What is the aprox duration of the ENV stages on the Grandmother?

Mother-32, DFAM, Subharmonicon, Grandmother, Matriarch
Post Reply
Mrtwoo
Posts: 1
Joined: Mon Mar 27, 2023 3:23 am

What is the aprox duration of the ENV stages on the Grandmother?

Post by Mrtwoo » Mon Mar 27, 2023 3:32 am

Hi everyone,
I want to try to port patches onto and from the Grandmother, but I could not find what is the approximately duration of the ADSR stages on the Grandmother. So, for instance, how long time it takes in seconds/milliseconds, for the Attack phase to complete, if I have the Attack knob on its maximum value? Is the relation to the knob scale linear to time, or is there any progression? Meaning, can I relate Attack Knob set to 1 = "N" seconds and than simply multiply "N" times knob position to get the total time?

Thanks.

User avatar
stiiiiiiive
Posts: 2536
Joined: Tue Aug 30, 2011 2:58 pm
Contact:

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by stiiiiiiive » Tue Mar 28, 2023 3:24 pm

Hi MrTwoo and welcome to the forum.

I don't have a GM but I'm usedto Moog manuals and I bet the values are indicated in there. Have you checked?

sdwillingham
Posts: 56
Joined: Wed Feb 16, 2022 1:42 pm

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by sdwillingham » Wed Mar 29, 2023 4:15 pm

I don’t have a Grandmother, but I have measured my Matriarch and I would speculate that the circuits are the same.

Unfortunately, the envelope design is not very good if you care about short timings. The old-school analog circuits used in these synthesizers depend on custom potentiometers to get good envelope resolution.

Here’s approximately what you can expect (measured attack times):
1) Roughly linear from 12 noon (2.2 seconds) to 5PM (13.3 seconds)
2) Roughly linear from 9AM (700ms) to 12 noon (2200ms)
3) Touchy and difficult to control below 9AM. Absolute minimum time is 2ms. No ability to get any attack between 2 and about 30ms. Hits 200ms around the 1st tick mark (7AM)

Sorry to say it , but this synth would be better with well-done digital envelopes. Analog envelopes are only great when you use much more refined potentiometers (such as in the Model D), or maybe restrict the timing range to 2 seconds max.

User avatar
stiiiiiiive
Posts: 2536
Joined: Tue Aug 30, 2011 2:58 pm
Contact:

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by stiiiiiiive » Thu Mar 30, 2023 2:21 pm

Now that's an accurate, useful answer :)

With the same potentiometers, I guess using bigger knobs can achieve more accurate settings.

User avatar
MRNUTTY
Posts: 319
Joined: Fri May 02, 2014 2:54 pm

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by MRNUTTY » Mon Apr 10, 2023 6:18 pm

I replace the envelope timing cap (usualy 10uf) with a smaller value, typically 2.5-5uf, in all my analog monosynths. i live for plucky fast envelopes. if I need a slow attack, I'll just turn the knob. adding a switch for different cap values also works. what's important is the End Resistance values at the CCW terminal, and a real audio taper - not an 2/3-piece linear approximation. the ideal part is a 10% audio taper pot, didn't have to be 'special' in any other way except a tight tolerance will match the front panel numbers up better. a mid point of 2sec's and an extreme of 10sec indicates a 20% taper these days i guess...
stiiiiiiive wrote: Thu Mar 30, 2023 2:21 pm Now that's an accurate, useful answer :)

With the same potentiometers, I guess using bigger knobs can achieve more accurate settings.
up to a point, these little 9mm pots only have so much rotational resolution. over an inch is a waste of panel space. too big and the torque will probably bust it past the mechanical stop.
VoyagerEB, Minitaur, LittlePhattyII, 4xSlimPhatty, Sub37, MF[2x101,2x102,103,104M,105,105B,105M,2x107,108M], 3xCP251, XV351, MP201;
2xMother 32, DFAM, Subharmonicon;
System 55 and Minimoog clones with lots of mods.

User avatar
MRNUTTY
Posts: 319
Joined: Fri May 02, 2014 2:54 pm

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by MRNUTTY » Mon Apr 10, 2023 6:31 pm

sdwillingham wrote: Wed Mar 29, 2023 4:15 pm Here’s approximately what you can expect (measured attack times):
1) Roughly linear from 12 noon (2.2 seconds) to 5PM (13.3 seconds)
2) Roughly linear from 9AM (700ms) to 12 noon (2200ms)
3) Touchy and difficult to control below 9AM. Absolute minimum time is 2ms. No ability to get any attack between 2 and about 30ms. Hits 200ms around the 1st tick mark (7AM)
sd, did you graph the Rotation to Attack timing? your description appears to be 2-part linear;
VoyagerEB, Minitaur, LittlePhattyII, 4xSlimPhatty, Sub37, MF[2x101,2x102,103,104M,105,105B,105M,2x107,108M], 3xCP251, XV351, MP201;
2xMother 32, DFAM, Subharmonicon;
System 55 and Minimoog clones with lots of mods.

sdwillingham
Posts: 56
Joined: Wed Feb 16, 2022 1:42 pm

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by sdwillingham » Mon Apr 10, 2023 10:52 pm

Yes, the taper appears to be largely two linear segments. But in addition to that, there are significant end-of-track effects and jumpy resolution at the CCW end. I’m not sure what is going on. I separately measured an Alpha 9mm 1M audio pot and it behaved somewhat better in the fine resolution.

Of course, 4 orders of magnitude is a tall order for potentiometers and required for designs to achieve millisecond resolution with 10 second max times. It really requires a physically large track and complex taper. To achieve timings like the Minimoog requires a log taper closer to 5%, but also continued tapering at the CCW end. Very hard to source, and to retrofit onto modern PCBs.

