Originally compiled by
Jyri J. Virkki
Welcome to the audio section of the Tips from the Garage. The
contents of this section are based on the information posted to the Miata mailing list
during the last few years. I have simply collected and organized the information into the
various categories below, thus I cannot guarantee that it is all accurate. If there are
any errors I will greatly appreciate hearing about it so that I can correct them. Some of
the information might be colored by the installation work I have done on my '93 Pkg.A
Miata and perhaps not applicable to all permutations of the car; if so, I'd love to hear
about these details so I can clarify the information.
This document should be considered heavily under construction and
thus incomplete. I have inserted many questions into the text, if you know the answer to
any of these, please email me so I can fill in the missing pieces.
- The console accepts standard DIN-sized headunits. There is enough
space for two full size components with a bit of space left over. The console contains a
removable mounting bracket where components can be bolted. There is a fair amount of heat
radiating up from the transmission tunnel though, so it might not be a good idea to pack
so many components in the console. (For the same reason, mounting an amplifier in this
location might not be the best choice). See installation hints section for information on
how to remove the console panel.
- Aftermarket Head Units
- Any aftermarket head unit in the standard size should be easy to
install in the factory location (pull-out units tend to be more of a pain to install, but
they are not that common anymore). Aftermarket units can be classified into tuners and
receivers, where receivers have an integrated amplifier but tuners do not, thus requiring
an external amp.
- Factory Head Units
- The standard factory head unit is a Panasonic AM/FM Radio &
Cassette, in a 1.5 height DIN unit. The following diagrams show the outputs on the three
Audio Signal Connector
Headrest Speaker Connector
The Panasonic head unit has a common problem that appears as a
failure to turn on in some occasions. Pressing the ON button produces a momentary flash of
the display but it does not turn on. The tape unit usually accepts a tape if one is
inserted, but does not begin to play it. It has been noted that the occurrence of this
problem is usually correlated to high humidity situations. Typically, driving for 5-30
minutes solves the problem and the unit begins to operate as expected (presumably after
the heat from the transmission has dried off the humidity?). Check here for a solution.
The factory unit has the capability to be programmed with a security
code which should theoretically deter theft [can't imagine it does though]. The code can
also be left unset, or deactivated. If the code is set and power disconnected to the unit,
it will require the code in order to function again. If you set and forget the code (or
buy a used car or unit which has the code set and unavailable), the Mazda dealer can
unlock the radio by using an universal code. It has been reported that some dealers will
deny knowing this code, or will attempt to charge unreasonably for the service. Attempting
random codes will lock up the radio after 3 misses (supposedly irrevocably but I don't
know if this is true?).
(are there factory head units other than the Panasonic?)
(information on MSSS??)
- Factory CD Changer
- (I have no info on the factory cd changer?)
- Aftermarket CD Changers
- There are two basic methods of connecting an aftermarket CD changer
to a head unit. For head units that have CD changer controllers, the supported changer is
simply plugged in to the appropriate connector. (Note that there are also a few
manufacturers with headunit changers - where the headunit itself is a "changer"
for a couple CD's).
For those head units that lack CD changer
controls, an alternate method is to use a changer that can transmit its output signal over
an FM frequency. The radio is then tuned to this frequency in order to listen to the CDs.
The advantage of this method is that it allows any changer to be interfaced with any head
unit. The disadvantage is the loss of fidelity the signal will suffer as it is transformed
back and forth from audio to RF signal. Whether the resulting sound quality is
satisfactory or not is largely a matter of preference. Thus, it is advisable to listen to
a similar setup before installing one if at all possible.
Installation options: The trunk is the most common location for
changer installations. Options include the floor just left of the depression; vertically
on a mounting board on the left edge of the trunk (doubling as a protector for the
fender), or vertically on the rear wall of the trunk. Mounting on a board placed inside
the spare tire is another interesting option. Smaller changers should fit in the glove
compartment. Another option is on the wall behind the passenger seat. There is not enough
space under the seats for a changer (or has anyone squeezed one under there?). Mounting
the changer horizontally instead of vertically will usually provide better resistance to
skipping, everything else being equal.
