Why is my radio so quiet? (long)

[ProZak]

Electronics whizzes, help me out.

I recently removed my factory tape deck and replaced it with an Alpine HU with iPod integration. Details in this thread. (http://www.bimmer.info/forum/showthread.php?t=18718) Worked like a charm after some fiddling, but the sound was a little hissy.

"Hmmm," I think to myself. "Must be the speaker-level output from the HU going into the BMW amp in the back; HU's internal amp introduces noise to the signal."

So I splice some RCA wires onto the speaker leads of the wiring harness adapter and use the 2-volt RCA outputs of the Alpine head unit. Sound quality is improved 1000%, I'm delighted, but at max volume on the head unit there's only about, say, 60% or less of the volume I had before. What gives? Is there some kind of weird wiring trick that the BMW amp is expecting to see, but isn't, so reduces available power? Or is it just a weak amp that was using a higher voltage signal before? Are the speaker outs on the factory HU amplified?

Anyway, I figure the long-term solution is to introduce aftermarket amps / crossovers, but I want to make sure short-term that I'm not shorted out somewhere and about to set my car on fire. Thanks in advance.

-Zak-

[ProZak]

Wow, nobody? *sniff* Y'all are making me feel lonely...

[mattyb]

Hi Zak. give it a little while. remember were all over the planet here and some have yet to have a chance to see this. wish i could help you but im hopeless at this kinda stuff. Best of luck though.

[SRR2]

The factory amp expects speaker-level outputs. If you were having noise problems, you probably had something connected wrong. You should use only the "+" speaker outputs from your HU to drive the amp. Leave the "-" outputs unconnected -- cut back and insulated.

[1995 525i]

Electronics whizzes, help me out.

I recently removed my factory tape deck and replaced it with an Alpine HU with iPod integration. Details in this thread. (http://www.bimmer.info/forum/showthread.php?t=18718) Worked like a charm after some fiddling, but the sound was a little hissy.

"Hmmm," I think to myself. "Must be the speaker-level output from the HU going into the BMW amp in the back; HU's internal amp introduces noise to the signal."

So I splice some RCA wires onto the speaker leads of the wiring harness adapter and use the 2-volt RCA outputs of the Alpine head unit. Sound quality is improved 1000%, I'm delighted, but at max volume on the head unit there's only about, say, 60% or less of the volume I had before. What gives? Is there some kind of weird wiring trick that the BMW amp is expecting to see, but isn't, so reduces available power? Or is it just a weak amp that was using a higher voltage signal before? Are the speaker outs on the factory HU amplified?

Anyway, I figure the long-term solution is to introduce aftermarket amps / crossovers, but I want to make sure short-term that I'm not shorted out somewhere and about to set my car on fire. Thanks in advance.

-Zak-

I chose to bypass the BMW amp because the wattage from my Alpine HU was more than enough to run my speakers. If I were you, I would wire the speakers directly to your HU then plan on upgrading your speakers and spring for an amp. Here is what I did with mine:
http://www.cardomain.com/ride/668949/3

BillB can attest to how my system sounds as he heard it yesterday. It wasn't expensive either. 5.25 component set I got from Ebay, the 5.25 rears I got from Walmart (sony), the amp was from walmart (jenson) and the subs I have had for over 10 years (kicker).

:)

Michael

[mistertonylee]

another idea. when you say (in the other thread) that you hooked everything up to the wiring harness, did you hook up both positive and negative wires to the harness? bmw designed it so that only the positive wires get attached up. had a similar problem with my aftermarked cd player/receiver/etc, but it was resolved when i disconnected the negs (isolating them with elec. tape, wire nuts, etc.)

Tony

[ProZak]

another idea. when you say (in the other thread) that you hooked everything up to the wiring harness, did you hook up both positive and negative wires to the harness? bmw designed it so that only the positive wires get attached up. had a similar problem with my aftermarked cd player/receiver/etc, but it was resolved when i disconnected the negs (isolating them with elec. tape, wire nuts, etc.)

Tony

Hmm. OK, I'll try that next and see what kind of sound quality I get. I agree that the on-board HU amp is more than powerful enough, but I'd like to avoid messing with the speaker wires if possible (my speakers are fine) I'll keep you guys posted; thanks for the input.

-Zak-