> wondering what kind of things I should mod to make it worthwhile...
I'm wondering what it is good for.
It MUST get a specific load for that photo-resistor to do what it seems to be there for. Indeed this is not a stand-alone patchable preamp, but a module to go into one of Altec's systems. Like for supermarket, ball-stadium, airport.... it isn't Studio stuff, and it isn't funky enough to be "kewl".
> Obviously need to change out the Toshiba A970's for something a little better (probably motorola 2n5087's?)
Not obvious to me. The A970 is a very fine part. Yes the text says 2N5087 is "equivalent, if not improved"; but I don't think performance here is actually limited by input devices.
What I would look at is those RC4558 chips. I thought they were the greatest thing since nickel-bags... back in 1973! But they won't pass high level treble without smearing. I'm startled Altec was still using them in 1994. TL072 is the obvious upgrade. NE5532 will probably work fine, altho R216 will induce considerable offset.
> Also wondering if using the "vox gate" feature is a worthy effort...
If it even works. I think it will need a lot of tinkering to re-discover the required output load. And my experience with simple gates says they may be OK for supermarket announcements but not for artistic speech/music work. External noise-gates with lots of controls are readily available at Banjo Joint and other fine rock-shops.