Aftermarket CD Changer
Even the most powerful head units cannot put out more than a fairly
low 20-30W output. External amplifiers are only limited by how much you want to pay. While
an amplified head unit can produce satisfactory sound, the addition of an external
amplifier can produce great gains in sound quality. This is especially true for top down
driving, where wind noise can easily drown out the music.
The signal can be delivered to the amplifier in one of two ways:
line level or speaker level. Using line level inputs is the most desirable method, but if
the head unit does not have line level output (usually the familiar RCA outputs), then the
speaker outputs may be used. Some amplifiers accept speaker level input directly. For
those that don't, most car audio supply stores sell transformers that will drop the signal
down to line level. If you are purchasing a head unit and plan to use an amplifier make
sure the head unit has RCA line level outputs.
- So which is the best amplifier? Any mid-to-high-end model by any of
the reputable manufacturers will provide excellent performance. Finding the
"best" is purely a religious argument, see rec.audio.car and its FAQ. Avoid
amplifiers that claim unbelievable power output at very low prices. When choosing
amplifiers keep in mind features that you might need now or in the future. For instance,
multichannel amps are useful for powering multiple sets of speakers, and/or the door
speakers and a subwoofer, all from one amp.
- Clearwater sells a package with an amplifier and all the necessary
wiring and mounting pieces that are needed to connect and mount the unit into the Miata
trunk. Many owners have reported being very happy with the unit and the ease of
installation. There are cheaper amplifiers of equal quality, and better amplifiers for the
same money (and much better ones for a lot more money ;-). The advantage of the Clearwater
package is its ease of integration into the Miata sound system. Whether this ease of
installation is worth the price premium depends on how much you enjoy wiring and
installation work. There has been one complaint about the Clearwater amplifier, and its
that it "pops" when turning on the system. Some owners report being really
annoyed by it, others don't seem to mind.
While it is true for all audio equipment, it is much more so for
speakers: listen to the various models you are interested in, and choose. Speakers
have very definitive "personalities" and there is no way to choose a speaker
that will sound good without judging them in action, because "good" is a highly
individual preference choice with regard to speaker "sound coloration".
The stock door speakers are quite weak and inefficient (although I
have to say they are better than most stock car speakers), and replacing them can make a
large difference. The stock door opening can accept speakers as large as 6.5",
although this will require a bit of customization (drilling some new mounting holes,
possibly nibbling away at the metal a little bit). It is a good idea to get the largest
door speakers possible since these will be the only source of bass in the system (unless
you are designing a very fancy system with large speakers in the rear deck and/or
- Components systems
Another option for the door are the so called component systems,
which have a separate small tweeter that can be mounted higher up on the door panels or
even on the A-pillars. One of the fancier factory packages (which, MSSS?) has such a setup
from the factory.
- Clearwater also sells a speaker set for the Miata. As with their
amplifier, the kit is well integrated into the Miata factory sound system, offering easy
installation, but better value can perhaps be obtained elsewhere. Most owners have
reported being happy with these units.
- Rattling in the passenger side door
- This is a very commonly reported symptom. There appear to be a
variety of common causes. There is a spring in the window mechanism that can vibrate
agaist its surrounding when the window is up (no tension in it). Try damping the vibration
of this spring. Also, the speaker rain shield could be the culprit. Another possibility is
to install a sound dampening product. Some popular choices include Dynamat, NoiseKiller
and Sound Shield.
- Water baffles
- The stock speakers include a baffle to protect the speaker from water
that gets into the door. It is a good idea to install this onto the aftermarket speakers
if they don't include a similar protector.
The headrest speakers help to fill-in the higher frequencies,
especially during top-down driving when the higher notes from the door speakers tend to be
drowned out by wind noise. On systems with separate component speakers in the doors and/or
having a high power amplifier, the headrest speakers can be largely unnecessary (or could
even hurt the soundstage, depending on personal preference). The speakers can be reached
by unzipping the top section of the seats (lift the "edge" on the top of the
seat, you'll find the zipper).
