MB PRO

The MB_PRO connector is used to connect a Sound Blaster card to a Modem Blaster card. The signals can also be re-purposed for other uses.

The pin arrangement is as follows:

9	7	5	3	1
10	8	6	4	N/C

The purpose of the pins, from the point of view of the sound card, are:

Pin	Purpose
1	Audio GND
2	Key, no pin
3	Line-in
4	Audio GND
5	Line out left
6	Audio GND
7	Line out right
8	Modem speaker input. On a sound card, this input receives a line-level audio signal from the modem.
9	Audio GND
10	Microphone in Isn't this mic out for the modem?

AC'97 mod

It is possible to connect AC'97 front panel pins to a MB_PRO header, although it's still a work in progress.

AC'97 pin	Sound card MB_PRO pin	Purpose
5	7	Line out right
6	6	Line out right GND
9	5	Line out left
10	4	Line out left GND

Maybe in the future, this table might get a microphone update if it's even possible. AC'97 lists a thing called "microphone power" and that seems nowhere to be found on MB_PRO.

NOTE: If you connect it like this, the line out coming through the MB_PRO header will be orders of magnitude quieter.

TAD conversion

Some sound cards have an MB_PRO connector but no TAD connector. A cable can be made to allow internal modems with a TAD socket to be hooked up to the MB_PRO connector:

Modem TAD pin	Sound card MB_PRO pin	Purpose
1	8	Phone line audio, from modem to sound card.
2	6	GND
3	9	GND
4	10	Microphone audio, from sound card to modem.

TAD pins 2 and 3 can also be patched to any of the other GND signals on the MB_PRO connector if that is more convenient. The two in the above table are just one possibility.