The Akai unit is silver-face in a wood cabinet, measures appx. 11.5" W x 5" H.
FRONT PANEL CONTROLS:
- master volume
- front/rear balance
- 4-input selector switch
- 3-position Mode switch:
1) 4CH Discrete (pass-thru from 4-ch source, controlled by master vol.)
2) 2CH Stereo (pass-thru stereo from source selected by the input switch, also controlled by master vol)
3 4CH Matrix (in conjunction with the 2 "Matrix" controls described below, processes the stereo source seleted by the input switch)
- 2 rotary "Matrix" controls, one for front, one for rear. When the front control is set max CCW, the front signal is maximum separation (as determined by whatever matrix the unit employs); when at max CW, the signal is basically mono, center detent is somewhere in-between.
When the rear control is set max CCW, the rear signal is max separation (again, as determined by the unit's matrix); at max CW the signal is basically mono, center detent somewhere in-between).
I suspect that the matrix employed is a simple, basic "Regular Matrix", and that there is no logic steering going on. Given that the unit probably was built in '71 or '72, I think this would pre-date any serious logic steering schemes then extant. However, all I can say is that the unit really sounds good and affords a huge amount of fun with the abiliity to adjust any sound field to taste with those rotary front/real "Matrix" controls.
I own two units, one bought on ebay ($10) in very good shape; another for about $30 in orig box (new old stock), virgin.
My 4.2 channel system employs one of the Akai units and my QSD-1000, switchable via a Zektor switch, and routed thru an Outlaw ICBM-1 Bass Manager, for stereo subs. Great sound, lotta fun. Depending upon what I'm listenting to, it can be hard to say which unit (Akai or Sansui) I like better - they each provide a different quad sound field (which is one reason I like the remote-controllable Zektor).