- Factory headrest speakers
- A common problem reported with the factory headrest speakers is that
many are connected out of phase. If the volume seems very low, this might be the case.
Simply reverse the wires on one of the speakers (one on each seat). If the sound
improves, they were wired out of phase.
To test phase polarity, take a AA 1.5 volt battery and affix a short
wire to each polarity. Then touch each of the two wires to the connectors on the stock
speaker. If the speaker moves inward, the polarities are backward. If it moves outward
then you have it right. Then look and see which connector on the speaker had the + from
the battery and match that to the wire on the stock harness from the car. Thanks to Mike
Pietrzyk for this tip.
- Aftermarket headrest speakers
- The factory speakers are fairly low quality cardboard speakers, many
owners have reported being happier with aftermarket units. Many manufacturers (including
Clearwater, see above) sell speakers that will fit in the factory location; any round
3" speakers should fit. Installing them requires some trimming of the foam in the
headrest since the factory speakers are rectangular.
installing headrest speakers into cars that came without these from the factory, you will
need to run the cables down through the seat backs and into a harness that plugs into the
factory radio (or connect them to the rear speaker outputs on aftermarket head units).
(How to obtain harness if not present?). The Clearwater package includes the necessary
connector, and the various Miata vendors should be able to provide the connector with the
other brands they sell.
This is probably the most commonly asked hard to answer question.
There just isn't that much space, so something has to give in order to install subwoofers
in the Miata. Some ideas (send me any subwoofer suggestions that are not be covered
- Bazookas or similar tube units
- These types of subwoofers offer a fairly convenient package; some
even have built-in amplifiers. The trunk is the standard location, but one large tube
subwoofer will swallow up most of the available space. Additionally, it can sound somewhat
boomy. Another option is behind the passenger seat; apparently the smaller units can fit
behind the seat without restricting its travel too much. A third interesting option is in
the cabin-trunk tunnels. The location is very convenient since it takes no interior space
at all. Reportedly, the smallest of the Bazooka line (5") tubes actually fit in the
- Spare tire subwoofers
- Very recently there have been a few manufacturers who have introduced
small subwoofers that fit inside the spare tire in the trunk. They take up no trunk space.
The sound might not be the best but it seems like a very convenient solution. (If you've
actually tested or heard these units, I'd like to know how they sound)
Note from Eric Williams:
Image Dynamics makes the IDQ 8" which fits 0.2 - 0.25 cubic
feet, depending on single or double voice coils. $80- $100
Phoenix Gold makes the Xmax 8" which fits a tiny 0.1- 0.3
cubic feet, with a large power handling, and excursion. $150- $200
- Very small enclosure subwoofers
- There are some subwoofers that require a very small enclosure to
operate. One such unit that I'm aware of is the 8" Kicker Solobaric, which only needs
0.33ft^3 of enclosure, there surely must be others (anyone?). Given the small space
requirement, these can be a good basis for building a subwoofer system for the Miata. I've
installed an 8" Solobaric in an enclosure placed behind the passenger seat. I'm happy
with it, it adds tremendous depth to the music. It does force the passenger seat forward,
enough that sitting in it becomes, not impossible, but undesirable.
- Custom installations
- These are limited only by your (or your installer's) imagination,
money, and willingness to give up space. Let me know of any interesting solutions to
- Michael Strittmatter describes his setup:
- I had a custom box installed for 2 8" sub-woofers behind the
seats on the rear deck. The box was built to exactly fit in front of the top when down,
doesn't block visibility because only ~6" tall, and the window only bends into L
shape, no creases. It's shaped like this (view from top):
Top folds down here
-- Sub Sub --
|__________________| (Full width between seat belts)
- It is possible to install a pair of free-air subs in
the rear deck panel. You will need to cut the panel on either edge and fit
the speakers through it onto the tunnels. This is a very nice solution if
you are willing to do the work. A set of 6" subs can be easily installed
and a set of 8" ones can be made to fit with extra work and care.
