I INSTALLED THE JB!!!
Step 1:
Ok here it goes. First of all, the legs of the pickup on the JB7 do not fit into the RG7-CT. The legs require fileing to shape them triangular. I would recommend placing the pickup in a plastic bag, and poking a leg through to work on it. This way no metal fragments stick to the inside of the pickup and F it all up. (trick i learned from working on rc engines.)
Step 2:
The tough decision. You just gatta ask yourself 1 question. Do i feel lucky? Well i didnt, allow me to explain. The pole pieces on the pickup stretch down pass the legs, and the RG7CT pickup cavity is too small, so the pickup will be pressed against the strings rendering the guitar useless unless something is done about it. You got two choices. Route the area in the cavity where the pole pieces are, or clip the poles. The way i figure, i'd rather not chop up my baby. I cut the poles (i read somewhere on this forum, it only affects the pickup by making it hotter. a user got that from seymour duncan cust support.) Think about it, if you make a mistake, would you rather it be on a $70 pickup or $1000 guitar?
Step 3:
Height ajustment. By now the pickup should fit in the cavity perfectly. But ut oh, how do you make it so u can ajust the height? EASY! Peel off the rubber bottoms from your old pickup and place them side by side under the duncan in the center. If they dont stay on, do what i did and place electric tape across them. Dont worry about them not being tall enough. Your pickup will be plenty close to the strings. To be honest, placing springs under the legs will be too much, cause you will be squishing the springs, and the pickup will be too high because the spring will be collapsed on itself.
Step 4:
Wire it up and RIP!
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My evaluation of the pickup is as follows. I love my 707's in my 7621. However, i think the tone of the JB is so unique, that one can not be compared to the other in a "whats better contest." The JB (and i guess especially after clipping the poles) has alot of HIDDEN gain! Beware! You may not think your crankin out crazy distortion, but thats because the pickup is so clear sounding. Harmonics ring out beautifully, and chords just have that amazing "I belong in guns n' roses cause it sounds like slash is playing these chords." Very smooooth sounding. DO NOT BE FOOLED, the JB isnt only for rockers. Harmonics on the Low B or if your like me, the Low A can now be done with ease.
If i was asked to compare it to the original pickup, i would say, "much more alive sounding", "much clearer sound", "wailing harmonics". The JB is the correction to the RG7CT that should've been made a while back.
Oh, and if you decide to route the guitar, send me pictures of the pup cavity before you install the pickup. I'm dying to see the work of one brave soul on such a beautiful and now "sounds as good as it looks guitar."