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COTK vs MOS LAB vcos?
MUFF WIGGLER Forum Index -> 5U Format Modules Goto page 1, 2, 3, 4  Next [all]
Author COTK vs MOS LAB vcos?
Rex Coil 7
Happy Flour Tortilla Day to ya's! I need some help before I spend money and begin efforts to move forward on something that the more informed and experienced members within the 5U clan are very well versed in. This post is long and wordy, but this topic generates a lot of questions ... questions that require background and intended use information to better address. Here we go ....

I'm a fairly serious novice when it comes to the subtleties and nuances of the finer VCOs when creating the old R.A. Moog type VCO sounds. I'm aware there is more to it than simply stuffing a synth cabinet with Moog design VCO circuits (such as gain structure, VCA choices, and use of the indispensable CP3 mixer circuit). But I'm also aware that use of the "right" VCOs ads a profound distinction. I am now a believer.

I've no intention of replacing my Dot Com VCOs in my normalized synth project. However, I'm already beginning the initial thought processes for designing another synth voice that will make use of more exacting R.A. Moog Modular VCOs. I reckon I'll need just two VCOs, along with a well chosen VCO mixer (ahem ... CP3 ... cough), and a LP+HP filter array, all piped outbound via a VCA that's Moog friendly.

Thanks to the very deep and well supported preferences of many other MiffWuggler members that are well versed on this exact subject (and their gracious willingness to share their own experiences on the matter), I've been able to narrow down the choices to MOS LAB and Club Of The Knobs offerings, as well as (perhaps) Oakley. I am not interested in doing what Tom of Noddy's Puncture has done (and done to a level of excellence when it comes to being usable in gig-to-gig live performance situations). But actually etching my own circuits and going through the trail of thorns and pebbles that are involved with such a venture is beyond what I'm willing to do. I'm sure there are other VCOs that would fit the billing that I am unaware of (which is another part of what brings me to asking the membership about this).

Ok, there's the background and preamble to the looming questions .....So let me end the babbling and boil this down to the salt:

** Which VCO circuit to utilize?

** Which modern VCOs provide the nostalgic sound(s) most accurately?

** And, adding to the needs, which ones provide means to do the most with (in other words, things such as Pulse Width Modulation, ready access to other modulation destinations, dual VCO interaction such as hard/soft sync and FM ... and so on)?

** Cost isn't too big of a deal, since I'm only needing two VCOs. But I'm not willing to pay modern day Moog production stuff type pricing (that is to say, I don't want to pay $2k for a flippin' VCO, just as an example).

** Availability ... I'm willing to wait a couple of months or so for a given VCO to become available, whether it is new or used. I know I've read that MOS LAB stuff kinda comes and goes regarding availability. I'm beginning the thought process roughly six months ahead of doing any actual progress here ... getting the gears and wheels in my mind rolling far ahead of time (which is pretty much how I go about doing most custom projects).

** Panel width is of no concern (meaning it doesn't matter if the VCOs are MU or MOTM widths ... I can adapt the cabinet to suit the format). So 1.75" units and/or 2.125" units are eligible. Most likely I will be repanelling them anyhow to deal with some normaled connections efficiently.

Ok, so there's what I'm curious about...

Once the Synthesizers.Com based Super Mini Modular synthesizer project is in proper flight and working, I'll begin to put some effort into this project. Remember, this is all aimed at making an additional voice, not really an entirely new synth. Preferably 5U rack mount as a format, but that's not written in granite. What with things such as Front Panel Express readily available, as well as many different means by which to cabinet another voice, there's room for flexibility within the design. Just to reiterate ... this new Moog voice will not be built into the Super MiniMod. I'm hoping to be able to put it all into about 8 vertical rack units by about 17" or so wide. In other words, an 8U rack max, with the upper 5U devoted to complex modules, and a lower 3U row devoted to mixers, routings, Ring Mods, and so on. Like a tiny System 35 ... sortof .. or a System 15 sans the upper most row.

Oh, and 15v power is a must, powering this additional voice will be done by expanding the 15v bus bar system that I've worked so hard at.

There we have it. My admission that I'm giving in to the "Moog is bitchin!" notion and will construct a voice dedicated to that end. Tom (Noddy's Puncture") and his excellent performance videos have really done a lot to sway my opinions, as have a few videos posted by CZ Rider of his own R.A. Moog modular.

Sorry for the length of this posting, I prefer to answer more questions than I generate right off the go.

