MOTM

From: gstopp@...,
cc: 
Subject: Emerson Moog secrets (really long)
Date: Thu, 07 Dec 95 12:03:49 PDT


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Sorry y'all in advance for the size of this post.

Excerpts from a 12-6-95 Email from jdm@...:

>
>Is this BEFORE or AFTER the mods you guys did? :) 
>

Before! We did nothing to the sound, we just made the sound more 
predictable and stable.

>
>But is $5000 for a System 15 worth that much more than a $1000 
>MiniMoog?
>

Well, I wouldn't pay $5000 for a System 15. I'd pay $1000, maybe $2000 
max (yes, even these days) but that's based on my own situation so keep 
that in mind. So they're almost even price-wise, and the modular will 
make better noises. But I wouldn't be without a Minimoog too, myself :)

>
>Oh come on Gene, we're not going to let you off THAT easy. Give us 
>the gory details (we could use more words on modular synthesis here)! 
>

Ow! Twist my arm! Oh okay. Here goes: first, see the chapter in Mark 
Vail's "Vintage Synthesizers" book about this machine if you want 
physical details about what's where. Okay, the main console near the 
bottom has all the main sound-producing modules in it. First there are 
three VCO's, each made from a 921A Oscillator Driver/921B Oscillator 
Slave pair. Now traditionally there are two or three 921B's for each 
921A, but in here it's different. Under the VCO's are two CV 
routing/Mixer console panels (model = Console Panel #3). VCO 1 and 2 are 
controlled by the CV routing on the leftmost one, and VCO 3 is by itself 
on the CV routing of the rightmost one. Each CV routing panel has four 
switches on it, for switch control of system-wide CV's to control the 
attached VCO's. On this system, CV1 is the keyboard, CV2 is the ribbon 
controller, CV3 the the output of the sample & hold, and CV4 is external 
(seperate per panel on a 1/4" jack). The VCF a few modules over also has 
a CV routing panel, except on this one CV4-external is a 
voltaged-controlled reversible attenuator that is controlled by the 
programmer upstairs as well as the panel knob. All of these CV routing 
panels as well as the S-trigger routing panels are an important part of 
live sound changes - I'll get back to these later.

The Mixers in the two console panels under the VCO's are 
voltage-controlled by the programmer upstairs with Vac-Tecs. The 
sawtooth outputs of the VCO's go to one mixer, and the square outputs 
plus noise go to the other. Both mixer outputs go to the VCF (which is 
modded for multiple inputs). The output of the VCF goes to a VCA and 
envelope generator to provide the main lead sound output. The sine 
wave output of VCO 3 bypasses the VCF and goes to its own VCA and 
envelope generator. Another envelope generator goes to the VCF 
reversible attenuator mentioned above, and yet another envelope 
generator goes to the CV4 input on the console panel that controls 
VCO's 1 and 2. All envelope times are controlled by the programmer 
upstairs, with Vac-Tecs on the time contant pots, so you have to turn 
them all up or else the front panel will override the programmability. 

The envelope generator that sweeps VCO's 1 and 2 is used for the 
"Hoedown" sound - some attack, all sustain, no release. The program for 
this sound must be selected - VCO 1 tuned to the root, VCO 2 tuned to 
the fifth, VCO 3 tuned to the root and not swept by the envelope because 
it's on a different console panel CV routing thing. This envelope, with 
a different patch, is also used in "Aquatarkus" live for the falling 
tone thing, with attack = zero, sustain = 0, and decay = long.

Keith had a certain technique to get his long climbing pitch sweeps. 
The trick is to start at the low end of the keyboard, turn portamento 
up all the way, and then "walk" up the keys slowly. You can't just hit 
a low key then a high one, because since this is exponential portamento 
the pitch will just zoom up. This way he controlled the slow climb 
rate. Also he played legato but lifted keys enough to cause S-trigger 
glitches which would fire off the envelopes randomly during the climb.

