ASK Amp Replacement - Alpine KTP-445U Install

I had thought for a while that my recently '08 CS didn't have any bass whatsoever. A quick disconnect of the factory non- BOSE ASK amp proved that it was dead. I searched for a mini class D amp and found the Alpine KTP-445U. It is smaller than the ASK and will fit in the stock location. Here is a comparison of the two and the parts that come with the Alpine: First, install the black mounting brackets on the Alpine and then set the assembly on the back of the ASK amp to mark the hole locations to mount the Alpine. Then cut off the "wings" of the ASK amp and drill 1/8" holes for pop rivets. View attachment 202803 Before mounting the amp in the car, check that the DIP switches on the back are set to "4 CH" and speaker level inputs. Don't turn on the high pass filter or the bass will be filtered out! With the AMP mounted to the wings, check fitment in the clips on the car and slide on the left side mounting clip. From there, cut the plug off the end of the factory wiring harness but be careful because there will be 12 volts present at the red power wire even with the key off! The solid red, solid brown heavier wires on the end are power and ground. The thin black with red stripe wire is the amp turn on signal. The two yellow wires are for the center dash speaker, don't use those. The heavier gray and red pairs of wires on the opposite end feed the door subwoofers. The rest of the thinner wires come from the head unit wiring and should be paired up with the Alpine unit as shown scribbled on a scrap piece of cardboard below. The pairs of wires are power and ground, ground having a brown or black stripe on the wire. The wiring diagram leaves a little to be desired because they don't show a 4 speaker input from the head unit to 2 speaker bridged output. Connect the 4 pairs of wires from the head unit to the amp and follow the wiring diagram for bridged output carefully and you'll be fine. Again, be sure that the DIP switch on the back of the amp is set to "4 CH" and speaker level inputs. I picked up the Alpine locally for $150 plus tax, same price as Crutchfield. Could be had for slightly less from other online retailers. My only minor complaint is for the lack of a Low Pass Filter but, keep in mind that this amp is really designed for adding power to a stock head unit. Overall, I am very pleased with the end result. The Alpine amp bridged, has more than enough power for the factory subwoofers. I had to turn the front and rear gain down to about the 3 o'clock position because at a higher level, the subwoofer output easily overcome even a modestly upgraded head unit.

Thanks for the writeup! I'm a bit confused on the relationship between the head unit and this amp. Does the headunit drive the mid and tweeter, while this amp drives only the door woofers? How many channels output is the headunit? Not sure if there's four amplified outputs with the mid/tweeters sharing a pair and the woofers getting a pair (sent to ASK amp as input)?

Head unit drives the mid and tweeters. This amp drives the door woofers. 4 channels out of the head unit 4 channels into the ASK amp, 2 channels out of the ASK amp.

Thanks, though I'm embarrassed to admit I still don't quite get it. Why do four channels go into the ASK amp (instead of two for woofers)? What are the mids/tweeters wires connected to?

If only 2 channels were used than the bass would be missing from the 2 channels that were not used. 4 channels go to the mids/tweets. Those same 4 channels are in a parallel circuit that is routed to the ASK amp.

Ah, that makes total sense now, thanks!

After doing more research and experiments I found that the 987.1 and 987.2 cars are different in regards to the ASK amp wiring. I just finished installing a JVC double-din headunit, and I would get no sound out of any speakers unless I had the amp remote power pin hooked up. I've read other sources as well that with 987.2 cars the front channel (mids/tweeters) and rear channel (woofers) are driven by the ASK amp, and my experiments on my 987.2 Boxster with SPP seem to confirm this. I'll be installing the same Alpine power pack and report back to this thread for the benefit of future readers. My next challenge is to figure out how to access the ASK amp since it is under the passenger seat on 987.2 cars.

So as not to confuse future readers, please consider starting a 987.2 specific thread.