Gimme Some Of That Moogy Goodness!!!!!

thumbs up
JohnLRice
Rex Coil 7 wrote:
15v power is a must, powering this additional voice will be done by expanding the 15v bus bar system that I've worked so hard at.
While both COTK and Mos-Lab VCOs need to be run on +-12v, both companies offer buss boards with 15v to 12v converters on them so supply voltage shouldn't be a problem?

And, have you checked out Synth-Werk? Arguably the most Moogy of the Moog clones . . . with the exception of the Moog reissues? spinning
http://www.synth-werk.com/content/modules
The PCBs are mounted to heavy duty half-enclosed back planes and all the panels controls attach to the PCB with MTA-100 connectors (like DotCom) and each module is setup to connect to +-15v DotCom headers and there are regulators on board to convert down to what ever voltage is needed.

While it seems like Synth-Werk modules would be super easy for you to integrate into your project, you might explain your project to Gerhard and see if he would be willing to sell you just the "guts" (PCB and maybe controls/jacks) to make things even easier and less costly/wasteful? I've never heard of him doing this but, asking should be painless? cool

johny_gtr
Quote:
The PCBs are mounted to heavy duty half-enclosed back planes and all the panels controls attach to the PCB with MTA-100 connectors (like DotCom) and each module is setup to connect to +-15v DotCom headers and there are regulators on board to convert down to what ever voltage is needed.


901A connects to 'dotcom' power bus. 901B's connect to 901A for powering.

Quote:
Availability ... I'm willing to wait a couple of months or so for a given VCO to become available, whether it is new or used. I know I've read that MOS LAB stuff kinda comes and goes regarding availability. I'm beginning the thought process roughly six months ahead of doing any actual progress here


If you just order 3 modules 901ABB or 901 plus 901, waiting time can be a lot less.
JohnLRice
johny_gtr wrote:
Quote:
The PCBs are mounted to heavy duty half-enclosed back planes and all the panels controls attach to the PCB with MTA-100 connectors (like DotCom) and each module is setup to connect to +-15v DotCom headers and there are regulators on board to convert down to what ever voltage is needed.


901A connects to 'dotcom' power bus. 901B's connect to 901A for powering.
Yes, thanks for clarifying! thumbs up
JohnLRice
This isn't the best quality recording, (recorded with a Sonic Port to an iPhone as an MP4 video then uploaded to a PC and reprocessed to strip out the audio and create an MP3 and then uploaded to Soundcloud! meh lol ) this little Mos-Lab voice sounds more than "Moogy" enough for me! cool

Sequencer: GRP R24
Bass Voice: Mos-Lab 921ABBB/911s/902 with STG Mixer and Grove Audio VCF
High Voice: SSL VCO/EG/VCA with Moon VCF and Corsynth frequency divider
Drums: Roland TR-505
[s]https://soundcloud.com/johnlrice/grp-mos-lab-and-friends[/s]
trentpmcd
I don't want to steal the thread, but one thing I didn't see Rex Coil 7 ask but I feel might be important to him (it is to me hihi) is the audio signal levels going between, say, Mos-Labs and Dot Com/Moon/STG/etc. Are they lower, so going from Dot Com to a Mos-Labs 904 you'd need to attenuate and going from a 921 (or upcoming 901) you'd have to boost to go to Dot Com? Is that right? Or do you just plug one into the other without an issue? (I'm seriously thinking a clone voice too: 901 ABBB, 904 A (B&C?), CP3(O), VCA possibly 914.)
josaka
pesonally its like this.. for fatter moogy tone.. go for synthwerk VCOs..
if you want PWM/Sync go for Mos-Lab..

I had pretty poor experiences with COTK and I am not alone..
Kaizke is vague unresponsive and feels like he doesnt give a toss basically unless you are "well known"(to him) or buying a big system.. I have seen posts (but cant verify) about his builds being not accurate and using sub par parts.. but I am only going on what other posters have said.. they sound good to me.

gerhard(SW) is a real joy to buy from.. responsive serious prompt efficient on point.. Seb(ML) does what it says on the tin.. kaize barely has a tin smile (bit harsh!)

