Opened up my MXR M-151 Doubleshot.

[z-zero]

First a small review on the sound of the pedal, its a terrific sounding quite switching pedal. No noise in the background and the distortion tone is is insane, sounds almost multi-layered, but no none musical tones ever come out of it. Built like and tank, I'm very pleased with the way this pedal sounds, both channel 1 and 2, but I prefer channel 1 (DD-11).

Inside the box I was surprised to see exclusive surface mounted compents, reverse engineering this baby is going to be a pain, but I think I'll try anyway, at least for channel 1 (DD-11 circuit.) The major ICs used were MC33179D, 33178, and I think the CD4016BCN. Also a 14013B. The PCB is a dual sided by the way.

Datasheets:

MC33179D and 33178 (quad and dual op-amps)

http://www.onsemi.com/pub/Collateral/MC33178-D.PDF

CD4016BCN (quad switch)

http://www.fairchildsemi.com/ds/CD%2FCD4016BC.pdf

14013B (Dual type D flip-flop.)

http://www.physics.utah.edu/~springer/phys6610/data_sheets/MC14013B.pdf

There are also numerous SM (surface mount) resistors and caps along with some SM transistors and diode configurations. Looking at whats in it would appear that the 2nd channel is really just switched into channel one with some different tone controls and active filters, but only time will tell.
Almost wish I'd just bought the DD-11 it would be easier to see the important stuff.  

The pots are as follows

Channel 1

Output - A20K
Bass - A10K
Mid - A10K
Treble - B10K
Gain - 1M

Channel 2

Output - A20K
Bass - A10K
Mid - A10K
Treble - B10K
Gain - 500K

There is also 5 small 4 legged IC's labeled JTp 37, but I'm having trouble gettin info on these. The parts count is high on this pedal the R and C number are both close to 200 each. There are 3 MC33179D quads and 3 of the duals. There are 6 of the CD4016BCN quad swirches, so there is alot going on. Only 2 of the dual D flip-flops. I wonder if I can borrow someones DD-11 to get an easier look at channel 1?

Just thought I'd throw this up and contribute something on my first post, the more I learn about the M-151 the more I'll share the info. I use it to play out every week so I'm looking at only tearing it apart once a week and spening an hour or so because I don't have alot of time really. Great site, I've been building stuff for a while and just recently got back into it. Thanks for the great site/community.

z-zero

[Mark Hammer]

Thanks for your generosity in sharing information here.  Much appreciated by many, I'm sure.

The number of 4016s is conspicuous.with respect to the number of switches on the chassis.  However, rereading the review in Guitar Player that Dunlop has posted reveals that the otherwise inconspicuous "Focus" button switches a whole lot more than its tiny profile would suggest.  In that light, the number of 4016s signals how much thought has gone into the user-friendliness of the "revoicing" strategy employed.  Hats off to them.

The Motorola dual and quad op-amps have been largely underexplored here, with the possible exception of the various Boscorelli circuits that indicate use of them.  Perhaps its time to explore what their strengths and weaknesses are.  Anyone care to provide a guided tour through the finer points of the datasheets, or maybe suggest contexts where they are sound choices?

[Marcos - Munky]

Thanks for share the info. I was searching for some info about it.

[Dave Z]

that sounds intense...considering the sze of the components most of use bui;ding your own will require a enclosure the size of a shoebox.

Nice to se esomeone is actually designing new stuff in the distortion arena...beeen looking for a modern DD maybe I'll check out the MXR. Thanks for the notes.

[z-zero]

The pedal is one of the best distorions I've heard in a while, one could get by with the DD-11 if you need to save a little cash and don't mind not having the 2nd channel. The 2nd is really only different from the first in that it has much more Bass in it. Better then a Mt-2 IMHO. Very good tone and it cuts through the rest of the band when I'm playing. So if your looking for a BIG guitar sound I highly recommend it. I'm running a Parker nitefly-SA through a Marshall MG100HDFX combo with a single 12" speaker. Makes the amp sound much bigger then it is and puts out a very tube like tone, but the response is much tighter becasue its all SS and VS stuff. Very pleased with my purchase. Its does not sound like any retro tone or the older stuff its very good and different. Some people say it colors the sound, but if you set it up right it can be very transparent.

z-zero