Upgrading SAAB 900 Audio If you do not have a big budget, you can change just the speakers
and still use the existing cables and amplifier in the head unit
which will probably give the best return for your money
I have only considered placing speakers in the existing positions
using the existing grilles, you would be able to achieve even
better results by installing custom shelves and large drivers,
but I prefer to change the car as little as possible and have
nothing visible from outside that shows that expensive audio equipment
is fitted. I also wanted to be able to remove the speakers when
I sell the car and not have anything that would put other buyers
off (like having cut new grilles into the door panels).
If you have Saab Audio System 2 fitted, then replacing the rear
and front dashboard speakers will just be a case of removing the
grilles and dropping the new speakers in. Cables are only run
into the front door speaker positions if you have Saab Audio System
3 fitted, otherwise you will have to run new cable into those
positions via the door-body cableway.
There are two pairs of speaker positions at the front of the
car, two 8.5cm spaces at either end of the dashboard and two spaces
big enough for 16cm drivers in the front doors. This gives several
options for upgrading and after removing the factory fit speakers
you can:
Replace just the
8.5cm dashboard speakers: 
Many
manufacturers make drop in 8.5cm speakers with separate tweeters
that will fit this position. The Pioneer TS-H871 is a typical
speaker that has a separate tweeter and will handle 60W max. This
is the easiest change to make as the grilles lever off quickly
and you could replace both speakers in 10 minutes with just a
screwdriver.
Remove the 8.5cm speakers and fit 16cm
speakers in the front doors: A better solution since the dashboard
speakers are not that big and having speakers in the door panels
will give much more bass (bigger and in a sealed enclosure). You
might have to run new cable into these positions and when choosing
a speaker you need to be careful that it will fit (the tweeter
should not stick up more than 1.5cm from the mounting rim otherwise
it will foul the speaker grille on the door panel). Installation
is also a bit harder since the door panel has to be removed (do
not try to lever off just the grille) and you will probably have
to drill screw holes for mounting the speaker (there is already
a 13cm cutout for the speaker to fit in).
Fit component speakers
using both positions: 
This is the best
option, 16cm mid/bass units are fitted into the door positions
and tweeters are fitted behind the dashboard grilles. The tweeter
will be much smaller than 8.5cm (perhaps just 2-3cm across) but
most will come with a mounting kit to fit into the hole. Most
systems like this come with a separate crossover to split the
signal into bass and high for the two drivers, about the size
of a matchbox (or a big matchbox !!) some will also give you a
choice of hi/lo setting for the tweeter. This is what I have fitted
into my 900 and the 16cm mid/bass unit gives exceptionally good
bass, you are now just limited by vibration of the door panel
rather than by the speaker. If you have a good power amp you may
be able to roll off some of the lower frequencies from the front
channel (say below 60Hz) which will let you drive the system louder
and leave the deep bass to the bigger rear speakers.
The 8.5cm custom fit speakers will probably be
about £60. Two way 16cm speakers from someone like Pioneer
would about be about £60. Component speakers are a lot more
and something like the Infinity Kappa 60cs I fitted to my 900
are £230 (includes bass/mid, tweeter and crossover).
The rear speaker positions can just about take the common 6x9 inch size, but you should check the exact size, since my 16x9 speakers needed the hole enlarging by a little. This is quite a large speaker and you should be able to get good bass from a speaker of this size. There are several options for placing speakers here.
Reasonable 6x9 speakers from someone like Pioneer are available for about £80, I fitted 100W Infinity 6903i speakers which cost £130
If you have spent reasonable money upgrading
the speakers, then the next step is to use a separate power amplifier
to drive them rather than the 12W one built into the Saab Audio
System.
There are lots of power amps available, you need four channels
of amplification and could go for a single four channel unit,
two stereo units or even four mono block amplifiers !!
When comparing outputs many companies will quote a Max figure,
but you need to look at the continuous rating and the amount of
distortion (THD) at this power. Some manufacturers will quote
a figure like "50Wx4 into 4 ohms at less than 0.05% THD (20Hz-20kHz)"
which tells you everything you need to know. You should aim for
0.1% distortion into 4ohms, 50W will give you a very loud system,
even 25W at this specification will be very good. Sadly many brochures
will not give the THD figure for the continuous rating or will
even just quote the MAX rating, which will always be much higher
than the continuous rating.
Cars are hostile places for amplifiers and the mechanical vibration
and interference from other electrical systems may affect the
amplifier. Sadly you will not know how well the amplifier resists
these two until you install and use it, but EC legislation will
require amplifiers to pass electromagnetic compatibility tests
from Jan 96 (EN55013, EN55020) so amplifiers sold after that date
will have to pass EM tests at least.