..but on top of the VCOs you will at least need cp3 mixers if you want the "sound" you are after.. and to my ears the SW CP3 are very good.. more effective than Mos-Labs(more features too) but this may be a little unfair as the 921 have less effect using them with the CP3 other than the 901.. or so a couple of people have said (seb from mos-Lab being one)
josaka
trentpmcd wrote:
I don't want to steal the thread, but one thing I didn't see Rex Coil 7 ask but I feel might be important to him (it is to me hihi) is the audio signal levels going between, say, Mos-Labs and Dot Com/Moon/STG/etc. Are they lower, so going from Dot Com to a Mos-Labs 904 you'd need to attenuate and going from a 921 (or upcoming 901) you'd have to boost to go to Dot Com? Is that right? Or do you just plug one into the other without an issue? (I'm seriously thinking a clone voice too: 901 ABBB, 904 A (B&C?), CP3(O), VCA possibly 914.)


yes you need to raise the level.. the Q114 or Q125 + Q108 do a good job..
(I also feed the signal back into itself on the cp3 mixer yes it adds a slight(to heavy!) distortion.. but its great smile )
or lower the others smile
kindredlost
No way I can offer any comparison between vendors as I only own the MosLab 901ABBB set but the levels do need a boost to be more in the level of the rest of the 5U setup. I use an Instrument Interface or a Signal Processor (dotcom) for that.

I also have the C3PO mixer for the VCO array and it sounds nice. I actually prefer it over the STG CP3 mixer for that duty. It is a single space module so it doesn't eat up a lot of space in the cabinet.
Neovintage
josaka wrote:
pesonally its like this.. for fatter moogy tone.. go for synthwerk VCOs..
if you want PWM/Sync go for Mos-Lab..

..but on top of the VCOs you will at least need cp3 mixers if you want the "sound" you are after.. and to my ears the SW CP3 are very good.. more effective than Mos-Labs(more features too) but this may be a little unfair as the 921 have less effect using them with the CP3 other than the 901.. or so a couple of people have said (seb from mos-Lab being one)


I don't want to steal the thread either but how can one be sure that the SW is the more "Moog"? Because Gerhard says so? Have anyone ever compared a SW901ABBB to a Moog 901ABBB? I'm curious about it. It will be good to compared also the upcoming 901s from Seb which are supposably pure clones.
I once read (I don't remember where) that Gerhard tried some components placement for best sound. I have seen some pics of the guts of SW and MS. They are both great work and clean. But I have noticed that MS use Moog PCB layout for some modules. It can easily be seen compared to the gorgeous pics of Dave Brown's Moog restoration : the new 901B revised, the latter 902, the latter 904B, 984. I never noticed SW does. I don't think this has to do with sound but for "authenticity" I find it better.
If anyone want to send me pics of the guts of its SW modules I'd like to see that.

Sorry again to alter the thread. Guinness ftw!
josaka
I have a mos lab 921 and ABBB and SW 901 ABBB + cp3 from both..

I read a ton of stuff watched every demo I could find (+Moog) before spending money on these.. Tom (Noddys puncture) who has built 901s to match his original 901s has tested the Mos-Lab 901 vs his own 901s.. and says that they were close .. not quite ..but close.. then comes the SW which claims to be an Identical copy of the 1964 originals.. seb from mos lab says.. "the 901 are the real moog sound" (he is now going to identically release the 69' moog 901)
users here who bought moog model 15s (and previously owned mos-lab 921)have told me the moog 15 seems more instant.. but with time you can match the Mos lab 921 to it.

the tones I have and are hearing echo exactly what many many people have claimed about 921/901 sound differences.. and one thing is 100% sure.. there is not a $30000 difference

but tbf in a mix with reverb fx etc.. its a bit of a mute point really..
CZ Rider
I have photos of original 1969 modules I can share. These have never been altered. Should note most of those Norlin era schematics are a mishmosh of different years and revisions. For instance the schematics of the CP3 mixer are a little different from the 1969 revision, and the 901 does not show where the extra trimmer is.
901A component side.


901A pc side.


901B component side.


901B pc side.


Another 901B component side.


The 901


901 other side.


These 1969 revision 901's have the CA3019 diode array. The 1967 and earlier revision used germanium top hat diodes. Those were the ones that a slight breeze would throw them out of tune. I doubt anyone would want to clone those?
Rex Coil 7
First off, thank you very much for everyone's participation. Very helpful and informative replies! I've learned a lot so far.

I might add that I have a Suit and Tie Guy "Mixer" which is as close as it matters to one of the CP3 incarnations. It certainly adds a lot of the Moog vapors to the works!

I also have a Q114++ Mixer (the new Dot Com 4ch multi-function mixer/distributor). I've played around with gain levels and it should be able to bring the Moog style VCO signals up to Dot Com levels.

