love of Ampeg and other Scroll Basses, Part 2
Continued from: http://www.talkbass.com/forum/f8/lov...basses-843684/
anyone still here?
Don't worry, everybody's gonna be here following the link from the end of part one.
Congratulations on your fine Vintage Scroll Bass. You seem to be experienced with building and repairing musical instruments, so you'll probably be willing to deal with your bass yourself, except for the parts you'll be ordering from Bruce.
I suggest you read quite thoroughly the part one thread (if you haven't done it already), for there is LOTS of useful information on restoring vintage scroll basses. Toward the end of the thread, starting with post #855, you will find a step by step restoration and rebuild of an AMB-1 original neck by Bruce, that's really enthralling (well, I think it is).
If you want to give a second life to #1172, I suggest you really consider asking Bruce -or Richard if he is willing to take the job- for the whole restoration job of your bass, for his mastery of this work is second to none (to my limited knowledge).
whew! I thought I did something to close it down!..any way I took everything apart (as I always do with anything old I get!) reglued some areas in the back that were a little loose, fixed the seam gap for now , the area by the pickup looked like the wood shurnk and came apart so I made some shims..took some hacksaw blades to clean up the gap before glueing, took the rca jack and put it in CLR to clean, here's the pickups should have it all back together in a day or so ..still would like to get an remake bridge.. I'm not really trying to restore her just clean her up and do a good once over
Thanks JB for the 'congratulations' I got it all back together and will probably pull the frets later ...I need to enjoy her like she is for now... here's my 'sound' check http://youtu.be/wN-p_eXQwM0
Nice work, Pat! Few of us are brave enough to actually attempt to repair one of these old beasts. Make it right.
An important tip about the Mystery pickup: There needs to be about 1/16" clearance between the underside of the the steel diaphragm and the tops of the magnets. With the diaphragm off, I lay a small ruler across the top surface of the wood chamber, going over the coil assembly. Check the clearance, and adjust it as needed with washers or shims under the two ears. Some came from the factory with washers under the ears to raise the coil. The depth of the routed pockets for the ears wasn't consistent.
Too little clearance, and the pickup won't work. I've had several Ampegs show up here where the pickup was "dead". The coil assembly had worked loose and stuck itself to the underside of the diaphragm. Those magnets are powerful!
Too much clearance, and the pickup gets weak and mid-range heavy. 1/16" seems to be the magic number.
By the way, an easy way to test the mystery pickup without having to put the whole instrument back together is to use a tuning fork. Set the pickguard, with the harness attached, off to the side, with the grey cable plugged into the RCA jack. Plug the harness into your test amp. Get your trusty tuning fork ringing, and hold the heel down on the black block in the middle of the diaphragm. You should get a nice loud A 440 out through your amp.
I didn't check the diaphragm height but I will... right now she's sounding fine I think I'm happy....Bruce I want to order a bridge do you have one...or does anybody else have one for sale right now it has a wooden bridge and is working fine but I thought about having the original setup on the bass anyone?
I'll get to answering your e-mail some day soon.....this weekend will still be kind of crazy with getting my new shop set up and operational. I'm still pulling tools out of boxes and trying to find things.
No, I don't have any completed bridges in stock, but I can make one up fairly quickly. Within a couple of weeks, anyway.
Not likely that anyone will have one for sale. Ampegs are rare instruments, and many lost their bridges over the years.
I wonder why someone would lose their bridge? but go head a make one up and I'm good for it ...let me know thanks!
just a couple more questions does anyone have a picture of the underside of the bridge cover looks like mine is missing some muting foam? so I'd like to see what the original looked like, also I would like to know the height of the bridge itself from the base to the top of the string saddles and the overall size I want to make an experimental setup with a mockup bridge until Bruce can make my bridge ...thanks
The AEB-1 bridge is 2.6" x 1" x 5/16" thick, made from 5/16" x 1" aluminum bar stock. With the saddles installed, the underside of the D and A strings will be about 0.450" above the bottom surface of the bridge. The bridge is made to match the 7 1/4" fingerboard radius, so the outboard E and G saddles are sitting about 0.055" lower.
The bridge adjusts up and down on two jacking screws, which are 1/4-20 x 3/4" long setscrews. They fit down into the two holes in the black block. With the correct setup, there should be about a 0.100" gap between the underside of the bridge and the top of the black block.
So, if you want to make a quick maple dummy bridge that sits right on the black block, it should be about 0.550" high under the D and A, and about 0.495" under the E and G.
You can also use a short length of 3/8" square aluminum bar stock and tap two 1/4-20 holes in it, spaced 1.557" apart. File the string notches in it. I think I made up one like that some years back for one of my test mule setups.
The AEB-1's bridge isn't fussy, in terms of affecting the sound of the pickup. A carved maple or ebony bridge might slightly soften the tone, but it would be right with the character of the bass anyway.
On the underside of the bridge cover, there should be a part stamped from thin steel, which has four fingers. Originally, on the end of each finger was a block of black foam rubber. If you want to, you can cut some squares of adhesive-backed black foam weatherstripping, and stick them on the ends of the fingers. That will be a pretty close replica of the original foam blocks. But, it's hardly worth the trouble. The foam muting system barely works at all. It was a silly design.
I think the reason why so many Ampegs lost their bridges is because of the lack of strings. The bridge isn't attached, and falls off without the strings on. Many Ampegs sat for decades in closets without strings. Many have shown up in pawn shops and auctions with no strings, no bridge, no bridge cover, no case.
Pat - nice work. welcome to our small little club. but we are a very dedicated folk :-)
sounds like you are almost there Bruce. I hate moving so i cant imagine what you have been through.
hopefully my AMB will one of the first things you get to work on, pretty please.....
thanks jim ..really glad to be a here and a owner ... here's one I found
one of those japanese ampeg AEB-1's showed up last night on ebay, didnt last but 20 minutes and it was sold. Anybody here grab it?
not I...was wondering has anyone ever put any foam or anything around and under the pickup ...my pickup picks up when I bump my bass or tap on it... thought some foam would help reduce that??
That's an inherent design feature of the Mystery pickup! No way to get rid of it, other than removing the whole pickup and replacing it with a boring Fender-type pickup. Remember, the Mystery pickup is a "mechanical percussive" design. The magnetic coils detect the motion of the steel diaphragm, not the strings. And the diaphragm is mounted right to the wood structure of the body. Tap on the body, and the diaphragm wiggles.
That's the fun of a Scroll Bass with a mechanical percussive pickup. Drumming and tapping on the strings gives you an extra thump on the notes, similar to an upright bass. An AEB-1 is not a Fender. It's made to be played with upright bass-style right hand technique.
Note: If the thumping is excessive, check to make sure that the coil assembly isn't loose and rattling around.
alright here I am playing my Ampeg, AEB-1 bass on you tube ..dig it! http://youtu.be/PmvWUajLEQw
and the chart if anyone wants to try...try to play it using open a, d, and g strings and stay at the fifth fret ...hard to do!
Well….it's no Ampeg, but close enough for now. Started this almost 3 years ago. Thanks to Bruce for the body, hardware and great advice. I'm leaning towards tearing it down this summer and refinishing it in black.
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