Hi Guys. I have to replace the amplifier in my 04 CTT. I understand I also need to replace the head unit due to the MOST. Are there any issues with going all aftermarket, other than losing the steering wheel controls?

 

I just had this done on my 04 CTT. A JL Audio Cleansweep and summing device were installed. Then I put in an MTX four channel amp and Infinity Kappa components in front and back. I kept all of the factory steering wheel controls. It has been a huge upgrade in sound.

 

Excuse my ignorance but what do the Cleansweep and summing device do?

 

the cleansweep and summing device alow youy to keep your factory head unit but use aftermarket speakers and amps. They aslo convert the factory signal to flat o your sytem can be tuned properly. I have A cleansweep and summing device in my cayman with Morel speakers,Morel Sub and Focal amps. In my Lexus I have a cleansweep and summing device with JL audio amps and Focal KRX2 speakers in fromt and back and JL Sub. Both my systems sound great I am told.

dave-t

 

Sounds great but does it matter that my factory amplifier is cutting in and out? Do these allow me to bypass it?

 

The way mine was done was to completely remove the OEM system after the head unit. This renders the head unit being used basically as a pre-amp. As already stated, the JL pieces re-equalize the signal to flat that is sent to the aftermarket amp. I should point out that I have to use the fade and balance on the amp, so it's a set-it and forget it. In a couple of days I'm adding tweeters to the dash, so if you have any specific questions I can ask my tech for you.

 

Cool, so did you leave the OEM stuff in your vehicle or did they remove everything except the PCM? I wasn't sure if I still needed the OEM amp in place or not...if not I can skip buying a head unit and go with the JL components.

 

After PCM, all gone. Right now, I'm fine without a sub, but respect the guys that add one, or two. If I didn't have the four zone A/C, I would have added the JL Stealth model.

 

Thanks very much, I appreciate the help. I'll start looking at going that route and retaining the factory head unit. Is there any loss in sound quality with this approach vice using an aftermarket head unit? I'm assuming not as the the JL units are intended to improve things by flattening the signal.

 

JoeDud,

A question for your tech guys, how do you defeat the requirement for the fiber optic loop through the oem amplifier? Do you simply close the loop at the head unit? I'm assuming you then attach the cleansweep to the oem head unit harness?

Sorry for all the questions, trying to get smart.
Cheers! Rob

 

TurboDelaney,

I spoke to my car audio tech and he corrected me insofar as the Bose amp has remained in the car. The head unit sends the digital signal through fiber optic to the Bose amp. Then the Bose amp converts it to analog and it's passed to the JL Cleansweep. The JL takes that signal and re-EQs it to flat while passing it to the aftermarket amp. From that point on, it's a simple wire install to the speakers. Sorry for any confusion caused on my part. I forgot to ask about the summing device, but I remember JL was heavily consulted and offered a lot of guidance in that department.

 

sorry to her your audio shop had to use the cleansweep, it is an ok piece or bandaid solution to the optical MOST system and is one of only a handful of options. You could of had your Porsche tech turn off the Bose system and the headunit will output a flat 20-20k frequency. you would need a male speaker plug to insert into the speaker output plug above the power plug part number 71-1784 from Metra.

no need to have the cleansweep try to reproduce something that was not there to begin with

 

Okay, my interest is peaked. So Porsche can disable the Bose, then I add the Metra part you've indicated, which it shows as Audi/VW (I'm assuming it fits Porsche also). What do I then need to do to connect an amp?

 

yes in PIWIS 1 they can take out Bose in coding, both in the gateway and the PCM, your headunit will turn on the speaker outputs. I will say that I heard of 2 people not being able to do this, but the 20+ times I have done this, I had no issues.

once you enable the speaker output it will be a high level out, my amps of choice are audison which accept speaker level inputs for a signal.

now i have measured the outputs at the PCM, and besides a huge rejection to radiated noise interference the signal is pretty much smooth.

Also, with the audison bit1, the cleansweep looks a little weak

 

Just realized though this approach renders my Dension IPod integration useless...so I need to find another integration option.