Poll — Would you rather have more Linear FMs or V/Oct?

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Which do you prefer?

2 Linear FM + 1 V/Oct
12
40%
2 V/Oct + 1 Linear FM
18
60%
 
Total votes: 30

thor.lucas
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Poll — Would you rather have more Linear FMs or V/Oct?

Post by thor.lucas » Sat Nov 09, 2019 7:21 pm

Hi,

So I'm designing a VCO module right now. Because of the size constraints I have placed on myself, I only have the option of either having 2 Linear FMs and 1 V/Oct input, or 1 Linear FM and 2 V/Oct inputs.

I originally was thinking V/Oct inputs are more important since they're used more frequently. However, the more I think about it, the more I doubt this since you're only playing one note, so once V/Oct.

Hmm... What do you think is more important to you?

gtrmstr53
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Post by gtrmstr53 » Sat Nov 09, 2019 7:34 pm

I like to work with audio-rate FM, so more options in that direction would be a plus for me. Also, if it's a thru-zero design I'd especially like the extra linear FM in.

thor.lucas
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Post by thor.lucas » Sat Nov 09, 2019 8:12 pm

gtrmstr53 wrote:I like to work with audio-rate FM, so more options in that direction would be a plus for me. Also, if it's a thru-zero design I'd especially like the extra linear FM in.
What do you mean by audio-rate FM? Linear FM or exponential FM? A good way to split up the three options would maybe be 1 V/Oct, 1 Linear FM, and 1 Exponential FM (both FMs with attenuation, but no attenuation on the V/Oct cause that doesn't really make sense)

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mskala
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Post by mskala » Sat Nov 09, 2019 9:08 pm

I'd rather have the second V/oct input because that's a harder feature to simulate with another module. I can easily combine two modulation signals for FM with almost any mixer, whereas V/oct pitch requires more careful handling with a precision adder.

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Dave Peck
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Post by Dave Peck » Sat Nov 09, 2019 9:48 pm

It should have BOTH, for different purposes.

A) 1V/oct exponential for PITCH control, so it tracks a V/OCT keyboard etc. for controlling the basic pitch.

B) Linear FM or through-zero FM for audio-rate modulation, for creating complex timbres like bell tones, without causing the base PITCH to change.

thor.lucas
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Post by thor.lucas » Sun Nov 10, 2019 1:54 am

Dave Peck wrote:It should have BOTH, for different purposes.

A) 1V/oct exponential for PITCH control, so it tracks a V/OCT keyboard etc. for controlling the basic pitch.

B) Linear FM or through-zero FM for audio-rate modulation, for creating complex timbres like bell tones, without causing the base PITCH to change.
Yes, that's the question. But which one of those would you want TWO of? I can have three total, since I already have sync, output, and waveshape CV. I only have space on the board for six jacks, hence three of them have to be split between linear FM, exp FM, and V/Oct.

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Leverkusen
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Post by Leverkusen » Sun Nov 10, 2019 3:19 am

I hardly use two FM inputs where I have them, the same with two v/oct inputs. What I like though is CV over FM amount. Or a different waveform output, or suboctave.

But assuming your circuit design is already mostly done, from the suggestions above to me v/oct, lin FM and exp FM seems to be the best option.

thor.lucas
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Post by thor.lucas » Sun Nov 10, 2019 6:19 am

Leverkusen wrote:I hardly use two FM inputs where I have them, the same with two v/oct inputs. What I like though is CV over FM amount. Or a different waveform output, or suboctave.

But assuming your circuit design is already mostly done, from the suggestions above to me v/oct, lin FM and exp FM seems to be the best option.
Thank you sir!

R.U.Nuts
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Post by R.U.Nuts » Sun Nov 10, 2019 8:15 am

You could make one 1V/oct input, one linear FM input and an exponential FM input that tracks 1V/oct when the FM attenuator is turned fully clockwise. So you could use that FM input either for exponential audio rate FM or for tracking pitch CVs.

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chuckg
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Post by chuckg » Sun Nov 10, 2019 10:27 am

Sideways thinking - is there room for a switch? Make the third jack switchable between 1V/Oct and Linear.
….working on it.

ashleym
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Post by ashleym » Wed Nov 13, 2019 7:01 pm

/\
A switch would take much the same space as a socket??

How small does the panel have to be? If it’s for yourself and it has to be restricted then you can choose. If it’s for the wider public, put up you panel design and we can see what other design choices you’ve made. You might not have sync and we all know VCOs are pointless without sync. Dare I say you get more useable tones from sync than you do audio frequency FM? I would rather have dunce than multiple v/oct.

Again if it’s for you only, and you’re not using :ripbanana: how about TRS sockets and wire out custom leads with 2 mono jacks and stereo one like an insert lead. This lets you use each “stereo channel “ as lin/exp FM and 2 sets of v/oct

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Navs
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Post by Navs » Thu Nov 14, 2019 3:20 pm

I voted 1 lin, 2 exponential.

Based on habit and convenience: 1 v/o for pitch, the second doesn't need to be 1v/o, indeed it could be even more sensitive but still exponential, e.g., for pitch-bending/transient chiff envelopes, and then one lin-FM input for timbral stuff.

How to set up your lin FM input could be grounds for another poll, tho :hihi:

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Navs
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Post by Navs » Thu Nov 14, 2019 3:26 pm

How space-limited are you? I'd also want the second exponential input to have an attenuverter.

The Plan B M15 is almost perfect in this regard. Just that over-sensitive PWM input that needs an attenuator ...

Image

thor.lucas
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Post by thor.lucas » Fri Nov 15, 2019 3:52 pm

Navs wrote:How space-limited are you? I'd also want the second exponential input to have an attenuverter.

The Plan B M15 is almost perfect in this regard. Just that over-sensitive PWM input that needs an attenuator ...

Image
Yeah I was planning on attenuating the 2nd exponential FM!

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EATyourGUITAR
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Post by EATyourGUITAR » Fri Nov 15, 2019 7:31 pm

I agree that you can use the exp FM as a second 1v/Oct with the FM knob fully CW. However, some potentiometers do not go to zero ohms on one side. You would need to buy decent pots and or sort them for 0 Ohms. If you don't use more than one octave, you can get away with less than 0 Ohms there.
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mskala
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Post by mskala » Fri Nov 15, 2019 10:46 pm

I'd be very impressed to see a pot that goes to less than zero ohms.

However, apart from any questions about the pot, the usual design of a V/oct input for an analog oscillator has the CV from the V/oct input going to an op amp virtual ground through a 100k resistor. If you have two V/oct inputs and you want them both to be accurate, then those 100k resistors will have to be matched - either by being close-tolerance, being selected from wider-tolerance parts, or by having trimmers of their own. Otherwise, your tracking adjustment can make at most one of the V/oct inputs accurate.

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