Grandmother - calibration, patches and the don‘ts

Mother-32, DFAM, Subharmonicon, Grandmother, Matriarch
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BLFTJ
Posts: 3
Joined: Fri Mar 22, 2019 3:59 am

Grandmother - calibration, patches and the don‘ts

Post by BLFTJ » Fri Mar 22, 2019 12:31 pm

Hi everybody,

I‘m new here so forgive me if the followin may seem stupid. I already own a subphatty, big fan, few other synths, toys... everything fine... I‘m about to buy a grandmother but i dont know much about the modular world. Plus i read a lot and found a few things that made me think...

First question:
I heard about issues with calibration of the mod wheel, tuning oscillators etc. A „need to calibrate“ grandmother. How would i find out if i need to calibrate something, will i hear it?

Second question:
For a modular-beginner... can i harm the circuits by patching somethin wrong? I mean is there any mistake that i should definitly avoid while doing patches?
Thanks in advance!
Greetings from germany!

liviou2004
Posts: 14
Joined: Thu Jan 31, 2019 5:47 am

Re: Grandmother - calibration, patches and the don‘ts

Post by liviou2004 » Sun Mar 24, 2019 11:00 am

Hello,
1- Yes it's better to calibrate. It's very easy to do. Have a look here : https://www.sweetwater.com/sweetcare/ar ... nd-update/
2- There's no risk to damage the GM with a wrong patch, don't be afraid.

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filtered
Posts: 268
Joined: Sun Jan 29, 2012 12:42 am

Re: Grandmother - calibration, patches and the don‘ts

Post by filtered » Tue Mar 26, 2019 1:48 pm

Example of calibration need, when I got mine, with the mod wheel all the way down, if the pitch or filter knobs were turned up, it would modulate the signal anyway- It takes 5 minutes, so you should just go ahead and do it regardless, in case it's just a wee bit off...

BLFTJ
Posts: 3
Joined: Fri Mar 22, 2019 3:59 am

Re: Grandmother - calibration, patches and the don‘ts

Post by BLFTJ » Fri Apr 05, 2019 1:28 pm

Hey guys,

thanks a lot for your answers, pretty helpful!

Grandma had to wait few more weeks, but next week or so, i‘ll go and get it!!!

Happy tweaking!!

robotecho
Posts: 19
Joined: Wed Jan 25, 2017 10:10 am
Location: Sydney, Australia

Re: Grandmother - calibration, patches and the don‘ts

Post by robotecho » Sat Apr 06, 2019 5:11 am

When I got mine brand new, osc 2 was in tune with osc 1 with the tuning knob turned a quarter turn to the left, and I had a weird keyboard issue where the notes would be fine and then get to a certain point and it was all a semi-tone out.

The calibration fixed it, but I had to install the latest firmware and go through everything a couple of times, it wasn't a process for the feint of heart.

It has been rock solid ever since, 4 or 5 months now.

Your biggest danger with patching the GM is that you will be pulled into Eurorack before you even realise it. That's what happened to me, all of a sudden I have MI Plaits running into the GM, and it is... incredible...
Moog Grandmother (Firmware 1.0.2) | Arturia Keylab 61 mk II Controller | Win 10 64bit, Core i7 3.6GHz, 32GB RAM | Studio One 3 | NI Komplete 11 | Focusrite Scarlett 18i20

BLFTJ
Posts: 3
Joined: Fri Mar 22, 2019 3:59 am

Re: Grandmother - calibration, patches and the don‘ts

Post by BLFTJ » Sat Apr 06, 2019 2:57 pm

Sounds like i really should go with calibrating directly after buying but i‘m gonna try to find out if there is something wrong by listening close...

