Flex Your PCD Mettle:

[Cerdic]

Re: Flex Your PCD Mettle:

I for one am waiting anxiously for post #782! You must have some premonition about what Zilch has got up his sleeve, Mayhem, and I can't wait to see what's comin' down the pike. ;)

On a serious note, I have got to stop looking at all these other builds, and start getting down to business on my SR build. All parts received, and finalizing a plan of attack. Sketchup is getting a workout.

Can you guys see any advantage/disadvantage to a side ported build with a 4" round port like the NQ, vs. a dual 1"x6" slot/rectangle ported build with the two slot ports side by side below the woofer on the front of the cab?

[Zilch]

Re: Flex Your PCD Mettle:

Can you guys see any advantage/disadvantage to a side ported build with a 4" round port like the NQ, vs. a dual 1"x6" slot/rectangle ported build with the two slot ports side by side below the woofer on the front of the cab?

There is an argument that rear-porting minimizes the likelihood of midrange "leakage" from inside the cabinet. Side porting may accomplish less of this.

In all cases, we have some control of where the port ENTRANCE occurs within the cabinet. Key is not "aiming" that at the rear of the woofer cone, though many designs violate this principle....

[ARSIS]

Re: Flex Your PCD Mettle:

ok... i'm gonna go with the deluxe. if i want to get this speaker to play down to 30-35 hz... do i have build a bigger box... port... or eq?

[Mayhem13]

Re: Flex Your PCD Mettle:

Build a sub!:D

[Flacjunky]

Re: Flex Your PCD Mettle:

I wonder what the lifespan is of the Titanium diaphram in the Selenium CDs.

Being made in Brazil, I might want to keep a reserve or 2 in stock.

[Zilch]

Re: Flex Your PCD Mettle:

ok... i'm gonna go with the deluxe. if i want to get this speaker to play down to 30-35 hz... do i have build a bigger box... port... or eq?

You'll need to use a box modeler to determine what might be done. None of the recommended Eminence designs get there:

http://www.eminence.com/pdf/cab-kappalite-3012lf.pdf

I am using assist at 35 Hz, but there is discussion earlier in this thread about using a second 3012LF in "0.5" mode to augment the bass. I am considering an additional pair of KDT cabs loaded with them to accomplish this....

[ARSIS]

Re: Flex Your PCD Mettle:

You'll need to use a box modeler to determine what might be done. None of the recommended Eminence designs get there:

http://www.eminence.com/pdf/cab-kappalite-3012lf.pdf

I am using assist at 35 Hz, but there is discussion earlier in this thread about using a second 3012LF in "0.5" mode to augment the bass. I am considering an additional pair of KDT cabs loaded with them to accomplish this....

hmmm... seems like a lot of work to get them to play lower. wonder if i could use the bc compression drivers and the jbl midwoofers. i know those jbl's will play lower. what is the frequency responce of the eminence drivers? sorry... i suck at reading those spl graphs

[edlafontaine]

Re: Flex Your PCD Mettle:



You can get the 3012LF to play down to ~30 Hz in a slot ported enclosure. So says MJK's Mathcad worksheets. There is a 3dB droop in the simulated response below 150 Hz. ~4.5 dB down from ~500 Hz. That should be more than compensated for by room gain.

[ARSIS]

Re: Flex Your PCD Mettle:

You can get the 3012LF to play down to ~30 Hz in a slot ported enclosure. So says MLK's Mathcad worksheets. There is a 3dB droop in the simulated response below 150 Hz. ~4.5 dB down from ~500 Hz. That should be more than compensated for by room gain.

nice... however, if i do a slot port design i want be able to use the kd trapezoid box enclosures :(

[edlafontaine]

Re: Flex Your PCD Mettle:

So sorry. That would need to be built in a box larger than the KD as well.

[Zilch]

Re: Flex Your PCD Mettle:

wonder if i could use the bc compression drivers and the jbl midwoofers. i know those jbl's will play lower.

Deluxe plays lower than HP -- the JBL is higher net efficiency, but 3012LF beats it on LF extension. Compare Fs of the two drivers (Eminence is 20 Hz lower,) and look at the specs of JBL products which use 2262H.

You can get the 3012LF to play down to ~30 Hz in a slot ported enclosure.

I forget the correct term; is that called extended bass shelf alignment (EBS) or something similar, where the box is tuned well below driver Fs...?

[edlafontaine]

Re: Flex Your PCD Mettle:

EBS? could be, I dunno...The box tuning turns out to be ~29 Hz

What Martin and others tell us is that extension is available to 1/2 an octave below Fs. Fs is 37 Hz for the 3012LF.

I aim for a room friendly response rather than be greedy and go for it all. ;) I think of it as managing the area under the curve.

[Zilch]

Re: Flex Your PCD Mettle:

Google is our friend:

http://www.danmarx.org/audioinnovation/theories.html

[Zilch]

eWave Altec Horizontal Directivity:

[Zilch]

Re: Flex Your PCD Mettle:

And for wavelet heads:



Even though I've notched out the spike, the resonance at and just below 20 kHz remains evident.

[No, I don't hear it.... :rolleyes: ]

http://www.audiomatica.com/download/audaesny2007.pdf

http://www.audiomatica.com/download/audaesny2007.pps

Reflection, resonance, diffraction, or whatever, it doesn't appear to hang around particularly long. 50 dB CSD: