MF-102 as an oscillator

The Moog Forum Moogerfooger Forum
1

Ok this is my question. If I had a MIDI-to-CV converter, could I use the MF-102 as a monosynth, by plugging the CV out from the converter into the frequency-CV-In of the MF-102?.

I know it probably sounds a little crazy, but I think that if you send a Pitch control voltage triggered by a midi keyboard into the Frequency in of the MF-102 you might have the cheapest (Good sounding!) monolead synth.

I’m a newby in Control Voltages so my question might be a little stupid, please beare with me! Tell me what you think!

2

I’ve routed pitch voltages from various keyboards into the MF-102 frequency jack. You would want an attenuator to cool that signal down a bit because the oscillating effect of the carrier isn’t really designed to be a VCO. Although the frequency can be controled in this fashion, the pitch would not be accurate unless the strength of the signal was fine tuned.

There would have to be some way to control the volume. I imagine the “mix” knob would suffice.

Also, if you tune the frequency just right (using the pitch CV and an attenuator) and feed the keyboard through the 102, the carrier in the ringing effect will form harmonics. Far out.

3

Try it out and let us know the results.

4

Check out this “Moogerfooger Station”!! Looks like a pretty nasty modular monosynth…

http://www.synthfool.com/sequeira.html

found it on www.synthfool.com if you want to check out the site

5

WOW! that’s a pretty nice station

6

kind of a ‘why didn’t i think of this before’ thing:

i patched the ‘carrier out’ into the main input on the 102.

haven’t popped it on a scope to look at it, but i do get a more ‘squarish’ waveform out of the carrier oscillator, something with more harmonic ‘meat on the bone’ to chew on with the 101 and the other moogers.

also, the waveshape can be VCed a bit by sending CVs into the ‘mix’ input.

if you’ve got a 251 [you DON’t?] lying around, you can attenuate this feedback, or sideback, or parallel patch or whatever you want to call it…

btw, this idea came out of my experiments on the vger, using the mod buss to modulate the LFO freq by its own square wave output - the triangle output was distorted into a more ‘ramp-like’ LFO shape. this trick works well on the 251’s LFO also…

so there ya go. the thing’s burbling away behind me as i type. i feel like an ancient VC pioneer, feeding my little voltages back on themselves. now i want to make one of those mooger ‘stations’ as mentioned above.

next up, i’ll dig my open reel tape deck out of storage and dust off the ol’ splicin’ block. samplers? bah! who needs em? ;D


x

7

Me too!!!

I’m getting my collection together as we speak.
I’ve just ordered the trio pack and then i’m eventually going to aquire 2 cp251’s and then build them together to form a nice Moog fx/modular.
I’ve been considering a small modular for sometime, but i wanted something a little different, as the regular modular thing has been done no end of times, plus i wanted a system for more audio processing than actual tone creation.

I doubt i’ll ever lay my hands on the 104, so this will have to suffice.
My only problem is, i think Moog may have something up their sleeves Fooger wise in the future, so i may wait for winter Namm before i start to construct a nice cabinet for them…love that one above!!!

I’m right with ya on the tape machine thing, that glorious sound and the most simplistic way of recording. :slight_smile:
They just beg to be used!

Never really got into splicing though, what do you use that for?

8

Forgot to ask.
Anyone actually had any success using the 102 as an oscillator source?
How is it stability wise, do it track ok?

Cheers
Jiggz

9

I’ve tried to use the mf-102 as an oscillator scorce. Hooked it up to my Micromoog. It sounded great (especially the square wave), but alas, it did not track correctly. You can make some really great noises, but you won’t actually be able to “play” anything.
-JBN

10

jiggz;

i’m somewhat OT here, but wanted to respond to your ‘splicing’ question.

back when i was a sprout, one edited tape physically using an aluminum block with grooves in it to hold the tape and also to fix a razor blade at the right angle to cut the tape accurately so that the cut ends could be joined with equal accuracy.

nowadays we all do this with a mouse. tape splicing is a cool technique to learn, but it’s damn tedious in practice, especially if the clock’s running…

having said that, i’ll offer this to anyone listening/viewing: because physical splicing is a physical thing, there is a different ‘feel’ to the result. this is hard to explain unless one has used tape splicing and digital splicing in parallel - although i can work MUCH faster using soundforge or Peak, i know that i work more carefully and with more thought when tape splicing.

there is more of a ‘soul’ to the resulting edit. i know this sounds insane, but it’s something i’ve experienced.

my comment to the forum was mostly meant as a joke, but it has a serious side to it. it’s my opinion that we should pay attention to things which may not be as ‘efficient’ as the newer tools. sometimes there is something useful, perhaps spiritual to be found in an older, cruder mechanism. analog synths, for example. :smiley:

ok, endrant.

lx

11

newname

Thanks for the reply.

