G8Pumpkin

First let me say I am 67 years old and spent about 15 years selling pro audio, 2" 24 track tape machines and 1/4 million dollar recording consoles back in the 80's and built a slew of very high end night club sound systems and did some acoustic design of recording studios so I do have some concept of audio although I truly am still an Analog guy. So this starts with my car and the crappy Bose system that I couldnt stand any more but did not want an all out sub setup and amps etc. So put a Kenwood DMX7704s head unit into it with Polk 4" mica coned coaxial with silk dome in the front doors along with 5 1/4" mica coned in the rear and kept the Bose amp and 10" Bose woofer in the doors. Was disappointed in how it sounded so went to work sound deadening things with Frostking under the carpets in the back and inside the doors, things got better, then added a Blockit rear mat and the 2 pieces that drop behind the seats, things got better again but still not what I would call decent audio let alone good. So in my looking every where on the web remember a piece about adding an additional power and ground wire around the PAC adapter as it seems it cannot feed enough power to run the Kenwood through its internal circuitry so basicly you leave the existing harness plugged in and run an additional Yellow and black wire from the plug in harness wire to the other side of the PAC so the higher voltage and current can get around the bottleneck inside the PAC adapter. I was skeptical that this would do anything but thought what the heck. Surprise it sounded better it was audible. I mentioned this to my ex partner who is a genius when it comes to electronics and he said to change the fuse to the Bose amp to a bigger one. Now I have my flameproof suit on and dont really care what others think and you can do this at your own risk personally I dont feel it is much of a risk and will explain further on. This will be a long post, any way the Bose amp has a 30 amp J style fuse sitting in a very hot fuse box when the car is at operating temp the fuse panel is way beyond 25 degrees C which is where they are rated at by the way, so anyway I put a 50 amp fuse in now I have an Audio system that I consider to be descent there is a massive change in the dynamic range of the system. So I looked at the Littlefuse spec sheets for J style fuses and there is a significant voltage drop so with a digital Amp that basically uses the Alternator as the supply there are no massive capacitors like you would find in a good Analog amplifier any change in supply voltage is critical and fuse acts like a variable resister on the supply side to the amp and that tiny small wire in the 30 amp fuse is trying to supply probably something in the order of 50-60 amps for very short time frames, milliseconds and shows up easily in a simple hearing test you do not need to have golden ears to be able to tell the difference. Thats the readers digest version Iam sure there are electronic engineers on this forum that will be able to give us a long detailed explanation of whats going on in side the fuse and thus how it strangles the AMP.



Now for part 2 of this got me to thinking to day about other crucial electronics in the car as far as how it runs, ECU, Fuel Injectors, Ignition system, fuel pump. So got out the manual and replaced a bunch of fuses only went up 5 amps over what was installed by the factory ie injectors where stock 20amp so changed those to 25amp etc changed about 6 in total along with the ECU used a 20 AMP J style so took the 30 amp that I pulled from amp and used that on the ECU. Big change in how the car runs and a change in the low frequency sound of the exhaust when I run it in bypass mode.



Car runs better and it changed the tone of the exhaust system probably due to the ECU responding better and the fuel injectors working better.



Anyway as I said this is not for everybody and I DONT LIVE IN FEAR OF MY CAR BURNING TO THE GROUND there still are fuses on everything and if something where to short out a fuse will still blow just a little slower but as I said at the top of the the post this is BIZARRE but it it does work amazingly well to the point that I may not change out the 10" speakers in the doors to the low profile ones I just bought.


Update on the 10" and some other details about what Bose is doing in the stock system, there is a high pass on the bottom end at 125hz at 12db/octave which explains the roll off on the bass aside from the driver itself does not have much in the way of low frequency response due to design so I tried a high mass 10 shallow mount that is flat down to 50HZ and was hoping to get 1 more octave on the bottom end than what the stock setup does ie get to 60hz flat and then roll off as opposed to the 125. Didnt work because of the high pass filter that I was not sure was in there until I switched drivers and measured the output, but with the changes to the output of the Bose amp with the fuse change it is acceptable now for bottom end and in terms of outright level in the system I can hear the radio just fine even over the exhaust in bypass mode which it had no hope of doing before. As to the rest Bose has a 12db/octave crossover at 500hz going to the stock 3 1/2" I now run that to the Polk 4" which I mounted to the door instead of the door panel, much easier will post some pics later of pink noise test for those who care.


Here is a list of the fuses I upgraded


odd fuel injectors 20 to 25

even fuel injectors 20 to 25

canister purge solenoid, Mass air flow sensor 15 to 20

fuel pump 10 to 15

audio amplifier 30 to 50 this is a J style fuse in the engine compartment this made a serious difference in Audio Quality and surprised the crap out of me to.



ECM #56 its the j style down on the kick panel fuse block not in the engine compartment 20 to 30amp this was the old 30 for the amp so just relocated it to the kick panel location

RDO/Sband this is the Kenwood head unit or stock head unit fuse 15 to 20


First pic is pink noise measured with a calibrated microphone of the polk 4" in the front door
second pic is the 10" stock woofer in the front door


3rd pic is combined response with flat eq setting.


last pic how I installed the Polk 4" in the door just made up some stand offs and long screws in stead of trying to attach it to the door panel like the factory speaker this is way simpler.

Landru

Interesting to say the least, crazy results for sure.
Only time will tell if any negative downsides, like overheated component(s) causing weird symptom(s), start to manifest.
If they did you'd know what to go back to.

In the meantime enjoy the improved music/performance.
No one here, EE or otherwise w/could've guessed.

TorchRedFred

I'm a little skeptical of your claimed results. That being said, even if they did work, they would probably not be for me. My Bose system is long gone, regardless.

Pb82 Ronin

Zero chance of making factory Bose ANYTHING sound good. As others have mentioned...full install is the only way to go in the C6.