Please explain the 911a

[EricK]

How exactly does it work?

Can you give an example of an application for its use? I know it is traditionally paired with two Envgens.

I purchased a Mos-Lab 911a dual trigger delay which is supposedly a close replica of the Moog. While Seb classifies it as a trigger delay, functionally it is delaying gates. In my limited experience with it I have to hold the gate open for the length of time on the panel for it to delay that amount.

It is not as if pressing and immediately releasing a key will get that gate delayed by 10 seconds. That will only delay by a few milliseconds.

It is proving to be not quite as intuitive as I thought it would be, but nonetheless it is a very interesting module.

I'm using it with my sequencers, and I'm discovering that I can't just delay any gate signal to any time.



Eric

[latigid on]

The trigger delays I know of have two controls: one to set the time between the original and delayed signals and a second to set the delayed signal's gate time. The MOS lab unit might be thought of as a lag generator where the output only turns on once it reaches the level of the input (like a comparator). To measure the length of the first gate and replicate it on the delayed output is trickier but not impossible.

[EMwhite]

Maybe there is something wrong with it.

Send it to me : )

Should be as simple as it appears, send it a gate with say a 1/2 sec gate on time and a 2 second delay and two seconds after you pressed the key to initiate the rising edge of the voltage gate, the output will send another gate.

What I do NOT know and have always been confused about is how long is the resulting, delayed gate and I think it will just be a trigger, which is a short duty cycle.

So if you are playing legato, the resulting delayed gate will just be a fixed 100ms or something.

The COTK module has a gate width output which addresses this. For plucked sequenced sounds this is fine and actually you are 'pinging' an envelope generator and can mess with release, have reverb on it, etc.

I just ordered a bunch of parts to build up a YuSynth gate delay (which the STG is based upon) and a vintage Moog design using parts which look on paper to be comparable. It will likely be another science project that I will never finish... I can tell you that Knotty Puncture built up a gate delay following the Moog schematic and it doesn't work, or didn't as of a posting he made a few weeks back (either here or on Muffs).

sigh...

[CZ Rider]

The Moog 911A was a support module for the 911 envelope generator. Simply put it made an ADSR envelope into a DADSR. And that is exactly how it works as the first stage being delay. If you release the key or S-trigger before the duration of the delay time, nothing happens. After the delay the envelope begins the other stages as the 911A passes the S-trigger. The 911 will act like any other envelope with a response from the S-trigger duration determining the slope of the envelope.
The Moog 911A is nothing like a digital delay and is just a timing stage that needs the S-trigger duration to be longer than the delay time to have any effect on the connected 911 envelope.
With the combination of the 911A and 911 envelopes, complex contours can be created. Can also be used for a delayed vibrato by patching a slow modulation source through a 902 VCA to the VCO input, controlled via a 911A/911 combo. The possibilities are there, just won't act like a delay where the input trigger/duration is mimicked. Moog envelopes are fast and the 911A can be set to give a double trigger in time with a sequenced piece or keypress. Lots of uses and the original R.A.Moog system IIIC/P had a three 911 and one 911A combo that was very usefull for non standard type envelopes. This is the setup I'm using now and really like the versatility of the original design.


I think some confusion comes from other manufactures calling a pulse a trigger, and a signal that has the same duration as a key press a gate. Moog S-triggers are like gates where the trigger duration is the same as the keypress duration, therefore the 911A was correctly identified as a dual trigger delay.
Not sure how close the clones are, but the circuits look the same.

[noddyspuncture]

Hi Eric,

I bought my R.A.Moog system with all sorts of modules.... some of them complete, unidentified mysteries...!
It also came with a DualTrigger Delay...albeit only a front panel with no actual circuitry.
So I decided to build my own... and put it inside the 911A case.

i built it because I found out I really needed one... as I play in an ELP tribute band.
And ELP's "Toccata" uses the module exclusively for the lead synth patch. Check it out on YouTube...

That is the what this module does.. it delays the effect of a trigger. But you do need to hold the note until it takes effect.

ELP's "Toccata" should clarify.

Cheers,
Tom

[EricK]

Thanks CZ and Tom.
I'm going to spend a lot of time with it.

I was initially under the impression that I could patch something such as using the Voyager's touchpad to activate a sequence, but it would be delayed. I see it is going to take a lot of playing around to get the hang of it.

What I have been experimenting with lately is having the q960 controlling the q119 except that the q119's shifts are occurring on the dotted 8th. It is like an audio delay except it is two synth voices.


(This is really just a test and I tried to recreate some reverb effects on board that I liked before but it started to clip the effect)
https://www.dropbox.com/s/5ghofy7d8woya ... y.mp3?dl=0

[robotmakers]

This is another way to think about it. The way these retro gate or trigger delays (like the Moog) work is the following: they take a GATE as input. The RISING edge of the gate is delayed. The TRAILING edge is unchanged. So, if you try to set the delay to longer than gate "on time", you will get no output.

Cheers,
Roger

[JohnLRice]

Thanks for all the explanations in this thread! I have the COTK C911A and I don't think I've correctly understood how it is supposed to work, until now hopefully! Must go experiment . . . .