Slims way out of tune after hours of warm up

The Moog Forum Little Phatty & Slim Phatty Forum
1

Hey all,

I know this topic is riddled with discussion largely stemming from people who don’t yet realize that their slims need about an hour to warm up. But this isn’t that.

I run an LPhatty + (2x)SPhatty poly chain, and the tuning starts to drift sometimes. Last night, about two hours into a session, I had to put the synths in autotune mode to fix the drift, and the numbers were hovering about 10 points off from 60. I used a digital tuner, and the synths had gone from C-C-C to, like, C-A#-D#. The LP was stable but the slims were off the map. Furthermore, the fine tune knob only changed things +/- a semitone or so. Putting tuning mode to “on” gave me a bit more range from the fine tune knob, but not enough to get them back to C. I gave up and ran the pitch calibration and went to sleep; this morning they were perfectly in tune.

I have had to do this about four times in the last year or so. I live in Chicago, so there are some temp fluctuations for sure, but not over the course of one session, as far as I can tell. And my building has radiator heat, so it’s not like they’re ever getting cold to the touch. I shouldn’t have to run the calibration that often, should I? I touched the fine tune knob when the synths were autotuning. Should I not have done that? Should I not press any (keyboard) keys? I waited about 5 minutes for autotune to try and find 60, but it would just rest at 72 or some other number. Why is this so finicky? I don’t think it’s a defect, as both slims do it.

Any thoughts, y’all?

2

I run the exact same poly- chain setup as you, and was also having some tuning issues.

As a fix, I let all 3 Phatty’s warm-up (just sitting with power applied, but no playing or adjustments) for about 45 minutes. I then ran ALL the calibration routines on all 3 Phatty’s, and have been VERY happy with the results!! They now sound like one, big 6- oscillator synth!

In general, I’ll let all my analog gear warm up about 15 or 20 minutes (minimum!) before playing or making adjustments, and don’t touch any controls while any calibration routines are running.

I did the all-inclusive calibration routine session about three months ago, and since then, I haven’t had any tuning issues as long as I let everything warm up first.

We’ll worth the effort!

Randy

3

Thanks for the reply!

Yeah I obviously don’t touch/move/bump them during calibration.

Your story was my story until a couple months ago. Since then I’ve had to do your same calibration routine twice. I haven’t done all the calibrations, just the tuning calibration. And I haven’t changed the default tuning range (what is it like, 12-124 or whatever it is…).

I was just wondering if there is any other thing I should be looking out for.

4

Try running ALL the calibration routines on all three.
Takes a while ( an hour + per synth, but of course you can run all three synths simultaneously), but I was amazed at the difference it made!