1992 Miata Stereo upgrade - 3/30/2003

Before doing this, I researched Miata.net for great info and suggestions - thanks to all those in the Miata community who have shared their experiences! What follows is a summary of my work, I hope you find it useful in your audio plans or projects.

It was time to replace the factory audio system in my 1992. The door speakers had deteriorated, my head unit had the humidity-power switch issue, and the headrest speakers were crackling due to a short somewhere.

I had installed the Pioneer 12 disc changer in 1995 (when I purchased my 92 Miata) and decided to keep it in the new system- the changer hooks to the head unit via the FM antenna. I decided not to make use of the headrest speakers in my new configuration, instead of spending money replacing the 4 headrests and re-wiring, I put my $500 budget toward a component speaker system for the door and dashboard locations.

Before/After pics


SONY CDX-MP70 head unit
52W X 4 CD/MP3/FM/AM/XM ready ($319 SoundDomain.com)

($169 SoundDomain.com)


($9.95 SoundDomain.com)
($4.95 SoundDomain.com)
($4.95 SoundDomain.com)

Total $522.70 with ground shipping


Summary of my door speaker install:

REMOVED the old:
I removed the Miata door panel and speaker panel (see easy to follow instructions on Miata.net). The paper original factory speakers had deteriorated in areas. I un-mounted the old speaker, removed the plastic rain shield for re-use (it is attached with glue to the factory speaker). I re-used the existing wiring in the doors as it still was good and saved me some time/effort running new wires.

INSTALL of the new:
I cleaned the speaker area with mineral spirits to remove gunk from original speaker adhesive, then wiped the area down again with alcohol. To try and cut some noise/vibration and get as much bass as possible, I installed a 10X10 damping pad in the speaker area. Used a hair dryer to heat the pad, removed the backing, and pressed it into the contours of the door speaker area. The new speaker was slightly larger than the original, so to attach it to the door, I had to drill 3 small pilot holes, re-attached the old rain shield with glue, and mounted the new speaker with 3 small sheet metal screws (carefully as to not bend the speaker frame). I lubed the window tracks and cable with white lithium grease and put the main door panel back on. For the door speaker panels (with smaller than needed openings), I used a saber saw to cut-out the factory one-piece speaker grill, and widen the round opening slightly for the larger new speaker. I drilled 4 holes in the door speaker panel to mount the new speaker grill cover. Using a nail to find, and a dremmel tool to clean out, I re-opened the plastic pin speaker panel receptacle holes in the door around the speaker area that had been covered by the damping pad. Then finally, re-attached the speaker door panel, and installed the new grill cover.

Summary of Dashboard tweeters- installed in vents

I saw a thread on the Internet on someone thinking it would be great if you could install tweeters in the left and right outside eye-ball vent locations. They are the perfect size and location, so why not? It Works! The vent and the eyeball are two pieces, allowing you to open the vent cover piece- remove the eyeball, and mount the tweeter inside.

I removed the outer eyeball vents - (see easy to follow instructions on Miata.net). Removed the eyeballs from the vents (front vent cover comes off easily). I installed the tweeters in the vents by first gluing my tweeter grill to the front cover of the eyeball vent (hot glue). Then I attached the tweeter mounting assembly to a small piece of wood (about 1 in square). I assembled the 3 piece speaker (tweeter grill already glued to the vent cover+speaker+mounting assembly attached to wood square) inside the vent and put a small screw through an existing opening in the vent into the wood square. The tweeter was then securely attached to the inside of the vent. The tweeter is a little smaller than the round vent opening (where the eye-ball used to be) this gap is probably good for allowing some airflow from the fan when running through the dash vents. Running speaker wiring was very easy, as there is a gap between the ventilation duct that the eye-ball vent inserts into and the dashboard, I ran the wires behind the dash, to the back of the head unit. The modified tweeter vents snapped easily back into place (getting them out again will probably be another story- hopefully not necessary).

Summary of the CD-changer install in the trunk-

I actually did this 7 years ago, from what I can remember- I removed the carpet, installed a wooden board using strong double sided tape, re-installed the carpet, screwed the mounting hardware for the changer into the wood. Wired the changer to the power antenna fuse, (in the trunk). Using the antenna splitter that came with the changer, connected the CD to one of the 2 inputs in the splitter. Ran the remote changer control wire through the Miata cockpit back wall, under the center console, to the dash. It still works great! And is now a good compliment to my single CD head-unit.

Summary of the Head-unit/deck install-

I removed the center console and center dash piece- (see easy instructions on Miata.net).
Removed the original Panasonic factory head unit.

Installed the new dash kit- the SCOSCHE MA1530 head install kit worked, but there may be better kits out there. It has a DIN opening for an "equalizer" that is useless (can you even by one of these today?). I had planned to mount my remote CD changer control in the dash, so I was able to do some "dremmel" work on the kit and create an opening for the CD changer control as part of the original opening and cover designed for the "equalizer". Also, the instructions for the kit tells you to mount it at four points to the Miata dash, and to use 2 B spacers in the top 2 holes. I found this to be incorrect- with the B spacers installed- the center dash piece would not re-install. I removed the spacers, and it went back into place ok.

The wiring harness I used, also from SCOSCHE worked fine, it came with the main harness, and a 2nd for the headrest speakers (I chose not to use the headrests). I re-used all of the original Miata wiring, including connecting the original ground to the new head unit ground wire. I installed the speaker crossovers in the space behind the head-unit, with all the other wires.

The SONY head unit mounted cleanly inside the DIN size opening in the kit. The detachable faceplate is silver (would have preferred black). The LCD display can be changed to any of 7 different colors (including a yellow-green similar to the Miata dash illumination), and is very bright- which will be good for top down driving in the sun, it can also be dimmed for night. The flip-out panel with tray mechanism/detachable front panel display work well and are a good anti-theft feature. 

Other comments-

The SONY came with a black plastic trim piece that should snap into place around the detachable faceplate and inside a standard DIN dash opening- But the trim piece will not fit given that the Miata stereo dash console opening is not 100% DIN size.

The SONY CD player does not like cheap CD-Rs.   I had difficulty playing MP3 CDs burned on cheap verbatim CD-Rs, they would play most of the time (except in humid conditions), but, there was delay in reading the disc when inserted, and skipping sounds if the disk had the slightest scratch.   I switched to MITSUI silver 74 Minute CD-Rs, recording MP3 CDs at 2X and they play great!   Now the MP3 CD plays almost instantly when inserted, and there is almost no noticeable delay between tracks.

That's all - Time to enjoy some good sound!
Matt - degma@mindspring.com