The online tapering graphs provided by the manufacturers are almost useless. The crucial information is in the resolution of the first 30 degrees of rotation. But, of course, analog synth envelopes are a very niche application.

User avatar
MRNUTTY
Posts: 319
Joined: Fri May 02, 2014 2:54 pm

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by MRNUTTY » Tue Apr 11, 2023 9:04 am

I have seen very poor performing potentiometers coming out of china in Behringer 'Alpha look-alike' potentiometers.
- they lack tensioner mechanism to control LF damping, using only a moderately viscous goop.
- the goop also has a bit of elasticity, making tuning difficult when the goop relaxes a bit, and moves the wiper. if I watch the timing envelope when adjusting this, i can see the timing move slightly in the reverse direction of rotation.
- the End Resistance (end of resistive track), is much too high for fast monosynth env timings. this is the gap where full CCW timing jumps with a slight CW turn.
- the two part linear 'solution' creates a discontinuous gap in the envelope timing around 60% rotation (where the element splice occurs), causing jumps or gaps in addressable in timing.

I used a resistance decade box to model the correct taper and value for the 911, 911A, and 961. the Alpha Taiwan 9mm pots have much better E.R. and a real audio taper. the change is remarkably better. I recommend them highly along with a 2-10x range switch on the cap to deal with the four orders. you found exactly what I found with 9mm pots. there are definitely better parts out there for this application.

I was hoping Moog used better pots. time to open them up i guess...

here i cracked open three types of pots.
3E741C48-C134-45E5-B912-BE305BE0C923.jpeg
here blue arrows locate E.R. and the Element Splice (the diagonal cut), and the wide wiper to help smear the splice. the way to tell Taiwan Alpha from this type of pot clone is the package pins are on opposite corners. you can also see the slightly brass colored collar on the TA part inside the manifold where the rotation stop is. Behringer parts has no such device. N.B. this is actually a reverse audio taper part here, the resistive element assembly is upside down and the slice is at 40%. the forward audio taper splice is at 60%.
80CF1567-1A35-41F2-89A4-3B8368D261D7.jpeg
N.B. when I say "Behringer part" i mean the part Behringer used, not that they make the part. these parts may be in other instruments other than behringer since they look remarkably like TA brand. Behringer also used a Bourne knock off (not pictured) also cost reduced to marginal performance.
VoyagerEB, Minitaur, LittlePhattyII, 4xSlimPhatty, Sub37, MF[2x101,2x102,103,104M,105,105B,105M,2x107,108M], 3xCP251, XV351, MP201;
2xMother 32, DFAM, Subharmonicon;
System 55 and Minimoog clones with lots of mods.

User avatar
MRNUTTY
Posts: 319
Joined: Fri May 02, 2014 2:54 pm

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by MRNUTTY » Tue Apr 11, 2023 9:36 am

I'd be willing to explore modifying my two M32's, SubH, and DFAM pots along with your *mother if you want to do it.
VoyagerEB, Minitaur, LittlePhattyII, 4xSlimPhatty, Sub37, MF[2x101,2x102,103,104M,105,105B,105M,2x107,108M], 3xCP251, XV351, MP201;
2xMother 32, DFAM, Subharmonicon;
System 55 and Minimoog clones with lots of mods.

sdwillingham
Posts: 56
Joined: Wed Feb 16, 2022 1:42 pm

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by sdwillingham » Tue Apr 11, 2023 2:00 pm

MRNUTTY wrote: Tue Apr 11, 2023 9:36 am I'd be willing to explore modifying my two M32's, SubH, and DFAM pots along with your *mother if you want to do it.
Great information and insight in your previous post. Thanks for offering to mod, but I am fine with doing the work myself. I plan to also do some version of Synthbuilder’s mods on my Matriarch and will modify the envelopes at the same time.

If you can recommend specific mouser/digikey/etc part numbers for good envelope pots, I’d be very grateful. Especially so, if you can locate 9mm pots with a taper below 10%.

The 2022 Model D reissue has really opened my eyes with respect for the value of envelopes with good resolution.

User avatar
MRNUTTY
Posts: 319
Joined: Fri May 02, 2014 2:54 pm

Re: What is the aprox duration of the ENV stages on the Grandmother?

Post by MRNUTTY » Tue Apr 11, 2023 6:06 pm

yeah, I meant just share the results of a swap. shipping stuff for mods never makes sense. :0)

I've gone through and swapped all the audio taper pots in the behringer gear; they're the Q in ladder filters, and any envelope or tigger/gate timing ADR pot; and any linear pot that has to do with tuning, or fine pitch CV. then the stuff actually gets funky. I also switch out the 10uf cap for timing ranges. also done it with the monosynths and paraphonics that all use the same RC timing circuits. it's way more accurate and responsive.

I've ordered all my replacements pots from Thonk in the Uk.

https://www.thonk.co.uk/shop/alpha-9mm-pots-dshaft/

you can start with RV09AF-40-20K-B5K to get a data sheet them pick your shaft type and length, and bushing type. but that's the foot print and package type we're dealing with.

being able to play around in the <20ms area accurately and repeatably is worth the time to do.
VoyagerEB, Minitaur, LittlePhattyII, 4xSlimPhatty, Sub37, MF[2x101,2x102,103,104M,105,105B,105M,2x107,108M], 3xCP251, XV351, MP201;
2xMother 32, DFAM, Subharmonicon;
System 55 and Minimoog clones with lots of mods.

Post Reply