both coils in each speaker are wired in parallel, hence why the 4ohm impedance becomes a 2 ohm impedance, so both coils will see equal current (still Kirchoffs law i am afraid!!) and thus equal power.
This technique is really the same as wiring four 4 ohm subs in parallel in so far as the amp ''sees'' electrically (i.e. 4 of 4ohm coils in parallel), but you are using two coils to drive one speaker cone.
I am not so sure how effective it is as the power amplifier must be able to handle such a low load impedance and still be stable, low impedance means larger current allowed thus more heat and unless designed to do so a very short lived amplifier.
mrlee
			
									
									Subwoofer box design for my cab (12")
Moderator: martauto
ImysE30 wrote:Hi all,
Can some talented fella on here into ICE, design a sub box for me please. The sub i have got is a DB Audio 3000w 1000 rms in 12". The space i have got in my boot are 11" (height), 38" (width) and 25/26" (depth). Box will have to be prism shaped due to height.
Thanks in advance
Imy
hi m8 i got a custom made sub box in my bmw convertible im selling it looking for 130pounds got 4x 12'' subs in there drops in perfect im giving the subs with it 1 of the subs is not working but 3 are working fine and gives great sound. 2 jbl's in there and 2 rockford fosgate.
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				ImysE30
 - Married to the E30 Zone

 - Posts: 22486
 - Joined: Mon Jul 07, 2008 11:00 pm
 - Location: Derby Massive!!
 
Install has finally be done, was going to post some pictures on Sunday but PC at home has broken down  
 
Gone for one 12" sub (1000w rms) and Vibe Amp. Will try to get pics up as soon as
			
									
									Gone for one 12" sub (1000w rms) and Vibe Amp. Will try to get pics up as soon as
Current Fleet:
E30 335i Turbo M3 Convertible Replica
						E30 335i Turbo M3 Convertible Replica
zaust wrote:Would need the power input's to be on the - on one sub and the + on the other, Or the first voice coil will take as much it want's before the other's. Yes negligable but still will happen. Unless physics has changed.. lol
zaust you right in your saying but that only applys to Series wiring of the coils not in parallel. like if you had 2 light bulbd and one battery wired in series the frist bulb will be better lit then the second bulb.

Zaust, quality only come it to play when using wire thinner then needed,  by having 1 wire longer and the other one shorter will only make the sub recive the input a lil bit later.  but the diffrence between the two will be so small that it wont be possible to tell by eye or by ear (unless each sub is either side of you at ear level , then it might be possible to tell). ive done many install's before and always had 1 cable longer then the other and had no issuse.    anyways lets just drop this as its never going to end. WERE both right in our own ways.
			
									
									
						NO offence to anyone but why do that? Make a right angled triangle that sits nicely in your boot with the slightly angled side pointing towards the seats and have the subwoofer that way. Better yet, get backseats with the centre arm rest and fold it down to expose the sub.
TBH, not my thing really to have woofer in the boot of a saloon/coupe as its just blocked off. No clarity, just vibration. Screws up the balance of the music.
And if i did, i'd do what i stated before. Or a raised boot floor with it all placed onto that, and a slightly raised perspex/see-thru glass with loads of holes protect the speakers, and still use as a boot (which will be shallower, mind you).
Now if you had a hatchback, or better yet a touring, then go for it!
			
									
									TBH, not my thing really to have woofer in the boot of a saloon/coupe as its just blocked off. No clarity, just vibration. Screws up the balance of the music.
And if i did, i'd do what i stated before. Or a raised boot floor with it all placed onto that, and a slightly raised perspex/see-thru glass with loads of holes protect the speakers, and still use as a boot (which will be shallower, mind you).
Now if you had a hatchback, or better yet a touring, then go for it!

Uni is killing the project.
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				mrLEE30
 - E30 Zone Team Member

 - Posts: 6589
 - Joined: Tue Jan 18, 2005 11:00 pm
 - Location: Sweating buckets in Bahrain
 
Make a right angled triangle that sits nicely in your boot with the slightly angled side pointing towards the seats
thats what i have done in my pics on about page 1 of this thread, bass is practically omnidirectional and thus it does not matter which way round the speaker faces, as i also mentioned in the same post.
its a cab with two firewalls and no rear armrest and thus no ski hatch holeBetter yet, get backseats with the centre arm rest and fold it down to expose the sub.
no hatchback E30 and as above he has a cab, hence the thread ''subwoofer design for my cab''Now if you had a hatchback, or better yet a touring, then go for it!
mrlee

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				streetbassincuk
 - E30 Zone Newbie

 - Posts: 53
 - Joined: Thu Feb 21, 2008 11:00 pm
 - Location: london
 
can easily fit 3 x 10" subs under the hood area in the boot, dvc's would be better, can have it sealed or ported, amps on the sides of the boot area to keep some of your boot. dyna-mat as much of your boot as possible, boot lid, rear panel, inner wings, should help keep it solid... 
			
									
									
						NayC  are you sure you own an e30?   lol , yes you idea was taken in account  as "mrLEE30" has done that with has cab,  the main thing is the height of the box as to were the box was going to be placed under the roof hatch and sit flush just before the boot lid. which still gave boot space , which is a lack of in cab's.   
Streetbassinck- yes is is possible to fit 3x10" sub the space but 2x10" were used as the amp output was not great enough to fully run 3x10" subs and the subs are 4ohm DVC , and yes dynamatt does help a lot and has been proven to give over 3 db in gain in SPL test.
			
									
									
						Streetbassinck- yes is is possible to fit 3x10" sub the space but 2x10" were used as the amp output was not great enough to fully run 3x10" subs and the subs are 4ohm DVC , and yes dynamatt does help a lot and has been proven to give over 3 db in gain in SPL test.


