Behringer Model D Oscillator Tuning 

This test should be included in reviews. Very useful info. I sold my Behringer Model D for exactly this reason, it was just too unstable. I also found the tracking across octaves a problem even after going through the alignment process many times. I suspect the Moog would be the same. I think where the Boog shines is with the simple typical mini moog lead sound (just like the original model d) where some drift adds to the texture of that voice. Some call it character. Back in the day I built and used live a Transcendent 2000 (like Joy Division used) and it was a nightmare with drift, often going way out by the end of the gig. I had to juggle the set list so pitch critical songs using that synth came first. When I switched to a Juno 60 with its DCO it was a revelation. Because of my workflow and the limited time I get to write music these days an analog synth is out of the question. With tools like Omnisphere or Diva I can switch on and work straight away from where I left off the day before. It would be interesting to see a chart of VCO stability for all new and vintage synths. I owned an original Korg MS20 for many years and I remember that as being very stable, even at gigs where the ambient temperature changed quite a lot between sound check and performance. I think you have touched on an interesting subject and presented it well.

What a star! Thank you for slogging through this mission.

Thanks. I went ahead and bought it anyway. I had been marveling from far for so long.

This is highly enlightening. Thank you so much for taking the time to put this together. Leaves me wondering where an original Minimoog falls on this chart. When I'm using an original Mini I usually print it and move on so I don't often go back and double check if its still in tune. Incredible though that the Yamaha's stay in tune better than all the modern synths. I wonder if they have developed some ultra high precision VCOs for use in their big poly's and that tech just carried over to the mono synths of the time as well.

Amazing work Tim, I own a Yamaha CS15, its true! Completely tuned always. And is my oldest synth... a very remarkable study you did.

Thanks for this, Tim. Such graphic explanations are most welcome. The upshot, then, is to allow some of these analog beasts (except the highly stable Yamaha CS-15) an hour or two to warm-up time before using them. Although the Model D never gets completely stable, it does seem to fluctuate within a fairly narrow range after 120 minutes. I think I can live with that. Many acoustic instruments (several of my guitars, for example) also drift out of tune, some strings drifting more than others, probably even more so than the Model D's oscillators. They drift in response to playing them, the room thermostat (HVAC) cycling in and out, and other factors. Occasional re-tuning is something you just live with for many musical instruments.

Excellent video. Thank you for producing it. This topic is why I occasionally consider flipping all my analog synths for digital synths. Sometimes I just want to work instead of waiting for my synths to warm up. But alas, warm and fat are hard to come by in the digital synth realm. My current rule of thumb is to not bother tuning anything until after a good hour. That also means everything is out of whack until it warms up. The positive is that I basically never have to tune anything unless I bump the dial.

I really appreciate your time and overview on this. I've been looking to add another monosynth to my other synthesizers that I use to write and record commercially licensed music (under performance rights organization BMI,Inc as a composer). From what you have shown and talked about in your video and based from many other posts that I have read from people on different web sites, there is definitely some units that are more stable than others.. all different even after long warm up times. I think I'm going to choose another Behringer synth. I love the sound of the Model D, but I need stability when writing and recording tracks. Happy Holidays to you.. wish you and yours all the best.

That was very useful and interesting, thank you! I’ve always wondered if playing the synths (after they’re stable enough for casual noodling) instead of letting them just sit has an effect on how fast they stabilize, but haven’t bothered to actually investigate.

I have same experience with my Yamaha CS synth (CS-15D). Absolutely rock solid tuning, they really have put amazing quality into thoose instruments.

Interesting analysis!

interessting analyse, thanks!

Thank you for covering this subject Tim. This is a topic which has always been of intrest to me since i began design my own prototype analog synth. I did a very similar test , and found the tuning was slightly off from switch on, from one day to another . As my circuits are all open on bredboard the ambient temprature is obviously an issue aswell. Im still wondering if the Behringer d expo is based on the 3046 transistor array or the ua726 ?

This video is a nice example why manufactures that made analog synths in the past, aren't going out of their way to re-make analog versions of those synths. And besides, we're living in the future..where we have synths modeled on vintage circuits, software synths, iPads and a Moog One. Great videos Tim S. love 'em.

Preaching to the choir here! I had a CS-40m that was rock solid on tuning. My Vermona '14 and perFOURmer are quite stable as well. My 2 Abyss are more mischievous on tuning though. But still love them!

