayhem,

I'm with Pete on this. Your sim has a 6 dB difference between the 50-80 Hz range and 500Hz. The response of the mid-woofer should be "flat" down to the point where you would get usable response/support from a sub along with room gain.

Room gain will be unique for you room. It is not unusual to begin getting some gain ~120 to 150 Hz and more with decreasing frequency.

Through your modeling you can move the area under the curve. Some of the energy at the lowest frequencies of your model might be better spent raising the response from ~70 or 80 Hz (or higher) to match the level of the mid frequencies.

This allows both the sub and mid-woofer to work in the ranges where they do their best...arriving at a "flat" overall response.

[Mayhem13]

Re: Flex Your PCD Mettle:

Hey Zilch....does a horn like this help to align the acoustic centers since it's offset? I just thought these might look pretty cool backmounted behind some nice figured walnut baffles.....sorta the JBL Synthesis look but if they're crap then they're crap no matter how good they look.:D

[Zilch]

Re: Flex Your PCD Mettle:

A horn like what?

[Mayhem13]

Re: Flex Your PCD Mettle:

Sorry...it was late.:o

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=292-2574

[Zilch]

Re: Flex Your PCD Mettle:

I think that's the one Gordon W suggests as a cheap sub for Altec 811s. The diffraction slot is obvious in that pic; it's not a "waveguide" in that there's no attempt to smooth the flare transition.

Synthesis in the vertical orientation sense? Not with wide dispersion in the long dimension just serving to spray the ceiling and floor with HF energy to generate reflections. There IS a 70° x 50° DDS waveguide more suitable for that:

http://www.ddshorns.com/CFD%201_5-70%20pro.pdf

Mate the 1.5" version with BMS 4555....

[Mayhem13]

Re: Flex Your PCD Mettle:

No horizontal.....but vertical seen here



and here



Forget the super horn up top......

[Zilch]

Re: Flex Your PCD Mettle:

K2-S9900 and Everest II.

The action's in the throat, not the lips.

JBL Consumer got smart and will no longer sell us components for their $60,000/pair speakers.

[We gotta clone 'em.... :p ]

[Mayhem13]

Re: Flex Your PCD Mettle:

Wanna test that Pyle horn anyways?....it's a bit big at 16.5" wide though. My thought for a JBL clone cosmetically anyways would be to backmount the horn and venner the face of the cab as a hole....removing the veneer for the 'lips' and gluing the veneer to the side walls.....all a moot point if the horn measures badly of course.:o

[Zilch]

Re: Flex Your PCD Mettle:

Wanna test that Pyle horn anyways?

You got no HOLM? ;)

[Mayhem13]

Re: Flex Your PCD Mettle:

Earl has em......not me. I've had my shots!:D

[Mayhem13]

Re: Flex Your PCD Mettle:

Ewave SR.......2cuft 51hz tune F3 48hz F10 40.3hz

[Zilch]

Re: Flex Your PCD Mettle:

What box modeler is that, Mayhem, please?

[Mayhem13]

Re: Flex Your PCD Mettle:

Unibox. Creates ZMA's and FRD's for Splice as well!:D

Get it here......http://www.pvconsultants.com/audio/boxmodel/unibox.htm

[donprice]

Re: Flex Your PCD Mettle:

I'm back to working up the models for the 15" Kappalite 3015, QSC WG, and B&C DE250. I measured the responses of each driver in the cabinet (w/ TrueRTA) and am working on the FRD and ZMA files in Jeff B's Response Modeler before dumping them to PCD.

A couple of questions come up while working on the woofer curves:

Does smoothing matter? Measured at 1/24 octave - looks better at 1/6 (or less).

Impedance # 1 - I can't measure impedance and Jeff B says to use the modeled impedance (see http://techtalk.parts-express.com/sh...1&postcount=57) rather than doing the curve trace. My model is missing the spike at the resonance frequency. Is that normal or did I miss something? ooops - ran wrong model - now two spikes using T/S parameters. OK?

Impedance # 2 - At what point (frequency) does it make sense to "model the upper frequency rise in the Response Modeler to overlay the traced impedance at higher frequencies". See post referenced in # 1 above.

Baffle diffraction and baffle step compensation - There seems to be little or no discussion in this thread on this topic. Is it addressed in the crossover design without discussion or it more or less ignored as inconsequential in eWave design philosophy?

Relative volume of FR curves - Is the efficiency difference between LF and HF curves "fixed" in PCD by assuming an L-pad resistance? Not sure if the question makes sense...

I think I've done all I can on the woofer curve...on to the HF stuff.