Poor sound quality in my 91 BMW

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Laserface
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10 year member here with my second post. I recently acquired a 1991 BMW 850i. When I got it, the factory radio would power on, but play no sound. I wanted to change out to something with Bluetooth, so I didn't bother troubleshooting the factory radio. I just changed it out.

I switched to a Clarion M508. I got it through Crutchfield. They sent and recommended a floating ground adapter for this car. I have the M508 wired up and working (through the floating ground adapter), but sound quality is awful. The system doesn't get very loud, has very little bass, and scratchiness that I assume is distortion above 2/3 volume.

I'm not an audiophile, I don't need the best sound. I just want the system to work with clear sound at a decent volume level. The problem is, I have no idea how to get there. I'm assuming that since the radio plays, and since I can tune the Fade/Balance in to confirm each speaker is working, that the issue doesn't lie with the radio. There are no direct fit speakers for this car. If I can get a decent volume level from the factory speakers, I'll be happy with them.

I can find very little info about this car and troubleshooting it online. Here's a list of questions or things I don't know and I'm seeking guidance on:
Does a 91 BMW need the floating ground adapter?
The "distortion" I'm hearing would lead me to believe a bad factory amp, or blown speakers.
How can I diagnose the factory amp for (im)proper function?
Moving the sound output around the car give identically terrible sound right or left, so that leads me to believe the issue is more likely the amp than perfectly symmetrically blown speakers.

The car has an 5.25" speaker in each kick panel, a 2.5" midrange and tweeter in each front door, and a 5.5" woofer, 2.5" midrange, and a tweeter in the rear package tray. To power all this with an aftermarket amp, what channel amp would I want? That's a total of 9 components (channels?). Two 2(3?)-way speakers, 3 midrange, 3 tweeters, and a woofer. Do I need a 9 "channels" to power all these components? For example, a 4 channel and a 5 channel amp? Or should the midrange and tweeters be on the same channel?

If I did switch out the amp it seems that switching out the factory 9 component setup for a 5 channel amp, 4 quality 3 way speakers, and a woofer would suit my need just fine. Or alternatively, I could run the smaller door speakers from the radio, and the larger kick panel speakers and a sub through a 4 channel amp?

If you've made it through my whole post, I applaud your dedication, and look forward to your input.
 
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There might be some signal Processing done at the amp which doesnt go well with the head unit's signal.

If it was me personally, I'd get a dayton DSP to have 8 channels of output, I'd add either a 6 channel amp or two 4 channel amps to power front tweeters, midrange and midbass, run new speaker wire to all speakers, run everything in network mode, tune all crossovers on the dsp and leave rear speakers on head unit power, your focus should all be on the front stage. If anything you can just disconnect the rears. A properly done front stage will sound best and thats how all high level setups are done.
 
I would first change out the speakers that are easiest to access. If the sound improves, you are golden. BMW uses alot of paper cones, and at that age I doubt they would hold up well in a car enviorment.

I have a couple of speakers I could try in the kick panels. They're the only easy ones to access. I'll try this and report back.

There might be some signal Processing done at the amp which doesnt go well with the head unit's signal.

If it was me personally, I'd get a dayton DSP to have 8 channels of output, I'd add either a 6 channel amp or two 4 channel amps to power front tweeters, midrange and midbass, run new speaker wire to all speakers, run everything in network mode, tune all crossovers on the dsp and leave rear speakers on head unit power, your focus should all be on the front stage. If anything you can just disconnect the rears. A properly done front stage will sound best and thats how all high level setups are done.

If I'm understanding this correctly, the DSP goes between the head unit and amp(s) to convert the 4 channel output into 8 channels? My Clarion M508 has 8 channels of output. Front, rear, 2-zone, and sub. I'd probably not mess with the 2-zone though. I could still run the doors, kick panels, and sub on a 6 channel with the rear speakers on the head unit like you describe, but skipping the DSP.
 
I have a couple of speakers I could try in the kick panels. They're the only easy ones to access. I'll try this and report back.