So those two issues are covered. Well, sortof. I suppose I should qualify that statement by saying that I agree that the CP3 is a necessary component when chasing the R. A. Moog modular sounds, and that I own one (a clone). That's what I meant when I said those two issues are "covered".

Anyhow ... ok, so it seems I need to do more research, write a few emails, and do some more homework to get this worked out. I really dislike spending money unnecessarily ... so I'm going to attempt to hit the nail squarely on the head first time around as I decide which VCO manufacturer to go with.

There have been a few things brought up that I was unaware of, it's clear those issues require some further research and decisions are required, that having been said.

I have become so spoiled with the Dot Com VCOs, they provide so much access to pretty much every modulation method required (PWM, etc..). So I'll have to think about how to deal with all of that as well.

Any more information that anyone can add will be met with a high degree of appreciation! This Moog stuff .... wow .... it's a somewhat "new" world to me. Removing the "training wheels" that the Dot Com stuff provides is going to be a fun adventure.

Thank you! More please!!!

thumbs up
Rex Coil 7
Looking at Synth Werk 901ABBB.

lol It took me several minutes to figure out that Synth Werk and Synthwerks are 2 TOTALLY different companies ... at first I thought "WTF? ... this place doesn't make Moog VCOs" when looking at Synthwerks. Ok, so I got that sorted out.

** How does one go about producing PWM with these VCOs?

** Can the Happy Nerding FM Aid be used with these modules? The output levels are advertised at 0-5v RMS. I suppose there's no reason why not ... seriously, i just don't get it

** I know from my own experiments with the CP3 mixer clone that using a VCA in front of each input of the CP3 a ~PWM-like~ effect can be created by modulating the input levels going into the CP3. The VCA output levels must be set to get into the slight distortion when those levels are at max amounts. So modulating the VCA with either an EG or an LFO can create pseudo PWM type sounds. If the SW 901ABBB is unable to provide PWM, then I suppose I can use other methods, such as using a VCA to modulate the input level of each input channel of the CP3.

** Same situation with Expo FM. It seems as though all 3 VCOs share any FM signals (through the 901A). Is this true? If so, would one 901-per-VCO be required to FM each VCO independently of one another?

I'm not complaining, just attempting to understand these modules.

Thanks!
josaka
Rex Coil 7 wrote:
Looking at Synth Werk 901ABBB.

lol It took me several minutes to figure out that Synth Werk and Synthwerks are 2 TOTALLY different companies ... at first I thought "WTF? ... this place doesn't make Moog VCOs" when looking at Synthwerks. Ok, so I got that sorted out.

** How does one go about producing PWM with these VCOs?

** Can the Happy Nerding FM Aid be used with these modules? The output levels are advertised at 0-5v RMS. I suppose there's no reason why not ... seriously, i just don't get it

** I know from my own experiments with the CP3 mixer clone that using a VCA in front of each input of the CP3 a ~PWM-like~ effect can be created by modulating the input levels going into the CP3. The VCA output levels must be set to get into the slight distortion when those levels are at max amounts. So modulating the VCA with either an EG or an LFO can create pseudo PWM type sounds. If the SW 901ABBB is unable to provide PWM, then I suppose I can use other methods, such as using a VCA to modulate the input level of each input channel of the CP3.

** Same situation with Expo FM. It seems as though all 3 VCOs share any FM signals (through the 901A). Is this true? If so, would one 901-per-VCO be required to FM each VCO independently of one another?

I'm not complaining, just attempting to understand these modules.
Thanks!


forget about what the .com stuff does.. this is just about tone and end results.
I had a .com set up before.. the end results I get with the ML/SW stuff seem quite different.. so much so that I dont touch the .com osc.. nothing wrong with .com at all !.. I just dont get the same feel as the SW..the ML either..
it could be partly that mentally we buy into these things.. I not sure that is it.. the .com has a harder sound more modern if you like ..less round and deep to my ears.. and start detuning the 901.. different sport smile

burdij
Rex Coil 7 wrote:
Looking at Synth Werk 901ABBB.

** Same situation with Expo FM. It seems as though all 3 VCOs share any FM signals (through the 901A). Is this true? If so, would one 901-per-VCO be required to FM each VCO independently of one another?



Yes, that is correct. In a 901ABBB setup, there is only one exponential converter and that is in the "A" module. The oscillator "B" module takes the exponential current from the backplane connector so you would need separate backplanes for each 901AB pair.