Very good data collection. On the CS stability, the older Yamaha synths used volt/ hertz instead of volt/ octave scaling. This helped make those instruments more stable. A small fluctuation in the key voltage causes an equally small fluctuation in frequency. When testing the model D, were you using MIDI as the note source or CV? I am curious if your results are showing a problem with the on-board MIDI-CV converter.

there's a YT clip of how to tune each rotary OSC pot - but of course that involves unscrewing it. But, would the drift be the same after the tweaking?

Damn you, Tim! What a great video and review! I just got mine Model D two days ago... I think it will be a relationship love/hate! You´re the man! Thanks for this great job.

Very interesting!

Thanks for sharing your findings. I have two of these and i think this is really just their nature. The Model D already has a very distinct character, that doesn't always play nice with others. This "drifting" could explain why. I currently use them less and less... On one hand i feel like selling them (or one), but on the other they just sound so beautiful solo i begin to question my approach towards them. Maybe it's a sign we probably will never get along, but maybe i should just accept their character into my music to capture exactly that... it's an odd situation right now. Do you know if the original Model-D had this drift too?

I'd love to see a temperature graph with these. I used to leave a thermometer in my synth when it had been running for a while and try to maintain the temp with an incandescent lightbulb when tuning the open synth.

Thanks for this. Aside: you've got a "CS50" chapter label in place of CS-15 somehow. I've got a CS-60 and it's only one osc/voice - it usually takes about 30-45 minutes for the 8 oscs to settle into stable tuning. Big heavy power rails! Of all my synths the OB-Xa and A6 have the least stable VCOs. Your D's behavior reminds me of the A6 with the bg and temp-tuning off ....it can drift a lot over some hours, and polyphonically it tends towards sounding 'eerie', imho it's the A6's primary sound characteristic.

Thanks for this video. I haven't bought a model D yet but was considering it. I just watched a Behringer vid about tuning the model D and the guy had to take the front panel off to tune all 3 oscillators independently. But you mention you re-tune often during a session. Is there an easier way to tune them? And is it possible to tune all 3 to different frequencies to make a major or minor 5th by playing one note? Thinking about making pads with a monosynth. On my Sub 37 I can change the freq of osc 2 up a perfect fifth which gives me an almost pad like sound from one note; playing both oscillators. Would be great to do that on a model D.

The elephant in the room is "re-tuning". If after stabilization, then retune to original frequency.....do the oscillators remain stable after re-tuning, or is more time needed for stabilization?

Thanks for the video. How long do modern Moogs take to stabilise do you reckon?

This is great Tim. Sounds like it is a bit of a hassle to do though. Did you automate the measuring process somehow?

Related: I am digging the way the Sequential Prophet 5 v4 implements tuning with some sort of lookup table that has very much reduced the need for me to hit the TUNE button much anymore. With polysynths, there is more need for pitch stability for many reasons, so im glad it's there.

Useful video, thanks. It would have been even more useful to have the Y-axises graduated in cents. But anyway it's a good thing you put them all on one graph at the end. Also, why not test both Model Ds you appear to have, to acount for difference between samples ?

As of today’s date comment: I got a Boog 2 day’s ago and got me curious about the tunning when I made a patch and when to eat dinner, when I come back it was all drifted. I saw your video and when to B and H in NYC early today (where I got mi Boog). They have a moog model D to play there... I dial the same patch for my lead sound (3 oscillator patch) in the Moog Model D and waited there about 1:40 hrs. And when I played it after it did had a drift on the sound. It also sounded quite awful, same as my Boog did. I fix the patch to my liking and I checked it about 50 mins later and it was some drift, not as drastic as before but it was there, to my surprise it did had some raw naughty sound that was pretty pleasant, but non the less drifted. I’m willing to bet this is the same behavior the Minimoog has, is meant to be there. Behringer could have added a tunner such the one find in the Deepmind but that would’ve take the original sound so many are after. I believe it’s part of the appeal and secret sauce the Model D has in comparison to other moog synth’s. It’s the analog reality, you can’t have it all. There’s a price to pay for real raw sound. Whether it’s a real Moog or a Behringer Model D, I think the spirit of Bob Moog is very much present in this synth and We all have to be thankful for that.

Thank you for this very important and informative video, first of all! Would you recommend buying this synth for its filter alone? Is the filter alone worth the price even if the oscillators prove unusable?