If I'm understanding this correctly, the DSP goes between the head unit and amp(s) to convert the 4 channel output into 8 channels? My Clarion M508 has 8 channels of output. Front, rear, 2-zone, and sub. I'd probably not mess with the 2-zone though. I could still run the doors, kick panels, and sub on a 6 channel with the rear speakers on the head unit like you describe, but skipping the DSP.
your clarion is only 3 sets of RCA outputs. You have the capability for dual zone which is if you have a boat which is what the head unit is used for. However the head unit has ZERO i mean absolute ZERO audio tuning capabilities, its absolute crap for any kind of real results vs whats on the market right now.

What are you missing? the ability to set crossovers actively which splits the signal so each speaker can focus on the specific frequencies it needs to focus on. Along with being able to adjust audio level controls of each since they are at different locations. The DSP also can time correct the audio so that each speaker reaches your ear at the same time. The clarion only has 3 bands of EQ while the standard in the industry for head units is 13 bands. The DSP has 10 bands per channel so around 80 bands of parametric EQ. So yes if you want any real results sound quality wise, DSP is the way to go.

What happens if you run your system without crossovers? All your speakers will sound like complete ass or blow or both at once when you crank it up. The clarion has zero capabilities of doing so.
 
your clarion is only 3 sets of RCA outputs. You have the capability for dual zone which is if you have a boat which is what the head unit is used for. However the head unit has ZERO i mean absolute ZERO audio tuning capabilities, its absolute crap for any kind of real results vs whats on the market right now.

What are you missing? the ability to set crossovers actively which splits the signal so each speaker can focus on the specific frequencies it needs to focus on. Along with being able to adjust audio level controls of each since they are at different locations. The DSP also can time correct the audio so that each speaker reaches your ear at the same time. The clarion only has 3 bands of EQ while the standard in the industry for head units is 13 bands. The DSP has 10 bands per channel so around 80 bands of parametric EQ. So yes if you want any real results sound quality wise, DSP is the way to go.

What happens if you run your system without crossovers? All your speakers will sound like complete ass or blow or both at once when you crank it up. The clarion has zero capabilities of doing so.

So in my scenario:
I could still run the doors, kick panels, and sub on a 6 channel with the rear speakers on the head unit like you describe, but skipping the DSP.
I would be running coax speakers in place of the factory components. A major simplification of the system that wouldn't require crossovers, right?

I realize this would be inferior sound quality, but I'm just checking my options for now.

I just tore into the car enough enough to understand its system. It has 12 individual speakers, split into 4 sets of 3. Each set is a 5", 3", and 1". In the fronts, the 5" is in the kick panel, the 3" and 1" in the door. In the rear, they're all together in a box under the parcel shelf behind a single speaker grille.

To replicate the factory setup, I'd need a 8 channels? One for each 5", and then one for each set of 3" and 1"? What if I wanted to add something like a 8" subwoofer? Where would that get it's input?

I'm confused on what exactly each speaker does. High, mid, low? I see 2.75" inch speaker being sold as midrange speakers, which I assume if the purpose of the factory 3". A component set with crossover, 5.25" woofer, and tweeter plus the 2.75" midrange would be identical in function to the factory setup? In this case, the crossover controlling the woofer and tweeter would act as one channel, and the midrange as another channel for 2 channels at each corner x4 is 8. That's accomplished with two 4 channel amps. In this case, how would I power the aforementioned 8"subwoofer? With the sub out on the head unit into an additional 2 channel amp? A 6 channel and a 4 channel? Run the rear speakers off of the head unit to free up 2 channels on one of the 4 channels for the sub?

The DSP doesn't act directly as a crossover correct? I'd still need to run the crossovers that came with the component set of speakers? The DSP is just helping more create the correct input on more channels, and offering fine tuning of the sound?

After actually seeing the the 12 component factory setup, I'm much more inclined to attempt to recreate that with modern equipment, rather than attempt to cheap out.

Thanks for you input so far.
 
