There are several steps to level calibration.
If you want to start from the beginning you will have to get an MRL calibration tape.
Chances are the record levels will do, so if you just want a quick fix for playback levels, record a few minutes of a 1 kHz tone for each track onto the type of tape you will be using at 0 VU. Next, play the tape back and adjust the playback levels internally to read 0 VU.
You get at the level adjustments by removing the top from the section with the meters in it. There are six circuit boards mounted horizontally.
From the position of standing in front of the 388:
The bottom two (closest to the VU meters) are for DBX – don’t touch those.
Top left card is for channels 1 & 3
Next card down is for channels 2 & 4
Top right card is for channels 5 & 7
Next card down is for channels 6 & 8
The variable resistors to adjust are R143 and R243 on each of the channel boards.
R143 is the 3rd from the left as you are standing in front of the 388
R243 is the 6th from the right
You make the adjustments with a tiny insulated jeweler’s screwdriver or plastic tool available at Radio Shack.
You think it's frustrating now... wait unitl you've been listening to 1 kHz tones all day.
