[Miata] NB stereo system upgrades

[Dillon]

I looked at a lot of different options before I went down this path.  Here
are some of my thoughts, semi-collected.

1) The Bose head unit isn't all that bad.  In fact, it's not made by Bose at
all (I forget who makes it).  If your Bose is working well and you like the
stock look, you can keep it and just replace the amp / speakers.  As you
mentioned there is also an aux-in mod if you need aux-in.

2) If your Bose does break, there is a relatively simple fix that I once
found online (after I ordered my new HU).  It involved opening up the HU and
finding a little plastic spacer that tends to fall out of place causing the
HU to eject CDs instead of playing them.

3) If you do decide to keep your Bose HU, I think there is an adapter you
can get that allows you to run your Bose HU into a real amp.

4) If you decide to replace your Bose HU, most HUs made today have all kinds
of stupid graphics, bells and whistles, and generally advertise "steal me".
Nakamichi seems to be one of the few exceptions, but they are pricey
(exceptional sound quality).  I went with a CD-400.  A Nak CD-45Z appears on
ebay for time to time and would make a great HU.  Avoid the CD300/350 and
the CD500 as they were made to a lower quality standard.  You might as well
get a JVC/Alpine/Pioneer over one of those.

5) The Bose amp is hard to get to, but you can unplug and bypass it, leaving
it in place.

6) The passenger tunnel is 6.5" wide in an NB, but most amps are NOT that
narrow.  The exceptions are the Swiss Audio 4400 (4 channels, not
particularly well regarded by audiophiles), the Lanzar Opti 4x400D
(discontinued, high-quality), and the US Acoustics 4000 / 2100 (4 and 2
channels respectively, discontinued, well regarded).  There is also an older
model Memphis amp that fits, and a Blaupunkt which if the plastic shroud is
removed will fit.  This was a big issue for me as I don't want to give up
any trunk space and I wanted the amp to be mounted such that it couldn't be
spotted from the outside.  There isn't much space under the seats.  There
are folks who have mounted a small amp inside their donut spare, so I
suppose that is an option.

7) Quality 6.5" coaxial speakers are a good option for the doors.  The
opening is 8" on a Bose NB but you can make an adapter ring out of MDF
pretty easily.  The alternative is 6.5" or an 8" component set with passive
crossovers in the door (sealed in plastic to protect from moisture).  If you
want the passive crossovers inside the cabin, or you want active crossovers,
you have to run a new pair of wires into each door.  Don't drill a hole in
the door!  With a little work you can wire them through the existing molex
connector.  That's what I have done.  If you replace the speakers, a cool
whip container makes a good shroud to protect the speakers from moisture.

8) Subs are hard to do in a Miata.  If you're like me and don't want to
sacrifice trunk space, desire stealth, can't fit one behind the seats, and
don't want to force your passengers to scrunch up behind a footwell sub,
your options are the "Hakuna" install in which a free-air sub is installed
in the metal parcel shelf or a footwell sub on the passenger side that is
tucked up around the glovebox.

That's about all I can think of right now.  If I were looking to do
something completely stealth, and cheap, that sounded good, I would keep the
Bose HU, pick up a 2 channel amp used from eBay that fits in the trunk
tunnel ($100), use an adapter to change the inputs for the Bose HU ($50?),
and get a decent set of 6.5" coax speakers from PartsExpress ($60-80).  At
that point you'd have a kickin' system that would way outperform the stock
Bose setup.  If I wanted to replace the HU, then you can get something
decent for $150-300.  I'd highly recommend a Nak CD45z from eBay.

I'm doing my system in stages, and will eventually have a 4 channel amp
powering component speakers, a 2 channel amp bridged to a small sub (dual
6.5" or single 8"), 3-way active crossovers, the Nakamichi CD400 HU, and an
Omnifi DMP1 hard drive MP3 player.  That will probably take me another year
to finish buying and building ;)


Regards,
Dillon
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