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harborman's Avatar
 
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Sub Woofer upgrade

I did that "in spare tire sub woofer" which others have installed and was posted on here before. I got the Bose sub for about $45 on ebay. It did not have the internal amplifier. Bose makes really good well engineered products.



I found a good bass amp. Boss R1100M, 1100 watts peak power and a class A/B amp. Class A/B provides cleaner sound rather than the class D's which are being used for sub amps. I paid $47, new for it plus shipping. It looks real quality.




I am placing the Boss Amp under the passenger seat. I connected the heavy ground lead under the Pod to a bolt used to hold the old Blau amp. No need to drill holes! The + was run through the passenger side from the rear. I fished the wire through to the side speaker hole and ran it down. No need to pull any thing interior wise.

I placed the Boss level control on bolt which holds the passenger try on. I had to use a longer bolt to accomplish this. But the control is not something you adjust often.



My head unit is a JVC I had installed awhile back. See previous posts on here.

End result......FANTASTIC. It provides just enough bass, more than enough and made a real improvement. Amazing for a 6" Bose sub woofer! The other best part, looks all stock, no boxes, stock looking.

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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L. Latest addition: 2000 BMW Z3 Roadster
Old 10-30-2012, 01:19 PM
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This is my head unit by JVC.

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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L. Latest addition: 2000 BMW Z3 Roadster
Old 10-30-2012, 01:24 PM
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Does smooth Jazz need bass??
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1979 928 85 Euro 2v motor,S4 Brakes and suspension, 1988 951 street legal track car(sold)
Neon SRT4 track car
Old 10-30-2012, 01:44 PM
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Everything needs bass, but I could go a lifetime without anything Bose.
Old 10-30-2012, 03:25 PM
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Quote:
Originally Posted by Danglerb View Post
Everything needs bass, but I could go a lifetime without anything Bose.
This one does the job! Sounds great. I have one of the best Bose amps ever made, a Bose 1801 which I bought new in 1974 for $1,100. I still have it. It weighs 110 lbs! Sorry for your bad experience with Bose.
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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L. Latest addition: 2000 BMW Z3 Roadster
Old 10-30-2012, 04:06 PM
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Quote:
Originally Posted by Pete R View Post
Does smooth Jazz need bass??
Ha, ha, of course it does. Guess I had that CD in the unit. The Iphone also works well with it.
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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L. Latest addition: 2000 BMW Z3 Roadster
Old 10-30-2012, 04:08 PM
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Love mine. It's just right for that size car and it even strengthens the hollow area under that flimsy cover. Actually I don't even use the cover anymore, just stashed it in a safe place in the garage.
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George in Indiana
928 Weissach #153
Cayenne S
Old 10-30-2012, 04:16 PM
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Quote:
Originally Posted by 19psi View Post
Love mine. It's just right for that size car and it even strengthens the hollow area under that flimsy cover. Actually I don't even use the cover anymore, just stashed it in a safe place in the garage.
The one I used had the 6" woofer with dual voice coils, no internal amplifier. I wired them in series for 4 ohm and I dispensed with the original connectors and just installed my own. Someone else here used a LA120 amp under the Pod but I did not like that amp so went with the Boss Audio one. You can control the levels and cut over frequency on it. My JVC had sub woofer output. Yes, it does just fine on bass, nice improvement. The cover does not seem to inhibit the sound either.
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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L. Latest addition: 2000 BMW Z3 Roadster
Old 10-31-2012, 05:29 AM
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I used the same sub with the Legacy amp. I ended up using individual sub outputs out of my Kenwood head unit to feed each channel and each voice coil. 2 ohms is cutting it close but I hammered that amp and sub all summer with no issues. The LA has gain control but lacks an adjustable cut out; however, that's no issue as the head unit takes care of the frequency side through some menu settings. I mainly wanted an amp to fit under the factory cover...something must have changed by '86 as I don't think I could fit a piece of paper under my passenger seat.

The head unit does a very impressive job at powering the 4 speakers so I was happy over not needed another amp for them.

Trying to figure a way to fit a Bose sub in another hatchback I own.
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George in Indiana
928 Weissach #153
Cayenne S
Old 10-31-2012, 03:20 PM
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Quote:
Originally Posted by 19psi View Post
I used the same sub with the Legacy amp. I ended up using individual sub outputs out of my Kenwood head unit to feed each channel and each voice coil. 2 ohms is cutting it close but I hammered that amp and sub all summer with no issues. The LA has gain control but lacks an adjustable cut out; however, that's no issue as the head unit takes care of the frequency side through some menu settings. I mainly wanted an amp to fit under the factory cover...something must have changed by '86 as I don't think I could fit a piece of paper under my passenger seat.

The head unit does a very impressive job at powering the 4 speakers so I was happy over not needed another amp for them.

Trying to figure a way to fit a Bose sub in another hatchback I own.
I had read some reviews on that Legacy Amp and it did not look good. Feeding two voice coils with different inputs in one speaker is something I had never heard of. It may be a counter active measure. As one feed is telling the speaker to move in one direction the the other may be trying to drive it in opposite. I would have to investigate this, but it makes no sense to me. A speaker is nothing but a transducer and giving it possibly two opposite signals at the same time would seem to negate the output or cause a distortion. Maybe your Bose had the two smaller independent speakers; mine has only one 6", but with two voice coils.

I opted for 4 ohm and wired the coils in series. It sounds just great. The Boss puts out plenty of power and no need to over drive that 6" speaker. Yes,, my JVC has plenty of power to drive the 4 speakers with the sub on it's own amp.

I am quite happy with the results anyway. Glad the other post on here made this a topic and drew my interest, cheers to him!
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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L. Latest addition: 2000 BMW Z3 Roadster
Old 10-31-2012, 04:54 PM
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Quote:
Originally Posted by 19psi View Post
something must have changed by '86 as I don't think I could fit a piece of paper under my passenger seat.
There is a chassis rail that goes across in front, but there is space behind for I think in theory feet of the rear passenger.
Old 10-31-2012, 05:20 PM
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Amazon had several bad reviews but if you look at some of the comments it was mainly kids screwing up the wiring. At about $30 I figured what the heck (I did the original install with the pictures).
According to Crutchfield you can wire independently without bridging the amp as long as the signal is the same which it is as it's a sub output from the head unit. They do mention distortion if it's two different signals.

Do you guys have a power passenger seat? I have a black panel at the rear of my seat which is flush with the floor and a narrow gap on top. All the power mechanicals are behind it.
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George in Indiana
928 Weissach #153
Cayenne S
Old 10-31-2012, 07:25 PM
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I do have a power passenger seat. The Boss amp fits nicely under it.

Ok on LA120 amp. The Boss is a better amp and was only a few bucks more. It is bigger and would not fit in the pod as outlined earlier in another post.

Yes, I think you will get distortion trying to feed one speaker with two different input signals in that dual voice coil arrangement.
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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L. Latest addition: 2000 BMW Z3 Roadster
Old 11-01-2012, 05:56 AM
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Anyone have a pinout diagram for the 6 pin connector that is on the BOSE subs ?

Would be nice
Old 11-01-2012, 11:18 AM
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Quote:
Originally Posted by dcrasta View Post
Anyone have a pinout diagram for the 6 pin connector that is on the BOSE subs ?

Would be nice
Look on Rennlist or do a search on here. One guy had it laid out. Or you can make up your own connectors. My Bose did not have the built in amp. You can pull the speaker and see the wiring, pretty simple.

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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L. Latest addition: 2000 BMW Z3 Roadster
Old 11-01-2012, 12:40 PM
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