jayc67

I lost 2 channels in the factory amp so I am just going to upgrade things rather than try to fix what's there.

I've decided to go with the Nakamichi CD500 since it looks like it actually belongs in the dash.

My question is on the rear speakers, the ones way in the back. Are they worth replacing and wiring up or do they not appreciably add to the sound? They were dead when I got this car so I've never actually heard what they sound like.

I have new Blaupunkt speakers in the doors and by the rear seats but I don't know about using those way in the back.

And, if it's worth putting something back there, what size are they and is there an easy drop in modern speaker that fits?

Thanks as always.

docmirror

IMO, not worth the hassle. I just took mine out, and used a coaxial 6.5 inch in the rear side seat area. I left the grills, but they are empty. I guess there is some reflected sound off the rear hatch glass, but I don't think it helps the sound appreciably.

Others will disagree...

jayc67

That's what it seems to me, but having never heard it I just wasn't sure. Thanks.

RKD in OKC

I love the look of a Nak in the 928 radio hole. I would have gotten the MB VI if I was getting a Nakamichi. It doesn't play mp3 or WMA, but it does hold 6 CDs so you don't need a changer. The CD-500 is still pretty cool though.

jayc67

I haven't ordered the head yet. I did go back and forth on the MB VI. I've not had good luck with in dash changers in the past so I tend to shy away from them.

That one is still a possibility. Whatever I get will be a Nak, nothing else seems to look "right" in the car to me.

RKD in OKC

I didn't have any trouble with this one in my 90 GT...



The only thing I didn't like is that it didn't have a volume ****. I prefer ***** to up and down buttons.

I found a set of 4 infinity Kappa 1in - 4in components for doors and rear bolsters. Replaced the 6 in woofers with some JL Audio 6 in subs. The previous owner had a 2 channel and 4 channel very thin Apline amps installed into a false rear deck. I added a Rockford Fosgate surround processor and it sounded fantastic.

White Lightnin'

Jay, the Alpine SPS-10C2 speakers are a perfect fit for the rear quarter window mounts. They are 4" and have a square frame that fits with the stock frame like it was meant to all along. The depth is good also. They have 150W peak power and 30W RMS. IIRC, they are out of production but still available new on eBay & other sites.

If you are replacing all 8 speakers -and want versatility in sound placement/volume/separation... I did- and I avoided the component sets that have a 1" tweeter. Not only do they not fit out of the box (need to create a disc to mount in the speaker hole drilled for the 1" tweeter), but the "crossover" that usually accompanies the kit is preset at the factory and not 'tunable'. I went with JBL 2-way crossovers that have 15 frequency combinations to tune the sound I want. Some other brands have tunable capabilities -just need to do some research.

BTW, I swapped the 8-speaker interior in my '88 for a 10-speaker interior from a '91... plus I have a sub. When it was the 8-speaker setup, I used a single 4-channel amp to run the 4 'pairs' of speakers through their respective crossovers, and a 1-channel amp for the sub. When I put in the '91 interior, I had to get creative so I didn't fry any of the components.

David Hawkins had a nice setup in his GTS for a while that utilized a powered multi-channel crossover with a seemingly infinite ability to custom-tune his sound (IIRC).

jayc67

OK, I went ahead and ordered the Nakamichi MB VI and it's really nice looking in the dash, thanks for that tip.

One thing I could use some help with please is where to pull power for the unit?

It's fused at 8A and I'd like to connect to something convenient rather than try to get back to the battery.

The 3A switched power was no problem off the factory harness, but the full time power on the harness was just for the clock so I can't really use that.

Where's a good hot spot near the console or CE panel for this? Any ideas?

Thanks!

Found a place with the Alpine speakers for the back too, they are not in yet. They are out of production but as mentioned, lots of places still have them.

Okv

I am installing a radio in the shark, and in this process I have read countless pages of information on stereo, install, wiring, boosters etc.
So, thank you all for sharing.

I only want to be able to listen to the radio occasionally, like the news and weather, possibly som background music.
I also do not want to destroy the car, and I like the idea of keeping the original system, at least the parts of it that makes sense.

I ended up with replacing the head unit with the cheapest, still reasonable quality one I could find.
Unfortunately it turns out the original Feinschmecker amp is broken, it blows the fuse when I force it on.
So, my original idea of reusing the amp and existing wiring, must be reconsidered.

