993 Premium Audio Upgrade - Head Unit
10-13-2017, 03:56 PM
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993 Premium Audio Upgrade - Head Unit
My ‘95 993 with Premium Sound (Alpine 7807 head unit & OEM Nokia amp, two deck speakers and three door speakers per channel) needed help: The head unit was always bloomy at the low end, but now it had also stopped reading CD’s. I decided to replace the head unit with one with good power, HD radio, Bluetooth and a CD player, plus Aux inputs and USB. I ended up selecting the Kenwood KDC-BT768HD from Crutchfield, along with which came a free Metra 70-1785 wire harness (with instructions for Audi and VM installs).
I gathered a headlamp, a small flat head screwdriver, electrical tape and some Posi-twist wire connectors.
Removal
Removing the original Head unit was simple enough. With all CD’s ejected, faceplate removed, and the wire harness and antenna disconnected, I dragged in turn the two silver latch discs on either innerside of the facia up while my other hand, underneath the dash on the back of the head unit, provided a gentle push to free the unit from the latch and the 1-DIN sleeve. With both latches done and taking care of the other leads on the rear of the unit, I gently pushed the head unit all the way out. With a small flathead screwdriver, I then levered the sleeve’ lugs back up to free it from the 1-DIN facia opening.
If you forget to remove a CD
, or to test, hook the harnesses back up:
Harness
The 993 harness has two ISO audio sockets, the A-Socket (power with three pins seated) and C-Socket (preamp with six pints seated) - there is no B-Socket (speakers). The head unit was connected to the 993 with an intermediate harness that fit the Alpine. The new Metra 70-1785 harness, a combined A+B socket plus a C-Socket replete with RCA terminals, is a little different from the Alpine harness: On the Metra A-Socket, the red and yellow wires are reversed and there is an extra pin seated with an orange Mute wire, plus two other additional taped off and unused function wires. On the C-Socket, there were only five pins seated on the Metra as opposed to six on the Alpine.
On the Metra A-Socket, I taped off the two label but unused wires, plus the orange mute wire. I chose to swap the red and yellow pins (battery and ignition) to be consistent with the Porsche standard, rather than the Metra standard. To pop the pins out of the socket I grabbed a paper clip, straightened it out, and inserted it in the gap on the pin side of the socket while pushing the wire towards the clip. This closed the catch on the pin and the pin and wire came easily out.
The included Metra instructions indicate that an amp remote on should be installed into the A-Socket - this was a loose blue/white wire and pin found in the packaging. As the Alpine harness A-Socket did not have a pin installed in the location specified in the Metra instructions, I did a little research: From other writeups on head replacement I figured that the amp remote on was the missing pin on the C-Socket, so I installed it there instead.
Using Posi-Twist connectors I wired the Metra harness to the Kenwood head harness and plugged the C-Socket RCA’s into the Kenwood preamp F/R outs.
Test and Install
Back in the car with the key off, the Porsche harness hanging out of the back of the dash, and without disconnecting the battery as it implores you to do in all the instructions, I connected the A-Socket and C-Socket and plugs, and the antenna to the Kenwood as it lay in the footwell. I turned the key, and it worked. I checked L/R F/R, and rearranged the RCA’s on the Kenwood.
I unhooked the Metra harness from the porsche harness and lightly electrical-taped it together for strain relief and tidiness. I also taped off the single green wire floating at the back of the dash which is the ground contact for the alarm system, per other writeups. It had not been used on my headunit, and it had a solid insulated connector on it, but even so...
After inserting the new Kenwood sleeve into the facia and pressing down on the tabs to lock it in place, I picked up the Kenwood and routed the Metra harness through the opening leaving the head supported and half in. I hooked up the A-Socket, C-Socket and antenna and performed a final functional test before gently pressing the Kenwood home with one hand while guiding the wiring from inside the dash with the other. Done!
Result
The Kenwood is quieter than the Alpine, due to differences in pre-amp-out voltage one imagines (Alpine volume was painfully loud at 25 and I never found the top but the Kenwood maxes out at 35 and still not as loud). The bass is much tighter and punchier with the Kenwood - it sounds good - better than I though the original speakers could. With more sources than the Alpine, each on the Kenwood sounds much better defined, but each is different. The Kenwood has a lot of settings for spatial compensation and a 13-band equalizer… Lots of things to tweak.
