I like listening to music in the car. I am kind of spoiled with the "Standard" system in the Portfolio. I have replaced everything in the XJS and thanks to being able to fit bigger speakers and various other things, it sounds quite good for a convertible. The XJS mods are not reversible, but the car is a mutt anyway, so originality is not important.

However, for the Series III, I am very aware of how original and well kept the car is, so I started out replacing things I could without modifying the car permanently. I updated the head unit and changed all of the door speakers to Polk Audio, but kept the original size (4") because I did not want to mess around with the mountings.

Unfortunately this did not give me anything like good enough sound. The main issue being I was trying to drive all of the sound through the 4" speakers, which were struggling because I was driving them directly from the head unit, and also they were trying to deal with the lower frequencies which was making them vibrate pretty badly.

I have done various stereo installs before but trying to do one on the Series III without doing any permanent modifications was going to be difficult. I was not willing to drill even a single hole into the car, so in the end I decided to work with the space under the front passenger seat. I got the smallest enclosed sub woofer I could find that got good reviews, and also the smallest 4 channel amp. I had measured the space out so I knew I would be able to get both of these side by side under the front seat and they wouldn't stick out into the rear footwell.

I had posted another thread on how to get a power wire through from the engine bay into the car. Although the battery and the components were both on the right hand side of the car, I had to run the wire all the way across to the drivers side, then back across to the passenger side. This was by far the hardest part of the job. In the end, the big fat cable runs under the bulkhead so its not visible. The fuse holder is hidden down the side of the battery....



Wiring to the stereo was "easy" just a lot of wires. The stereo is 4 channel, so I had to bring all the wires out and down to the amp under the seat, then bring all the wires back up to behind the stereo so they can be reconnected to the speaker feeds.

The loom is shown in the bottom left hand corner of this picture, wrapped in the wire tidy.



There really isn't a lot of room around the delanaire climate system, but somehow I got them through

The finished article is reasonably tidy....





The sound is pretty impressive. I have the amp set to pass 80hz and above only, so the speakers don't have to handle any bass and can get more power in the higher frequency range. The sub handles everything below 80Hz

I am "done" with the sound upgrade in the Series III :-) and I never even cut a single wire in the car

 

Cool

Cheers
DD

 

Good info! What model enclosed sub and amp did you get? The sub looks familiar, I just can't put my finger on it.

Did the amp make a big difference on the 4" speakers? I'm a little surprised you didn't try to put the amp under the driver's seat.

Does the sub and the amp heat up the passenger seat cushion?

 

@FastKat

Amp..... Rockford Fosgate PBR300X4 Punch BRT 300-Watt Ultra Compact 4-Channel Amplifier
Sub.... Clarion Mobile Electronics SRV250 Powered Subwoofer

I can't 100% say the amp makes a difference to the 4" speakers if you do an apples to apples comparison, but I have just always run additional amplifiers in any upgrade I do "just in case". One of the key features the amp delivers though is a selectable high pass filter. Setting this allows you to push much more sound to the 4" speakers without them having to handle any bass, which they do badly. I guess I could just have installed a tunable filter to achieve this, but I thought the amp was a belt and braces approach, which is usually my approach to most things.

I did think about using the space under the drivers seat, and if I hadn't been able to find a sub and amp that fit under one seat I would have done this. Obviously, just having 1 seat out and having all of the wires going down one side of the car is easier than 2, but not impossible. If others try this and want "more" either amp or sub, then the 2 seat install would be a good way to go.

The sub gets warm. The amp gets hot. There is so much of a gap under the seat that there is absolutely no heat transfer into the seat. There is obviously a little bit of bass transfer into the seat, so I need to turn the sub down a bit when carrying infirm passengers :-) The seat cushion was initially a bit loose on the frame and at pretty high volumes (volumes you couldn't have sat comfortably in the car at) it would rattle. I found this out while testing the system after the install so I went back and bent the cushion bracket a bit to make it a tighter fit against the seat frame and stop the rattling.

