Mangrove drift

Just thought I’d share the results of a little test with you all. I’ve been having some problems with my synth detuning between soundcheck and performance, so I just tested how long it takes a mangrove (my main oscillators) to stabilize. Turns out it’s about an hour…

Test results retuning every 10 minutes:

10min - drifted +4cents
20min - drifted +1.5cents
30min - drifted +1cent
40min - drifted +0.5cents
50min - drifted +0.5cents
60min+ - drifted 0cents (stable, yay!)


i can’t speak specifically to mangrove, but i’ve observed my analog oscillators take longer to settle in colder temps. warmer temps stabilize faster. i also remember playing a MOTS set as the sun was setting and as it got colder my rack went out of tune :confused:


Do multiple Mangroves drift in tune? That would be neat.

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I’ve noticed that my Mangroves tend to drift quite a bit for the first half hour or so of patching, after that I don’t have many issues,

I usually will sync my other oscillators to the mangrove square too so the drift is across the board, and usually well within my musical tolerance.

(I live in minnesota and it’s getting much colder now though, so i may have to report back on how the temperature effects that)

Reminds me of reading how Harald Grosskopf (recording the album Synthesist) had to put a 60 watt lamp on his synth to warm it up and keep the tuning stable. :grinning:


They all seem to drift upwards in pitch. Need to try it :wink:

I guess I should re-do this test, too, once winter reaaaally sets in. For science.


I remember reading an older Echospace interview where he mentions outside his synths outside in a shed in the winter for a while to get them to drift in interesting ways lol

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I’ve found this to be 100% true. The same also holds for Just Friends if using in sound/cycle mode (which I often do). I have 2 mangroves and 2 JFs I use as oscillators, and if I don’s leave the synth on for about an hour, they all drift out of tune. too. After that though, they seem pretty darn stable.


I’m posting here because I remembered this discussion and thought this was my issue, but…
My Mangrove doesn’t play well with my other oscillators after any period of time. I’ve had it for about a year and its sat out of the case for a lot of this time because of this. Recently I’ve been trying to find the issue and this is what I’ve found:

  • When I plug a voltage source at zero volts into the pitch the pitch increases around +35 cents. This is true of both Ansible with no pitch CV enabled, and the Keystep. I have checked this behaviour on both of my STOs, obviously analogue too, and they don’t change when the Ansible or Keystep are plugged into pitch at zero volts.

  • The tracking is woeful. I’ve tried the trim procedure multiple times with the keystep and with OP 1 into Ansible midi mode and I’m loosing a semi tone over 2 volts even after correcting at either end multiple times. I also have little faith in being able to do this because of the point above.

I had been using the Mangrove primarily for bassy drones which is the only thing it would manage given the issues described above but I would love to use it like others do. Does anyone have insight into this issue and possible remedies? I know @Galapagoose is busy right now. Any help/feedback is appreciated.

My modular synth sits under a window, and it never settles unless I close it.

I just recently recalibrated my Mangrove using voltages from a Teletype - It took quite a while, as I was going perfectly backwards with the trim pot. Once I figured that out, I repeated the process a few more times until I hit the sweet spot on the pot. Pre-calibration it would drift way too heavily across the formant knob, and only track reliably for about 1.5-2 octaves. It’s good now for about 4, and doesn’t do the wacky formant pitch falling anymore.

Mine also increases a little with a 0v cable into pitch, but so does my DPO. I’ve always assumed this was stray electricity and the nature of the beast, and tune it after making the connection.

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I think you should expect that the pitch will rise when you plug into the pitch input due to the slight offset a cable will have. Have you checked what your devices (ansible/keystep) are putting out with a multimeter to make sure the voltage is correct? Also check to see how much your Mangrove drifts after 10 minutes/20 minutes.

I have 2 that I tune separately (only with the square output) after warming them up and they stay in tune together pretty well.

This is a known design issue, isn’t it?

This is not typical for most VCOs.

Really? I’ve experienced this even on my ER-301, which is digital. Plugging in and assigning pitch, I get a change of 12 cents. Had this also happen with Clouds, where the pitch rose after plugging in a cable and my frozen buffer was then out of tune with my other sounds.

Anyways, as a rule of thumb, I always tune and adjust after plugging cables in to my sequencers/etc.

@bushel thanks for the response. My case is in a room that doesn’t fluctuate much in temperature even between seasons and I ran the tests described above after I’d left it on for a couple of hours so I’m discounting temperature for this issue. The voltage issue was a consideration though as I’m not sure that the Keystep is accurate. That’s why I checked with the OP 1 into Ansible. I expect Ansible to be pretty spot on and haven’t any issues with it with other oscillators. You’ve kind of described my issue though with the tracking and the formant knob making it pitchy. I will persist on the calibration. To check, you plugged a zero voltage from a voltage source and then tuned and then calibrated? What do you mean by “I was going perfectly backwards with the trim pot”?
@Jonny as noted above, it had definitely warmed up. I have checked the pitch increase from zero volts from the same sources on my other two oscillators and it doesn’t happen so although what you and @bushel makes sense it doesn’t hold true with all.
I don’t have a reliable multimeter.
@jnoble I did not know this was a known design issue. Is this confirmed? And I didn’t think it was typical behaviour. Thanks for confirming.
I’m keen to enjoy the Mangrove as much as everyone else seems to. I love the sound but find that when I turn to it, i can’t rely on it and I waste time tuning and tweaking rather than making sounds.

This happens with both mine and also with one of my Dixies. I think it’s fairly common.

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So you’ve measured that you’re getting 0 volts out of Ansible and then 2 volts? A digital mutlimeter is super handy in troubleshooting eurorack. I’ve found that In MIDI mode that can be slightly confusing as the MIDI keyboard must be playing the lowest note in the lowest octave for you to get the zero voltage. Not to say you’re doing it wrong, just that we don’t want to assume anything if you’re having trouble and not getting the expected results.

BTW, I found this post since I was curious if this pitch jump was a design issue and it looks like it is (although I’ve experienced it elsewhere in smaller amounts compared to the Mangrove):

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it’s good to know, was considering 15 min as ok, and was often, recalibrating it.

Still have to recalibrate it correctly around every two weeks i think.

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I think some of you are assuming that “zero volts” coming out of CV sources is really “zero”–I think you will find otherwise in most cases. The 12 cent offset mentioned above is only 10 millivolts …

I built a couple of precision adders a while back and spent a fair amount of time coming to grips with offsets and volt per octave tracking in my rig as a result. It was instructive.

As an aside, I own a Fluke 77 and a Fluke 87 and neither is even theoretically good enough for volt per octave calibration–you need a good bench meter like a $1,400 Agilent/Keysight 34465A (or a vintage $120 calibrated HP3478A like the one on my bench). Interestingly, my O’Tool+ appears to give exactly the same readings as my HP bench meter, which is really impressive! Your mileage may vary.

Thank you. This eases my concerns. I will just take it as a quirk and work around it. This video posted in teh Cod Mac thread discusses it at one point. Its good to be aware of with other modules too…