Fitting Amp Under Seat Of MK3?

I’ve got a 2006 NC Sport, I’ve already replaced the HU with a Pioneer one, but still find the setup a bit weak.  My commuting car has an underseat sub that works really well, but it has more room for it.  I’m thinking of getting some Focal 8" component speakers and fitting an amp under the passenger seat.

Just wondered if anybody has done this please?  It seems a bit tight under there, but I’m sure it will fit.  My other question is regarding seat removal?  Is it straight forward to do this, as the seats have SRS airbag tags on them?  I tried to remove the seat once before for something else, but couldn’t figure out how to unplug the large strange looking cable socket underneath the seat.  I didn’t try for long though.

I was also wondering about running the RCA cables away from the power cables.  I thought about removing the center console, there are obviously cables under there, but I’m guessing that the RCA could be kept away from those.  Whereabouts have other people ran them?

My other question is regarding running a live cable to the battery, is there a decent grommet that can be fairly easily accessed for that please, which one did other people use for their install?

Thanks for any help.

IMHO - fitting an Amplifier under a seat is asking for trouble. A power amp needs ventilation for cooling, without that you’ll burn it out sooner or later. In the meantime you run the risk of cooking the seat as well. Sensible place is in the boot, yes you’ll lose some space, but you can’t have both if you care about spending money.

Frankly, as former P.A. Engineer, I don’t understand why anyone feels a need for more audio power, but then there’s always someone that does. I was amazed early on in that career to discover cinema sound systems in the 60’s had 10 watt amplifiers. Now people want 50/100 Watt amps in a car? We used to fit 20W amps in auditoriums, running at half level! Main reason for poor audio reproduction is poor efficiency speakers, cinemas use the best available. Impossible to achieve that in a car. Size does matter.

Hi yes an underseat sub is the way to go!Thumbs Up If you have already upgraded your original Mazda audio unit to a descant one capable of powering an external sub-woofer, then do it, you will not be disappointed. Ok I have already replaced the original audio and installed Clearwater speakers. For me, the stock audio setup, was a tad too much base with very little in the way of equalizer adjustment leaving, the sound, at mid to high volume distorted and unsatisfying.

With the addition of an underseat subwoofer (and controller) I can have extra clarity from my new speakers and can turn up the extra  base when I want. The sub I have installed is positioned under the passenger seat and ordinarily runs in the background just picking up the odd lost base here and there, but has a controller that lets me ramp up the background base for a truly awesome sound. Woot


I agree with this.

I used to build my own amps and speakers, and ended up with a ‘bridge amp’ for car use, giving me (when the engine was running and charging a full battery) approx 25V p-p across a 4 Ohm load.  This is approx 19Watt RMS (true hot power) or approx 150Watts PMP (Peak Music Power, what most modern car amps and speakers are rated at).  The speakers were also reasonable, 8" dual-cone Hi-Fi units rated at 30W RMS in custom tapered transmission-line cabinets for a flat response. Remember also that the speaker impedance is inductive at higher frequencies, so while the low bass might take 20W the high audible frequencies might only be using maybe half a watt or less and yet still sounding just as loud.

With that thirty-year-old system my ears distorted before the Hi-Fi did; if I stood outside, beside the car, the sound was clean and pure, but inside … too loud.  

Thanks for the very interesting facts about hifi, Gerryn & Richer FX.  I’m into home hifi, but understand that the car is a different environment.  I’ve had best results in cars with a subwoofer of some description, I just thought that 8" mid/bass drivers would create decent bass, I mainly listen to heavy rock/metal music so don’t need lots of it I guess.

Sparks, that’s a bit like the underseat sub in my other car, just a different brand.  I take it that Kenwood one is active and has a built in amp too?  How much did you raise the seat by?  Was it both front and rear that you raised it, and what did you use for spacers?

some of the sound from car door speakers can be lost due to resonant vibrations penetrating the door panel causing it to shake and vibrate. These losses are a nuisance in an open top car, so applying sound deadening to the interior of the doors is necessary to gain the full benefit of the installed speakers.

The Kenwood sub I have fitted is a dual sub model with an active amplifier which allows extra adjustment. It is purposely designed by Kenwood to be fitted under a seat so the sound can bounce off surfaces, and will not get hot.

I have raised both driver and passenger seats at the rear whilst keeping the front mounts original, not raised. I used

M10 x 60 x 1.25p Metric Fine Pitch Hex Bolts AND M12 NUTS AS SPACERS 

In the end I opted for some Focal Integration ISS 200 8" component speakers in the doors.  The NC has lines on the speaker housing, where to cut out to fit an 8" speaker.  I just cut it out with a hacksaw blade, there is also a lip that needs cut off. The tweeters fit in the existing housing after removing all the gooey crap that holds the original one in place.  I’m not sure that the original tweeter position is that great, but I don’t want to drill into my door cards, so made do. I tried these with just the head unit powering them at first, it was an improvement, but nothing special.  I fitted a 70 watt RMS amp under the passengers seat yesterday.  This is a huge improvement, still not as good as using a subwoofer, but for a fairly easy fit, I’m sure there is not a great deal better.  It is loud and sounds pretty good, way better than the garbage that was originally fitted, not muffled at all, with decent bass.

I thought it sounded harsh at first, but I set the fader to just the front’s, eliminating those waste of space rear speakers, and it sounds way better.

Certainly worth doing if you have an NC. I might add a sub at a later date.

Rather than the boot, there is plenty of space behind the seats you will need to remove the panel to gain access though.

Thanks, I didn’t know that.  I might move it, although I’m getting no problems with it under the seat.  These speakers seem to be getting better the more I use them, or I’m getting used to the sound.  I’d definitely recommend these I’m really impressed, need an amp though as it’s not worth it using a head unit.