The arrangement is different for the 921ABBB oscillator banks. Each 921B oscillator has an exponential current converter. The 921A has only signal amplification (actually reduction as the internal standard is 0.5V/Octave) and range calibration.
Rex Coil 7
921 vs 901 .... I've seen posts that go into saying that the 901 is "the old sound" and the 921 is "the other old sound".

Sonically speaking, what are (or is) the difference(s) between the two? Or is it just a matter of them being technically or mechanically different?

This Moog stuff .... a completely different ethos, no doubt about it!

cool
burdij
The story of the development of the 921 to replace the 901 was an evolutionary one in the history of the Moog Company. It rapidly became obvious that the initial design of the 901 had two major issues, tuning stablility an pitch range. The stability issue was caused by the uncompensated exponential converter, a problem that was never corrected and the second issue of range was caused by the use of a unijunction transistor as the sawtooth core of the module. A unijuction has current issues at the extremes of its switching range so the oscillator was limited to a linear range of about three octaves.

The 921 oscillator was developed in the early '70s during the golden era of analog integrated circuit design. It was during this time that RCA introduced the CD3046 transistor array which rapidly became the go-to part at Moog for such things as exponential converters, sine converters and as the core of operational circuits which up to that time were made from discrete transistors. Another part, the LM1496 balanced modulator, allowed the development of the excellent soft sync function built into this oscillator.
Rex Coil 7
How do the differences change the sound? Said another way, is there a reason (sound wise) why one would want 921 setup over 901 setup? What am I to listen for when I check out videos/audio demos as I compare the two?

Secondly, is there anything DIY available for this stuff that does not involve making the circuit boards (etching, drilling, etc..)? In other words, are there any PCBs available that "do Moog"?

burdij wrote:
The story of the development of the 921 to replace the 901 was an evolutionary one in the history of the Moog Company. It rapidly became obvious that the initial design of the 901 had two major issues, tuning stablility an pitch range. The stability issue was caused by the uncompensated exponential converter, a problem that was never corrected and the second issue of range was caused by the use of a unijunction transistor as the sawtooth core of the module. A unijuction has current issues at the extremes of its switching range so the oscillator was limited to a linear range of about three octaves.

The 921 oscillator was developed in the early '70s during the golden era of analog integrated circuit design. It was during this time that RCA introduced the CD3046 transistor array which rapidly became the go-to part at Moog for such things as exponential converters, sine converters and as the core of operational circuits which up to that time were made from discrete transistors. Another part, the LM1496 balanced modulator, allowed the development of the excellent soft sync function built into this oscillator.
josaka
for me its a little like 909(921) vs 808(901).. both sounding good.. the 808 being more bassy . and a warmer sound.. obviously its not as noticable on the moogs..!!
the 901 are a little more wild and free than the 921 as well.. the differences are not huge.. but if you had both I think most people would go for the 901 sonically ..they just have that funk.

smile


burdij
If you are auditioning a single oscillator of any kind or manufacture, you are going to be hard pressed to say one oscillator sounds "better" than another. What are the possible factors that can make a pure wave sound different than another pure wave of a similar form.

The first would be frequency. Small differences in frequency are noticeable because our hearing and perception have innate expectations about frequency and specific expectations about pitch due to built in (instinctual?) biases. Musicians can be trained to produce frequencies that are "on pitch" and some people even have perfect pitch where they can tell you what the pitch value of a specific frequency wave is.

The second factor is the wave shape. If a wave is a perfect sinusoid, it will have only one harmonic. Slight deviation in the shape of the wave will introduce harmonic content at different levels. This is probably the most noticeable difference between different oscillators. The fidelity of a sine wave depends on the type of conversion from the waveform produced by the core oscillator and the sine output. It is the simplest wave in terms of harmonic content but the most complex to generate with good fidelity (lowest harmonic content).

The third factor is how faithfully and accurately the oscillator follows the control source. For an oscillator that is free running, this doesn't matter but these oscillators really aren't useful for music production as an "instrument". Here is where I think the major differences might live between the 904ABBB and the 921ABBB subsystems.

I like to think of an analog of the tone production system, that of the pipe organ. The pipe organ derives different voices by combining different stops of pipes each of which produces almost a perfect sine wave tone to achieve the sound of a totally different musical instrument such at an oboe. By mixing the tones at different amplitudes and partials, a new sound is created. This is a type of synthesis based on the concepts of the Fourier transform. Any complex function can be reduced to a bundle of sine waves of specific, harmonically related, frequencies and phases.