I was more wondering why you would use splicing so much?
Was it some sort of compositional production technique?

Also, how did you join the tape back up together…sorry for all the questions!

Doki Doki
As for the oscillator tracking of the 102, well i’ve since learnt that this is where the cp251 would come into play to get the 102 to play in tune with the Micromoog.

The problem is, the input of the 102 has a lower voltage rating than the output of the Micro, so this is where you would use a cp251 attenuator on the ouput of the Micro to lower the overal signal level and slowly bring it in to tune.

I may have misunderstood something here, but i think this is the general idea. i think maybe the cv/offset on the 251 may come into play somewhere but i’m not entirely sure.
Maybe someone can throw some light on this?

Jiggz

12

yo, jiggz.

I was more wondering why you would use splicing so much?

not that much. i just happen to have a tascam 32 mastering deck and a splicing block. also, i’m so ancient that i learned to edit on analog tape. getting back into the CV thing via moogers and voyager, i figured it’d be ‘fun’ to edit tape again.

Was it some sort of compositional production technique?

yes. if i’m working with ableton, logic, or even digital editors like soundforge or peak, i’ll be a lot more nitpicky and second-guess-y about my edits. with tape, it’s usually one best shot, then you move on. [i can go into detail, but we should probably take conversation private to do that.]

also, i’ve found that the results with tapeloops are …this is hard to explain… ‘different’ from results with digital tools. i can try to make assymmetrical loops with digital tools, but there is a different feel. to be honest, it’s probably a more ‘professional’ feel. but that opens another can of worms: i’m getting tired of ‘working’ music. i’d kind of like to get back to the emotional place where i ‘play’ music. computer based tools just feel like ‘work’ to me. probably because they are work…

Also, how did you join the tape back up together…sorry for all the questions!

no worries, i’m flattered that you ask. you can use 3m splicing tape, made for the purpose.

on the other hand, you can splice tape with regular cellophane tape, although it’s rather thick and doesn’t make for good splices. also, there are two cutting techniques which bypass use of a splicing block. [once again, we should probably take this private lest we incur the wrath of the admin for these distinctly UN MOOG exchanges! :smiley: ]


cv from your micro - attenuation via 251:

I may have misunderstood something here, but i think this is the general idea. i >think maybe the cv/offset on the 251 may come into play somewhere but i’m >not entirely sure.

i should dig out the moogs and test this first, but there is the possibility that the 102’s VCO is not exponential, but linear. if so, you’d get a situation happening where the oscillators would be in tune at one point on the keyboard, and gradually go out of tune in relation to each other as you played different notes. btw: examples of old ‘linear’ VCO synths include the korg ms series, yamaha cs series, PAIA modulars.

\

Maybe someone can throw some light on this?

i’ll set up my moogs and test this, will post back l8r.

another detail, might just be myth, an old synth tech told me this:
old electrocomp synths weren’t set up at 1v/oct, but more like 1.1v/oct or something. he said the original minimoogs were shipped with slightly higher scaling, also. this may just be BS, my old mini tracked just fine when fed CV from a MIDI/CV xverter…

happy patchin’, jiggz!

lx

13

newname…look forward to hearing your conclusions!

If you’re right about it being linear, then it is perfect for use with my MS10, but i can’t test this as it’s away for a service a the moment.

As for the tape splicing, i’ll PM you.

Jiggz

14

ok, i tested with my voyager.

assuming the voyager is exponential [pretty sure it is], the 102’s carrier VCO is as well. it is indeed scaled ‘higher’ than 1v/oct, more like 1.4v/oct. i found that i could get it to track accurately by attenuating KCV output [taken from my 351] to appx 75%. obviously you could do this with one of the attenuators on a 251, or even throw the entire voltage mixer at the thing for a much bigger palette to play with.

so jiggz - this rules out playing traditional music from your ms10. [but who wants to play traditional music on a synthesizer, anyway? yucky. :stuck_out_tongue: :wink: ]


to recap:
-attenuate the voltage a bit. you can do this with a 351 or a 251.

in setting this up, i noticed that it reacts a bit differently from most VCOs - the voltage response appears bipolar, so you can’t scale it by hitting a low note, tuning the oscillators to unison, then hit a high note and attenuate until they’re in unison again - you have to find the ‘span’ of attentuation that causes the 102 VCO to respond at 1v/oct, then use the front panel tuning control to tune it in with your other oscillators.

