Home | ER-101 | ER-102 | ER-301 | Wiki | Contact

v/Hz scaling


#1

Whist waiting for my 101/2 combo to clear UK customs I decided to search for guidance on making a voltage table for my Metasonix R54 which is V/Hz scaling, couldn’t find anything worth while which could help me, could anyone point me to some resources?

I suppose this is the sort of thing I need.

What I am struggling with is what V/Hz actually means, how much does the frequency increase if you gave the oscillator 1v?


#2

i don’t know the maths however i once did a customs scale on the 101 for a not 1v/oct filter and also for the r54 and i had to do it note for note with a tuner nearby…aaand it didn’t really work out since the r54 would not track that well and was quite prone to temperature changes…


#3

Hey! I think I can help out here… Hz/V in some ways is simpler than V/oct because what it does is linearly follow frequency.

So let’s say 1v corresponds to a frequency - 220hz - then each successive volt will add exactly that frequency. Bringing it into the world of octaves, your first octave (220-440) would take 1v, and your next (440-880) would take 2v. So, basically, the voltage required to go up an octave doubles each successive octave.

But, this means that the semitones aren’t equally spaced either, like they would be in V/oct. Instead, the voltages that correspond to a semitone increment according to the frequency-semitone ratio, i.e. 2^(1/12). So, if your base voltage is 1.000, the voltage for your next semitone would be 1.000 x 2^(1/12) = 1.0594. The next would be 1.0594 x 2^(1/2) and so on.

I’ve attached a BIN file named HZPV which has 3 octaves (1.000v - 8.000v) scaled to Hz/V (that’s pretty much the useful range of my MS20-mini) but you could add another two octaves from 0.25 - 1.000 as well! You’d calculate it the same way, starting with 0.25 x 2^(1/12) or 0.5 x 2^(1/12) depending on whether you’d want one or two octaves more. I used a function calculator to give me a table of results, but my maths knowledge is pretty rudimentary and I’m sure there’s a quicker way to simply script an entire index.

HZPV.BIN (200 Bytes)


#4

@kilchhofer, @jurassicshift, yeah that’s what I thought I would have to do lol, the VCO part of the r54 is very interesting but it is a savage beast and goes where it fancies.

ATM I use if as a FM modulater for my Jomox Modbase09 and it is fabulous at coaxing supplemental brain scraping basslines out of the Jomox as well as an awesome bass drum, I would love to tame the tuning over about 2 octaves though, the r54 should track over 4v supposedly, jurrasicshift’s table should help me get the most amazing tuned brainscraper in existence.

Thank you for the nudges people.