Adjusting the sub level is easily achievable as it has a remote control, which I have sitting in one of the ashtrays....



Again, this is just sitting there and is easily removed and stuffed under the passenger seat out of sight if I'm doing Pebble Beach Concourse :-)

 

Thanks for the info! I ordered a Pioneer receiver that looks just like the one you have! It has a high pass & low pass filter that not only allows you to select the frequency but also the crossover slope. That really impressed me.

I've been trying to decide if I want to add an underseat sub like you have or a set of 6x9's to the rear parcel shelf. The underseat sub seems easier.

 

I usually go for big speakers in the back on an install. The issue for me was either mounting them above the shelf and having them visible, or cutting the shelf, neither of which I wanted, so I had to look for a different way. I have to say this sub really impressed me and even with the small 4" speakers low in the doors it really is a pretty complete sound. Ideally I'd love tweaters positioned higher up either in the dash or in the pillars but thats just not going to happen in my Series III

If your head unit has adjustable cross overs, I'd say try it without the amp first.......

 

I've just done this without the amp in my '86 Sovereign.

I used 4" Alpine SPS-410 speakers in the doors, which sounded great off the "4 x 52W" Sony head unit, but same low-end sound problem as you of course.

The Sony has a pre-amp subwoofer output (RCA jacks), so I added one Kenwood KSC-SW10 powered subwoofer under the passenger seat. Tons of room for it there. It would not fit under my drivers' seat because that seat is height-adjustable and I have it down a bit. (Nor does it fit under the passenger seat if the Sovereign's thick fuzzy floor mats are in place.)

The result is all the missing bottom end of my music is there now, as loud or quiet as I like.

I was going to buy the same Clarion powered sub that you have but changed my mind last minute just because I'm going to replace the Sony head unit with a new Kenwood media receiver.

I am indebted to you and Doug for your discussion about getting the power cable through the firewall. Thanks!

 

@Greg

Glad it worked out for you.

I have recently put the same sub in the cubby box behind the front seats in my XJS. Also fitted the same amp do do the crossover part. Sound is much improved but its a tough job to getting a ragtop sounding good.

 

Ya the crossover part....that's the weakness of my system. I just turn down the bass a bit on the Sony head unit and leave the subwoofer crossover as high as possible (only 125HZ on the Kenwood).

 

I seen to recall in a different thread I saw somewhere, but cannot find, that a good place to get thru the firewall with the power wire is on the passengers side, in the area of where the steering column would go thru if it were a right hand drive car. Can anybody confirm or deny this? I have the same sub as OP and plan to put in soon.
Thanks.

 

Well thb, I did investigate the hood release cable grommet area thoroughly and found the perfect way through the firewall, however on the left side of this left-hand drive Canadian car.

There's a grommet just above the steering column, very conveniently located for running the power lead to the console. I just dismantled the fusible link so that the wire would fit through the grommet/hole.

 

Well, I answered my own question yesterday when I installed the same Clarion sub as the OP. There is a 1/2" plastic plug in the passenger foot well in the LH corner at the bottom where the transmission floorboard and firewall meet up. I just drilled a hole in the plastic plug to run wire thru and then used some liquid electric tape to seal it up. Much easier than crossing power wire over to drivers side and then out.
Only "problem" I encountered was finding the speaker wires to tap into for a signal for the sub. I could not find the stereo amplifier that is supposedly behind the glove box. Does my '87 with the factory AJ8700 not have one?
I finally did find the speaker wires for the RH forward door and used them for a signal. The speaker wires are black (+) and black/white (-). The LH front door speaker colors are the same. According to another source, the colors aren't matching what my car has. I couldn't find/trace the LH door speakers to use for the LH signal for the sub, so I just used the RH wires only. The sub sounds great as it is right now. If I can find or figure out where that amplifier is or where the LH speaker wires are, then I might fix. But for now, it sounds good.
Dale