The 901ABBB subsystem is going to be able to achieve better inter-oscillator stability and tracking of the multiple oscillators because it has only one source of exponential current with one set of defects and tracking characteristics. The 921ABBB subsystem has three sets of exponential errors and tracking issues.

One has to keep in mind though that, on the one hand, the overall tracking errors of the 901 system may need to be constantly adjusted to keep it musically useful where the 921ABBB could be carefully set up and adjusted to produce an equally superior composite waveform with all the depth and sonority of a well adjusted 901 oscillator bank but with less issues of overall tracking and having better musical utility.

As a manufacturer, and if I were building clones of such modules, I would be less inclined to make clones of the 901 and more inclined to clone the 921 with the intent of solving the issues of composite tracking and adjustability of multiple oscillators.
Rex Coil 7
The pipe organ analogy is the same as a Hammond, the exact same system is used to obtain different timbre. The drawbars control the amplitude of different harmonics, each one being a sine wave.

Ok, so I'm gathering that a lot of what makes Moog VCOs do what they do has to do with tracking (in this case, 1v/oct). The 901s (as a gang) have their tracking controlled by a single module, the 921s track individually. The other aspect would be various types of clipping and inaccurate waveforoms that tend to interact with one another in pleasing ... well most of the time ... ways.

Hmmm ..... that said, it seems as though these aspects can be emulated with careful and purposeful tweeking and adjusting of VCO tracking (per VCO), as well as creating various types of ~imperfections~ in the base waveforms through various methods.

Wow, ok there's some stuff I need to think about here.

hmmm.....
burdij
Rex Coil 7 wrote:


Hmmm ..... that said, it seems as though these aspects can be emulated with careful and purposeful tweeking and adjusting of VCO tracking (per VCO), as well as creating various types of ~imperfections~ in the base waveforms through various methods.

hmmm.....


At the time that the 921 modules were being developed, the Moog company was also working on the Minimoog D and the principles of precision tracking adjustment were incorporated into the design of the oscillator section of that instrument with the addition of zero adjustments for each of the oscillators.

The 921A could only compensate for the overall span or tilt of the pitch control function so that a 1V change in the control voltage would cause exactly one octave of change in each oscillator output. The master tuning control served as a zero offset so that a specific voltage could be set to a specific octave's C pitch. All the additional tracking would need to be made by internal adjustments in each module. Probably a better design would have been something like this:



In this design, there would be a separate amplifier with zero and span adjustments for each output so that the imperfections in the tracking of each downstream oscillator (tilt and zero) could be easily adjusted. In fact, a module like this could be used to compensate just about any fairly linear set of oscillators (i.e. accurate 1V/Octave, octave to octave) to allow their tuning to be brought into unison and possibly recreate the desired harmonic sonority.
Rex Coil 7
If I'm not mistaken, I believe Tom (Noddy's Puncture) made the "span" controls accessible at the front panel.

noddyspuncture wrote:
I added multi-turn trimmers to both my 901a & 901b DIY builds for all calibration controls, accessible from the 'gap' in the rear cutout just above the circuit board. I used 'D' connectors instead of the standard 22way original connectors so could use that 'gap' instead of drilling holes. I then converted all my original 901a's & b's to the same..!




To make sure I understand your drawing properly, is it safe to say that the per-module "zero" controls are the same as "offset", and the "span" controls are the same as "range"?

I've been thinking of ways to emulate some of these quirks with Dot Com VCOs. Incorporating a super fine tracking control that is front panel mounted on each VCO might go a long way towards producing some of the Moog "imperfections" that are so embraced by those that love the sound.

Sure, the Dot Com Q106 VCO has an adjustable FM input, where one could adjust the tracking in certain ways. But it's too coarse. I'm thinking about perhaps moving the tracking trim pot function to the front panel, which would also liberate the adjustable FM input for other uses. Or, routing the 1v/oct signal through a range controller of some sort before it hits the tracking FM inputs, on a per-VCO basis.

While the use of such a feature wouldn't instantly make a Moog VCO out of a Q106, it may help to produce a more convincing approximation. If nothing else, it may add a certain charm to the Q106 that the Moog stuff seems to hold as it's own. At least that's what I think.

hmmm.....
burdij
Rex Coil 7 wrote:


To make sure I understand your drawing properly, is it safe to say that the per-module "zero" controls are the same as "offset", and the "span" controls are the same as "range"?


hmmm.....


Yes, that is correct.
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