Can I power an amp and an active sub from the same cable coming from the battery?

Discussion in 'ICE, Sat Navs & Dash Cams Forum' started by goatywoaty, Sep 13, 2007.

  1. goatywoaty

    goatywoaty
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    Basically in my boot I have my amp and I was wondering if I bought an active sub, would I be able to have a cable coming from the terminal on the amp where the power cable joins it, to power the sub?


    TIA!
     
  2. Mylo

    Mylo
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    No reason why not, as long as you fitted a decent gauge of wire to start with ;)
     
  3. goatywoaty

    goatywoaty
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    Cheers Mylo, it was quite a hefty bit of cable so I guess it should be fine :)
     
  4. Mylo

    Mylo
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    good stuff :thumbsup:

    The only thing I wouldn't daisy chain is the earth wire.

    I used to use gold plated splitter blocks for the power cables but they are all show to be honest.
     
  5. goatywoaty

    goatywoaty
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    Thats cool - my earthing point is a bolt in the boot anyway so i can run another lead from that to earth it. I just didn't fancy the mega hassle of running another power lead from the battery again :D

    Do you think the remote in to turn the amp on will be ok to daisy chain into the active sub to turn it on?

    Thanks again for your help :)
     
  6. Mylo

    Mylo
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    That will work fine as well :)
     
  7. goatywoaty

    goatywoaty
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    Cheers, thought it would be fine. Only issue now is having a sub in the boot along with 6x9's in the parcel shelf. I know normally a sub would make the 6x9s bounce up and down because of the pressure which would stop them sounding as good because they wouldn't be able to move as freely, but hopefully ill stop this as I bought a port to pop in the parcel shelf. Its only a cheap system i've built from 2nd hand stuff though so not bothered if it doesn't sound amazing. Hopefully it won't sound too rubbish though :)
     
  8. goatywoaty

    goatywoaty
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    Ohhh good god! I think I might have problems :(

    I've just noticed in the manual for my active sub (an alpine one that uses the MRP-M350 V-Power Class-D mono amp) that it says always use the provided power cable. The power cable that comes with it has a 20amp fuse built into it. (i dont think the amp comes with it anyway as its 2nd hand). Anyway I was wondering as my current power lead going to the amp has a 60amp fuse in it, will this cock up the active sub or blow it up etc etc?

    Whilst looking up my wiring kit (Autoleads PC4-27) to find out what fuse it had in the power lead, i've just read a review of it where a chap says:

    "I wouldn't recommend running a Class D subwoofer monoblock amplifier on this, usually you should run about a 4 gauge or a 2 gauge for these types of amplifiers. "

    So this has got me even more worried as the active sub uses a class D mono amp!? Crikey!

    I'm just trying to think of any other info I should add -- My amp is a dragster one, I think it is fairly powerful 2x200 watts at 4Ohm in case that makes a difference?

    Anyone have anything to put my mind at rest?

    Thank you!
     
  9. bk0903

    bk0903
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    if your current power lead has a 60 amp inline fuse, it will almost definitely allow too much current through to the amp, so yes there is a possibility the amp may get damaged.
    what i suggest is to use a power distribution block and a ground distribution block.
    they sound complicated bits of kit, but there not.

    the thick power cable connected to the battery at the moment is connected to a conducted block, which has outputs for smaller power cables coming out, so you can power multiple amplifiers.
    same principle with the ground distribution, thick ground cable between a distribution block and the ground bolt, and all your amps connected to the block.

    i'll admit, this is a bit of a long winded way about it, but its neat and tidy and if you choose to change your amp config at any point, its alot easier.

    also, if your sure about the 20 amp inline fuse on the power cable for the alpine, you could put a 20amp inline fuse between the distribution block and the amp, therefore no more than 20 amps would reach the alpine amp, and your other amps would run as normal as they wouldnt be affected by this.

    just as a example:
    http://caraudiosecurity.com/shop/product/products_id/2758.html

    hope it helps.
     
  10. John7

    John7
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    Sorry - That is completely wrong. The amp will only draw what current it needs and will not be damaged.

    What is important is that the power lead from the battery can supply enough current to both amps. The 60 amp fuse will be fine, as long as the main power amp is rated at less than 40 amps. What gauge cable have you got running from the battery to the amp, 8 gauge or 4 gauge? If you got 4 gaugethat should be ok to run both amps. What is the current draw of your main speaker amp?
     
  11. goatywoaty

    goatywoaty
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  12. bk0903

    bk0903
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    i apologise, that is my mistake, i've just spoken to a mate who has confirmed that i was wrong :oops:.
    john7 is correct in that the amp will draw as much current as is needed.

    im pretty sure that amp kit has 8 guage power and earth...
     
  13. goatywoaty

    goatywoaty
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    Thanks guys.

    So John says that 4guage would be ok to run both amps, does that mean the 8guage (10mm??) that I have is therefore not suitable?

