Couldn't find a manual either, but if I had to guess, minimum attack would be fast...?
Could be wrong. Cranked to its fastest attack and fastest release would yield the most obvious difference (not necessarily the best) in the sound as you adjust the threashold to have the comp react to the signal. You might be able to find out from that.
I forget where I read this, but when I was learning about compression, I took the following advice and it opened some understanding for me...
- Start with slowest attack, fastest release (easier to hear on something percussive like a snare or a whole kit)
- Set the ratio on the high side (10:1 would be on the high side, whereas 2:1 would be on the low side)
- Then bring the threashold down so that the signal starts to trigger the compression.
Note: with this type of experimentation, don't have the compressor always doing compression. Have the signal only "working" on the peaks (to varying degrees).
From there you should be able to "choke up" on the attack, making it faster and faster, listening as you go. With something like a snare you'll hear it darken up. When you hear that you may want to back off and make the attack a little slower. That would give you a sort of middle of the road kind of compression.
- Then back off the ratio a bit, maybe bring it down to between 2:1 and 4:1 or so.
- Lastly, you'd probably want to change the fast release to something a little less fast. Toooo fast a release can be kind of weird.
Of course that's just a little bit of help to get you to a bread and butter understanding of compression. There's so many ways you can alter tone and make music more (or less) impactful as you want. There *are* times where you may want to dig in and have the compressor always working, but if you're just getting going, save that for later.
Lastly, I will say that, while the advice you may read in a lot of books and interviews is awesome, I found that people were often referencing a very specific unit. In my naevite, I would read about the attack amounts and dial them up on my crappy 1992 Digital Performer compressor and wonder why I didn't hear the sound of what they were describing (which was like, an 1176
Anyway, I hope that's helpful.