Pioneer + Piezo in a 3 cu ft slotted box - diyAudio
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Old 24th September 2007, 09:49 PM   #1
ajh is offline ajh  United States
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Default Pioneer + Piezo in a 3 cu ft slotted box

So I built this box the other day when I had a little time to spend on it. (I rarely get the time)

Anyway, I wasn't think at all apparently when I did it and things didn't come out right. My question is whether there are things that I can do to try to help my FR response besides hacking my box down to the right dimension.

The boxes as built are actually 3.5 cu ft. and the slot is 3" X 11.25 (3" all across the front of the box). Currently the slot does not have any depth at all as it only occurred to me later that maybe it should?

I plugged the as built numbers into WinISD and a curve that matches what I hear. Basically, I got much lower bass response but the string bass for example was very soft.

I could saw the bottom of the box off, put a new bottom in and recreate the slot correctly.

I don't understand how the port size/depth affects FR or if there is any other way to smooth out the FR in the 3.5 cu. ft. boxes.

Other than the bump in the bass, it sounds really good. Vocals are much more clear...

Thanks to Godzilla for his site and his offer to help me verify the measurements before I built it. Unfortunately I had already built the boxes...


Any suggestions would be appreciated... (besides pay more attention next time )

Thanks
-Andy
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Old 25th September 2007, 03:43 AM   #2
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Try this (it might save you rebuilding the box)... get a chunk of fairly high density foam rubber (the exact foam i'm thinking of is the blue foam around the circumference in an Apple digital board service box)... Use it to cover the existing port. Make sure it is "sealing" up the slot.

This will give you an idea of whether making the box aperiodic will make it useable. If thiskills the bass too much, load a couple bricks into the enclosure (or pieces of wood or anything that will use up sonme volume)

dave
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Old 25th September 2007, 02:55 PM   #3
GM is offline GM  United States
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Greets!

This is a decent size cab for the B20, but to get the most out of it requires a much lower tuning, so try Dave's tweak and if you decide you want a more extended LF than damping the cab's tuning peak, then install a tightly sealed blanking plate to block off the large vent and experiment with a much smaller 4" diameter pipe vent in the 1 - 5" long range. Do all tuning experiments with the speakers in their in-room positions since down low the room's acoustic modes dominates, so you want the speakers to blend as best as practical rather than what may look good in a computer sim. Note too that you should tune each one individually since rarely does the same tuning work in a typical room unless they are positioned well away from any boundaries (at least several feet).

GM
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Old 25th September 2007, 03:07 PM   #4
ajh is offline ajh  United States
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Thanks for the suggestions! I will try them out. I am so relieved b/c it would probably be a while before I could get them cut down and refinished.

Thanks,
-Andy
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