How to modify Bento Box osc to get analog exp TZFM?

Hello all!
How to modify Bento Box osc to get analog exp TZFM?
I know that to get lin FM of analog synths I should switch Bento box to exp mode,
but what I should do to get exp FM, exp TZFM and lin TZFM?

 

It's impossible because the signal can not get below 0 Hz if its modulated exponential. You kinda scale the fm amount in semitones instead of a fixed frequency. therefor the lowest frequency of the modulated oscillator gets halved with every octave you rise the amount and never reaches 0. a little sidenote: for this reason the waveform / overtones stay steady on every note.

 

But what kind of process is the basis of this? (Seems like this is possible in Rubicon)
Intellijel Rubicon
http://intellijel.com/wp-content/uploads/2012/12/Rubicon-Manual-V1.01.pdf
from Rubicon's manual:
TZFM EXP/LIN switch
- Selects the type of FM modulation the TZFM input will be.
This switch determines whether the response of TZFM is linear or exponential. The exponential setting is not really 1V/oct, and really just gives a
more extreme response to the modulation signal
but A100's manual talks: The most common exponential scale is 1V/octave. In this mode thru-zero is not possible as the exponential function cannot become negative.
Intellijel were wrong?
Also I found these

• Switchable linear and (for the first time in any module) exponential tzfm
• Linear index vca for dynamic control of tzfm depth

 

I think they just kept the term of "TZFM" but in fact it can not be thru zero. What Doepfer says is absolutely right.

It could be possible that they are talking about another fm method here. There is also a linear mode but with an exponential scaling. This means that the amount of fm is not a fixed frequency like usually in linear modes but rather its a fixed ratio but just for the amount, the modulation by itself is still linear. In this case the fm amount redoubles with every octave on the keyboard and leads to a steady sound (no change of the waveform over the keyboard) but it now can reach negative values.

 

How to make it possible in Bentobox?

 

By calculating the Amount in pitch values and converting it after that to freq values (P2F). Just check the "DX" mode of the Sirius VCO here https://www.native-instruments.com/de/reaktor-community/reaktor-user-library/entry/show/9451/

 

Awesome! Thank you my friend!