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Discussion Starter #1
Hi everyone, I'm new to the Mo and to this forum. I've had my Mo for about 2 1/2 weeks now, and it has just under 600 miles on it. 2004 SE AWD. I really like it, it's my first non-American car (I've had 6 American cars!). I have the Bose "premium" audio system, but I have to say it's not what I would consider "premium". My 4-year-old Pontiac Grand Am GT's Monsoon system sounds a lot better.

I'm currently looking into ways to beef up the Mo's sound system. I've done custom installs in past cars I've owned and friends' cars, everything from a simple amp/speaker swap in a friend's car to a $14,000 trophy-winning system in my '98 Grand Am.

My biggest complaints with the Bose system are weak mid/highs and distortion. I currently have the bass set to -1 and treble all the way up at +5, and I'm still not satisfied with the sound. After careful listening at each individual speaker location I've concluded that the majority of the system's sound currently comes through the front door speakers. The rear door speakers are very weak and distort easily, and they don't contribute much to the mid-bass. The tweeters are fairly sad as well.

My requirements for my retrofit system are that everything must appear stock and no visible components (amps, speaker boxes, etc.) are hanging around. The last thing I want to do is sacrifice my cargo area for a sub-box.

I'm looking at a complete system overhaul, and would like to get some feedback from other audio enthusiasts out there that have worked on the Mo.

Currently I'm considering putting my 5-year-old MB Quart components in the front doors. The door openings are 6 3/4", and my Quart drivers are 5 1/4". With the extra space I can fab up a mounting panel to angle-mount the tweeter. The rear doors would be fit with a nice set of 6 1/2" drivers to pick up the mid-bass frequencies, brand to be determined at a later point. The sub is the real fun part. I am thinking of losing the left-side storage tray, flipping the spare over, and taking some fiberglass to re-work the spare tire area and left-side cargo area into a single space. I will probably lose the 2" deep storage tray that sits on top of the spare, and by doing so I can raise the tire up 2", giving me more airspace. With the spare flipped over and raised, that will create a cavity under the tire where I am thinking of putting in one of these bad-boys:
http://www.pioneerelectronics.com/pna/article/0,,2076_4057_104401920,00.html

Amplifiers are up for discussion as well, I'm thinking a JL Audio 300/4 under the front passenger seat, and some respectable subwoofer amp that will supply the required power to the Pioneer sub (which wants 300W-800W). It's a 4-ohm speaker so I'm thinking if necessary I can add a 4-ohm resistor in parallel with the speaker to get a 2-ohm load off of whatever amp I choose, thereby letting me choose a physically smaller amp and getting more power per square inch of install space needed. Anyone used the Planet Audio Big Bang series of digital amps?

Thoughts? Ideas? I'd love to hear em.

Thanks.
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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I think it all sounds (pun) intriguing. Lots of work. Have you consider what will happen if you ever trade. I bet it will sound fantastic. There have been some teeter replacements done on the forum.
 

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GripperDon

As far as future sales/trade-in of the vehicle, if I do a re-wire I will do it all alongside the factory wiring, rather than cutting anything out. That way, everything can be reversed with minimal effort. That's how I try to do all my installs whenever possible.
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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I have been following your posts and also would like to improve the Bose system. However I am thinking of less radical things.

I would love your suggestions on simple things like changing speakers , adding caps or chokes to speakers to in effect move cross over points, maybe change some speakers. But not the amp or the Bose sub (if you want to call it that)

In other words some solder and speaker in the same place changes. Idea appreciated.
 

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Discussion Starter #5
GripperDon said:
I have been following your posts and also would like to improve the Bose system. However I am thinking of less radical things.