Everything is, overall, much better sounding: It has made apparent the weaknesses in the original speakers and amp. Speakers need to be next.
I gathered a headlamp, a small flat head screwdriver, electrical tape and some Posi-twist wire connectors.
Removal
Removing the original Head unit was simple enough. With all CD’s ejected, faceplate removed, and the wire harness and antenna disconnected, I dragged in turn the two silver latch discs on either innerside of the facia up while my other hand, underneath the dash on the back of the head unit, provided a gentle push to free the unit from the latch and the 1-DIN sleeve. With both latches done and taking care of the other leads on the rear of the unit, I gently pushed the head unit all the way out. With a small flathead screwdriver, I then levered the sleeve’ lugs back up to free it from the 1-DIN facia opening.
If you forget to remove a CD
, or to test, hook the harnesses back up:Harness
The 993 harness has two ISO audio sockets, the A-Socket (power with three pins seated) and C-Socket (preamp with six pints seated) - there is no B-Socket (speakers). The head unit was connected to the 993 with an intermediate harness that fit the Alpine. The new Metra 70-1785 harness, a combined A+B socket plus a C-Socket replete with RCA terminals, is a little different from the Alpine harness: On the Metra A-Socket, the red and yellow wires are reversed and there is an extra pin seated with an orange Mute wire, plus two other additional taped off and unused function wires. On the C-Socket, there were only five pins seated on the Metra as opposed to six on the Alpine.
On the Metra A-Socket, I taped off the two label but unused wires, plus the orange mute wire. I chose to swap the red and yellow pins (battery and ignition) to be consistent with the Porsche standard, rather than the Metra standard. To pop the pins out of the socket I grabbed a paper clip, straightened it out, and inserted it in the gap on the pin side of the socket while pushing the wire towards the clip. This closed the catch on the pin and the pin and wire came easily out.
The included Metra instructions indicate that an amp remote on should be installed into the A-Socket - this was a loose blue/white wire and pin found in the packaging. As the Alpine harness A-Socket did not have a pin installed in the location specified in the Metra instructions, I did a little research: From other writeups on head replacement I figured that the amp remote on was the missing pin on the C-Socket, so I installed it there instead.
Using Posi-Twist connectors I wired the Metra harness to the Kenwood head harness and plugged the C-Socket RCA’s into the Kenwood preamp F/R outs.
Test and Install
Back in the car with the key off, the Porsche harness hanging out of the back of the dash, and without disconnecting the battery as it implores you to do in all the instructions, I connected the A-Socket and C-Socket and plugs, and the antenna to the Kenwood as it lay in the footwell. I turned the key, and it worked. I checked L/R F/R, and rearranged the RCA’s on the Kenwood.
I unhooked the Metra harness from the porsche harness and lightly electrical-taped it together for strain relief and tidiness. I also taped off the single green wire floating at the back of the dash which is the ground contact for the alarm system, per other writeups. It had not been used on my headunit, and it had a solid insulated connector on it, but even so...
After inserting the new Kenwood sleeve into the facia and pressing down on the tabs to lock it in place, I picked up the Kenwood and routed the Metra harness through the opening leaving the head supported and half in. I hooked up the A-Socket, C-Socket and antenna and performed a final functional test before gently pressing the Kenwood home with one hand while guiding the wiring from inside the dash with the other. Done!
Result
The Kenwood is quieter than the Alpine, due to differences in pre-amp-out voltage one imagines (Alpine volume was painfully loud at 25 and I never found the top but the Kenwood maxes out at 35 and still not as loud). The bass is much tighter and punchier with the Kenwood - it sounds good - better than I though the original speakers could. With more sources than the Alpine, each on the Kenwood sounds much better defined, but each is different. The Kenwood has a lot of settings for spatial compensation and a 13-band equalizer… Lots of things to tweak.
Everything is, overall, much better sounding: It has made apparent the weaknesses in the original speakers and amp. Speakers need to be next.
04-11-2019, 03:09 PM
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Join Date: Apr 2019
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Looking at Pioneer AVH-3300NEX
I am looking upgrading my aftermarket system on 993 1995 911 Cabriolet with a Pioneer AVH - 3300NEX. This has a display head that pops out. Does anyone have any experience with this unit.
