Ordered and installed a 700RB-II preamp board in my 700RB-I. There wasn't too much solid info about the upgrade here (or at least that I could find), so I thought I'd post some pics and my thoughts/experience/findings. Board was about $85 or so.
I'm no master bassist, but I'm no stranger to amps and electronics. Construction
The 700-RB-1 preamp uses lots of tantalum capacitors (some say inferior in some respects to other types) and carbon film resistors (some say noisier than metal film). Looks like what may be some electrolytic signal caps too, which is arguably not ideal.
The 700RB-II preamp uses all Metal Film resistors as well as nice box film caps. Pots are definitely a different make, and look sturdier. Opamps are TL072 on both, but a different make. Sound
Noli Valdez from GK said about the differences between the two boards: "The gain structure between the two are very similar, the voicing is a little bit different, Mark II boards are more oriented towards 800RB sound but you can always set it two your preference via EQ controls."
I've never played a 800RB, so I can't comment there. Noli was great to work with btw.
In practice I found the new board had a good amount more gain on tap. Sounded like the same structure, but just more of it. I could easily dial in "too much" with the boost knob. Overall I felt the 700RB-II preamp sounds much warmer and slightly less "hi-fi". It definitely can growl.
I use a 5 string ESP J1005 with Cobalts and a GK 410T-XB cab. I felt the low B was much stronger and it seemed the fundamental came through more. The "XB" cab really goes low. I felt the 700RB-II preamp responded better to my effects (you can check my profile for a list). The Green Russian Muff blended with dry into the amp set neutral with boost cranked and contour at 9 oclock sounded pretty delicious. The VT Bass with plenty of gain sounded great as well.
This could have been my imagination, but I feel the RB-II preamp could get more dynamic/percussive. I believe my wife yelled at one point "good god the dishes are shaking!" (like she's not already used to that
) I may have just been turning it up more because I was digging it. The two boards, 700RB-I on top, 700RB-II on bottom: The board installed:
I actually plan on making a standalone DI/Preamp out of the 700RB-I board to use with my PC and/or Epiphone Valve Jr that I modded for bass. I just need to find/make a suitable 15v/35v supply and I'm in bidnizz. I'll probably start a new thread about that eventually.