Hey guys, thanks for the feed back.
Here are the answers to my own initial questions:
- The dash speakers are both individually capped at the drivers.
- The doors are crossed over at the amp.
- The rears are not capped at all and are running full range.
I successfully installed the amp on the weekend and i'll give you a run down of what i did, what i didn't do, and my review of the system now, along with some tips and hints for anyone wanting to do this as well.
My initial intention was to run the doors and dash on channels 1&2, rears on channel 3&4, and save 5&6 for the sub install down the road. So i bridged the front speaker leads at the HU with the rear speaker leads and then disconnected the rear speakers. This bypassed needing to run new wire to the dash. I ran new wire directly to the rears and tapped the speaker wires in the doors at the amp in the trunk. the doors and dash were run in series to bring the impedance back to 4 ohm since each driver is running 2 ohm and my amp isn't stable to 1 ohm had i run them in parallel. After a quick test it was apparent that the levels of the dash and door drivers were not matched well at all. The dash was about 3 times louder than the doors. As i suspected i would have needed a properly built 3 way crossover to pull this off in order to attenuate the dash speakers and balance the output of the 3 speakers.
On to plan B. I ran the dash on 1&2, rears on 3&4, and the doors on 5&6. This worked out perfectly. Since the dash drivers were capped i fed them a full range signal to avoid over processing. I tested crossing them over but found that they were capped at a much higher frequency than i would have crossed them over at using the amp so a full range signal suited this setup. The rears are being run with a very generous 50Hz crossover point. I found that the OEM free air drivers being used were able to handle a full range signal at high volumes but to avoid stressing the voice coils i crossed it over as a safeguard. The doors are being run at a 500Hz 12dB crossover point. I initially tried a normal 120Hz 12 dB sub bass crossover point but the drivers didn't really have the balls to pull it off at volume so i settled for some mid bass at 500Hz. It was better than no bass at all.
I tuned the whole thing to be fairly loud and distortion free at 50vol with fader, balance, and sub level set to zero on the HU. normal listening seems to settle in around the 30-35 vol level. the treble setting had to be set to -2 to keep the dash from sounding too bright. i'd like to pull the cap off the 3.5" dash driver and crossover much lower using the amp. This should allow me to take the gain down on the dash and reduce brightness properly so that i can zero out the treble setting.
Overall impressions... this is how the system should have sounded from the factory. It doesn't hit you in the chest and is by no means an SPL setup but the low frequency extension is acceptable at normal listening levels. With the stock setup, i could barely go past 40vol without hitting some major distortion on the doors. This tells me the factory amp for the doors is pretty much garbage. Now the system is loud, clear, and much fuller sounding. I know that there's an aftermarket sub solution that includes new tweeters which would indicate that the tweeters are lacking, but i haven't found this to be true. With a clean amp and adequate power the stock dash is actually way too bright.
If i had to do it all over again and i didn't have the cash for a 6 channel amp, i'd do a small little mono class d with something like 100W rms and a built in crossover. Run all four corners off the head unit and run the sub amp off the subwoofer channel built into the HU. You'll have independent control of all 5 channels, and proper power and crossover point for the doors. You won't get as much volume from this setup but you'll fix the gap in the response curve of the system.
as i mentioned earlier my next step is to remove the cap off the 3.5" and cross it over at the amp as a temp solution until i build my sub. Once i build my sub, i'll rewire the sytem to put the doors on channels 3&4 and run them as mid bass since there's a bandpass filter option on those channels, and run the real sub off 5&6. This essentially solves the problem of building a 3 way crossover. It becomes a bi-amped front stage. I won't use the rears anymore as the rear fill in a coupe is not as significant as it its in a sedan. Also with the doors as midbass i won't need the rears to cover that part of the curve anymore.
Tips and Tricks
- Run your power wire on the driver side. There is a nipple on the fire wall that seems to be made for this purpose. Cut off the tip of the nipple and run your 4-8ga through it.
if you use 4ga, a bit of liquid soap to lubricate will make it easier to pull through. strip a few inches of insulation off to feed it through initially otherwise it will be too hard to start threading it. 8 ga should go through without having to strip the insulation. The other reason to run the power wire through the driver side is because the signal wires are easier to run down the passenger side of the transmission tunnel and you don't want them running side by side. most amp wiring kits have enough wire to run from the battery to the driver side, down the transmission tunnel, and back over to the passenger side where i mounted the amp. the car is that short.
- cut the foam with a couple inches clearance to provide breathing room for cooling. I chose a class D amp since it runs cooler which is required for a mounting location that has no airflow.
- ground the amp using the existing ground wire mounting point near the passenger side rear speaker. don't drill into the car if you don't have to.
- tap the remote lead from the amp in the back. It's the dark green wire.
- bridge the dash and rear speakers at the HU to avoid running wire to the dash.
- tap the door speakers from the amp in the back
- remove the cap off the 3.5" dash speakers and cross it over using your amp to improve mid range fullness and reduce brightness.
- test and tune with the rear trim panels installed. Since it's an infinite baffle design the response curve changes considerably if you tune it without the baffle in place.
- tune the car with both doors closed, and windows up to simulate normal listening conditions.
- Access the amp with the back seat folded down. you can pop your head into the normal driver side listening position easily from this spot while simultaneously being able to make adjustments.
I'll update this thread again when i cut the cap on the dash mids.