The amplifier could be fitted under one of the front seats (if
it's a small one) or in the boot. I have mine fitted to the back
of the rear seat which is one of the few flat places available
to mount a big amplifier (27cm square). You will have make sure
the cables are not fouled by the folding of the rear seat and
might like to fit some protection to the terminals to save them
from knocks by luggage in the boot when the seat is folded .
For best sound quality you need to connect the amplifier to the
head unit using the pre-out connection on the head unit, some
amplifiers can be driven from the speaker output of the head unit,
but this involves two levels of amplification and should be used
as a last resort. Do not expect the best sound quality if you
do this !! The Saab Audio System head unit does have pre-out although
it is on a non-standard 8pin din socket. I could not find a source
for this cable from either Saab or Clarion, so I had to make my
own up (details under fitting hints).
A 25W x 4 amplifier such as the Kenwood KAC-645 is about £200,
the 50W x 4 amplifier that I fitted to my 900 was £400.
CD player
The Saab Audio System is already capable
to controlling a 6 CD multi-player, the 900 head unit is made
by Clarion who also make the CD changer supplied by Saab dealers.
You can either buy this unit, or take a chance that one of the
units sold by Clarion will work. The protocol is called Clarion
C-Bus and I have the Clarion CDC605 fitted which works
fine.
The Saab 9-3 will not accept third party CD changers, you have to use a Saab original part, since the head unit and changer communicate via a kind of LAN and have to be 'mated' via software to talk to each other. Only the Saab changer has this firmware - nothing else will work. The changer is made by pioneer instead of Clarion.
The CDC605 fits into the Saab cage, but it is now discontinued
by Clarion. Any of their 6cd players will do, the CDC635 is
a current model and I have had several reports that this works
fine. Do not try any of the 12 or 18 disk models, the 900 head
unit can only access the first six disks.
Whatever CD player you choose, Saab have made it very easy to
add the player to the Saab Audio System 2. The car will already
have the CD changer cable installed running from the head unit
to the left side of the boot behind the trim panel.
You can mount the CD player either directly onto the floor of
the boot (in which case you will have to drill holes in the floor),
or buy the Saab CD player mounting kit which is a very strong
steel cage that bolts to the side of the boot (mounting points
are behind the trim of all cars) and which will protect the CD
changer from blows. The cage holds the CD changer with little
brackets that match up to the mounting holes in the side of the
CD changer, the Clarion CDC605 has holes in exactly the right
places and is a perfect fit. You should be able to find a Clarion
for £250 in the UK, the Saab audio brochure lists £429
for the Saab multi player. The steel mounting cage is about £70
A recent addition to my car is a Bazooka 8" subwoofer. It is powered by an old Kenwood stereo amp I had sitting around from my old car. The amp is fed by a convenient pre-out from the main amplifier and adds the L+R inputs togther to power the sub in bridge-mono mode. There is a great improvement in the bass by fitting a sub, and you can really hear it, even though it is sitting in the trunk. The main amp has switchable high passfilters for the front and rear channels, which restrict the amount of bass going to the front/rear and let the subwoofer take care of this. This is very useful, since the front channels cannot handle a lot of bass without the door panels/trim vibrating.
The sub was quite cheap, under a hundred pounds, and well worth
the money. It is easily removable if you want to carry lots of
stuff in the boot (the straps make it easy to remove).
To help deaden vibrations
in the door panels you can stick a thick rubber mat to the inside
of the door panel. This comes in a roll and you can buy it from
car audio dealers (I used Fosgate).
Cut the mat approximately to size, then heat it up real hot with a hairdryer or hot air gun (this is very important). Then push it firmly onto the inside of the door panel, following all the contours.
Finally cut the hole for the speaker and your door panel will
vibrate less.
Go for the Saab Audio System 2, it has better security than
standard audio size units, better ergonomics (the buttons are
big, widely spaced and recognizable by touch) and a very clear
and big display. It also has nice integration with other parts
of the car which other units cannot provide (like setting the
clock, getting louder when you drive faster).
I did not upgrade to the Audio System 3 since I felt the money
would be better spent with other companies amplifiers/speakers.
I fitted a Clarion CD multi-player in my 900 since this it worked
with the Saab Audio System, has fitting holes in exactly the same
places and is £150 cheaper than the dealer fit option. Unfortunately
in my 9-3 I could not fit a third party CD changer, so had to
pay the full Saab price for a changer.