Vintage Revolution - Pedal Pro

[obiwanjacobi]

Triaxis is a good example of digitally controlled device. All the controls are implemented using opto resistors.
Opto resistors are great sounding components but have two main problems.
1) The resistance range between each components may vary 200-300%.
2) LDR (opto resistor) are slow components. From low resistance to high resistance, due to the dark current, the transition may take 500ms !

So LDRs are good for certain slow real time controls that do not require fast transition. (Eg. Tone, gain).
Using MIDI cc to control LDR currents is fine as long 128 levels resolution offers enough resolution (tone and gain controls)

The problem is that each technology used to control an analogue parameter (eg. digital pot, LDR) should to be selected according to their limitation and drawback.
Example:
If you try to control Tempo with LDR you will end up facing thermal drift.
If you try to control Tempo using a digital pot, you will not have enough resolution.

PedalPro is much more then LDRs and digital pots.
It is a waveform synthesizer capable of producing up to 8 modulation waveforms and real time controls that can be synchronized with a very high resolution and insensitive to temperature swings.

So if you need to span 16 bits for Tempo, 10bits for filter frequency, 8 bits for effect depths using midi RPN it would lead to a convoluted programming + latency .
Standard midi cc would be good for latency but poor from resolution point of view.

Thanks to the ADES protocol the user does not have to think about resolution and latency. He can modify the analogue parameters according to its measurement unit (eg. Hz for frequency, dB for gain, percentage for depth, BPM for tempo) and set the appropriate range without thinking about how max and min limits will be mapped.
For example with Pedalino you can set the Tempo of the tremolo to span between 100.0 BPM to 300 BPM in no time. Further you can see on the display when the expression is approaching to 200 BPM.

To conclude, Midi protocol was not designed for real time control of analogue parameters but for midi keyboards.

Sorry, I still don't get it

But I wont bore every one with going on about it.

Ciao,
about the 4 processors:
When I started the architecture and the feasibility study, I had in mind always a multiple-waveform synthesizer.
This is the real big difference with rest of the digital controlled devices.
If you have an analogue pedal, the waveforms that you can generate are very limited.
Thanks to this flexible architecture, each processor can be loaded with up to 16/18 different waveforms.
So that the waveforms used for the chorus can be different for the phaser, wah, and tremolo.
Further I always want it to reproduce the compression curve of a Vary-mu (Fairchild).
So, the secret is the PedalPro is not only in the component selection but also in the way we control the waveform generators.
Keep in mind that I want it to have no limitation in number of simultaneus waveforms and the ability to synchornize tjhem all with 4 values of relative phase (0 90 180 270).
If you want to have more info, I will be happy to answer more questions on the matter.

Regarding Digital Pot and volume controls, the PedalPro has 4 ways of controlling the volume. Each of them relates to a different technology and placed in different chain position.
1) VCA voltage controlled amplitude of the compressor using compression parameter. By increasing the attack to 85ms, you can transform your compressor in a powerful volume control/saturation control (if used to drive a distortion). This VCA (compressor) is placed in the beginning of the chain. Technology matched pair transistors
2) Opto resistor changing the gain control of the boost. Range -6dB: 25dB also placed in the beginning of the chain but after compressor and pre loop. Technology LDR
3) You can also use the VCA in the Tremolo as a volume control, by activating the function FOOTC. Technology matched pair transistor
4) Main stereo volume control via digital potentiometer placed at the end.
Technology dual potentiometer

I think syncing waveforms is great but do you need an individual processor for each waveform output? What MCU do you use (are they small)?

Thanx.