    I've just a few minutes ago got it all wired in and its sounds great, but i'm worried in case I blow it all up :D :suicide:
     
  14. Ayub

    Ayub
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    What you really want to do is inform us peps of what kit you are rigging up and model numbers.

    We can talk about size of cables later.
     
  15. Mylo

    Mylo
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    Post 8 has the rough details :)
     
  16. John7

    John7
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    10mm cable is 4AWG and is rated up to about 70 amps max.

    Your 60 amp fuse should be fitted as close to the car battery as possible - the amplifier end shoud be terminated into a splitter block, 10mm in to 2 x 8mm out. connect both your amp and subwoofer to the outputs using their respective wiring kits. The negative leads from each should be connected to a clean chassis earth connection point using 8mm cable.

    The auto-power on lead can be daisy chained to each amp.

    You might also consider fitting a 1 Farad capacitor to the subwoofer power line to help buffer the power demand if you're into window rattling bass!

    Regards
     
  17. goatywoaty

    goatywoaty
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    Hiya mate,

    Speakers - Audiobahn AS69Q:
    http://www.caraudiocentre.co.uk/product.asp?product=21812

    Amp - Dragster DA 2002

    Cant find much info on this apart from 2x200 watts at 4Ohms, 2x360watts at 2Ohms.

    I bought it from these forums a while ago - a pic here:

    http://img429.imageshack.us/my.php?image=dsc03624smallhy8.jpg

    Active sub - Alpine SWD-2000:

    http://www.incarexpress.co.uk/view_product.php?partno=SWD2000

    which uses this amp:

    http://www.incarexpress.co.uk/view_product.php?partno=MRPM350

    Headunit (not sure if this is needed)- Sony cdxs2200:

    http://sony.co.uk/view/ShowProduct....verview&imageType=Main&category=ICA+CD+Tuners

    This is powering a couple of small 10cm pioneer speakers in the front:

    http://www.pioneer.co.uk/uk/products/25/131/201/TS-G1009/index.html




    I have the amp in my boot powering the 6x9s on my parcel shelf. In my wiseness I put a 3" port in the shelf too as I thought the sub would push the cones of the 6x9s up and down when they are trying to do their own thing (am I correct in thinking that this mess the sound up?)

    Just hooked the active sub up to the amp in the boot. Have daisy chained the power, the remote in and the signal from the headunit via rca splitters.

    Both the amp and the amp on the active sub are grounded to the same bolt in the boot and not daisy chained.

    I recall that the 60 amp fuse which is inline on the main power cable is very close to the battery.


    The whole aim of this is to be as cheap as possible and to sound ok. I know it won't be balanced as there are 6x9s which are full range behind me, but as i've only got a cinquecento there is no room for full range speakers in front of me unless I mess around modifying things (that would cost a bit I imagine so a no no, also I don't want anything on show).

    I must stress that i'm happy to spend money on maintaining the car etc but i'm not one for chavving it up etc :thumbsdow Spending a bit of money on second hand amps and speakers for the car is cool though as I can get most of it back if I sell it later hopefully. Soundwise, i'm not after a thump thump that can be heard streets away, but i'd love a solid kick that I can feel.

    Having hooked it all up i've had to turn the sub up loads as I couldn't really hear/feel the bass. I'm now wondering if i've made the wrong choice of sub. I thought being such a small car, an 8" sub would give me that kick, but I’m not sure if I’m expecting too much from it. Also the thing is that the boot is pretty tiny so I don’t have much choice in subs either. I thought a small active one would be a good choice.

    Thanks for the help and advice everyone. Any more suggestions of things I could do would be great :smashin:
     
  18. John7

    John7
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    I would imagine the 6 x 9's would push out a fair amount of bass themselves. You may have "shot yourself in the foot" so to speak, putting the port in the parcelshelf. Most in car subs are designed to work in a sealed boot environment. I wouldn't worry about upsetting the 6 x 9 speakers once you have the correct phasing set up they should be OK.

    Try blocking up the port tightly with some rags - also check the phase of the sub - if it's set incorrectly it will have the effect of cancelling the bass from the 6 x 9 speakers. Quick way to set it corectly is to play some bass heavy music and listen - then try again with the phase switched over. It should be obvious when its correct as there will be loads more bass in one position.

    What setting have you got the LPF set to? I would start at 100/120Hz and reduce it until you find the best bass sound
     
  19. Ayub

    Ayub
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    Hi Kiran, the audio bahn are imported from the states by a close friend of mine and i know they are good gear.

    I would go with 4 awg from the battery to the rear of the car with an inline fuse holder with a 40 amp fuse.
    I would then install a "distributer" This would be houses in the rear of the car with 4awg in and 8 awg out to the amp. Its not really a "high power system) hence the audio cabling needed is minimal.

    If you need to buy your kit and wanted it fitting contact chinks on 01274 663037 and tell him i said to sort fitting out and he would be happy to help.
    ( for around £100) i would say that would be fully inc.)

    Oh and demand a discount !
     

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