And this is why old Yamahas are a bit too precise (but equally enjoyable) compared to Moogs. We think of "thick, lively" oscillators when thinking of the Minimoog and you've perfectly explained in these graphs why is that so, where some of the "analog mojo" lies. In fact older model D boards and Musonics models drift a lot more with the slightest change of room temperature and they're valued almost double the price of a vintage Minimoog. What baffles me (maybe infuriatingly so) is how Behringer has managed to nail the free-running discrete VCO sound in a mass product, SMT tech and all. It shows that it can be done if manufacturers want (and they usually don't). I really hope they can be as diligent in further products.

thanks for all the effort. great info. I wonder how my new monologue behaves, more like the CS-15 or more like the boog^^ model-d probably needs 24 hours to stay half way stable lol (if that even ever happens) but, yeah "character" *cough*

I love(d) my Model D but since last week. Even after a long time of being on my OSC's are not just out but going up or down one octave or more from any key, it is so out, like an out of tune guitar. To have c2 closest to being in tune with c1 I need to play the C2# key then it is still a bit out. You can hear a clear drift if just holding any key down. Has anyone else had this experience. Tuning the OSC's on the PCB does not solve the problem either. So frustrating!!!

Do you know if this issue has been solved with the new Model Ds ?

I guess I can't really complain because of how cheap it was (got one on sale for 225), but I'm finding I need to ride the tuning knobs constantly, even after calibrating it. Oh, and calibrating the tuning revealed that some of the tuning knobs are not properly centered (need to be a few degrees right or left of center to tune with Osc 1). Still sounds really good for a sub-$300 machine, but I wish they had added stable oscillators while they were adding all the extra features.

Despite the fact it is unstable do you still enjoy the synth? Or would you advise someone to not buy it?

very usefull

What were the environmental conditions of this testing? This appears to be a home studio in England I presume. My guess is there's no air conditioning in this room: temperature and humidity control. As others have wondered, how would a Moog D operate under the same conditions? Did Behringer make a very poor approximation of the Moog D or did they make an approximation that's too good (ie- favored trueness to the original over solving the issues)?

Very interesting! It would have been great to do the measurements on all 4 Model D in the same room. That could tell a bit about the cause, is it the design, cheap components. Maybe put a temperature sensor in each and plot that too :-D

COOL.

Up and down, up and down but I don’t think I heard you mention by how much. What’s the scale on the frequency axis of the model d graph? (On mobile can’t see it right now). It doesn’t look like a lot. How does this compare to genuine model d ? Edit: so watched it again in HD on a big screen. After 80 mins all three oscillators seem to drift by no more than about +/-1 semitone or less. That doesn't seem like a huge amount for a VCO. The only question we should be asking is how it compares to other Behringer D's and genuine Moog Model D's.

Thanks, that was reallly interesting. I've read before that you should leave a synth 15 - 30 minutes to warm up. Apparently not. I'm curious now how a minimoog behaves whether reissue or original. I think the general consensus is that the originals are very drift prone and unstable.

The PolyVox dishes up some nice tooth-wiggling bass from memory. Must be hard to keep in good nick though. I think these tests would be interesting to repeat at various times of the year or at various room temps in air conditioned environment. The original Moog Model D was quite variable from instrument to instrument..some stable and some would drift wildly. I wonder how the reissues compare, given they are reasonably faithful recreations. So yeah, for most of these examples, get up, shower, have a full breakfast, open your mail, talk to a few people and you should be right to go by elevenses LOL.

Where come from the vintage filter you put on camera?

I wonder whether the MInimoog suffered/suffers from the same issue...

How come my model d sounds detuned when I'm using only one oscillator? It's tuned on one key but "off" when I hit other notes up or down like there's an lfo going on or something but it's just a single oscillator. And it's happening with all 3 independently.

I wonder if the oscillators in the Model D are also in the Deepmind 12 & 6 ?

I wanted to buy a model D but now I hesitate... :'(

Interesting findings. A good idea is to low cut the mic when recording speech. :-)

Very revealing, thank you for doing this. But it's important to keep in mind that the actual amount of detuning that is happening in that graph of the Behringer D, although higher than the other synths, is still very, very small after about an hour and fifteen minutes, considering the fact that many patches intentionally include far more detuning between the three oscs than the amount of variance shown. So such patches won't sound like they are going 'in and out of tune', they would sound more like they are just exhibiting very slightly faster and very slightly slower 'beating' effects between already intentionally detuned oscs. It's also worth noting that lots of other types of instruments don't maintain their tuning over three hour as well as ANY of the synths in this test. For example, a lot of guitars. These comments aren't meant as a criticism of the test, (again, thanks for doing this!) it's just a comment about perspective, and how this amount of detuning may or may not be perceived in use.

