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Old 27th May 2004, 08:03 PM   #1
VEC7OR is offline VEC7OR  Lithuania
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Default Car subwoofer (2x8" fancy design discussion)

So, my friend wants a subwoofer for his Renault 19.
Goal is actually getting most Db per W from those 8" drivers (ripped off from some old USSR speaker with fried tweets and decent mids).

Driver specs (claimed, not measured yet):
Qts = 1 or 0.4 (had 2 sources to verify)
Vas = 45-50L
Fs = 30 Hz
Pm = 50W (100W peak)
Z = 8 Ohm
R = 6.8 Ohm
Sens = 84 or 87Db w/m (not sure as with Qts)
Cone is made of paper, spider iz almost 5-6", surrond is rubber, magnets are rather large for a 8", drivers aint too bad, considered we got them almost free.

Box size - maximum ~120l (yup its big for a car but trunk is big and we arent afraid to put a BIG sub in there )

Availailable amplification power is around 60W per channel and ~120W peak.

From the specs I can say - use sealed/4th BP box in 1 case and vented/6th BP in second.
Isobaric box isnt my game in this case coz loosin 3Db is alot with that amp and with rather large box size allowed.

I tired of those vented/sealed/BP boxes coz already built a dozen of those, so I wanna try smthng different, like sticking a TL sub in the car (well you have to remeber that video of guy with 6.5 subs making 30hz in a black Golf that stuff put on the roof was jumping) or maybe a horn or something otherwise fancy.

Fancy design suggestions needed.
Horn & TL are already considered.
In other words just discuss.
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Old 27th May 2004, 10:23 PM   #2
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I doubt you could fit a LABHorn in your trunk, but that's always a possibility.
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Old 28th May 2004, 01:54 AM   #3
VEC7OR is offline VEC7OR  Lithuania
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Well maybe but we're on a budget here tho...
Basically I wanna learn smthng new, just suggest what are there drivers are good for except Closed/Vented/BP( learning is onto me :P ).

P.S. I was seriosly considering biulding 1-2 pairs of LABs for some sound reinforcement, but thats couple of years ahead from now... neither I need them that much nor have time and $$$ for them....

P.P.S. Either way I can use those babies in some home system, we have 10" sub driver laying around, so we'll use that sometime too.
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Profanity took a very interesting form in Russia where there exists a language of sorts, most of its words based on four basic profane roots - nouns p...is, wh.0.e, c..t and verb f..k. It is possible to sensibly communicate using just these four basic roots.
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Old 28th May 2004, 05:16 PM   #4
qi is offline qi
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How about a 20" x 20" x 25" doube-decker Bose Cannon (25HZ-75HZ)? The long double-folded labryinth would be 12', the short one 4'...
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Old 28th May 2004, 05:25 PM   #5
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for 2 : Q = 0.4 a push pull MLTQWT is possible.

sreten.
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Old 28th May 2004, 06:21 PM   #6
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Could you build both?

I have always wanted to compare MJK's ML TL with the Bose Cannon
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Old 28th May 2004, 07:36 PM   #7
VEC7OR is offline VEC7OR  Lithuania
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Hm at first glance horn looks appealing , taking into account that I suppose I can fold it inside ~80-120l box(40-35hz cutoff) (purdy much the same as 3 sectioned BP box +/-), the only problem is that dont know a hell about horns (atleast now, not googling alot) and hornresp proggie is a bit confusing...

Bose cannon ~ is a 1/4 TL ? BTW is one end closed or both are open ? has anyone dissected one ? how it works basically ?

Well I know what a TQW is but what mass loading has to do with it ?

How much SPL per 1W can I hit with those designs appox. (in BP its possible hitting around 89Db/w/m but I dont want to cut on low end that much) ?
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Profanity took a very interesting form in Russia where there exists a language of sorts, most of its words based on four basic profane roots - nouns p...is, wh.0.e, c..t and verb f..k. It is possible to sensibly communicate using just these four basic roots.
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Old 29th May 2004, 12:04 AM   #8
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I'll go the HORNY WAY

After googling for some time I found plenty of material and from first glance I think I'll try something around isobarically loaded hyperbolic/exp folded horn. Futher investigation of speakers from which the drivers were taken proves (they used ported design) that their Qts should be in .3-.5 range and efficiency would be 87, not 84 Db W/m, this proves that they are rather siutable for horn application as their EBP is in 115-70 range(200+ is preffered ). As for construction I think I'll use MDF frame and horn itself will be formed from polystirol foam using hot wire cutting to make it light and sturdy.
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Profanity took a very interesting form in Russia where there exists a language of sorts, most of its words based on four basic profane roots - nouns p...is, wh.0.e, c..t and verb f..k. It is possible to sensibly communicate using just these four basic roots.
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Old 29th May 2004, 12:59 AM   #9
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Bose Cannon is opened at both ends -- one taming the other's irregularities.

It is a "poor man's corner horn" (see www.cardhouse.com/x09/wave.htm).
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Old 29th May 2004, 01:26 AM   #10
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Mass Loaded Tapered Quarter Length Transmission Line...

1. An advanced design in the "quarter wave space"

2. Gross over simplification: a TL with a port at the bottom

http://www.quarter-wave.com/Gallery/Gallery.html
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