[btw, if you don’t have a 251 or voyager-equipped 351 but you’re handy with a soldering iron, go to the moog archives, look around in there for ‘port-a-pots’. most likely a simple 150k linear taper pot can be used to make one of these useful little patching tools…]

-if you are using a 251 or something that can send out lots of interesting CVs, consider patching ‘carrier out’ into ‘audio in’. this will give you a mixable [via the mix knob or cv] sine wave one octave above the carrier. if you overdrive this and play with the mix around the 12 o’clock area, you get a decent waveform to filter, etc. it responds well to VC as well, producing a neat ‘vintage electronic music’ sort of tone…

-the LFO on the 102 does not track a keyboard, and isn’t really supposed to be an audio oscillator. nevertheless, if you’ve got a 251, you can use the bias voltage on the little voltage mixer to goose this LFO up into the low to mid audio range. this can be a lot of fun to monkey with, especially if you start CVing the ‘amount’ and ‘rate’ inputs.

i think to really exploit these features, one would have to consider something which can chuck out a lot of control voltages under plenty of user-specified control. something like an encore expressionist MIDI->CV comes to mind. i can see how someone [with a lot of time on their hands to make weird noise] might set up keyboard ranges which selectively change ‘amount’ levels and ‘rate’ levels on the LFO while perhaps sending a varying voltage to the ‘mix’ control. etc.

if chaos is your bag, a sherman filterbank can be misused to provide four nominally synced voltage resources - goto the sherman.be site, dive into their forum and search for a gilles post with a title like "A UNUSED FILTER EQUALS 4 DIFFERENT LFO’S ! "

ok, fellow audionauts. enjoy. hope this helps…

lx

15

Thanks for all the info newname. After reading this topic, I’m about 99% sure that this idea will work using my 102, Rogue, and a CP-251 (and its attenuator). Right? I just don’t have a 251 to try it out… looks like that will be my next “gear” purchase, not just for the attentuator, but all those CVs will be fun to mess with.

16

yes, that’s right. btw, there is much fun to be had when you ‘scale’ the 102’s oscillator differently from your keyboard - the nature of ring modulation is such that you’ll find that sounds become ‘clangy’ and then resolve at various points on the keyboard… sometimes it’ll sound like a chord, sometimes like a bell, sometimes very electronic.

the 251 is definitely a cool tool, i get a lot of use out of mine.

check these out:

http://moogarchives.com/portapot.htm

portapots are attenuators, built very quickly with no case and very little soldering.



good luck!

x

17

One other easy device to make is a voltage pedal. Just take a 9volt battery and a 9volt battery connector from radio shack and solder it to a male 1/4" jack. I believe positive goes to the tip and negative goes to ground. Then plug the jack into the input of a volume pedal. Now the output of the pedal will be 9volts attentuated by the pedal. This will let you use CV inputs(as opposed to pedal inputs) on older Moogs. Many inputs are meant for +5 to -5 volts, and it might not be good(I’m not sure) to give them 9volts so just use an old battery that is only putting out 5 volts…

The only problem with this device is it only spans the positive range of the CV input.

Does anyone know how to make it range the negative values?

18

Thanks for the replies.

But, would I need such a “port-a-pot” with stereo connectors? Being that the keyboard out on the Rogue and the frequency input on the 102 are both stereo. How do I make one? There’s not much found through a Google search. Just a lot of info about portable toilets :smiley:

19

I think the Keyboard Out on the Rogue is both input and output; that’s why it’s “stereo”. You don’t have to use a ring/tip/sleave stereo cable unless you are making use of both in and out at the same time. It’s probably written underneath the jack, or in the manual, which is ring and which is tip. Ring and tip, in case you don’t know, refer to the jack itself-- just read the manual (if you haven’t already)for your Moogerfooger or Rogue: they’re both very well written, and this info is describe there.
with the Moogerfooger, the stereo type jack is implemented for a different reason, but again, it is not necessay to use stereo cable.

To make one of these port-a-pots: simply buy male and female Mono 1/4" jacks, and a potentiometer. I think the pots are maybe 100K or 50K value (same values you would find inside Moogerfooger exp. pedal–same purpose). It would’nt hurt anthing to use a different value-- but these 100K would work the best probably. Just solder them all together the way they look in the picture: the Male jack tip to input of Pot- Pot output to tip of Female jack. you might connect the grounds together too.

20

Alright, thanks. That seems to make sense. If anything, my stepdad is an electrician, he might be able to help me put it together properly. I’m pleased to hear that what I need to attenuate the Rogue’s CV output for the 102 is relatively inexpensive. I can find the parts I need at RatShack? I would still like to get a CP-251, but considering the cost…

One thing though. The 102 has stereo jacks for such things like Freq, Mix, Amount, and Rate… right? Or am I totally off. I have the manual somewhere, but it’s somewhere in a box. I see that the tip is the “keyboard out” for the Rogue. So if the tip is a CV input on the 102’s Frequency jack, then all is well? I’m asking because I seem to recall that the expression pedals use stereo jacks. Thanks again for the help, I do appreciate it! I just dont know much about this stuff. And I don’t know anyone close by who knows about old synths and CV and stuff. (I do know some people who are anywhere from a few hours to a few days’ worth driving distance away… hehe.)