i have a 2010 mazda 3 hatch with the bose system...dude i bought it from put in a cheap aftermarket head unit and did a shitty job (for example, the DIN sleeve wasn't even attached, so you could just slide it in and out)

anyway, yesterday the audio was going in an out (but the unit was still on), so i turned off the car and pulled it out...the electrical tape that connected the vehicle wiring adapter to the HU wire harness had come off of several and there were two unattached wires...one was black (ground, i think) and the other orange (for dimming and probably unused, since i couldn't find a mate for it)

anyway, since they were so shittily connected, i took the remaining tape off, retwisted (they were all lose), and re-wrapped...i plugged the HU back in and everything lit up fine...but when i try to play music (from the USB drive or radio or whatever), a fast-paced, constant sound that's between a click and a pop is all i can hear and adjusting the volume on the HU does nothing

thoughts? i don't have a wiring diagram that would come with something like a crutchfield kit...the only wire that doesn't have a mate is the orange one and only one group of wires had 3 (a purple, and blue with white stripe, i think)...the rest all had direct mates that matched colors

5/29/2014 1:47:10 PM

I'd pull it back out and check each wire connection and turn the radio on after each. I had a similar problem before, I think it was the ground, but this was 6 years ago.

[Edited on May 29, 2014 at 6:01 PM. Reason : .]

5/29/2014 6:00:37 PM

lose the twist-and-tape and do it right

5/30/2014 10:56:13 AM

i'm 95% sure it's the shitty bose amp...i'm ditching the 10-speaker crapfest and putting in 4 decent speakers

the bose sub isn't very good, but i'll probably use it since it fits inside the spare wheel and it was already rewired to be run from the head unit

6/3/2014 7:21:20 PM

Did he send amped output to the Bose input?

Should be pre amp out but still adjust volume on the low peer output.

6/3/2014 7:32:17 PM

^ What he said...Are you sure that amp is still supposed to be in there? On my 4Runner the installation instructions basically had me take the factory amp out and wire the head unit straight to the speakers. Most of those factory amps aren't much more powerful (if any) than a decent head unit anyway.

6/3/2014 8:12:19 PM

If you buy the correct bypass and wiring kit you can keep your amp.

6/3/2014 10:30:14 PM

Quote :

"shitty bose amp "

Wat

6/4/2014 7:01:10 AM

Quote :

"Did he send amped output to the Bose input? Should be pre amp out but still adjust volume on the low peer output."

Quote :

"What he said...Are you sure that amp is still supposed to be in there? On my 4Runner the installation instructions basically had me take the factory amp out and wire the head unit straight to the speakers. Most of those factory amps aren't much more powerful (if any) than a decent head unit anyway."

Quote :

"If you buy the correct bypass and wiring kit you can keep your amp."

the sub looks to have been rewired by the previous owner since SOMETHING was attached the preamp outputs on the back of the current HU...the stock radio didn't have preamps

the default wiring with the bose system has every line going through the amp...there are three bundles of wires that connect to the amp...input, output, and what i assume is power or something (not sure, haven't looked at the diagram)

i know very few of the details because virtually no one keeps the stock bose system once they decide to upgrade anything but the head unit...each speaker (supposedly) has an mini amplifier attached to it, and i ASSUME it gets passed power from the "main" amp under the passenger seat (which would account for the bundle of input and output wires connected to the amp having more than 10 each)

furthermore, all of the bose speakers are 2ohm instead of 4...i don't really know what this means, but apparently everyone thinks it's stupid and annoying

i won't pretend to understand how all the wiring and audio works...i've put in aftermarket speakers (no subs, no components) and HU in every car i've owned, but that's following instructions provided by crutchfield...past that, i'm ignorant

NO ONE on the mazda forums likes the bose system (hence the "blose" nickname) and it's frequently recommended to run new wires and replace the speakers before the head unit if you're on a budget

i'm fairly certain i can use the existing wiring and only run new speaker wire to the area under the passenger seat where the amp was (i've removed it), then splice the new speaker wire to the existing (preventing me from having to run wires all over the car)

Quote :

"Wat"

the bose amp is an overpriced, underpowered hunk of garbage that is required for the audio system to work

6/5/2014 10:24:36 AM

On a Bose stereo typically the entire head unit is a pre amp. Or it was on moms infinity and the couple c4 vettes I messed with.

