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Using a synth as an FM source?
MUFF WIGGLER Forum Index -> 5U Format Modules  
Author Using a synth as an FM source?
Rex Coil 7
Oyay Compas!

The trick of using a sine wave at audio rates (tracking the same 1v/oct signal the VCOs are following) piped in to the attenuated FM input of a VCF is something many of us have done. It sounds great with just a sniff of depth used to modulate the filter's cutoff.

If I were to run a sine wave out of an outboard synth into the audio interface (to bump it's level up to modular levels) could that sine wave be used in the same manner as any VCO's sine wave as an audio rate modulation source?

It seems as though this would work. Have the outboard synth track the same 1v/oct signal as the internal VCOs are following ... send the outboard synth's output into the Instrument Interface for an output level bump ... and send the instrument Interface's output to the Cutoff FM input of the VCF.


And could the same thing be done, but instead send the Instrument Interface's output to the Expo FM input of a VCO for "FM" sounds?

If so, using a synth such as my Kurzweil could send a super ~freq stable~ audio rate waveform (as a modulation source) into the modular for more stable "FM" sounds since the digital synth has far better frequency stability for use as an audio rate modulator.

Can this actually work? I'm hoping the answer will be a resounding "yes"!

Thanks ... as always I value the experience and opinions of the members within this subforum.

Y'all be bitchin ~n~ shit!

cool Rex.
Of course it'll work - it's an audio signal just like the output of the VCO. You probably won't even need to boost the level if you're only going to attenuate it again on the FM input
Rex Coil 7
unrecordings wrote:
Of course it'll work - it's an audio signal just like the output of the VCO. You probably won't even need to boost the level if you're only going to attenuate it again on the FM input
Sorry I asked such a rudimentary question. Thanks for the help.
Rex Coil 7
The Volca FM is working FAMOUSLY as a modulation source. They can be had used for less than a buck twenty ($120.00). I traded an unused distortion stompbox for one in mega-great shape.

Using a single operator (as carrier) it produces a solid and sound sine wave. Using it's own LFO to modulate the output level or frequency of that sine wave is no different than recurrent modulations that are modulating an LFO/VCO that is used as a modulator itself for some destination. Using fully blown algorithms it works just as well.

That thing has onboard arpeggiator, 3 track sequencer, modulation tracks in the sequencer, parameter lock on a number of sources, an audio rate LFO that is assignable to several destinations, and many-a-way to modulate the signal that you ultimately send out to modulate your voltage controlled module. AND it saves up to 32 programs as well as 16 sequences ... so lots of outbound modulations available at the selection of a preset.

Using an entire outboard synth as a modulator works very well, you get not only the modulation wave but modulations of the CV modulation wave used to modulate your modular destination module.

Whole lotsa modulations goin' on, mens! All for half the price of a single VCO.

thumbs up
yep, I've got a Minibrute hacked up to export a bunch of outputs to a 25-pin connector I can plug into a breakout box to use similarly. It's great.

The only weakness with an outboard synth as a secondary oscillator is that it's super hard or impossible to sync it as well as say a q106. But you can't beat the price
Rex Coil 7
ranix wrote:
yep, I've got a Minibrute hacked up to export a bunch of outputs to a 25-pin connector I can plug into a breakout box to use similarly. It's great.

The only weakness with an outboard synth as a secondary oscillator is that it's super hard or impossible to sync it as well as say a q106. But you can't beat the price
I don't usually try to use it as a ~VCO~ ... I just use it as an outboard audio rate modulator. I run the outboard synth through a Q118 Instrument Interface (or a Q114++ which works just as well with the channel option set to 100X) at which point the outboard signal is now at full-on modular levels. Then I use the outboard synth signal as an audio rate modulation signal.

In the event I do want to use it as an extra VCO in the audio path, I have put a Q147 Distributor after the Q118 so I can distribute the boosted signal from the external synth to CV inputs and into the pre-filter mixer as an additional ~VCO~. I started using my Kurzweil (precious precious Kurzweil) for this outboard purpose .... until suddenly the MAIN LEFT/MONO jack stopped working on the Kurzweil. Getting warranty coverage was a total fucking BITCH of a major ass freekin hassle. The trouble has nothing to do with Kurzweil as a company, or any reluctance on their part to help me out. It had everything to do with the distributor (and frankly the dealer I bought it from). I know this will sound pretty unbelievable, but I had to email the repair distributor FOUR TIMES and call them ... ready? ... NINE FOOKING TIMES before I even got a response. E.v.e.r.y. single time I called, I got sent to voicemail. I left very polite, articulate, clearly spoken messages with my return phone number left at the beginning and the end of each voice message. NINE TIMES!!! I even tried calling their accounts receivable mailbox figuring if they thought I was someone that owed them goddam MUNNEYCHECK they'd for certain call me back. Nope. Each email, and each voice message I gave them a full week to reply. I feel I was more than polite, more than fair, and more than patient.

(And this distributor is no little mom-n-pop shop .... it's friggin American Music and Sound in L.A. for crisakes!! They are BIG ... as in nearly Sweetwater big).

