BRZ Amp install without cutting, splicing, or otherwise hacking into any factory wires:
Today I installed an Alpine KTP-445U 45x4 RMS amplifier in place of the OEM amplifier. This amp is designed to go behind a factory or aftermarket stereo to provide more power to the speakers. The Alpine works on a 15A circuit which is (conveniently) identical to the OEM amplifier. The OEM amplifier runs only the 2 door speakers and I wanted to retain this setup to only power my Infinity Kappa 62.11s in the doors. The OEM HU provides plenty of power for the Reference 3.5s in the dash.
The OEM amplifier connectors are the same connectors used in 1987 and up Toyotas. (credit: RandomHero on FT86Club.com
http://www.ft86club.com/forums/showthread.php?t=42239) So, in order to install this amplifier without cutting any wires, the only item needed is the Metra 70-1761 Radio Wiring Harness.
Here is the amp and Metra harness out of their packaging:
IMG_4169 by
zdr93523, on Flickr
Then, following the advice of RandomHero on FT86Club.com
http://www.ft86club.com/forums/showthread.php?t=42239 I removed the pins from the Metra harness and repinned the connectors to colors that match the amp connections. I used a very small jewelers screwdriver to unpin the connectors and had no issues.
Before:
IMG_4170 by
zdr93523, on Flickr
After:
IMG_4171 by
zdr93523, on Flickr
The next step was to remove the front input RCA connectors from the amp harness to accommodate the line level inputs and make all of the proper connections.
Note: Please do not post any wiring criticisms or "you should've soldered," etc... If you can splice wiring in an F-16 (you can, and we do), you can certainly do it in our cars.
IMG_4173 by
zdr93523, on Flickr
Here is the harness with all necessary connections. Note that none of the rear output wires are used.
IMG_4176-4 by
zdr93523, on Flickr
Once the harness was done, the amp was ready to be installed. I removed the factory amplifier (3 10mm nuts). Then, I connected the amp and performed a functional check and some tuning. I ended up setting the front gain to 1/2 power and the 80hz HPF on. The HPF does not defeat all frequencies below the cut off, it just filters 12dbs off of the frequencies below the cut off. Basically, it makes the bass coming out of my 6.5s sound clean.
OEM amp in top left corner of pic:
IMG_4178 by
zdr93523, on Flickr
Harness connections with OEM amp removed:
IMG_4180 by
zdr93523, on Flickr
HPF adjustments on the bottom of the Alpine amp (final settings with 80hz filter ON not shown):
IMG_4177 by
zdr93523, on Flickr
To mount the amp, I used the OEM amp mounting points and the cable that runs through this area as mounting points for the supplied zip ties. Using this method, the Alpine amp is secure and has airflow all of the way around it, including underneath.
IMG_4182 by
zdr93523, on Flickr
Here's the final pic. I left the wires long and unused wires intact in case I add speakers or remove the amp and want to use it in another car. I may clean up the wire bundle a bit, but for now, the wires are secure where they are. I will cut the zip ties after a day or two of driving once I am sure that they don't need to be tightened.
IMG_4183 by
zdr93523, on Flickr
Review:
Wiring in the house and in car install took less than 2 hours. Then I sat in the garage for another hour or so listening to it. With the Kappa 62.11s and OEM amp, I could turn the volume up to 60 without distortion. Now, the this little Alpine beast set to a little less than 2/3 gain, I can turn the volume to 30 on some songs. It sounds really good at reasonable volume levels like 12 (used to be 30).
Alpine KTP-445U: Highly recommended!