Stereo Project Write Up

When I had my console out for the five speed project, I ran new RCA’s and speaker wires for a future stereo project. The last couple weekends I’ve had time and motivation, so the stereo project is now complete.

The high-end speakers were done sometime ago, details are on my site here. - 1989 Jaguar XJS Coupe

Because originally I had simply hooked a new deck and new speakers up using factory speaker wires, I knew I was going to have to pull new speaker wires, because we all know the factory speaker wires suck.

Here we are pulling new speaker wire through the factory boot. In the upper left you can see my clear hard plastic pull tube, and then in the lower right you can see it coming out at about a 45° angle. I’ve already snaked it through the boot in the door jam.

If you have to do this job, have some dry silicone spray on hand, it makes it way easier if you coat the wires before you pull them. Here we’ve pulled the wires through, you can see the new black speaker wire taped to the pull tube.

This part of the job is done, the other door was wash, rinse, repeat.

The amps and subwoofer will go in the little parcel areas on each side of the boot. Step one is to build an amp board that can be easily put in and out, and sort of looks like it belongs there. I found a relatively close match on the carpet at Home Depot, this is a little bit of a budget project, and I wasn’t gonna spend a bunch of money on perfect matching carpet in the boot. The holes are wire pass-thrus.

Now we carpet…

Test fit…

And wire…

Wiring up and test fitting in the boot.

Yes, I made the wiring look nicer before I buttoned it up.

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Here are the technical details if anyone is interested:
The high-end amp is the red amp, it’s an older two channel Orion that I’ve had forever, I really like these amps. Orion was manufactured in Tempe AZ not far from me. Their red HCCA amps can be driven to a half an ohm in stereo, or bridged to one ohm. It is running the Polk speakers for the high end, which are 4 ohms wired in parallel, so the app is seeing two Ohms.

The low end is all Rockford, which also used to be made in Tempe. Their corporate office is still here. The sub is a 10 inch 4 ohm dual voice coil. The amp is a 250 watt mono that can be run at two ohms. Paralleling the two voice coils shows the amp two ohms so it’s making 500 watts. The amp has a small remote volume control, I ran the wire for that thru the console as well. When I re-veneer and reconfigure the ski slope I will make a place for it.

The amps are wired with 6 gauge wire on the positive side back to the fuse block which is 4 gauge to the battery. The ground wires are 6 gauge to a ground stud on the back of the amp board which is then 4 gauge to ground.

These lug crimpers are the ticket for working with heavy gauge wire.

Next we build and carpet the sub enclosure. It needs to be sealed so it is glued, nailed and caulked.

Test fit the sub, and in the car…

Carpet the enclosure…

Cut the carpet out and fit the sub.

Button it all up and we are good to go.


Well done Bob.
Love the standard XJS boot accesories – car cover, dust buster, and fire extinguisher at ready access. And maybe a little box of critical spares

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It’s my spare Marelli cap and rotor :grimacing:

As far as the sound I am 85% happy. There are a whole lot of adjustments in the bass amp and also in the head unit. I am figuring out which are useful. Most are not. One thing I am not happy about are the rear speakers overpowering the fronts, which goofs up the sound stage a little. They are bigger speakers with less restrictive grills so they are going to be a little louder at the same power level. They are also pointing right at my ear, where the fronts are a little more blocked, especially with a passenger in the car. I may put passive crossovers on the rears to taper the highs a bit. I may put some fabric over the grills. I may also add a pair of tweeters up front, high in the door maybe, or on the a- pillars. The highs up front are not quite as bright as I like.

The bass is nice and tight. I’ve built a lot of sub enclosures so I know what I like. The ideal sealed enclosure volume for this sub is .59 cf, I came in at .55, so pretty good. I will probably tweak a few things on the low end. Gain, crossover in the bass amp, etc. Bottom line is that for now I am just going to drive it and get used to everything.

This will definitely help the front stage.
The original door placement for the speakers at the doors is very bad for mids and highs.
Obstructed and very uneven distances.

If you really want to build a nice front stage this is what I did and worked very well:
Mid Bass speakers on the doors - perfect placement with all the volume of the door behind.
Mids at the kick panels, tilted towards the seats - more equidistant, less obstructed.
Tweeters at the side of the kick panel pointing towards the seats - even more equidistant and almost a straight line to the occupants.


