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Replacing Bose Amp for Main Speakers

Discussion in 'In-Car Entertainment' started by rweerasi, Jul 7, 2004.

  1. rweerasi
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    rweerasi New Member

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    [Jul 7, 2004]
    Hi guys,

    Nearly finished my install.... :)
    Thanks to all for the help in the posts.

    Can anyone tell me whether i can plumb an amp in to replace the Bose amp powering the main speakers.
    I've already replace the Bose sub.
    I followed the instructions on here and it was fairly simply to plug in to the Bose sub plug.
    Is there a similar plug on the other side? And if so, can anyone point me at a wiring diagram.

    cheers


    Rich


    #1
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  3. imported_bayliss
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    imported_bayliss Guest

    [Jul 8, 2004]
    hhhmm I just found this out the hard way, and I'm just in the process of binning the audi sub/enclosure and making a new enclosure. I have a new head unit powering the cabin speakers (which don't sounds "that" bad) and have a sweet apline amp (with crossover) ready to power the new sub.

    I haven't decided yet as to an 8" or 10" sub - all depends on how much room I have in the recess - anyone done this yet and has any pics?
    #2
  4. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 8, 2004]
    Well if you can get a 10" in there I'll take my hat off to you. I've made about a dozen of my patented Stealth subs for the A3/S3. Constructed of 18mm MDF it is a straight swap for the OEM sub (Bose or non-Bose). It can house either 6.5" or 8" JL Audio unit, and needs about 300w usually from an Alpine MRV-T505 or similar.
    It works incredibly well for such a small enclosure. I can make just the enclosure for you (including gold terminals, wadding etc) for £70. Have a look under stealth sub on the A3 forum for some rave reviews.
    #3
  5. imported_bayliss
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    imported_bayliss Guest

    [Jul 8, 2004]
    i found it hard enough to get an 8 " sub - how the hell did u get a 6.5"???? hahahah
    any bargain (but good quality) 8" subs on the market you know of. i wasn't expecting to have to buy one until i read all this and haven't buggeted for one!
    think i'll give the enclosure shot, but you'll be hearing from if/when i fail!

    cheers

    PS looks good!
    #4
  6. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 9, 2004]
    I chose JL Audio, as the were the ony people who do a proper 6.5" sub. They also do an 8", as do Polk Momo, RE, Phoenix Gold, a whole host available from CarAudioDirect.
    The Polk unit looks really good, I think it's new, but for the money it is a bargain.
    Just remember the enclosure is way too small for any sub, so it has to be very solid or else it won't work. I had to rebate all the joints to make it work as MDF isn't very strong when screwing into the end grain.
    Good luck, Andy
    #5
  7. imported_bayliss
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    imported_bayliss Guest

    [Jul 9, 2004]
    thanks Andy, just trying to find a good sub, but I don't have the budget for anything I want! always the same huh!
    going to check out caraudio direct now thanks

    anybody have any second hand 8" subs??
    #6
  8. imported_bayliss
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    imported_bayliss Guest

    [Jul 9, 2004]
    PS when bridging left and right on a typcal amp (alpine) does this make it 2 OHMS? do I need to buy a 2 OHM asub?? (the polk's a 4)
    #7
  9. Dean_T
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    Dean_T Active Member

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    [Jul 9, 2004]
    nope /ubbthreads/images/graemlins/smile.gif

    first of all you need to find out what the amp is stable at when bridged, im guessing it would be 4 ohms?

    you will then have to find a sub which will show a 4 ohm load;

    --- single 4ohm VC

    --- dual 2 ohm voice coil, wired to show a 4ohm load

    HTH /ubbthreads/images/graemlins/smile.gif
    #8
  10. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 9, 2004]
    Bridging an amp just doubles the power (or more) for a single channel, it doesn't effect the impedance. Most amps are stable at 2ohms in 2 channel mode, but can only run in 4 ohm when bridged.
    #9
  11. imported_bayliss
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    imported_bayliss Guest

    [Jul 10, 2004]
    great - so I can fit a 4 OHM sub when bridging! thanks

    all i have to do now is attmpt the enclosure!! haha

    wish me luck!

    Dave
    #10
  12. Dean_T
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    Dean_T Active Member

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    [Jul 10, 2004]
    I've just brought an Image Dynamics 8" sub, in the midst of building a box for it at the moment - will be powered off two bridged channels of a Tru 4.65 /ubbthreads/images/graemlins/laugh.gif
    #11
  13. imported_bayliss
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    imported_bayliss Guest

    [Jul 11, 2004]
    get some poics in when you're done /ubbthreads/images/graemlins/smile.gif
    #12
  14. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 11, 2004]
    This is what you're aiming for, it's a bit of a squeeze but well worthwhile.
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  15. Dean_T
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    Dean_T Active Member

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    [Jul 11, 2004]
    whats the total cu. ft. of that box Andy?
    #14
  16. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 11, 2004]
    Not enough
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  17. imported_bayliss
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    imported_bayliss Guest

    [Jul 11, 2004]
    is that an 8" in there andy? (still haven't started mine yet - waiting till the sub arrives this week)
    #16
  18. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 11, 2004]
    Yes, that was one of the few 8" versions I've done, as you can see the thing only just fits, and I had to shave off a few mm's on the inside of the box for the cage to fit.

    To be honest due to the restrictive size of the enclosure the thing can't move as much as it would like, so the improvement in bass is only marginal over the 6.5". With either size you really have to drive the units hard, about 300w RMS, as the enclosure doesn't give you the performance boost you'd get with a correctly sized box. Having said that, the thing really pumps it out, very impressive for such a small sub.
    #17
  19. imported_bayliss
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    imported_bayliss Guest

    [Jul 12, 2004]
    I've already ordered an 8", so I'll soon find out.

    is it not worth porting the enclosure to let it breath? or do you loose "punch"?

    as I have a single CD/mp3 HU, I don't need the space on top of the enclosure for a changer, so I'm thinking of making it taller (more cubic inches)

    I've got a 180 RMS alpine to run it. I do have a huge 4 channel 400 watt kenwood amp, but I'd never find the space to fit it! haha

    Should I be putting some wadding/sound deadner inside the enclosure?
    #18
  20. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 12, 2004]
    Tried porting it, but it loses punch and you need a bigger enclosure for ported designs. You can't make the port long enough to work properly.
    Also you can't really make it taller as the bodywork curves inwards so you'd have to have a more elaborate shape, which is tricky using MDF.
    I use speaker wadding on the inside, from Maplins.
    #19
  21. imported_bayliss
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    imported_bayliss Guest

    [Jul 12, 2004]
    would finishing it off in acoustic carpet make any difference???? (sorry if that's a dull question)
    #20

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