Finally, I had to contact Kurzweil themselves and pitch a man sized bitch fit about my THIRTEEN WEEK ATTEMPT to get the distributor to respond. Suddenly, inside of fifteen minutes, I got a phone call from the repair distributor by an extremely polite and unbelievably helpful and eager service authorization and repair manager (who behaved as though he'd just received a major ass chewing from someone above him) who was very willing to not only take care of my troubles, but also authorized to pay for the shipping of my beautiful PC3A6 BOTH WAYS. He issued a warranty repair authorization case number right there, right then, and apologized to me up one side and down the other.

So my main digital synth is off at the doctor's getting the output jack issue taken care of. It's most likely just a cold or bad solder joint, since the problem kindof clears up after the synth saturates with a little heat after being powered up for about an hour. Anyhow, meanwhile I've been using the traded-for Volca FM as a digital modulation source and a digital VCO. Which is actually working extremely well in that role!

Indeed, so well that the need I felt to save up for one or two Happy Nerding FM Aid modules has subsided completely. The Volca FM has all of it's own modulators, and produces those killer FM/wavefolded type sounds with expertise and aplomb. No matter whether I use it as an audio rate modulation source OR an FM/wavefolded sonic addition piped in and mixed with the analog VCOs. I paid $60.00 bucks for the distortion pedal that I traded for the Volca FM.

All is well tonight. Well, with the exception of not having my prized (and long wanted) Kurzweil PC3A6 ... the king of the Kurzweil lineup when it comes to their performance synth models. I prefer 61 note keybeds, especially so since the PC3A6 uses the mighty mighty FATAR TP/9 keybed. It's reasons like that which make me call the PC3A6 the top of the performance synth heap within the Kurzweil catalog.

Bla bla FRIGGIN ASS BLA!!!!! Yakkity danged yak! Once again.

Ok ... bye byes.

cool Rexola.
You can use anything as an FM source! Here is a Cwejman PH4 FMd by a TR909 hihi

[soundcloud url="" params="color=ff5500&auto_play=false&hide_related=false&show_comments= true&show_user=true&show_reposts=false" width="100%" height="166" iframe="true" /]

Patch description in my patching thread: thumbs up

Cheers Guinness ftw!
Rex Coil 7
(that audio file really sounds NEAT!!)

I don't know ... the whole notion is just not something that crossed my mind before.

What I know now, is that using a Volca is about the least costly method I can think of to add a stable digital sine wave FM source, which includes all of it's own recurrent modulation sources. And instant changes made by simply changing programs in the Volca. Damned cool, I tell ya!

Same thing with using my Kurzweil for the same purpose. It is so stable, and has so many bloody modulation methods/options/sources to modulate the modulation signal ... one program has THIRTY TWO layers, and I can pipe up to four separate programs out of four separate jacks, each one controlled by it's own MIDI channel. That comes down to meaning I have up to four individual FMCV sources available, which are instantly changed by simply selecting a new program from memory banks.

Or I may have one or two output jacks sending out actual programs that are being played by me or a sequence or an arpeggiator to my audio mixer, and one or two output jacks sending FMCV signals into my modular .... all simultaneously.

Add to that whatever I can conjure out of the Volca FM to modulate the modular synth. I have thirty four modulation destinations normaled to thirty four modulation input jacks mounted on a trunk line interface panel for the modular project synth. So there's puhLENTY of destinations to send these CV sources from outboard synths.

The potential is really mind blowingly cool!

Trampoline Dancing Star spinning

EDIT! HOLD UP ... hold up hold up hold up .... hold .... thuh fek .... UP! I used to own a Kurzweil K2600S 76 key. I recall it having SIXTEEN output jacks, one per multi-timbre voice. One of them beasties would provide up to sixteen separate FM source signals. And to make this even sweeter .... the 2600 was available in RACK FORMAT!!!

This shit's MONEY I tell ya! MUNNNAAAAY!!!

(scoots off to eBay ...)

nanners thumbs up woah applause
Rex Coil 7
Ok a few things have happened. I got in two Volca FMs for testing of this concept. Since then the opportunity to own a Nord Micro Modular presented itself, so I jumped on it (my 5th one of these since 1999 or so). It's worked out very well for more than just ~this~ purpose so far. Damn those things sound so good. That said, the Volca FMs are being sold.

I have an assload of Dot Commage, much needed parts, much needed Euro modules, and other gears all on it's way in support of my synth project. Meantime, I've been working on everything other than building panels into modules. Once the panels are up ~n~ runnin' I'll be doing even more tests using the Nord Micro as a modulation source, as well as an additional "voice" added to (or in place of) the Dual VCO Voice modules in the project synth. This should prove to be interesting!

I've much to post in the project thread ... coming up soon! I have a lot to photograph, and I've been putting together progress posts along with pics I've already taken along the way over the past month.

Dang me ... these little Nord Micros are just so stinking potent! Modulator, external signal audio processor, and sound source. In stereo no less.


(unsubbed ... my subscriptions are totally out of control and I need to thin that list out .. PM me if you need to say anything of relevance to me regarding this topic or my postings).
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