So in my scenario:

I would be running coax speakers in place of the factory components. A major simplification of the system that wouldn't require crossovers, right?

I realize this would be inferior sound quality, but I'm just checking my options for now.

I just tore into the car enough enough to understand its system. It has 12 individual speakers, split into 4 sets of 3. Each set is a 5", 3", and 1". In the fronts, the 5" is in the kick panel, the 3" and 1" in the door. In the rear, they're all together in a box under the parcel shelf behind a single speaker grille.

To replicate the factory setup, I'd need a 8 channels? One for each 5", and then one for each set of 3" and 1"? What if I wanted to add something like a 8" subwoofer? Where would that get it's input?

I'm confused on what exactly each speaker does. High, mid, low? I see 2.75" inch speaker being sold as midrange speakers, which I assume if the purpose of the factory 3". A component set with crossover, 5.25" woofer, and tweeter plus the 2.75" midrange would be identical in function to the factory setup? In this case, the crossover controlling the woofer and tweeter would act as one channel, and the midrange as another channel for 2 channels at each corner x4 is 8. That's accomplished with two 4 channel amps. In this case, how would I power the aforementioned 8"subwoofer? With the sub out on the head unit into an additional 2 channel amp? A 6 channel and a 4 channel? Run the rear speakers off of the head unit to free up 2 channels on one of the 4 channels for the sub?

The DSP doesn't act directly as a crossover correct? I'd still need to run the crossovers that came with the component set of speakers? The DSP is just helping more create the correct input on more channels, and offering fine tuning of the sound?

After actually seeing the the 12 component factory setup, I'm much more inclined to attempt to recreate that with modern equipment, rather than attempt to cheap out.

Thanks for you input so far.
DSP acts as a digital crossover that you can choose any frequency from 20hz to 20khz high pass, low pass, bandpass, slope control, type of crossover aka linkwitz, bessel or butterworth etc... tweeters usually handle 3000hz-5000hz and above, midrange around 250 to 3000 and midbass is 80 to 250hz each driver does its own job which allows better separation and clarity and output.

Yes you can do a coaxial but thats playing the sound quality lottery so if you are a gambler feel free. I prefer 100% guaranteed results.

test the impedance of the speakers with a multimeter, if they are 4 ohms then on the 1st 4 channel amp you can wire all left tweeters to channel 1, all right tweeters to channel 2. All left mid to channel 3, all right mids to channel 4, Now the next 4 channel amp you can wire all midbass speakers to channel 5 and 6. Now with with the channel 7 and 8 and you last amplifier channel you can bridge that for a low powered dual 2 ohm or single 4 ohm subwoofer. You wont have front and rear fade capabilities but you'll have much better sound quality overall due to having full control over the sound.
 
The issue I have with mounting the sub is that my car doesn't have a large pass through between the rear seats where'd I'd want to put the sub (picture attached). Could I mount the sub on one side, and the box on the other, as long as both sides are sealed at the hole? Is having a divider like that in the middle of the box going to cause issues? On the sub side, there'd be just enough of the box to get a good seal, and mount the sub, and the remaining volume would be on the other side of the divide in the trunk. I've read a small bit about "free air" sub setups, but I'd like an enclosure if possible.

I've always used Crutchfield, because my ventures into car audio modification have always been minor. When I started driving, it was simply to change out a head unit so I could play CDs, then later, AUX input, now Bluetooth. So I'll be linking products from there, because that's the site I'm familiar with. I'm open to suggestions though. The 2.75" speakers I found that I thought might fit best, as well as the shallow sub, were Kenwood. I like stuff to be all the same brand (OCD is a hell of a drug) so I'm linking all Kenwood stuff. I'd definitely shop around before purchasing anything, and I'm open to mixing/matching brands to save money.

Assuming I ran all this through the Dayton DSP

This takes care of the 5.25", and the tweeters. I'd obviously need 2 sets.

These for the mids (x2)

Subwoofer

Amp (x2)

Am I on the right track, or am I missing something?
 

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