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Messages - Xavier

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PreenFM2 / Re: Change MIDI parameters
« on: August 18, 2019, 10:20:55 PM »
Hi! how can I change the MIDI parameters to associate it to another values?


You have to re-compile the firmware.
Then it's easy, change the value in the following enum :


PreenFM2 / Re: New filters
« on: August 17, 2019, 08:49:58 AM »

I haven't tried it yet, but thanks a lot for sharing this.  :)

PreenFM2 / Re: Bug when using editor
« on: August 17, 2019, 08:48:37 AM »


No it's not a known issue.
Pressing INST+MENU should reinit the engine without the need to reboot.

Do you use the plugin or the standalone version ?
Can you try without plugin your keyboard directly in the preenfm2 midi in but in another midi that you redirect to the plugin (that's the config i use) ?

PreenFM2 / Re: Basic waveforms with FM
« on: August 17, 2019, 08:40:23 AM »
Hi Xavier,
when I read this for the first time (in an older thread), I assumed it was a typo, but as you repeatedly say it's a low-pass filter, I am curious now... because for all what I recall, it is a high-pass filter which is required to get rid of the DC-component of the resulting spectrum in case of FM (PM does get rid of the DC-component inherently)...

Yes, sorry. It was a typo, it's a high pass filter, as you said to get rid of the DC-component.

PreenFM2 / Re: Latest firmware : 2.10 (2019 june 13th)
« on: August 04, 2019, 10:53:57 AM »

Thanks a lot for these interesting links.

I doubt any of them would fit the required low CPU usage.
Once the preenfm plays 8 voices of 6 ops algos, the CPU left i very small.

It would also takes time (i don't currenly have) to implement them.

If anyone wants to give a try, i can guide you through the code files.


That's a nice idea, but I don't think i will ever implemented this in the preenfm2.

You can use a keyboard that does that for you.
My old Novation SL49 compact has zones that do that very well.
I imagine many other keyboard can do that.

PreenFM2 / Re: modulating the frequency of an OP/OSC in octaves?
« on: August 04, 2019, 10:45:23 AM »

Not sure i fully understand but I don't think you can do that.

You can try to use step sequencer in the LFO. You will get jump in frequency.

PreenFM2 / Re: Basic waveforms with FM
« on: August 04, 2019, 10:42:18 AM »

BTW: just curious, but what was the reason for not using phasemodulation but real FM?

The reason is that the preenfm started as a simple FM attemp and turned into a synthetiser over time.
I was even not aware at that time that other synths used Phase modulation.
Phase modulation avoid a pitch shifting when cascading 3 operators or more without any CPU impact. And i think that the reason why 80s synth used it.
FM needs a low pass (EDITED :!!!!TYPO <= It's a HIGH PASS) (few HZ) after operators to avoid this pitch shifting.

I don't remember the maths, but PM/FM spectral diferrences should be obvious when cascading at least 3 operators.

Thanks for the nice words...
but i don't have any plan to PM to the preenfm2 ;)


PreenFM2 / Re: Strange behaviour starting up
« on: July 28, 2019, 02:27:41 AM »
Sorry for the delay I'm on vacation far from home until august 5th.

That cannot be a firmware problem.

That's likely a bad solder joint or a missing 'led' resistor.

PreenFM2 / Re: output routing
« on: July 09, 2019, 09:29:26 PM »
...I just saw, that the two 12-bit channels of the MPC4922 are combined for the 18 bit resolution of the output. So my educated guess is: the PreenFM2 is two channel audio out by design.


But you can redirect one instrumnent to one mono channel and a second one to the other.
Go to the mix engine menu, then turn right or left one of your op while holding down the mid left button. That will turn all mix* at the same time.


PreenFM2 / Re: Latest firmware : 2.10 (2019 june 13th)
« on: June 26, 2019, 01:30:41 PM »
Thanks for your interest ;)

2) I'm sure the LP filter is not very good as it's a simple formula (CPU light) i found on the web. A better one would be heavier and could unlikely be handled by the preenfm2 CPU without sacrifying some voices.
Writting good filter algorithms requires time and skills i don't have.
But if you find some opensource interesting ones, i can take a look.

3) All waveforms must loaded in RAM at runtime, so that the CPU can access them efficiently. RAM is much faster than Flash storage.
The RAM (192kb) is quite full. UserWaveform takes 24kb of them.


PreenFM2 / Re: Random patch resetting - was yellow oled issue
« on: June 25, 2019, 08:07:56 AM »
I'm not sure at all about your conclusion  ;)

Could you post high quality pictures of your PCB without OLED, both side ?

PreenFM2 / Re: Latest firmware : 2.10 (2019 june 13th)
« on: June 25, 2019, 08:03:55 AM »
Hi thanks for the nice words and thanks for the suggestions.

I'm afraid the replies to your questions are :

1. Yes but you can already do that with the scala file (not ideal i agree).
I think someone already made a custom firmware with this. I would need to merge it.

2. I don't think i'll ever do that. But who knows. FM synthesis should not rely on filters ;) even it's it's a good to have.

3. No it's limited by the memory of the preenfm2 which is already full.

4. No, that would be too much work.

PreenFM2 / Re: Random patch resetting - was yellow oled issue
« on: June 23, 2019, 10:54:36 AM »

I never heard of such a problem before.
All that sounds like bad solder joint or shortcut somewhere.

Maybe around the 74H165 and the encoder/button area with the 2 network resistors.
It can also be a ground problem that would make the encoder/button to randomly trigger values and the display not to be stable.

The only solution is to take time with a multimeter and verify carfefully all solder joints.

You can start by checking the voltages of the first schema here :

Then use the second one o verify the tracks that start at MCLK, MQH and MLD on the preenf405 to the 74HC165 et resistor network.


PreenFM2 / Re: Latest firmware : 2.10 (2019 june 13th)
« on: June 13, 2019, 11:09:17 PM »

A little new release 2.10 is available :

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