Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Misc Schematics and Layouts => Topic started by: davohilts on January 05, 2020, 07:20:37 pm

Title: Looking for Rickenbacker M11 schematic using 12Ax7's in the preamp
Post by: davohilts on January 05, 2020, 07:20:37 pm

I'm looking for a rickenbacker M11 schematic for the model that has 4 inputs and uses 12AX7 preamp tubes, can't find it anywhere on the web so thought I'd check in here, thanks for any help!
 Note: the common one I've come across has octal tubes in the preamp and 3 inputs!

Title: Re: Looking for Rickenbacker M11 schematic using 12Ax7's in the preamp
Post by: sluckey on January 05, 2020, 09:02:19 pm

That pic screams homemade to me.

Title: Re: Looking for Rickenbacker M11 schematic using 12Ax7's in the preamp
Post by: K Teacher on March 31, 2021, 10:01:37 am

Hi,
I also have been looking for the Rickenbacker M-11 using 12AX7 in V1 position and 12AU7 (?) in V2 -- PI.
My understanding, after studying several pics on the web is as follows:

a)   M-11/ 3-Inputs w/ 12AX7 preamp:
This circuit uses a paraphase-splitter and its circuit is similar to the Lectrolab R500, which can be used as reference. The Lectrolab R500, uses 12AY7 tubes but the circuit is practically the same.
Link:  https://el34world.com/charts/Schematics/files/Lectrolab/Lectrolab_r500.pdf

NOTE: careful, there are Lectrolab R500a, b and c, which are completely different circuits.

b)   M-11/ 4-Inputs w/ 12AX7 preamp:
This circuit uses 12AU7 phase-splitter inverter/ concertina (like the Rickenbacker M-16) and its circuit is similar to the Harmony 305a, which is the same as Harmony 306a minus tremolo circuit (V5 – 6SH7).
Link:  https://el34world.com/charts/Schematics/files/Harmony/Harmony_h306a.pdf

My understanding is that all of these three amps brands were built in California, so I wouldn’t be surprised if all of them were designed by the same person or copies of each other with small changes in the circuit.
Hope this helps…