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SUPPORT FORUMS FOR DECWARE SPEAKER PLANS >> Wicked One Support Forum >> Help with compression chamber volume!
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Message started by zachdude1100 on 08/18/11 at 01:22:47

Title: Help with compression chamber volume!
Post by zachdude1100 on 08/18/11 at 01:22:47

I've been browsing these forums ever since back in the day when I built my 36x36 Wicked One box, and sadly I blew one of my el cheapo MTX drivers in it. I just built the box and slapped those bad boys in and away I went, but now the Rockford Fosgate P3D210's that I bought to replace them require a smaller box volume although ironically being much much bigger themselves. I've calculated the 4th order bandpass volume requirements to be .424 ft^3 front and .628 ft^3 rear. Now, I've read enough topics and the directions to know that I can change the rear chamber to whatever it needs, but what should I do about the compression chamber? I'm not convinced I need to take away half a cube of volume since this isn't really a true bandpass design because of the horn and not port. I've heard both ways to change it and just leave it be.

Here are the specs:
Qts: .5
Vas: .865 ft^3
Fs: 27 hz
F3: 26.5 hz
Calculated tuning: 41.63hz

If I plug in the current ~1 ft^3 front chamber and calculated rear chamber into WinISD, I get the nastiest peak ever, like 6 dB. Is it really going to do that or is there more physics at play here than I understand? Any answers would be appreciated. ;D

Title: Re: Help with compression chamber volume!
Post by Hondab100s on 08/18/11 at 15:24:43

I usually just concern myself with the sealed portion of the box matching the suggested sealed box volume by the Manufacturer. The ported portion may not register properly with any bass response program as it's not really a 4th order bandpass box. The port in this box is not the same size throughout as it would have to be in the program you would choose to use.

Title: Re: Help with compression chamber volume!
Post by HT-EXT on 08/18/11 at 19:42:56

I am not sure but I typical shot for the ported chamber to be ¾ the size of whatever the seal chamber calls for or as close as possible. I find the enclosures programs to work quite well but do not always represent the actually response of certain type enclosures. For instances the Half-Wedge builds look terrible on paper but in person are very impressive. I would be tempted to go on and install the Rockford and see if you like how they sound without any adjustment.

You might be surprised!!!

HT-EXT

Title: Re: Help with compression chamber volume!
Post by zachdude1100 on 08/20/11 at 00:42:03

Hey guys, thanks for the quick responses. I decided to just leave the compression chamber volume alone and just lower the sealed volume. It turned out extremely well and is quite possibly the loudest per watt I've ever heard while retaining AMAZING SQ. I've never heard this clean of bass before and I've built a lot of ported and sealed boxes. Thanks so much to the guys at decware for making the plans for this box free. It's totally worth the extra effort of construction.

-Zachdude1100