I would love your suggestions on simple things like changing speakers , adding caps or chokes to speakers to in effect move cross over points, maybe change some speakers. But not the amp or the Bose sub (if you want to call it that)

In other words some solder and speaker in the same place changes. Idea appreciated.
My feelings are that unless something is done to clean up the amplification, not much else can really help a whole lot. The starvation of clean power is really our #1 enemy right now. The rear door speakers can't possibly sound as bad as they do if they were getting proper power. I'm not familiar with the PAC adapter yet, as I haven't ventured into overhauling my audio system yet (other financial obligations looming... new house being built), but perhaps one solution might be to use the PAC to add a second, small, amp in conjunction with the Bose amp. Use the Bose amp for the interior speakers and a small dedicated sub amp for the Bose sub. That would help take the strain off the Bose amp, and a small sub amp can easily be mounted in the open space next to where the existing factory amp lives. That would clean up the system quite a bit. Maybe pulling the door panels off and taking the speakers out and getting some part numbers off of them, etc., might enable us to find some information on the frequency response of the individual speakers, and then perhaps we could tune the speakers with chokes to clean up the sound a bit.
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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How about taking the subs outputs from the existing Bose amp and feeding thm into a seperate amp using high level inputs (like some amps have) and then letting it feed the twin inputs of the sub woofer.

This would take the subs load off of the Bose amp, not require a ny PAC units Just buy an additional amp to run the sub only but being fed my the sub outputs from the Bose. It would also leave the crossover point of the Bose what it is now.
 

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Discussion Starter #7
GripperDon said:
How about taking the subs outputs from the existing Bose amp and feeding thm into a seperate amp using high level inputs (like some amps have) and then letting it feed the twin inputs of the sub woofer.

This would take the subs load off of the Bose amp, not require a ny PAC units Just buy an additional amp to run the sub only but being fed my the sub outputs from the Bose. It would also leave the crossover point of the Bose what it is now.
Hmmm.... that's a good idea. I wonder how well it would really work, though. Even though the high-level inputs on the second amp should introduce a proper impedance as to cause the Bose amp to send a fairly weak signal down the path, I've seen cases in the past where poorly designed amps will still send a fully amplified/distored signal into the second amp, which will then step it down to low-level, then re-amplify it. End result -- sounds like poop. I think the real determining factor here is how well the Bose would behave in this scenerio, and I don't know the specifics about that amp. I wonder if anyone out there knows?

You also mentioned the "twin inputs" on the subwoofer... is that what's going on with that wacky wiring harness/plug? I was curious what proprietary magic was going on there, but I haven't taken the plug out to investigate. Is it running 4 wires for 2 channels/stereo? That's silly to run a single sub in stereo mode. But, there's definately something more than a standard single +/- input going on there... so is that the case?

Oh, that reminds me of my other concern -- the impedance of that sub. I know that Bose systems typically use some totally wonky impedances on their speakers, like 2, 1, and sometimes 1/2 ohm! If it's something disgusting like 1 or 1/2 ohm, good luck finding an aftermarket amp that will be stable at that load and not cost an arm and a leg, not to mention most super-high-end amps like that are huge and won't fit in the small space I'm thinking of.

This diagram on PAC's website is what gave me the idea of easily adding in a supplemental amp (assuming the sub is running at a sane impedance). Your idea might work just as well, though, if the Bose will send a clean enough signal to the second amp.

Thoughts?
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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I will measure the resistance of the Bose woofer circuits. (I know resistance is not impedance but at these very low frequencies it will not be too bad) If they are high I would be surprised. So an Amp with good stability at low impedance is required and many automotive 12 powered amps for sub are that. I can read about the amps input load on high level to find the right one. I am going to assume the Bose output will be relatively clean and that with the reduced load it will be even cleaner.


Form what I can tell the Tweeters are wired in parallel with the front speakers and the rear speakers are by then selves. It looks to me as if both channels feed the sub and that they are depending upon the very lows to be in phase for producing output and as the phases get out as the frequencies go up the twin voice coils will just cancel and not produce speaker cone movement.
 

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Discussion Starter #9
GripperDon said:
I will measure the resistance of the Bose woofer circuits. (I know resistance is not impedance but at these very low frequencies it will not be too bad) If they are high I would be surprised. So an Amp with good stability at low impedance is required and many automotive 12 powered amps for sub are that. I can read about the amps input load on high level to find the right one. I am going to assume the Bose output will be relatively clean and that with the reduced load it will be even cleaner.
If you're feeling adventurous, maybe you can measure the other speakers as well? Not that it really matters for the application we're talking about, but it would be good to know. :D Also, most car audio amps prefer 4ohms, even in bridged/mono mode. Many/most of them are happy at 2ohm also, but with higher THD. You don't find many that are stable at 1 or 1/2 ohm. I'm not sure if that's what you meant, I wasn't clear on what you were saying, so I just though I'd clarify.


