Replacing stock AMP with DSP/AMP retaining stock head unit

Wanted to share the setup I ended on for my 996.1 after a significant work and re-work. I'm super happy with the results and the system sounds amazing to me, always could have some areas of improvement but for my listening it's a good balance of price/performance. There are also some places where I could have saved which I will call out. The Goal Unlike a lot of other upgrades I have seen I wanted to keep the stock stereo cassette and CD changer, we still play tapes and CDs just for nostalgic purposes and keeping things as OEM as possible is important to me. I also wanted to add bluetooth and much better sound. I also wanted to reuse the existing AMP bracket/placement and be able to easily reverse all of this. The DSP: MATCH UP 6DSP Went with the MATCH UP 6DSP as the core of the system, a 6-channel amp with 7-channel DSP. It fits easily where the old amp did and provides enough power to where max volume is something I would not want to listen to for long. Specs for reference: Channels A-D: 65W RMS @ 4 ohm (3 ohm minimum) Channels E-F: 90W @ 4 ohm / 160W @ 2 ohm, these are the beefier channels, designed for subwoofer duty but usable for anything 1x mono RCA preamp output for an external amp, I'm considering adding a UP-FX1 at some point if I want to add independent timing for each channel but it seems expensive for what I would gain. MEC slot, running the Bluetooth module in mine Configured entirely through their DSP PC-Tool software over USB, I bought a EVERSOLO EM-01 MIC to tune the system Wiring To keep everything reversible I used Rennspec adapter harnesses: Porsche Amplifier Wiring Adapter 1999+ (18-pin) PCM Input Porsche Amplifier Wiring Adapter 1999-2016 (20-pin) Base (Sound Package Plus) These adapters break out the factory speaker-level outputs into a standard format the 6DSP's high-level inputs can read, without cutting or splicing into the factory harness, wiring via the diagram is a bit hard to understand but doable. The head unit, CD changer, and tape deck all still function exactly as they did from the factory, they just feed into the 6DSP first, which reprocesses everything before sending it to the speakers. The DSP if bluetooth audio is detected takes precedence so if bluetooth is playing it will just have that going to the speakers and if not then it's whatever the stereo is playing. One thing I haven't been able to figure out is the sound is not as loud as I want it to be from the factory stereo, I've pushed the gain all the way up on the inputs but they are just very low, enough to listen to fine but nothing like as loud as the bluetooth gets, any suggestions would be great. I also have yet to EQ the inputs which I need to do at some point but because 90% of the time I'm playing bluetooth music it's a later project. Channel Layout With two dash speakers, two door speakers, two rear speakers, and two subs to power across 6 channels I had to combine some of the channels. Before I did this I set everything up with no subs and it sounded great, could set independent delays for every speaker so that would be a very good setup to go that route. I could have added a second amp to this to power the back two SUBs via the mono out but that added another cost to get an amp that would be small enough to fit on the other side of the AMP braket and after listening to the differences I don't think it's worth it. Channel A = L Dash Speaker Channel B = R Dash Speaker As I have the higher frequencies coming from these speakers I felt it was important to keep them on their own channels to control the delays. Channel C = The factory door speakers are 2 ohm, which is below the 3-ohm minimum for channels A-D individually. Wiring both in series brings the combined load to a safe 4 ohm. Since the door speakers are crossed at 800Hz and below (just handling midbass duty, not the critical vocal/midrange stereo image), losing independent left/right delay, left/right output and per-speaker EQ on this channel made sense. Channel D = Same logic here, since these are pure ambient fill, run not as loud as the dash speakers, and I was going to mono-sum the content anyway independent channels weren't worth sacrificing a channel for. The speakers I have are 4 ohm each (8 ohm combined). The DSP allows to change per channel gain so easy to adjust for. Subs on E/F (independent): Each sub gets its own full 90W @ 4 ohm channel with independent DSP control: crossover, subsonic filter, DBE (Dynamic Bass Enhancement), and SubXpander all dialed in per channel. When I was running a single sub I kept the doors independent on E/F to support their 2 ohm and dropped the rear left speaker for the sub on channel D and that sounded great as well. I would probably go that route if I had a single sub. I tried a setup not using the rear speakers and I did not like it, just didn't have enough high end for my tastes to mach how much bass I was driving. Speakers: Dash speakers and rear speakers are Alpine S-S40, to me they sound perfectly fine, they did not sound great with the factory amp but with this DSP they are great, glad I didn't overspend here. Door speakers, I first tired swapping the door speakers by buying Infinity REF507CF 5.25" speakers and using just the woofers expecting a upgrade and it was awful. I was measuring everything with REW and PC-Tool and it was obvious that they couldn't play into the lower hz like the factory speakers could. I did upgrade the door enclosures to the ones from the 2002-2004 996/986 and that made a big difference. Would recommend this upgrade to anyone who has a 996.1, cheap on ebay and made a big difference, not sure if the difference would be heard as much without the DSP but when pushing the speakers it is a big upgrade. The part number was 99664555100 Subwoofer Box Built a sealed enclosure housing two JL Audio 6W3v3-4 subs (6.5", 4 ohm, 75W RMS each). This fits perfectly behind the seats though it sticks up just a tiny bit from making the floor flat in the back it's not much storage space lost. Was a bit intimidated building an enclosure box but it didn't take long and really glad I did. DSP Settings: The PC-Tool is awesome, lots of guides on youtube and after spending hours in REW I'd recommend just using PC-Tool to set the EQ, it works great, makes a massive difference. I went through and set all the high-pass and low-pass filters, slopes gains, delays and if anyone cares for my settings DM me. Hope this helps someone, any recommendations on how I can improve on this I'd love to hear.

This is a superb write up, great work. Nice protip regarding speaker door enclosures too. I�m just getting moving toward a CarPlay unit, so I have other motivations than your mission statement, but my car already has a budget single DIN pushing the OE amp, so the integration/next sreps/low hanging fruit are all really handy. Thanks.

This is a superb write up, great work. Nice protip regarding speaker door enclosures too. I�m just getting moving toward a CarPlay unit, so I have other motivations than your mission statement, but my car already has a budget single DIN pushing the OE amp, so the integration/next sreps/low hanging fruit are all really handy. Thanks.

Thank you for the excellent write up. I also love having the stock head unit and CD changer so I can listen to my old collection. I'm going to look into getting the door enclosures you recommended (part number 99664555100 ), did you use the door enclosures with the Infinity REF507CF 5.25" speakers or the stock speakers? I've got a cabriolet so I'm not going to be able to build out a big Sub Box, and am exploring maybe getting one or two enclosed subs to fit in the rear seat footwells.