M12 Amp

[aoresteen]

2010 Update

I've done some more work on my M12. In 2005 Kendrick Amps re-did the M12. New tubes, caps, rectifier, and OT. They recovered the cab. Came out great!



It was expensive to have it done but worth it IMHO.

In Jan 2010 I had Jeff Andrews at Andrews Amp Labs in Atlanta tweek it up a bit. He put in a weaker preamp tube as it would dime out at 4:00 on the vol. Now the vol control is much smoother and it doesn't dime out so soon. During a phone call with Jeff I mentioned that I wanted to add a 15" cab to the 12" speakers. Jeff told me that it had 10" speakers in it. Well, the M12 came with two 12" Jensen speakers so I assumed that Jeff was mistaken.

When I got the amp back I measured the speakers. Sure enough, it had 10" speakers in it just as Jeff had told me but the front grill openings were for 12" speakers. Strange.

After a little investigating I discovers the truth. Someone had installed a SECOND baffel board with 10" opening to the orginal baffel board. It was screwed and glued in place. I pulled the baffle and the speakers.



After removing the screws the second baffelboard was securely glued in place. I used a regular steam iron to heat up the baffel board and use a putty knife to work the second baffel board free. After about 45 minutes I got it free.



The 10" speakers in it were made in 1975 by Eminence. My guess that sometime in the 70's, someone did an "upgrade" to the M12 and replaced the speakers with 10" instead of the factory 12" size.


The Rickenbacker M12 came with Jensen 12" P12Q speakers. I decided to restore the amp to the orginal speaker specs so I ordered a pair of Weber 12A125-A 16 ohm. These are vintage correct P12Q speakers. Wired in parallel that would be an 8 ohm load and with a 15" Weber 8 ohm external that would bring the total load to 4 ohms.



Putting the amp back together, I installed the 12" Webers and gave them a go. They sound great, much better than the 10" Eminence speakers that were there.

I had J Design Speakers make me a matching 15" external cabinet and I ordered a Weber 15" California speaker for it. Sounds great and looks perfect.

Here's the rear view of the amp and cab:



Now for the front.



I've only had a few hours playing the stack but it sounds sweet!. The speakers need more time to be broken in but I am very happy with this '59 Rickenbacker M12.

[libratune]

Tony -- interesting story, thanks for sharing. Your finished M-12 project looks great!

Do you know what material Kendrick used to do the recover?

[doctorwho]

Tony -- interesting story, thanks for sharing. Your finished M-12 project looks great! ...

+1

[Rick-Sixty-Six!]

looks good,

but I preferred the 'genuine vintage aged look' ..

Steve

[redtoploader]

Did kendrick give you back the original OT??

[aoresteen]

Did kendrick give you back the original OT??

Sorry for the long delay in responding. I was deployed to Iraq last year from April to Oct.


No they did not. They told me it was shot and had to be replaced.

[aoresteen]

UPDATE Oct 2011

When I last left you it was was April 2010. I deployed to Iraq and didn't play the M12 much. I remember it cutting out on me again but as I was deploying to Iraq I didn't have time to monkey with it.

When I got home last November, the dang thing was popping & cracking so I put it aside and focused on my other amps.

Last September I finally got around to using it again and what a disaster. The amp screamed and popped and cut out. Totally unuseable. I took it back to Andrews Amp Lab in Atlanata and Jeff looked at it again. He found two problems.

1. There was a microscopic cracked solder joint on the ciruit board. Resoldering fixed it.

2. The power tubes were loose in the sockets. The power tubes had undersized pins (a known issue for the year the tubes were made) and in the old sockets were not making proper contact. Solution was to:

a. Replace power tubes or
b. Replace sockets.

I had Jeff do both. It is now rock solid - tour ready! Sounds so sweet!!!!!

What a long crayz trip it has been!

[w1nn1e]

Late 1960's. Cool amp that has schematics available. Worth fixing.
It's best not to recover if you can live with it. I found that silver
paint from Michaels will touch up the wood showing through.
These were usually a single 12 Jensen. You scored a good one.