We can use "Aquatarkus" live (I think it's on side 3 of the vinyl version 
of "Welcome Back My Friends...") to demonstrate all this stuff. First, 
assume VCO's 1, 2, & 3 into the VCF into the VCA, no modulation, all EG 
times = 0, all sustains = max, VCO 3 sinewave VCA/EG off (via console 
panel S-trig switch). Then:

*Beginning of song, organ intro, synth lead with VCO's tuned 
root-fourth-fifth.

* Change preset to VCO unison w/filter sweep

* Guitar chord/feedback during synth silence for re-configuration - 
disconnect VCO's 1 and 2 from all CV's so they sit at a low droning 
fifth interval, sample & hold at low sample rate through heavy lag 
randomly changing the VCF cutoff for a background "WWOOOOWWW" effect, 
VCO 3 sine wave solo turned on to play over this. The sample & hold 
also slowly triggers the main sound envelope, which has a long 
release, so that the drone is sustained. This goes on for a while, 
sine wave theme is from Dick Hyman's "Minotour", I believe.

* Solo ends, short silence while VCO's 1 and 2 are re-connected to 
CV1, the sample & hold infulence on the VCF and S-triggers is shut 
off, and delayed vibrato is added from some modules in the expansion 
cabinet above the main one (921 VCO at low frequency, gate-delayed 
envelope generator and mod depth VCA) and the patch is changed to 
VCO's in unison with the filter wide open and envelope times zero.

* Modular and Minimoog played together, in the typical Emerson 
"stretch both arms out and play two keyboards across from each other 
at the same time" style. The Minimoog is on top of the Hammond L-100, 
across from the C3/Modular setup.

* Solo gets a little delayed while "Hoedown" envelope generator is 
kicked in on VCO 1 and 2 CV4, set for attack = 0 and long falling 
decay, and portamento is set to max for the "walk up the keyboard". 
The EG fires off once in a while during the climb.

* VCO 1 and 2 EG mod turned off, solo ends. You may notice that the 
vibrato gets left on all the way to the end of the song.

Okay now it may appear that I have devoted my entire waking life to 
the pursuit of figuring out old ELP solos, but that's not the case! 
Believe me! I just happen to remember all of this from about five 
years ago. Okay I'll go on.

Regarding the ribbon controller - flip on CV2 on all console panels 
and the ribbon controller takes over. Oh yeah don't forget to enable 
it on the S-trig panel as well or the thing won't make any noise. 
Anyway during the ribbon controller solo in "Tarkus" (side 2, after 
"Stones of Years", I forget the name of the part) there's some "ray 
gun" noises produced by the ribbon controller - the pitch starts high 
and falls rapidly like repeated envelope triggers with attack = 0, 
decay = tiny, and sustain = 0. Here's the real story:

On the Moog 956 Ribbon Controller there is plastic coating on the metal 
ribbon to insulate it to keep the holding capacitor charge from being 
discharged by your finger so the pitch doesn't droop. Well on Keith's 
ribbon there is a gouge take out of the insulation about 7/8 of the way 
up, so if you touch this part the pitch will fall as the cap gets 
discharged through your finger. If you're comfortably sitting in a nice 
cozy living room playing the Moog it will discharge slowly. If you're 
on stage under hot lights sweating like a pig it will discharge quite 
rapidly. Press the ribbon down to the current strip and then let it up 
but keep your finger on the ribbon, and this is the effect. Now I don't 
know it this insulation was scraped away intentionally or if the ribbon 
got run over by a road case one day....

There's a few other things, like the sequencers controlling another 
voice made out of modules above the main console, or more esoteric FM 
effects, that are more subject to speculation so I can't be specific 
about those patches. I could ask Keith about it but 1) he probably 
won't remember and 2) he probably doesn't WANT to remember. One does 
get sick of things after a while, after all, even big Moogs.

Alright enough typing for now. Hope this was interesting....

- Gene
gstopp@...