SirNut

Howdy everyone. I'm new to the C4 world and one of my first projects weill be refurbishing the factory audio system. The old head unit fried before I bought the car and as of now i have taken it out, replaced it with a nice Pioneer with bluetooth and connected a special harness from Crutchfield into the old bose wiring. the front speakers play music but at full volume on the radio they aren't very loud at all. some songs are hard to hear on the highway(volume at 62/62) i've already looked at a PAC line booster to increase the signal going to each amplifier unit. as of now i have these capacitors on hand: 493-4505-1-ND (1uf 50V) x 4, 604-1109-ND (10uf 16V) x 8, 604-1115-ND (47uf 16V) x 8, 495-2561-ND (.47uf 63V) x4, 565-1931-ND (56uf 16V) x 8.

I ordered these after reviewing an amp repair from a 1988 model. it seems as though my 92 has more components but the same capacitors. First are these resistances all accurate? and second does anyone know of any good write ups for a 91-93 C4 amp repair? any help would be great!

PS, i do have audio going to each speaker, it is just very very quiet. no squeals or hiss just low volume especially in the back. I can feel the cones moving slightly but cant hear anything

snoopdan

why would anyone want to fix that old bose junk?

BOSE = Buy Other Sound Equipment.

Just rip that crap out and start new.

Just BOB

That doesn't really answer the question that was asked, does it?

The original Bose system had a relay that supplied 12vdc to the speaker amps. If your wiring adaptor doesn't put power on that relay, or if the relay is bad or missing you would get very low, or no audio from the speakers.

Wheel Stander

I'm going to offer some thoughts assuming (1) your C4 was previously equipped with a BOSE system and (2) your new head unit directly powers the original BOSE speakers and was installed so as to eliminate the signal path previously routed through the CDM.

With regard to point (2), the CDM functions similar to a signal-processor or preamp in a home audio system ... the CDM does NOT provide any sort of amplification. Also, the BOSE head unit, unlike your new Pioneer, does NOT power your car's speakers. Rather, the speakers are powered by the individual amplifiers built into the BOSE speaker enclosures. That said, the BOSE head unit functions more like the ancillary components (e.g., tuner, CD player, cassette player) connected to a home system.

Now, consider this. The BOSE speakers and amps included in the factory system are both rated at 1 ohm ... very unusual and very efficient. Using such low impedance allows these physically small amps to produce (relatively speaking) very big power - 50 watts. Chances are the amplifier built into your Pioneer head unit is rated at 4 ohms (maybe even 8 ohms). That means the power produced by the Pioneer is only 1/4 (maybe even 1/8) as efficient as the power sent to the speakers by the BOSE amps. Stated another way, if the Pioneer were to produce 50 watts max power at 4 ohm (or maybe 25 watts at 8 ohms) that would be the equivalent of the BOSE amp sending out a mere 12.5 watts (or 6.25 watts) to your speakers. Because your new power source is 4 times (or 8 times) less efficient than the BOSE amplifiers, the "gain" sent to the speakers by the Pioneer would have to be 4 times (or 8 times) greater than the BOSE to produce the same level of volume. Also, assuming that the volume control on the Pioneer is calibrated to be "linear" you would have to turn it 4 times (or 8 times) farther to get the same volume. Hence, if you previously listened to your car audio with the volume turned "halfway", now you would have to crank the Pioneer 2 (or 4) full turns to generate the same "halfway" volume and doing that, I'm sure we agree, is pretty much impossible.

For more detail information, I strongly recommend you take a look at this website ...

http://carstereohelp.com/chevrolet.htm