Tin Tuirtle Design

Installing Tubes in a JMP-1

clock September 18, 2011 16:08 by author Bald Turtle

After I got in from working on the shed tonight I decided to retube my Marshall JMP-1. Its an older unit that I purchased used in 2006, and manufacture date is around 2003. It has been a great unit and I use it with my Alesis Quadraverb that is 25 years old. The JMP-1 has never been touched but when I got back from China this last time it started sounding really ragged. I had a pair of 12AX7s and decided to go ahead and pull it open to see if I could retube it.

The worst part about this job is pulling off the top to get at the board. There are 3 phillips screws in the back and on on the top that must be removed. Then you have to remove 3 allen head screws from the rack mount ears (6 screws total) before it will come loose. Once its open it is important to guard for static. I use a wrist band cause I am old school, but you can just ground to the case and should not have any problems. My JMP-1 had noname tubes tagged ECC83 so I would bet they are the original tubes. I pulled the schematic from Dr. Tube's site which is a great site for any kind of manual or tube amp schematic. I wanted to know which socket was V1 and V2. I had a Mullard 12AX7 that has some nice cleans for V1 and a Ruby Tubes 12AX7A for V2.

Once I screwed it all back together and remounted it in the rack it was back to normal. I wish my playing was good enough to really put it to the test but unfortunately I don't play enough to really do much. I will say it sounds amazing and has an incredible variety of tone. My unit runs into my PC so that I can use it for playback. I have an old, old copy of Reason that I can record with but I just never seem to have the time.



2x12 Guitar Cabinet

clock March 13, 2011 04:46 by author Bald Turtle

Put up a tab for Projects and a quick page for my 2x12 guitar cabinet.  I need to do some more work on formatting and figure out what I really am aiming for with this site, but its fun to get some pics up.

 

 



<<  June 2018  >>
MoTuWeThFrSaSu
28293031123
45678910
11121314151617
18192021222324
2526272829301
2345678

View posts in large calendar
The Turtle's Shell

Search the Turtle

Search the Turtle

The Turtle's Postings
Front window assembled
Spraying Bay Window Parts
Cherry & Bocote Knife Block
Chicken & Sweet Potato Stew
Window trim is almost done
Halibut with Purple Potato
Back to Missouri
Front Window Project
White Chili
Casserole for Movie Night

Essential Woodworking
David Savage - Furniture with Soul
Marc Adams School of Woodworking
David J. Marks - Gallery
Hickory & Oak Sawmilling
Lee Valley - Tools and Hardware

Essential Cooking
FoodTV.com
Essential Beijing
City Weekend Beijing
The Hutong
Beijing Air Quality Index
An American Doctor in China