Useful info about the stock stereo.
The New Beetle head unit is manufactured by Clarion in Mexico. The CD Changer is manufactured by Matsushita (Panasonic) in Japan. The VW unit has a different connector than a Panasonic, but adapters are apparently available. A genuine VW CD Changer and bracket cost ~$320 in mid 1998 at Russell Automotive in MD. You should also check with Carousel Motors.
The stock NB head unit has a 6db boost around 25 Hz. It appears that this can't be changed.
The stock rear speakers are woofers only, and have a low pass filter built in.
Here is a quote from the Car Audio FAQ:
5.5 What is "rear fill", and how do I effectively use it? [HK, JSC]
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"Rear fill" refers to the presence of depth and ambience in music. A
properly designed system using two channels will reproduce original
rear fill on the source without rear high frequency drivers. Since
recordings are made in two channels, that is all you will need to
reproduce it. What is captured at the recording session (coincident
pair mics, Blumlein mic patterns, etc.) by a two channel mic array will
capture the so called rear fill or ambience. Many of the winning IASCA
vehicles have no rear high frequency drivers. Also a lot of this has
to do with system tuning. If rear high frequency drivers are added,
however, the power level of the rear fill speakers should be lower than
that of the front speakers, or else you will lose your front-primary
staging, which is not what you want (when was the last time you went to
a concert and stood backwards?). The proper amount of amplification
for rear fill speakers is the point where you can just barely detect
their presence while sitting in the front seat. Separates are not a
requirement for rear fill; in fact, you may be better of with a pair of
coaxial speakers, as separates may throw off your staging.
Although the head unit has line outs, MBQuart reports that they are noiser than the amplified outs (!).
The stock unit has a switched power out for controlling an amp, but no connection to it. Here's what you do:
From the dealer's parts dept., order:
1) 4A0 972 643 Yellow housing for line out/amp control
1) 4A0 972 663A Green housing for data connector
1) 000 979 125A Wires w/connector pins which fit above connectors
You don't really need the green housing, but getting it allows you to combine these two with the existing one (they snap together) to get a neat install.
Looking at the back of the line out connector (in order, l-r, the connectors are:line out, data, speaker out) the pinout is:
1 2 1=RL 2=FL
3 4 3=GND 4=+12 switched
5 6 5=RR 6=FR
If you want to play with the line outs, get three of the cables. You can cut each cable in half to get 2 connections out of it. 3 cables & 2 housings = ~ $15.
You'll also need tools to remove the head unit. VW sells these, but I made my own by cutting down a hacksaw blade. Make two like this:
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You push these into the slots with the pointy side toward the outside of the head unit. This will force the release clips inward and allow you to slide the unit out. Make sure you have the code before disconnecting power.
If you want to use a line converter instead of the amplified outputs, you may need to modify the line level converter. I had to modify mine, since the head unit looks at the output impedence - if it is not low enough it won't put anything out! I think I needed to get below ~110 ohms.
The head unit can detect clipping on the outputs. If you turn the volume up high, and it causes clipping (likely if you also have the bass turned up), the unit will automatically turn the volume down to reduce clipping. This is a good thing.
The head unit does not have a mute input. If you're installing a cell phone car kit, this would be useful to mute the stereo while using the phone. You can simulate this, however. The ignition on wire going to the head unit only needs to provide a couple of mA to control the head unit. If you wire a 1K resistor in line on this wire, the head unit will still go on/off with the ignition. You can then connect a low going mute output from a handsfree kit to the side of the resistor closest to the head unit. This allows the handsfree mute output to pull this low, making the head unit think that the ignition has been turned off. Works fine for me.
If you want to replace the head unit, Scosche makes an adapter. They will accomodate any regular sized aftermarket deck, while retaining the original stereo cutout hole.
Annoyed by the BLS (Blank Skip?)
Does your deck fast forward over songs, and/or take 10 seconds to skip over 2 seconds of silence between every song?BLS is where the radio attempts to detect and skip over sections of blank tape. MSS is where _you_ press a button telling the deck to skip to the next song. BLS is annoying, because it often mistakes quiet music for silence. MSS is annoying, because it just doesn't work (for me), but is easy to live with, since you can just not use it
Once BLS is removed, you will have to manually, and with great effort, press the FF button after the last song on a tape has been reached in order to quickly get to the other side. As far as I can tell, that's the only thing BLS is supposed to do automatically, unless you've got a collection of weird tapes with large gaps in between songs.
To remove the radio, you'll need some special tools. These are described above.
Make sure you have the unlock CODE before proceeding.
1) Remove the radio from the dash.
2) Take off the bottom cover, which is held in place with two screws.
3) This will reveal a large circuit board. The area of interest is the front right corner (near the Scan button).
4) Look for two small resistors. The label next to one says "R828" Printed on the resistor is "822" The second resistor is next to the first, it is labeled "R821", and marked "334"
5) To get rid of the blank skip, you want to remove these two resistors. The easiest way to do this is to use an "Exacto" type knife and pry up on one end while melting the solder at that end with a small soldering iron. If you're very careful, you can end up with one end of each resistor just poking up into the air, so it's no longer making contact, but could conceivably be resoldered to restore normal (defective) operation.
6) Close everything up, and reinstall the radio. You will need to enter the SAFE code in order to get it working again. Instructions are in the manual.
That's it.
Now, if you want to know what you just did, or want to try and fix it so this feature actually does something useful, a bit of explanation:
The blank skip is controlled by a Sanyo LA2000 IC. You can get a datasheet for this chip here: http://www.elisnet.or.jp/login-sanyo.htm (terrible interface, however)
R828 (822 = 8200 ohms) controls the input level to this chip, it is the lower part of a voltage divider, the upper part of which is 100K. Changing R828 to a higher resistance will feed a higher signal to the LA2000, effectively lowering the detection threshold. (The "blanks" on the tape will need to be quieter in order for BLS to kick in)
R821 (334 = 330,000 ohms) forms an RC network with C812. This provides a time constant to the LA2000. Increasing the resistance of R821 increases this time constant, increasing the integration period for the LA2000. (The "blanks" on the tape will need to be longer in order for BLS to kick in.)
So removing both means that the tape must, in theory, contain an infinite length of absolute silence before BLS cuts in. In practice, this isn't actually the case, but for our purposes here, it doesn't matter.
I don't think that the MSS (Music Search System?) is controlled by this chip. There is a Phillips IC, a TEA0675, which has support for MSS and may be used to implement this. MSS has never effectively worked for me, so I just don't use it. This mod may, or may not, change MSS behavior. I don't use it, so I don't care, so I didn't test it, but I don't think it will.
Disclaimer: I can't be responsible for the work you or others may do to your radio. This information is correct to the best of my knowledge, and this worked for me. It may not work for you. You assume all risk. Eat your peas.
Have fun!