Amp wiring question

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jakesmith

Original Poster:

9,461 posts

170 months

Tuesday 16th January 2018
quotequote all
I am about to upgrade the stereo in my 987 Boxster, new head, amp, speakers
It has the Bose system, which has a small amp in the front boot. Hard to find out the Bose specs (as they are usually a bit crap so they don't publicise them). I am proficient in doing this but was wondering about one thing...

I want to install the stereo with as little change to the car as possible so have bought a special connector from the US for £40 that allows me to access the car's wiring loom at the amp, without having to cut anything. It is a female version of the plug that connects to the amp, so what I will do is unplug the Bose amp connector, and plug this special female plug into the car's loom - it connects to the car side of the loom and gives me speaker connections, plus it carries the power feed and ground to the amp, so I will gain access to the permanent 12v and ground going into the car's amp

https://www.ebay.co.uk/itm/Porsche-Radio-Stereo-In...

Normally when installing a new amp, I would run a big thick cable with a fuse holder etc to the amp from the battery, however this seems like a bit of a gift to be honest, there is a power and ground feed capable of running the Bose amp already in the right position. The amp I am installing is a small class D Focal 4.350 and requires according to the manufacturer, 4mm squared power cable. Having looked this up that is only 2.3mm diameter cable.

When the plug comes in a few days I can measure the diameter of the copper part of the power cable and if it is 2.3mm or more wide, use these existing cables for my power and ground, right? Will save me time, hassle, and having to drill hokes in the bulkhead / introduce possible electrical noise.

Would you follow this methodology, or would you just follow standard process and put in a beefier cable? I don't need larger capacity for the future.



Pope

2,633 posts

246 months

Tuesday 16th January 2018
quotequote all
The need for large capacity cable arises when you want to run large subs that consume lots of power; stiffening capacitors are used for larger installs. As your 987 hasn't the room for that type of thing, and you don't want to expand the install in future the benefits of large cross section cables is unnecessary.

The latest systems - BOSE / Burmester in Porsche cars have great sound and bass capability using standard cross section cabling too.

In my experience the biggest benefits are made with correctly located and built enclosures for the speakers.

jakesmith

Original Poster:

9,461 posts

170 months

Tuesday 16th January 2018
quotequote all
Yes that's fair, all I am doing is replacing the head unit, dash mid range speakers with 4" Focal components, putting in a load of Dynamat in the doors, and then amping up the 2 speakers in each door - leaving the Bose woofer in place as I did that in my 997. The combination of a better head unit, with proper eq, and the ability on the 4 channel amp to set cutoffs, made a big difference to the car on my 997. I don't play it that loud (any more) it's more about quality
I will be installing a sub too but it is active and came with it's power cable so no room for error there, it is surprisingly thin cable too which made me think that how most people wire up their amps with 8AWG is probably overkill
Anyway this amp will at most be putting out 315W and that is broadly comparable to the Bose setup
The fuse on the circuit is 25W
I am assuming that if the amp does put too much load on the circuit, the fuse will blow before the wires heat up and start a fire?