Form what I can tell the Tweeters are wired in parallel with the front speakers and the rear speakers are by then selves. It looks to me as if both channels feed the sub and that they are depending upon the very lows to be in phase for producing output and as the phases get out as the frequencies go up the twin voice coils will just cancel and not produce speaker cone movement.
Are there any actual crossovers for the front speakers, or are they just wired in parellel and counting on the speakers not reproducing certain frequencies? All I have to say to that is "ewwwwwww". Any _decent_ component speaker system should have an actual crossover in there to separate the frequencies, obviously, but also to match the impedance of the other speakers in the car (so everything is running at 4ohms/channel, for instance, rather than 2ohms/channel in front and 4ohms/channel in back). Simply being parallel-wired would help explain why the front speakers produce so much more volume than the rears.. either that or the rear speakers are REALLY crappy, or the amp is unbalanced.

I had not thought about the sub being dual voice coil... a sub that small in a system as poorly designed as this -- I'd honestly be very surprised if a DVC driver is in there. Feel free to prove me wrong and fire a hearty "I told ya so" at me though, as I'm genuinely curious now. I am assuming that the stereo inputs are mixed into a mono channel and sent to the sub, making sure it doesn't miss any signals from the L or R channels, but without the need of a dedicated sub channel off the head unit. The "crossover", it seems, is just Bose counting on the frequency rolloff of the speaker itself, unless there's a low-pass choke in the sub somewhere. Ewwww. Maybe I'll have to disassemble my sub and investigate what's inside the magic black... um.... cylinder.

"Premium" my arse! :rolleyes:
 

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special-k said:
After careful listening at each individual speaker location I've concluded that the majority of the system's sound currently comes through the front door speakers. The rear door speakers are very weak and distort easily, and they don't contribute much to the mid-bass.
FYI - the front and rear door speakers are the same.

As for the amp, it's a 6 channel amp with two channels bridged to drive the subwoofer (the subwoofer is a DVC unit that is 1 ohm when using both VC's). The door speakers are 2 ohms.

Dave
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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My front speakers are ovals and read door speakers are circular. The Sub is a dual Voice Coil my schematic, sight and measurement. Looking at a scope the signals to the sub differ from one coil to the other. I played a Cd with lots of base on one channel only to tell.


The only external cross over is a cap across the tweeters up by the tweeters they are in parallel with the fronts according to the service manual schematics. The phase shift as frequencies rise will provide a nice rolloff for the sub woffer without any inductors required. They may still have one in the "Black Box" but I can't find it.

I found a nice 100 watt per channel SONY that has high levels inputs and claims stable operation with 2 ohm load. About, what I measure for each voice coil in the sub woofer.
 

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Discussion Starter #14
Re: Re: Calling all audio enthusiasts...

Dave N said:


FYI - the front and rear door speakers are the same.

As for the amp, it's a 6 channel amp with two channels bridged to drive the subwoofer (the subwoofer is a DVC unit that is 1 ohm when using both VC's). The door speakers are 2 ohms.
Whoa... color me surprised.

I figured the drivers in the doors were the same, but the sound from them is anything but the same... hence my theory that either the front speakers are pulling more of a load off the amp (due to being parallel-wired with the tweeters) or the amp favored the front channels. I can fade completely forward and the sound in the cabin doesn't change all that much, if I fade rear though it's very obvious that the rear door speakers aren't performing anywhere near the fronts.

Where did you find this info, by the way?
 

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Discussion Starter #15
Re: Re: Calling all audio enthusiasts...

Dave N said:


FYI - the front and rear door speakers are the same.

