The Moog Modular Model "25"

Last update: September 2001

The Moog Modular "Model 25"

(click for a larger pic)

Model "25" specs

            Model 15 cabinet
    +-----------------------------+
    |  9   | 9 | 9 |   9  | 9 | 9 |
    |  2   | 2 | 2 |   0  | 2 | 2 |
    |  7   | 3 | 2 |   4  | 2 | 2 |
    |      |   | B |      |   |   |
    |      |   |   |      |   |   |
    +-----------------------------+
    | 9 | 9 | 9 | 9 |  9  | 9 | 9 |
    | 2 | 2 | 2 | 2 |  2  | 2 | 2 |
    | 1 | 1 | 1 | 1 |  1  | 6 | 6 |
    | B | B | B | C |     |   |   |
    |   |   |   |   |     |   |   |
    +-----------------------------+
    | C | MIXER  |TRNK| MIXER | G |
    | V |        |----|       | A |
    |   |        |    |       | T |
    | I |        |CV  |       | E |
    | N |        | PRC|       |   |
    +-----------------------------+

    Mod     S/C/Mod     Description
   -----------------------------------------------------
    927     Custom      5 band formant filter
    923     Stock       LP/HP/Noise
    922B    Custom      Dual VCA
    904     Stock       LP Filter
    922     Modified    VCA, (902 base, variable/reversable gain)

    921B    Modified    VCO (with front end from 921A)
    921C    Custom      Dual LFO, (sine, ramp, square)
    921     Stock       VCO
    926     Modified    EG, (911 base, added delay)

    CV IN   Stock       CV trunks from keyboards
    Mixer   Modified    3x1 mixer, +/- out, DC bias, coupling
    TRNK    Stock       Output trunks
    Mixer   Modified    3x1 mixer, +/- out, DC bias, coupling
    CV PRC  Custom      CV processor, (inverter, bias)
    GATE    Stock       GATE trunks from keyboards

    Quan  Module          Specials
   --------------------------------------------------------------------
      3   921B VCO        Reworked frontend, added PWM/SYNC
      1   921 VCO
      1   923 LP/HP/NOISE
      1   904A LP VCF
      2   902 VCA         (2) voltage controls, Reversable Attenuation
      2   Jensen VCA      DC capable
      2   911 EGs         Added Delay
      2   LFO             CEM based, no voltage control
      1   5 Band
          Formant Filter  Dual ganged 10turn pots, no VC, from Electronotes
      2   3 in mixer      In/Out DC capable, Rev Attenuation, Variable Bias

History

The system was put together by Dr. David Jensen, an engineer from Moog who left in 1974. The "M-d 25", as Dr. Jensen named it, is made up of stock Moog modules, modified modules, and totally custom modules. The machine was built in 1974 on site at the Moog factory. All of the custom panel work is labeled with the classic Moog lettering and outfitted with stock Moog knobs and the general Moog feel. The cabinet is from a Model 15, with the power supply from a Model 55.

Many of the modifcations that Dr. Jensen made (such as adding delay to the stock 911 EGs or rolling the 911A Oscillator Controller into the 911B VCO) were planned for later revs of these modules, but Moog never brought them to market. Projects such as the Mini were on the drawing board at the time, and the future didn't look very "modular".

I bought the system from Dr. Jensen in June of 1996; 2100 miles in 3 days, what a drive! And, if that trooper in Tennessee is reading this, I just wanted to say "hi" and thanks for not being about 2 miles closer to the border when I was running over 100 MPH...

The list of modifications is fairly extensive, these are some of the highlights:

      921B VCO
        Functionallity of the 921A is rolled in
        Variable pulse width and PWM is onboard
        10-Turn pot for frequency
        Octave switch runs from LO to 64x

      902 VCA
        Dual voltage control inputs
        Variable gain VC input, (-/+ 3x)

      911 EGs
        Functionallity of the 911A is rolled in
        Max ADR times increased

      3x1 Mixers
        DC capable
        Reversable attenuation
        Gangable inputs
        Variable DC Bias

No, it's not for sale. :)

Back to "The Wall"