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Old 30th May 2003, 07:08 PM   #1
diyAudio Member
Join Date: May 2003
Location: Washington
Question sub woofer box

I just got a new subwoofer for my car but I dont know what kind of box it needs... all it says in the manual is that the VAS (cu ft) neet to be 1.847 it doesnt say if it has to be a sealt box or if it needs an opening.

can anyone help me please

her are some infos about the sub

Legacy LW1276D 1200W
4 Nom. Impedance
Dual Voice Coil
120 Magnet Structure
36.5 Fs (Hz)
7.51 Qms
0.96 Qes
0.74 Qts
90.8 SPL (dB)
1.847 VAS (cu ft)
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Old 1st June 2003, 02:34 PM   #2
Doug is offline Doug  Canada
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Location: Guelph, Ontario, Canada
Default Sub box

Thid driver has an EBP ( efficiency bandwidth product ) of 38 which would indicate that it is better suited for a closed box. I can work the box volume out for you if you want. As tis is a dual voice coil woofer, how are you going to connect it to the amp? Hooking them in parallel will give you a nominal impedance of 2 ohms and connecting them in series will give you 8 ohms. Or you can just use one voice coil for 4 ohms.

On the specs you posted it says nominal impedance of 4 ohms, is that per voice coil?

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Old 1st June 2003, 08:07 PM   #3
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Location: Washington
okay the amp is 2 Ohm Stereo Stable and Bridgeable into 4 Ohms
the subwoofer is total 4ohms

well right now i got it only pluged in on one channel and in bridged mode... so does that mean i should switch it to normal mode and just plug one outlet into the amp as left speaker and the 2nd plug into the right speaker or should i bridge both plugs on the subwoofer and huck it up as bridget to the amp?

thanks for ur help
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Old 5th June 2003, 08:52 AM   #4
Doug is offline Doug  Canada
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Default Sub box

Do you have just one subwoofer or two?

I would connect the 2 voice coils in parallel for a 2 ohm impedance and put the amp in bridged mono mode ( 2 ohm stable) Thats for one subwoofer. If you have 2 subs, it will be different.

Do you or anyone have a link for the Legacy LW 1270 D? I've looked everywhere on the net and can't seem to find it.

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Old 6th June 2003, 04:48 AM   #5
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Location: Washington
Default Legacy LW 1270 D

well I only got one sub right now. I bridged the amp and the sub.

to me it seems like the Legacy LW 1270 D isnt a new sub right? cause I couldnt find it online at legacy. when did you get this sub?
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Old 12th June 2003, 08:57 AM   #6
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Location: illinois
Or you can just use one voice coil for 4 ohms.
the common misconception of dual voice coil subwoofers and is completley false

if you only hook up one voice coil you throw off the original theil small parameters to where it reacts completly different than expected

i would say build a sealed enclosure with about 2.0'^3
which would yeald about what your looking for after factoring in the space taken up by the driver

you have three safe options for hooking it to your amp that will give you enough power to at least use it

option 1 is run it to only one channel of the amp with the voice coils in parallel (2 ohm stereo)

option 2 run the voice coils in series and bridge to the amp (creating a 8 ohm mono configuration)

option 3 run each voice coil to its own channel on the amplifier (should give you the most power out of the bunch, you will have a each channel of the amp running its own voice coil in a 4 ohm load)

i would say go for option 3
and as for box i would say try to build a box with a internal volume around 2 feet cubed as stated above
one of the great things about sealed enclosures is they are easy to build and not as touchy to being the wrong size
alot of times you can move it about .25 feet cubed either way and wouldnt notice a difference

with a larger sealed enclosure you raise the effeciency of the subwoofer but sacrifice a peakier responce, and easier for the subwoofer to bottom out and damage to sub, increase lower freq response

too small and you take away from effeciency ,raise power handling slighty, and it will make the over all response not as flat, loose lower freq response

but sealed boxes are not as susceptible to these as other box configurations

there is a program you could use also

its free and helps alot in building enclosures

well i guess i got kinda long on that but i hope this information helps
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