Hello. I also have a V6 which I bought new back around 1996 or so. I have the manual around somewhere, but it does not provide much detail. Some time ago, I was reading on another forum and ran into the guy who designed the amp! Kind of handy. Got this info
1) Don't go messing around inside if you are not a tech. The voltage in it can hurt you even if it is turned off.
2) The Deep and Bright switches are upside down to Americas (Up = Off same as wall switches in Britain)
3) Pull on the Mid Knob boosts 500hz which is an odd choice, but was picked by the bass player for Pink Floyd (post Roger Waters)
4) The Deep switch in the Down (ON) position actually cuts mud ~160hz
5) The Bright switch Down (ON) sends all the highest highs around the cut-only volumn knob. So the higher you put your input gain, the less it does which is a plus. You can use the 'Active' input to turn the knob up higher, but I am not sure it matters. Anyway it is WAY too much if your cab has a tweeter
6) The V6 runs really well with 6550's as installed by a good tech! I have not had KT-88's in years. (Have Tung-Sol 6550's in there now that are great!)
7) The EQ is very vague. I used a noise generator and spectrum analizer to show that Bass is like 1K on down, Treble is like 100hz on up, and mid is cut only and I forget what the center is. Makes no sense, but comes from an old Fender Showman design.
8) The V6 sounds great with a sealed cab! It was sitting on top of one I could not afford when I got the amp. Should have got the matching cab! Oops! The EQ makes much more sense on a sealed 4x12 cab.