Damn i heard that a lot.. that warning about getting pulled into eurorack stuff. :roll:

But i will take that risk.

erwincoumans
Posts: 2
Joined: Tue Jul 14, 2020 4:38 pm

Re: Grandmother - calibration, patches and the don‘ts

Post by erwincoumans » Tue Jul 14, 2020 4:46 pm

filtered wrote: Tue Mar 26, 2019 1:48 pm Example of calibration need, when I got mine, with the mod wheel all the way down, if the pitch or filter knobs were turned up, it would modulate the signal anyway- It takes 5 minutes, so you should just go ahead and do it regardless, in case it's just a wee bit off...
I have the same issue after updating to the latest (1.06) firmware of Grandmother. Tried calibrating the pots a few times, but the effect is still there.

alex.allred
Posts: 3
Joined: Wed Jul 29, 2020 11:48 am

Re: Grandmother - calibration, patches and the don‘ts

Post by alex.allred » Wed Sep 02, 2020 11:31 pm

Hey there, I've had my GM for just over 30 days now and it's been great. However, I've noticed that my oscillators are out of tune by 6-7 cents. I can get oscillator 1 perfectly in tune using the fine tune knob, but this significantly flattens oscillator 2. Consequently, because they are out of tune, I can hear modulation happening between the two oscillators when I bring up the levels with the mod rate and mod wheel turned all the way down.

I've re-calibrated the oscillators, re-calibrated the pots, at least 10 times now, and the problem persists. The modulation that's happening is not significant, but it is definitely noticeable. Especially when I change the modulation wave to square. I can visibly see the pitch changing when using a tuner in Ableton.

Does anybody have any insight or tips on how to possibly resolve this? I might need to get in touch with Moog support before my window is up to have the instrument returned to the supplier. If I'm unable to resolve the issue, I'll end up exchanging it for another...

calaverasgrande
Posts: 97
Joined: Sat May 09, 2009 3:43 pm

Re: Grandmother - calibration, patches and the don‘ts

Post by calaverasgrande » Mon Dec 21, 2020 6:09 pm

I cannot speak for whether the Grandmother circuits are protected against bad patching or not. But Moog stuff is generally pretty robust. And for the most part you have to patch a voltage or current that is an order of magnitude higher in order to damage something. Like patching a speaker out to a line in. Which will over current the daylights out of the poor opamps sitting there.
There is a generally accepted good practice that you should patch to the source first, then the destination.
For example, patch the ENV + out to the PWM in on OSC 1. In that order, not the other way around.
The idea behind this is that if you patch from input to output, while plugging in your connected plug will contact ground then signal, while being 'live'. Introducing the possibility of loud thumps which can hurt your speakers or ears.
If connected the right way around, it won't reach speakers until fully connected.

The other often mentioned idea behind this is that on the Eurorack side there are a lot of small companies. Maybe just one person. Which may have some not so robust designs around some of their patch points. So you don't want to 'surprise' the module with sudden abrupt shorts to ground or jumps in voltage. I think that was more true 10 years ago than now. And even then not entirely true.
Roland Sh09, Taurus III, Elektron Digitone, Doepfer Dark Energy, OB6,

pahlin
Posts: 3
Joined: Fri Jan 15, 2021 3:53 pm

Re: Grandmother - calibration, patches and the don‘ts

Post by pahlin » Sat Mar 27, 2021 3:55 pm

I finally got around to running the calibration process on my GrandMother. I should have done this day one!

After calibration, the 2 VCOs were as perfectly in-tune as a pair of VCOs can get. I could never get it that close before...which is a bit surprising, You would think it's just a small tweak to the freq knob for VCO2 would do it.

So I hooked up the GM to a tuner. It showed that it was 5 cents sharp - toggling between +5 and +6 cents, so say 0.055 semitones. I fiddled with the Fine Tune Knob to get it close to 0. Embarrassingly, that's when I first noticed that the fine tone knob had a click-feel to the center position. That's when I noticed a hidden feature:

When the fine tune knob is in the center position, the VCO frequency is very stable (according to the PC tuner). If you tweak it just slightly, the frequency starts slowly oscillating - the amplitude is only ~2 cents, but it makes a difference. When it is in this mode, it is much harder to get the 2 VCOs in-tune. It's like a "vintage mode" (unstable oscillators :D )

I ran the calibration one more time with the fine tune knob in the center position and after that, It was perfectly tuned according to the PC tuner.

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