6/5/2014 11:13:28 AM

i'm not entirely clear on the role of the preamp and amp when used in combination

i figured a preamp had no amplification capabilities, but rather controlled everything and provided the initial power source...the amp would provide additional power (and therefore amplify) whatever's sent to it (but it doesn't process it)...a preamp is always required, while an amp is not always necessary

is that true or am i off-base?

in my case, i figured the stock HU was too weak for 9 speakers and 1 sub, so the amp was used to "inject" power into the signal between the HU and speakers

in the new setup (which i haven't gotten around to installing, yet), the aftermarket HU is powerful enough to send the signal to each of the 4 speakers (and possibly 1 sub) with sufficient power without the need for an amp...does that sound right?

also, while i'm at it...what gauge speaker wire should i use to run from the new HU to the old amp's speaker wires? the consensus seems to be that i can use the existing speaker wire that went to the speakers from the amp, which makes my life easier because i just need to run a little speaker wire from the HU to under the passenger seat where the amp used to be, then splice (rather than running all new wire to the doors)

6/11/2014 8:31:11 AM

The chain is always SIGNAL -> PREAMP -> POWER AMP, they're just not always separate.

A preamp takes a signal and prepares it for power amplification. Line-level signals (iPods, etc.) are pretty hot, so there's not much to do other than some optional EQ/processing. Then it goes to the power section to be made audible.

Most integrated amps in cars have the preamp and the power amp in the same unit, because you're only dealing with 30 watts per channel or so, and that much circuitry easily fits in a standard head unit. The step to separate power amps comes when you have subs, etc., because they need power block amounts that won't fit in a standard dash. In that case, the head unit is only used as a preamp to interface/process the signal, and the head unit's small standard power amps are either bypassed, or the unit is made for a separate power amp and doesn't have a power section of its own.

6/13/2014 6:24:17 AM

ah, got it...thanks for the explanation

okay, so what might cause no sound at all to come from the speakers? i ran 4 new speaker wires from the back of the HU to under the passenger seat where the amp used to be...i spliced the new speaker wires to the amp's old output wires (those that go to all the speakers)

actually, i've only done one speaker so far, since i wanted to test it before going on to the other 3...anyway, no sound at all...i'm fairly certain the connection is good, but if that's the only explanation, then i suppose that could be it

but if not...what else might it be? the HU powers up and shows sound output from the tuner or USB drive, i just don't hear anything...i'm still using the wire harness to vehicle adapter for the power, ground, illumination, etc because i had already wired that up, i just separated the 4 relevant wires from back of the HU and spliced those to the newly-run wires (the ones that go under the seat)

6/15/2014 10:04:41 PM

You can test your speakers/wiring to them with a AA battery. Your hu could have a blown internal amp

6/16/2014 12:23:01 AM

^^ If you have wildly-mismatched impedances, that can cause sound issues as well.

6/16/2014 3:26:04 AM

^^ interesting...i'll give that a shot

^ i should have mentioned that the speakers are new..."normal" 4-ohm infinitys (the old blose speakers were 2-ohm)

6/16/2014 6:17:01 PM

thanks for the battery suggestion...that was a huge timesaver

i ran new speaker wires from the HU to under the passenger seat where i tied them into removed amp's output wires and everything is good for the (4) new 4-ohm speakers

now...is it possible to use any of the remaining 3 small speakers (center and one in each rear pillar) and/or the 2 tweeters (one in each front sail panel on the door) from the HU or is that asking for trouble since they're all 2-ohm?

i'm mostly interested in the tiny front center speaker and the tweeters...but not enough to risk using them if it will cause problems...i'd settle for just using the tweeters (which are connected to the new door speakers i installed today)

6/18/2014 9:38:56 PM