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Power supply for small underseat subwoofer

craiginuk

craiginuk

Member
Just ordered a small underseat sub to help with the bass in my 944. I will be mounting it under the front passenger seat. Any ideas where it is best to run power from? I guess I could run a fused line from the battery in the back but I'm guessing it would be easier from the front. Would cigarette lighter be the best option?

What have others done?

Thanks

Craig
 
I like your thinking! Yes i do. Is there an obvious power feed there i can splice into then? Would be handy as the sub will be right there and i think the seats have a 30A fuse too.
 
Depends on what current the seats use when the motors are cranking - if they have a 30 amp fuse its for a reason - I`ll bet its high and will certainly spike to near max when the motors start up so be careful about adding to it.

 
True - hadn't thought of that. Any other ideas? I guess a fused line direct from battery would be safest option then?
 
ORIGINAL: craiginuk

True - hadn't thought of that. Any other ideas? I guess a fused line direct from battery would be safest option then?
Click to expand...

It would depend on what controls the power to your sub - e.g. would power from the battery mean the amp is "on" all the time? I would think you would want power to the sub controlled from the stereo unit so the amp is on only when the stereo is on. What does the wiring diagram for your stereo look like? Many have power out for antennae - perhaps there is power out for an amp also or to a relay to control amp power?

The following in an excerpt from a document called 924/944/968 Stereo FAQ - you can find it on Rennlist.com and several other places too. Maybe this is an option....

Power connectors The wiring diagram in the Haynes 944 manual is nearly useless. A better idea is to go to your dealer or a shop that has the factory service manuals and photocopy the pages for your exact car. Public libraries often carry the Mitchell's auto repair manuals. These are also a good source of accurate schematics. Crutchfield (http://www.crutchfield.com) can provide adapter harnesses to avoid the need to cut up your wiring. The six-pin connector commonly used in mid-80s has two large pins and four smaller ones:
  • Pin 1) Brown - Ground (large pin)
  • Pin 2) Red - 12v switched power input (large pin)
  • Pin 3) 12v illumination power input (from pin 4)
  • Pin 4) 12v radio-switched output (to pin 3)
  • Pin 5) 12v radio-switched output (to power antenna)
  • Pin 6) Permanent 12v input (to maintain memory)
A second set of power connectors are provided for the optional equalizer/amplifier:
  • Brown - Ground
  • Red/white - Permanent 12v power
  • Red/black - 12v when radio is switched on
 
Hi Colin,

It's 270mm diameter and 69mm high. Looks like it will fit as long ans the seat is not dropped down too far.

I'll have to offer it up before I mount anything but am hoping it will fit. One of the lowest ones out there :)
 
Ummm, go easy with that. 69mm is a pretty tall thing, and much taller than the space available under the seat (doubt there is 30mm there with the seat down). The seat motors are powerful (they are designed to deadlift fat german blokes, hence the 30a fuse) and will crush the sub if you lower the seat onto it.

If you do go this route then think about some kind of modification to the seat so that it only drops part of the way down. Or - and here's an idea - mount the seat on some blocks on the floor so that it won't descend fully onto the sub. That would be quick and easy and cheap, and also be readily reversible.


Oli.
 
ORIGINAL: craiginuk

Hi Colin,

It's 270mm diameter and 69mm high. Looks like it will fit as long ans the seat is not dropped down too far.

I'll have to offer it up before I mount anything but am hoping it will fit. One of the lowest ones out there :)
Click to expand...

I'd suggest you get a 15 stone person to sit in the seat before you measure the available space..[;)] unless you intend never to have a passenger.?
What about mounting it in the passenger footwell over the ECU ? you could cover it with carpet and a grille and it would probably work better there too
 
I have seen speakers mounted on a board sloped down the front of the rear seat base ie in the foot well .
 
Thanks all - I've had a rethink and am going to mount it in the rear RHS cubby. There was a CD shuttle (no longer used) in there when I bought the car so the RCA lead is still there and terminates near the head unit. Power from the battery will be nice and easy too. Will just need to get a switched positive from the blue wire of head unit to the back of the car and should hopefully be sorted then.

Wasn't too happy about having to have the passenger seat in its highest position all the time anyway so this will be a much better solution. I'll report back on the hopeful improvement once I have it installed. This is the unit I'm going for by the way.

http://www.caraudiocentre.co.uk/product_m-usw10_p-25817.htm

Haven't received it yet but have disapeared into the garage with a couple of dinner plates (also 270mm diameter) and it looks like it'll fit with ease. My very understanding wife now thinks I have finally lost the plot though [:D]
Cheers
Craig

 
sounds like a much better solution in the rear ,as these subs need airflow to work. The ad says 300W but thats Father Christmas watts [:D][:D] I see they don't show the true continuous rms output
 

ORIGINAL: craiginuk

True - hadn't thought of that. Any other ideas? I guess a fused line direct from battery would be safest option then?
Click to expand...


Would work but would be a permanent live so not recommended unless you put a switch in line and remembered to switch it off.

Best way is to find the fuse box, find a permanent live from it and fit a relay so the ignition livens it up. You could power the relay switch side off any normal supply. The relay provides the main power switching to a permamnet live. Fit an in line fuse before the switched side live into the relay.

Same would work from the battery but you`d need to run the switching wires to an ignition energised supply.

If you can find an ignition switched live on the fuse box so much the better but 30amps draw is high so I`d doubt if there was one you could use safely.

 
you probably should have a timed relay supply or the direct surge from the battery ,on switch on, would probably trash the speaker cone. Thats why all car and home HiFi has a few seconds delay before the amplifier is powered up after you switch on
 
Thanks all, will have a look at instructions when i get it. I'd assumed there would be a built in relay so it would need an always on feed from the battery as well as a switched feed from the head unit. Can't find anything online but will have a look when it arrives - hopefully in time for the weekend!
 
i would suggest you put a fused live from the battery 30 amps,it looks like the product you have ordered has a built in amp so it would need a switched live from ignition or head unit (some head units have a wire to power up external amps) i am a electrian by trade(20 years) and i now work on car engine wiring /ecus for ford , jag and landrover. i have also instaled quite a few ice systems for people i know a few years back alpine stuff costing £1000s using ofc cables etc. maplin electronics do complete amplifier wiring kits for cars( code nb52g or l82ak) for about £20,these would make the install easier, hope this helps
 
I would use original connector for sound system. All 944's (oval dash) have extra connector for equalizer/amp available. Just add wire to that connector.
 
I've got a pioneer TS-WX50 'spare wheel' sub that fits nicely inside the spare wheel. fused straight of the battery and uses a remote lead from the head unit to switch it on/off. It has more than enough output for me.
I think pioneer do a new model but it'll be more £££.
 
Oooh it's arrived and actually looks a tasty bit of kit.. Really solid and made of alluminium. Came with a full wiring harness. Now I wish I wasn't going out tonight! Will hopefully get a "garage pass" at some time over the weekend.

Craig
 
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