As for the amp, it's a 6 channel amp with two channels bridged to drive the subwoofer (the subwoofer is a DVC unit that is 1 ohm when using both VC's). The door speakers are 2 ohms.
Uhhhhhh, it's very possible that I need more caffeine, or a bat to the head today, because I'm having a blonde moment (no offense to any blondes out there LOL)

If it's a DVC 2-ohm driver, it would seem the purpose of that would be to run one voice coil off of each of the 2 channels of the amp in 2 ohm/stereo mode. However, if it's wired in parallel with itself to get 1 ohm, and then connected to 2 bridged channels of the amp... oi veh! Seems like someone put a lot of effort into sucking as much juice out of that poor little amp as possoble. No wonder it has horrible distortion problems.... :(
 

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Discussion Starter #16
GripperDon said:
My front speakers are ovals and read door speakers are circular. The Sub is a dual Voice Coil my schematic, sight and measurement. Looking at a scope the signals to the sub differ from one coil to the other. I played a Cd with lots of base on one channel only to tell.
OVAL? Are these aftermarket or something new for 05?


The only external cross over is a cap across the tweeters up by the tweeters they are in parallel with the fronts according to the service manual schematics. The phase shift as frequencies rise will provide a nice rolloff for the sub woffer without any inductors required. They may still have one in the "Black Box" but I can't find it.
One area where I admittedly don't know much is the actual electrical/electronics engineering, so to speak. How does phase shift simply by frequencies changing? <puts on the learning cap>


I found a nice 100 watt per channel SONY that has high levels inputs and claims stable operation with 2 ohm load. About, what I measure for each voice coil in the sub woofer.
How big is it physically? I've looked at a few small amps, especially by Planet Audio, who has a digital amplifier line called the "Big Bang" series, which are physically quite small for the lower powered units, and would fit quite beautifully next to the stock amp...
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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My speakers are stock. If you don't want to take off the grills, just look in the service manual.

The wave length of low frequencies are so long that it is difficult with modern mikeing to actually record lows that are not phase coherent. As you go to Higher frequencies the wave lengths get shorter and it is very easy to have the waveforms vary from one channel to the other PLUS both coils are wound on the same coil and can only effectively move together (in phase).
 

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Discussion Starter #18
GripperDon said:
My speakers are stock. If you don't want to take off the grills, just look in the service manual.
Yeah I gotta pick up a service manual. I saw you made a post in another thread with a place to get them for like... $20 was it? Then a couple days ago I saw someone made a post referencing service manuals on ebay in a searchable format on CD for $15 or so... did the service manual give you an actual size for your door speakers? Mine are 6 3/4" round, and Crutchfield.com says the same speakers are in the 05 as the 04. Crutchfield, however, has been known to be wrong. They still seem convinced that there are speakers in the rear hatch, and, unless I'm really stupid, there aren't.

The wave length of low frequencies are so long that it is difficult with modern mikeing to actually record lows that are not phase coherent. As you go to Higher frequencies the wave lengths get shorter and it is very easy to have the waveforms vary from one channel to the other PLUS both coils are wound on the same coil and can only effectively move together (in phase).
I think I understand this at a rather basic level... perhaps a few beers with my friend the physicist are in order so he can further confuse me. :)

This whole phase cancellation thing goes back to the post I made a little while ago... if we do indeed have 2 channels coming off the Bose amp into the sub, what you said makes perfect sense, it will, in effect, act as it's own pseudo-"crossover" and roll off at higher frequencies as the phases start to separate on the channels. That would work if the sub is being run in 2 channel / stereo mode... whereas, if it's actually being bridged off the amp, running in mono into the sub which is parallel-wired to drop the sub to 1ohm and pull more juice out of the amp, then we lose the phase cancellation effect. Am I thinking straight here? My head hurts. :)
 

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GripperDon said:
My speakers are stock. If you don't want to take off the grills, just look in the service manual.


Grip, I believe the service manual illustration is showing the non-Bose speakers, or it's wrong altogether. I can assure you that the front and rear Bose speakers are identical and they are 6.5" (nominal) and round.

Dave
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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DAVE!!! YOU ARE CORRECT
and the manual is wrong all together!!!. The manuals shows the same thing for 04 and 05 and both show an Oval 4 screw retainer for the front and a 3 screw retainer for a round speaker in the rear.

But that is sure not what is in my MO. They are both round. I do know there are two independant voice coils in the sub beacuse i measured those myself and the amps output on the scope
 
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