Added info:
Depending where you are in the world, there were 4 7909 models:
- 7909 U.S.
- 7909L U.K-EUROPE
- 7909J JAPAN
- 7909 30th anniversary edition U.S.
1.) The original 7909 has the "pull out" feature. Basically, you can slide out the head unit from your dash. While so many people jump up and down yelling, "that's cool," The consumers in Japan will not accept that. The pull out feature results in each connection, each contact meets a barrier since the 7909 basically "plugs into" it's cage. In other words, the signal is sent, met by the cage terminals but still needs to send that signal to your amplifier...it's not a constant flow. Alpine 7909 30th anniversary and 7909J, do not have the pull out feature and, each connection, each contact has a direct path to your amplifier. Believe me, that pull out feature was a major failure in the original 7909.
2.)The 30th anniversary and 7909J have small black box marked, "Alpine." That is actually a small external DC/DC convertor....the results is a cleaner power supply, cleaner signal and a more solid image. Original 7909 does not have that.
3.) 7909J has a "Black Out" CDS button. Press it and all tone control and lights circuits on the head unit are turned off. This allows a cleaner signal as a result of less interference and full voltage being needing to feed only the laser and spinning mechanism.
The 30th anniversary and original model has the CDS Button. It's a tone control bypass switch. There is an amber led that comes on when engaged. It bypasses the two sliders on the top of the unit....bypassing what is know as a noisier section of cd players. Cool feature.
4.) Vocals are cleaner. There's more detail with out the brightness that original 7909 has.
5.) 7909 30th anniversary and 7909J have Copper plated chassis for noise/interference reduction.
6.) All models play CD-R.