When replacing the antenna (or installing one on a car that came
without one), it is a good idea to purchase the original Mazda antenna. The reason is that
many aftermarket antennas mount onto the fender itself, which is very thin sheetmetal and
can be bent by these antennas. The factory antenna mounts on a bracket inside the trunk
and passes through the fender, thus placing no stress on it. Mast and body are Mazda part
numbers 0000-81-005A and 0000-81-1005.
- Removal of console
- In order to remove the console piece which covers the radio, it is
first necessary to remove the central piece over the transmission tunnel. Remove the
screws inside the handrest storage compartment, the one under the ashtray piece, and the
two screws on the sides near the front, and remove the shift knob. The center piece can
now be removed. There is a wire connected to the ashtray light which needs to be
disconnected before completely lifting the piece away. The next step is to remove both
central eyeball vents. In order to do this, simply insert something though the vents that
will allow to pull them out. A bent coat hanger works well, so does a string. Now pull
(hard!) the vents out. If this doesn't seem to work (never worked for me), another removal
method is the following: Get a very small flat screwdriver and wrap it in some cloth (to
protect the dash); insert the blade between the outer circle of the vents and twist. The
vents should pop right out. Once the vents are out, remove one screw behind each. At this
point, the central piece of the console can be removed.
- Ignition Noise
- Ignition noise is a common, and very hard to trace problem in car
audio installations. It is characterized by a whine that varies according to engine RPM.
The best (preemptive) solution is to do a careful installation. The rec.audio.car FAQ
covers this subject in some detail.
- Following is a list of various Mazda cubbyholes that can be useful in
installations (thanks to Cynthia Paloma). The black plastic radio storage bin/dash
pocket/cubby is referred to as a "Stereo Ornament" in the Mazda parts catalog.
Metrawire supposedly also makes a Mazda Miata fit kit for aftermarket radios, it is part
number #71-7901. This might be available from audio shops, but I have no specific contact
- FC02-55-235A - 1.5 DIN (same size as stock radio w/cassette). This
part comes from the 90 Miata only. Can be cut down to size to fit under a 1 DIN sized
aftermarket radio, providing plenty of space and reportedly looks good.
- LA03-55-235A - 0.5 DIN (same size as the space under the stock radio
- The following Mazda part was listed in the Winter 1990 issue of Miata
Magazine on page 12: 0000-81-0147 - 1 DIN (supposedly OEM on all Euro-spec Miatas). *Note 1
- The following is a Mazda 323 part: B092-55-235B - 0.5 DIN, only 2
inches deep. Mentioned in a letter in Miata Magazine under "Extra Storage
Space", p. 18 continued on p.41.
- Tunnels into trunk
- There are two tunnels that run from the trunk into the cabin. Both
can be reached from the trunk; the right one by removing the spare tire, and the left one
by removing the panels that cover the gas tank fill tube. From the cabin, first lift away
the carpet (held by many plastic pins) and then remove the large metal sheet held in place
by countless screws. In order to remove this piece, it can be helpful to remove the
plastic piece covering the seat belt towers, otherwise it is necessary to bend the metal
panel a little bit in order to ease it out.
provide an easy way to run wires between the trunk and cabin. In addition, the space can
be used for installing various components such as a crossovers or amplifiers (there might
not be enough ventilation for higher power amps that generate more heat though).
- Amplifier in trunk
- The deep section in the middle of the trunk offers a nice location
for a large amplifier that won't fit elsewhere. Constructing a false floor to cover this
section then allows regular use of the remaining trunk space.
- Using an external source (e.g. CD player) with stock radio
- The stock radio does have signal inputs that may be used
to connect some other source.
*Note 1: We've been informed that this part has
been discontinued by Mazda. (Not confirmed by Mazda.)
Custom Miata Install Showcase
- The rec.audio.car newsgroup is a good source of discussion on all
aspects of car audio. See also the FAQ of
the newsgroup which has a great amount of useful information about car audio in general.