CV Note problems

Hello, I have the problem that my Hapax plays the notes too low via cv. When I play C5 comes C0.
This also means that I can’t play high notes. In the setting it is -5volt to +5volt. Calibration with a voltmeter didn’t help. Does anyone have a :bulb:

what does C5 show on the voltmeter?

in eurorack v/oct is not absolute, its relative.
so it sounds like the oscillator your feeding into, might well have its coarse tuning to low, so increase it.

note: there is no standard about voltage ranges for v/oct for input/output, so oscillators are different.

I look later with Voltmeter.
My Vco is Erica Synths VCO 2

C5 shows perfect 0.00 Volt

that seems ok then…

as the hapax goes C0-C10 , so C5 = mid point = 0v
(you can also see the midi note number on the hapax C5 = 60)
and so therefore C0 = -5v , C10 = +5v

its worth bearing in my that midi does not dictate what the octave numbers are…
so, different manufactures choose ‘middle C’ as C3,C4,C5. depending on if they want the lowest C to be C -2, C -1 or C0

and as I said this all becomes even more ‘irrelevant’ with v/oct…
since depending where your ‘coarse tune’ is on an oscillator, you might have A5 might be 110, 220, 440, 880hz :slight_smile: its all relative.

modular is different, which is cool, as it leads us different places :slight_smile:

So i think i found the Problem.
I need volt from 0.00 volt to 10 volt.
I order the Doepfer A-183-2 Offset/ Polarizer /Attenuator - Attenuator Modular Synthesizer.


I just looked at the specs on the Erica Synths VCO 2
it doesn’t mention the v/oct range - but that’s a pretty unusual range for an Osc v/oct input.
(have you verfied the v/oct is unipolar)

anyway the OSC range is limited to C0-C8 (to 8v) ,
it also has a ± 3 Octave switch, so that covers 7 oct!

frankly 5 octaves with that would cover mention applications.

be very careful using an offset/attn… they won’t necessarily track well…check to see if its designed for v/oct. you have to be extra careful with v/oct.

the proper way of doing this is using a precision added - so you should use an voltage source (the A183-2 should be fine for this) but then feed that , and the v/oct signal (from hapax) into a Precision Adder module.

of course, you can fudge it, but it you’ll likely regret it :wink:

again… if you are thinking of set n’ forget of the course tune, then Id say … thats generally NOT the way eurorack works… this is why (virtually) all oscillators in Eurorack have a big tune knob… its not just for fine tuning - its expected to be used to get different ranges.

Im test with my Erica Synths Sequencer Voltmeter and note C10 =10 volts. That looks super. :wink:

as I said, there is no standard for eurorack for v/oct range. ( * )

the Hapax specs clearly state its ±5v , a not uncommon range for many modules.

(though, its hardly surprising if Erica Synths modules ‘match up’ :wink: )

(*) example:
Mutable instrument, possibly the biggest brand (after Doepfer) in Eurorack, uses -3v to +7v.
my guess is that this odd choice , was so that both ±5v and 0/10v modules would get around 5v usable.

Today Doepfer A-183-2 Offset is coming Installation complete and it work’s fine :wink:

1 Like

cool, but you would have been better off with the A-185-2, if you read that, it tells you why.

but if the A-183-2 works well enough for you, then thats ok.

This topic was automatically closed 21 days after the last reply. New replies are no longer allowed.