Using a mains powered sub in a car ?!

Discussion in 'Automotive Electronics' started by YorkshireDave, Jul 10, 2016.

  1. YorkshireDave

    Thread Starter New Member

    Jun 12, 2016
    2
    0
    I have a semi-working mains powered KEF 2010 sub. The PSU is giving lots of problems which is apparently normal for these. The previous owner carried out lots of mods to it to try to resolve the issues but each time it's switched on it buzzes like a whole hive of angry wasps.

    So. As I would love a sub in my car, and I understand the PSU puts out 15vdc (obv at reasonably high current), how feasible/realistic is it to: a) drive the amp with 12V and b) to use a dedicated output from my stereo to drive it? The sub had both hi and lo level inputs but that's all I know at this point. I fully realise I'd have to re-construct the case volume etc to fit my available space, but I'll worry about that if/when I get it working from 12v ;-)

    Been told this is the cct diagram

    Many thanks
    David
     
    Last edited: Jul 10, 2016
  2. #12

    Expert

    Nov 30, 2010
    16,257
    6,757
    That power supply you linked to has what I call a split 15 supply. It has both positive and negative 15 volts (compared to ground). You're not going to get that out of a car battery unless you add an inverting power converter to get the -15Volt part. This brings the problem of needing high current from a voltage inverter.

    I think I would discard the amplifier in the sub and start over with one that can work with only car voltages. They are very available in today's market.
     
  3. YorkshireDave

    Thread Starter New Member

    Jun 12, 2016
    2
    0
    Hi #12.
    Thanks for the reply.
    Just after I posted I found the complete schematic and then realised it's a split supply.
    I understand about discarding it completely and I agree it's the eminently logical thing to do. However... Is there any way of using any of it? I'm not looking for massive power from it so, in my state of simple naivety, wondered if any of it could be repurposed ?!?
     
  4. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,226
    To get any significant audio power from a 12V battery you need a bridge output stage, which doubles the effective voltage applied to the speaker (in effect acting like you have a ±12V supply for standard amplifier).
    The original amp doesn't do that, and the speaker is rated at 4Ω, so the maximum output power with a 12V supply would be about 4W, which is way too low for any effective bass.
    I don't see any effective reuse of any part of the original amp.
    I agree you should do as #12 suggests and buy a car subwoofer amplifier which will give you adequate power.
     
  5. #12

    Expert

    Nov 30, 2010
    16,257
    6,757
    If you are going to be an electronics nerd, you have a nice power supply for experiments and personal projects. Other than that? It ain't worth squat as the power for your sub-woofie-in-a-car application.

    Trying to go with a 120 volt power inverted to run this amp in a car will be more expensive and less effective than an amplifier built for cars.
     
Loading...