Amplifier wiring

[mintedstereo]

Hi,

What's the preferred way of wiring layout when fitting an amplifier in a Megane? I've searched and found the method of removing the glovebox and passing the power through the firewall - but then what? What side to run the cable up? Where do people prefer their amp? Under the seat, or in the boot? I gather the power cable and RCA should run up either side of the vehicle or at least adequately shielded from each other, but is there any other tips, learning experiences etc? Wiring diagrams?

I've replaced the front speakers with the custom pioneer set, and have a new pioneer deh-4200sd headunit. Now to fit this amp...
https://www.caraudiodirect.co.uk/jbl-gto1004.html
to be honest, it looks a bit big for under the seat, but i've still to measure it out properly.

[Anthony]

To route the cables just pull up the door sill trim. Inside there are cable clips you can run them through. I did try and run my RCA cables down the other side of the car, but I found finding a route through the centre console to the other side was quite difficult. In the end I just ran them next to the power cables and I haven't had any interference, but my setup only includes an active subwoofer so hearing any interference is more difficult.

The best place for the amp is the boot. Under the seats wouldn't be the best as they need enough air around them to keep cool and perform their best. Try screwing it to the seat back or something.

I noticed the amp you have produces 100W RMS per channel. Don't the Pioneer TS-Q131C's (I assume you have) only handle 35W RMS?

[mintedstereo]

Without pretending that I know what i'm talking about - I went by a this information, and a recommendation.

Pioneer TS-Q131C main features

Frequency response 40 - 28.000 Hz
Sensitivity (1W/1m) 90 dB
Maximum Power 180 Watt
Nominal input power 35 Watt
Woofer size (cm) 13 cm
Woofer material KEVLAR® brand composite cone woofer with butyl rubber edge
Tweeter size (mm) 25,0 mm
Tweeter material Soft dome tweeter with Neodymium Magnet

[Anthony]

hmm you should be OK then if they can handle 180W max.

[davelowe]

Without pretending that I know what i'm talking about - I went by a this information, and a recommendation.

Pioneer TS-Q131C main features

Frequency response 40 - 28.000 Hz
Sensitivity (1W/1m) 90 dB
Maximum Power 180 Watt
Nominal input power 35 Watt
Woofer size (cm) 13 cm
Woofer material KEVLAR® brand composite cone woofer with butyl rubber edge
Tweeter size (mm) 25,0 mm
Tweeter material Soft dome tweeter with Neodymium Magnet

Some speaker manufacturers will go to great lengths to disguise specifications. I would guess that the nominal input power stated at 35W is in reality the maximum continuous RMS rating at the resonant frequency when mounted in an enclosure. The 180W figure may refer to a 1 second burst of a sine wave signal or just about anything else. Fortunately most speaker damage occurs when the amplifier distorts due to clipping oddly enough, which will not be a problem with your set up. The problems you will encounter if you overdrive the speakers are a) overheating the voice coils leading to them melting and sudden silence, or b) straining or ripping the suspension (the outer 'butyl rubber edge'). The best test is to install the units in the enclosure you will be using, and then gently push the cone in to measure it's maximum deflection. Then play some music with a large bass content (or better still use a signal generator and sweep around from 30 - 120Hz) and observe the deflection at different volume settings. If it approaches your measured deflection, back off the volume control to avoid damage.

At 90dB /W / m they are not very sensitive. I would be interested to know how loud they actually get at 35W - possibly not as loud as you might think.

[mintedstereo]

Thanks for the information guys.

Another thing. What about the speaker wires? Can I utilise the speaker wire that is already in position, or replace it all? And how does it work re: the tweeters on the dash?

[davelowe]

https://www.jbl.com/resources/Brands/jbl ... nglish.pdf

In traditional audio systems - ie hifi the amp sends out the full frequency response to 2 channels (stereo). Each speaker cabinet has a crossover which filters the frequencies supplied to the different drive units. Usually 2 or 3 units. They all specialise in reproducing signals in a particular band. Example: woofer - 30 - 1000Hz, midrange 1000-5000Hz, tweeter, 5000-20000Hz.

The crossover improves sound quality, but more importantly, prevents low frequencies from hitting the tweeters, which would die immediately. The exception is if the tweeters are piezo technology - these do not require a crossover. I'm not sure if the units in the car are or aren't - someone else will clarify that.

Anyhow, you seem to have full range speakers (not uncommon in hifi either). No crossovers are required for those - you just wire each speaker to the appropriate pair of terminals on the amp and observe the correct polarity so the phasing is correct. You also have a full range amp. So, until you know about the tweeters, just wire all four speakers up as per the pdf and ignore them.

It's all a bit arse about face. Are you trying to get a sub unit installed or something? You don't seem to have the right kit for it. I'm a bit puzzled.

More details....

[mintedstereo]

It's all a bit arse about face. Are you trying to get a sub unit installed or something? You don't seem to have the right kit for it. I'm a bit puzzled.
More details....

Arse for face? I don't understand. What's wrong with the kit I've bought? I do plan to fit a sub in the boot by bridging the rear speakers. Am I on the right track?

[davelowe]

It's all a bit arse about face. Are you trying to get a sub unit installed or something? You don't seem to have the right kit for it. I'm a bit puzzled.
More details....

Arse for face? I don't understand. What's wrong with the kit I've bought? I do plan to fit a sub in the boot by bridging the rear speakers. Am I on the right track?

Erm, not really no. I would take a line level output from the amp you have - the RCA unfiltered - and wire that into another amp with a lowpass filter. Power the sub from that. That's in an ideal world though.

If you just want to improve the general sound then the kit you have seems okay.