Very nice write-up Bob - question - why is there no tube holes mounted in the bass speaker enclosure, for the escape of the air back pressure from the back side of the speaker during cone movement - has the design of the speaker changed that much, since the '60’s (when I learned about building speaker enclosures for home entertainment use) - the air flow path help reduce the wear of the cone material mounting - never found needed for the midrange and tweet speakers, just the bass speakers - Tex.

So I did things the lazier way. Works significantly better. I can’t undersell the importance of adding a subwoofer to these cars.

I started off by upgrading the head unit and speakers. The speakers are a must. I used 2-ohm JBL GTO Stadium 620 speakers. They are 6-1/2" speakers, and they will fit. (not all 6-1/2" speakers will)

I then added a Class D Alpine KTP-445u amplifier to all four a speakers in the car. It’s small and it fits in the area where a glovebox should have gone. (I have no photos)

Still unhappy, I then added a Class D Kenwood KSC-SW11 Amplified Subwoofer to the mix. Adding this took about a half hour.

I can’t understate what a difference adding the subwoofer was. I wish I did it years ago. The difference when driving with the top down is night and day. I’m not thumping or rattling anything, I was just tired of having the Alpine amp cut out when playing anything loud with bass. For me, the bass adjustment is literally at 50% on the control. I think I started at 70% and dialed it back twice. It fits perfectly in the back seat footwell area, behind the passenger seat. Let’s face it, no one is using that space…ever!

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Hi Tex-
Sub enclosures can be vented aka ported or sealed. The port times the sound waves off the back of the speaker to compliment the front. As you probably know there are specific formulas for port volume vs. enclosure volume that are unique to the speaker. Rockford gives the data for both ported and sealed enclosures in their manuals.

Sealed enclosures can be smaller for the same speaker. I also much prefer the way they sound. To my ear the base is tighter, more of a boom boom vs a wuhhhh wuhhhh. Better definition between the notes.

The trade off is a narrower range and sometimes some peakiness or resonance. That’s usually due to a poorly sized or poorly sealed enclosure. The range I handle with good high end speakers.

At the end of the day it’s a personal choice thing.


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Well Bob - thank you for the update of education (always glad to learn) - Tex.

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Very well done and intelligent modifications by you guys.

I with my helicopter pilot ears am just thankful that my 95 coupe a/c works so I trundle around with windows up and the stock stereo system fits my needs.

Otherwise I might be inclined to plunge into following in your footsteps.

@Aristides this looks great! Giving me ideas…

Tell me about that dead pedal…

A pedal from a broken foot air pump and a 5mm aluminium bracket I had lying around that was perfect for the job.

Here is a better photo.

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Hey Bob, dumb question , what is the head unit you’re using with this set up ? Post a picture.
Still looks like a lot of work to listen to your Justin Bieber collection. LOL !
Seriously though It is on my project list. Just haven’t landed on a proper head unit to suit the look of the car.
Aristides has a great one but I can’t seem to source one anywhere.

Hi Gary-
It’s this Kenwood. I’ve been using Kenwood lately, because pioneer kind of gave up the ghost in my opinion, and I’ve generally been pleased with Kenwood‘s quality of late.
It does not have a CD player, which means it’s a bit shallower, not that that’s an issue in an XJS, because a full-size single din unit will fit. One thing I definitely didn’t want was Alexa. It was a little hard to find a Kenwood with no Alexa.

All of the new decks have a ridiculous amount of stuff built into them, in my opinion. Various frequency shaping crossover boost this change that speaker size stage and on and on BS.

If you don’t start with really good amps, provide them really clean power and solid ground, with really excellent quality speakers, nothing else is going to matter. No deck can make up for poor quality gear downstream.

I don’t know if I’d recommend this deck. I’d say it’s fine. I need to live with it for a while and see what I think. There’s nothing I instantly hate about it, I just haven’t lived with it long enough to decide whether or not I love it.

Edit- huh- Looking at the pictures I don’t think I have the beauty ring on it. I guess I better track that down.

Looks good Bob, thank you.
A lot of the new car audio stereo head units light up like holy Tokyo at night.
Call me old school I would still like to get a CD player in there.

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