Instead I rewire to use the head unit 4-channel outputs, wiring was easy and could be done stealth.
I connect the front door systems to the front, and the rear woofers to the rear output.

Sound is kind of acceptable, but it is evident that some kind of low-pass filtering is necessary for the woofer, and perhaps it is possible to use the rear tweeter and mid-range as well.

So, I decide to re-design the rear filter, to make it a 3-way, driven by one channel.

It is in this process that I find the factory wiring for the rear tweeter and mid is swapped.

Woofer filter:
Series inductor 6.8 mH. (Does not need to be high-grade with ferrit core like the one I happened to have laying around, but keep the series resistance rather low, below 0.5 ohms).

Smaller inductor gives more midrange.

Mid+tweeter filter:
First: Swap yellow and green wires on output of crossover mounted on rear of woofer.
Reuse original crossover filter.
Filter and level correction in front of original crossover:
Series capacitor 100uF, series resistor 5.6 ohm, to ground resistor 3x 3.9 ohm
in series.

Adjust resistors in front of filter to preferred tweeter-mid level.
5.6R+3x3.9R gives a low tw+mid level.

All resistors 10W.
Capacitor bipolar 50V.

Overall efficiency of rear system with new crossover is lower than front door systems, so it may be necessary to adjust fader somewhat in rear direction.

Don't worry about the 2 ohm rating on the woofers, as they are actually more like 3 ohm, and most amps will not have problems driving these.

docmirror

Yes you can use the tap for the clock. I think there's also a slender yellow wire that is always hot in the center console for the orig radio. The always on connection just runs the memory and a clock if the radio has one.

Okv

How does this sound?

Overall, quite nice, very good for news and the weather report and background music.

It is much better than the BOSE-system on the Cayman, especially the lower midrange and upper bass level is far better, and what bass there is does not sound like Jeremy Clarkson doing a 911-review.
And there is no need to "stuff" the sub.

It can not play loud, mostly due to the woofers limited excursion, they bottom out pretty easy.
Lower bass is totally absent, and tonal balance is improved by using the bass-boost functionality on the head-unit.

Ambience and instrument location is garbage, as it always is in a car.

High range is pleasant, but not necessarily very detailed.
Makes you wonder why they have used cone-type tweeters, as in 1991 domes had been around for, say, 30 years..
But, paper cones are a good choice of material for speaker cones, it sound lively and pleasant.
Most speakers I designed in the 80's used polypropylene membranes, wich tend to sound more dead and boring.

The ambience and sensation of room on The Baltimore Consort - Jean De Nivelle simply is not existent, and the dynamics of the string instruments are also mostly lost.
The drums does not have the proper attack and physical presence.
But, it sounds pleasant, without being too synthetic-like in the sound.

On Sammartini - Sinfonia En Sol Majeur 1., it is apparent that it sounds nice, and you feel good cruising in the 928, with the baroque instruments trying in vain to be heard above the rumble and occasional snarl from the engine.
Still, the sound fills the cabin, but there is just not the sence of physical presence of the instruments - you can not like reach out and touch them.

The attack on the drums on Yello - The Race is reasonable, but bass level and control lacks, so there is nothing of this "floor-moving" sensation you get at home.


The head unit is a new Kenwood CD+radio.
It has a 4x30W-or-something-close amp.


Music used in the evaluation:

The Baltimore Consort - Jean De Nivelle
Sammartini - Sinfonia En Sol Majeur
Yello - Flag (The one with "The Race")
Shark with RMB, x-over and Carl's mid-section: Easily makes any sound system obsolete, has all the physical presence that is needed.

M. Requin

And thanks for the detailed evaluation!

Alan

The obvious answer is to tap into the "Booster" fuse - the one for the stock amplifier.

Forthe 10 speaker system:
The rear speakers are configured as a single woofer per side fed from an active cross over (low pass filter) in the factory amp and then a seperate rear channel per side which feeds a passive crossover directing mid to the rear quarterpanel speakers and treble to the tweeter next to the woofer.

The front has a channel per side feeding a passive crossover that connects to the mid-woofer/tweeters in the door.

When swapping to a 4 channel head unit system (2 channels per side) you ned to adapt somewhow if you are to use all 3 rear speaker (locations) per side. A 3 way crosssover is one option as above...

If you are to drop a speaker the quarterpanels would be the most obvious choicce due to location/projection & available replacement space.

Alan