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Discussion Starter #1
Hi everyone!

I have a more unique setup in my Altima Coupe, born out of over-ambition and free time (which I don’t have now).

Straight to the point my current problem is I fiber glassed midrange pods (more like chambers) that sit behind the footwell carpet with cutout for grills driver/passenger side so that the speakers are directly on axis. I had calculated the approx. volume the woven-glass cones would require and laid down the “back” in fiberglass to conform to the firewalls shape, then used and MDF front and mated it to the fiberglass with resin and glassing over the edges to complete the “chamber”. I tried to make it very thick and used cloth, matt and cat hair in layers.
I think they quite resonant and there’s just some really crappy, nasally harsh sounding quality to them.
I was thinking of using foam baffles or something similar, although if they did truly seal totally with that small amount of rear volume I’d expect there to be some major compromises in the sound for speakers designed for doors? I think the infinities parameters lean towards infinite baffle.
I really don’t want to re-fiberglass and unsure that’s the main issue, although the sealing might be part of it, I think resonance as well. I already have the rs180’s in the doors. Is it possibly just the cones aren’t that conducive to such enclosures? Is my thinking off in terms of on axis placement? They fit rather well otherwise in their location, I can’t fit corner pods at all, cars way too small.
Do those rear foam baffles work, perhaps that in combination with a different driver more suited? RS150 or similar reference driver? The Dayton references seem like great off axis response and very clean…

50.9cs
BL (T-m)
3.69
DCR (ohms)
2.35
Mms (g)
9.11
Sd (sq cm)
102.1
Cms (µm/N)
Vas (l)
5.21
Fs (Hz)
88.4
Qes
0.87
Qms
6.09
Qt
0.76
SPL 2.83V
93.4



Gear is: Peerless 1” titanium Tweeter (just tossed infinity 10.9 Textile few days ago), Infinity 509CS Mid Woven Glass Cones 5.25” in footwells, RS180-4’s in Doors, Infinity 10” sub in trunk, Power is Pioneer 8604 4 Channel 100 RMS /Per Channel, 20 W Class D mini Amp for Tweeters, MiniDSP 2x4, Pioneer 80prs Head (Mini DSP was being used to split the mids signal and tame the RS180s crossed with Mids, Now just switched to crossing tweeters with mids and splitting off midbass using passthrough on the main amp before going to DSP and back out to mids and tweeters)
 

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Have you taken any FR measurements to pinpoint any offensive large peaks in the response?
 

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Discussion Starter #3
I have to do so again, will try to tonight. I haven't measure in a long time but l think 200-300hz and mid 1000s. I'll post when I get something
 

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Based on your description of the fabrication, I don't think the pod itself is resonating. Rather, I'm thinking the size and shape of the airspace is causing resonance. Try adding some polyfill stuffing. The general rule is 1lb per 1 cuft, but of course u can adjust up or down from there. The stuffing should help dampen resonances, and will have the added benefit of increasing the effective airspace. It's also cheap and easy to try.
 
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