Interesting... I’ve noticed I have to give it a little tweak every now and then as I work on it. Not just the tuning either. Still good value but like you it’s the only analog I have that does this... just counted ... I’ve got 10. Nice video. I do love a good graph - there’s no arguing with those numbers :)

Hi Tim. Thank you for all the information. I think IM having a peculiar issue with my Model D. I bought used but it is in pristine condition. The issue is I can hear notes going in and out of phase. Using just one osc I, when I hold a note I can hear very noticeable comb filtering. I have verified that this is also coming out of the head phone jack so if is not my preamp or sound card. Have you ever had this issue?

So the main reason I am looking to buy this synth is to handle all my sequenced bass lines live. It would be going on the road. Do to the tuning issues would you recommend avoiding it? I mean I can’t be certain I can wait at a gig with the thing warming up for over an hour...

that was an interesting & enlightening experiment... i have a behringer d & an arturia microbrute... i always give them at least an hour to warm up before i use them... although the model d's tuning does drift slightly over time, especially oscillator 3, it's nothing compared to the drift of the microbrute... it always goes way out of tune, while the d is only slightly out... that's been my experience, anyway...

How much of a problem in practice do you find it?

Nothing to stop them using DCO's their still analogue oscillators, deepmind shows you can still add some drift if that's your bag. My boog goes so far out even the tuning knob can't get it back in range, had to leave it on overnight before I could calibrate it as it was impossible to get even close. 2-3 hours I wish. lol

Sounds like cheap caps, did you try to replace them?

if you have a model d go through the callibration procedure and the osci's is gonna stay in tune.

I have to ask, if you had an issue with the Behringer D tuning, then why did you go ahead and buy four of them?

So it drifts +-1Hz after 1 hour of warmup? How is that an issue?

never knew that guy from Human league had yt channel :)

Immediately after watching this, I told myself this is why i'll never buy a minimoog or a clone, but after some quick reflection i don't feel as strongly about it. With the Moog design, you basically have to tune up regularly/often, with others less often but still some. So you put a tuner on the input line or tune by ear, not really that big of a deal. What's more alarming to me in this video is these 1hr+ warmup times. I thought i was being generous giving 15min.

Thank You for this video. I know that Behringer has a so-called "calibration" video regarding actually physically opening up the unit every time to tune the OSC with a screwdriver... I'm sorry to say, that kind of piss poor design on their part. There are other analog synthesizers out there, that have a external tuning knob on the surface of the unit for that same purpose. It seems to much of a hassle to do all of that tuning after a few months... I can't invest in a synth like that.

I have a reissue and a Boog, both drift pretty much the same way. Not so surprising if Behringer copied the circuits wholesale!

Somebody should work on a better tempco mod for the Behringer Model D like it was done on the Minimoog. yusynth.net/gear/MINIMOOG/MODS/modif-tempco.jpg I know it can be tricky due to SMD but not impossible !

Cant you just calibrate it?

I find once it’s warmed up it stays in tune for me.

This is all very peculiar. Please think with me: At 4min:30sec Tim explains his graph. Horizontal axis: time = 15 min/div. Vertical axis: pitch = 0,5 Hz/div. At 11min:00sec Tim shows the pitch fluctuation of the Model D. After one hour the pitch of oscillator 3 fluctuates between -0.2 and +0.1 of a vertical division. This is 0.15 Hz. Oscillator 2 is slightly better, oscillator 1 slightly worse. To give you an idea: a semitone up or down would be 12 Hz, so the fluctuation we are talking about, is 12 / 0.15 = 1/80th of a semitone. What if you would try to turn the pitch of the Model D 0.15 Hz up or down? The total range of its pitch knob is some 150 Hz (from 367 Hz to 510 Hz). So you would have to turn the knob 1/1000th of that range. Can you? And if so: would you hear it? Who wants to get rid of this synth because of this behavior? By the way, did you know that the oscillator drift in Behringer DeepMind synthesizers is made adjustable on purpose? Quirks mean character, perfection is dull…

I'm gonna have to sell my Behringer Model D. When I thought about getting into analog synths, I understood that you had to tune them, but I did not understand that they won't stay tuned. I definitely prefer digital in that case. Analog is not worth it!

Yamaha rules (I have a cs10)