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Changed the bose sub for aftermarket sub but it’s very, very quiet

Discussion in 'In-Car Entertainment' started by Garrity, Feb 6, 2007.

  1. Garrity
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    Garrity New Member

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    [FONT=&quot]Unplugged the bose sub and made a sort of adapter at the weekend, but when I wired it into my aftermarket amp and sub it wasn’t very loud at all – infact it was pants. I’m at a bit of a loss, does anyone know why this may be the case? Could it be that I just need a really powerful amp, or could the size of the wires I was using effect this (I circuit tested the power cable and it was pushing +12V into the amp).

    Anyone help would be appreciated.

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  2. jonmusicman
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    jonmusicman Member

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    I think its to do with the ohm rating of the sub. I think someone will back me up on this. Bose needs to be 2ohms most others are 4ohm. I think?
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  3. Wicked666
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    Wicked666 Active Member

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    amp won't be powerful enough. It was designed to work with the bose sub in that particular way. If you've connected a 4ohm sub and the bose sub was 2 ohms then you've halved the amp power to the sub anyway.

    Also is sub in a sealed or ported box?

    Thicker wires help reduce loss of SQ. If the wires are struggling to pass the current then you'll smell a burning smell.
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  4. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    What amp are you using? The pre-outs on the Bose loom are pretty feeble (less than 1volt), so you will need about 300wrms for the amp to drive any sub adequately. Also the Bose pre-outs are left front and right rear (or vice versa), so you need to ensure you have the fader on mid on the HU to get maximum signal to the sub amp.
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  5. Garrity
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    Garrity New Member

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    That could be it - never looked into what amp I had as it came with the old car and ran the sub OK.

    The amps a JBL P80.2 ( Output 4 Ohms: 40W x 2 | Output 2 Ohms: 80W x 2 ) http://www.monstermarketplace.com/Automotive/Landing2677a2671.html

    The sub i've got is the passive twin 10" encloser - looking at http://www.fliaudio.co.uk/ they could be a 4 ohm subs.

    I'm guessing that amp's no good from AndyMacs comment "The pre-outs on the Bose loom are pretty feeble (less than 1volt), so you will need about 300wrms for the amp to drive any sub adequately."

    What do people think, dump the sub (my sister want me to give it to her as a birthday present) etc and look at investing (will have to save the pennies) - though i'm guess an amp with 300 wrms is big dollar.
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  6. fdussud
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    fdussud Member

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    www.caraudiosecurity.com have a soundstream 240 amp that is about 114pounds. That should be adiquate for your 10. I was running two 12" subs on 300 watts RMS and that was really loud.
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  7. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    You're trying to drive 2 x 10" subs off a 2 x 40w amp?
    I think that could be your problem, or rather that definately is your problem.
    You need 2 x 250 wrms to drive those babies (regardless of the puny pre-out feed), i.e. 2 amps bridged or one big amp like an Alpine V12 MRV-F540 (200wrms x 2 bridged into 4 ohm).
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  8. Garrity
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    Garrity New Member

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    Um... It would appear that way, though it used to run fine in the old car - how odd, i guess that's why it's not working to well - haha - thanks for the help guys.
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  9. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    You could bridge it and run one of the 10" subs on the bridged 160w output, but it's still barely enough. No idea how that amp could possibly be used to drive 2 subs in your old car, bit like driving 2 subs off the HU's internal amp!
    You can pick up Alpine V12's on ebay for less than £100. That's where I get mine for my stealth sub installs, bought about 20 of them so far & never had a duff one.
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