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this is not directly related to the PreenFM in any way, so please bear with me for this off-topic post... But I think it could be interesting for the one or the other here. I always wanted a RoboVox (who doesn't?). But getting the chips is getting more and more difficult and I didn't want to rip it off one of my extension-cards. So, I tried to emulate the thing on a microcontroller (UNO R3 with AT16U for USB). I am quite pleased with the result:

I am currently in the process of smoothing out some rough edges in the FW. After that I would be pleased to share it.


Can someone please confirm, that these NRPNs (Algo, Velocity, NumberOfPolyphonicy, Glide) do actually work like they are supposed to with the current FW for the preenFM2? (Before I file a bug-report to Image Line and these NRPNs just don't work because the preen has a bug there and not FL Studio...)

I am following this list for setting up the CCs/NRPNs for the preenFM2 in FL Studio 20.8:

All NRPNs but the lowest four seem to work... CC for Algo works, NRPN for Algo doesn't...

preenFM2-FW: 2.20


Sometimes it's quite handy to be able to translate the modulation-indices of one FM-synth to the other. And sometimes you are just curious why you seem unable to replicate some timbre with a different FM-synth, as well...

The following was fine-tuned by ear and verified using a spectrum-analyzer:

DX-7          PreenFM 2(*)
  50.00no matching value: 0.01 is too much 0.00 is too less
100.00no matching value: 0.01 is too much 0.00 is too less
150.00no matching value: 0.01 is too much 0.00 is too less
250.01no matching value: 0.02 is too much 0.01 is too less
300.03??hmm?? bigger jump than expected..

(*) These values are averages over different octaves. The reason for this is: The PreenFM2 seems to have a (quite strongly) varying modulation-index in between different octaves. To get the same spectrum but shifted upwards by one octave you have to decrease the according MI a little bit (sometimes even relatively drastic and not subtle changes are required to keep the spectrum decently steady...). This is neither noticeable on a real DX7, nor on dexed nor FM8. And it's a little bit unexpected, too. (hhmm,... just thinking... could this eventually be due to the high-pass-filter required in between each of the operators for "real" FM with more than 2-Ops?)

Another interesting finding, when trying to estimate the above table: Looking at the spectra obtained by modulation-indices of 0.25, 0.50, 0.75, 1.00, 2.00, 3.00, 4.00 and 5.00, from an ideal 2-OP FM without the high-pass-filter and comparing this to the spectral output of the PreenFM2, I wonder if the MIs really are the modulation-index or just something quite close? Alternatively the highpass-filter could introduce some IMD here, too. The effect is strange and like this: The wrong partials get canceled out and the wrong partials get amplified (mainly in the low frequency-end), resulting in the inability to do the expected FM-highpass-spectra with really high mod-indices. Hmm,...


preenfm2 and preenfm3 / The Preenano-Accident...
« on: December 20, 2020, 08:29:31 PM »
Today I started creating a "phosphor"-Patch for my all-electronic(a) "elements"-bank. This didn't work out. It does not sound chemical... :P


currently the preenFM2(/3?) has 7 standard and 6 additional user-waveforms. The standard waveforms consist of all the usual "analogue"-type "basic"-waveforms (sine, triangle, square...) and some "special" ones allowing for different side-band spectra...

As FM-synthesis in fact is some sort of additive synthesis, it strongly benefits from some more "special" modulator waveforms allowing for better control about the number, position and strength of the harmonics in the generated sidebands.

I have no idea, however, if the PreenFM2 would have enough RAM left for this (I really wouldn't like to sacrifice the user-waveforms for that). But if there is enough RAM left for the stunt and if there is enough interest in this I would/could donate some specifically crafted waveforms in this regard.


PS: Why not using the already existing user-waveforms for that? Well, it would limit the ability to share the resulting patches...

preenfm2 and preenfm3 / Sequencer to Op-Frequency Mapping?
« on: December 17, 2020, 02:04:30 PM »

I tried to figure out the mapping in between Seq1/2-values and Operator-Frequencies as such I can do the following:

Set up two operators at frequency at frequency "f". Alter the frequency-multiplyer of one of the operators to "n times f", with "n" being the value seen in the according sequencer (Seq1/2).

I tried to set this up in the mod-matrix (Seq1 --> [Multiplier-Value] --> OP1-freq) but whatever I set for the multiplier-value I seem unable to achieve the desired result.

Why do I want to achieve this? For some sounds I would like to create it is essentatial, that I can modulate the frequency of an operator to be an exact integer-multiple-step of the frequency of another one. If there is another way to achieve this (scaled LFO output quantized and used as OP-frequency-multiplyer, maybe?), this would be fine, too...


(Edith says: typo fixed)


this might be a known issue of some sort but a quick search in the forum did only reveal something about "hanging"/"freezing" notes but not about what I experience when updating the FW or accessing the USB-Stick. In both cases the PreenFM2 wants to reboot afterwards. It seems like it reaches the reset but hangs directly after. I have to turn it off and on instead. Is that a known thing? And what can I do to mitigate it?



I have a question regarding the modulation of the frequency of a modulator...

Is it possible to quantize the frequency of an oscillator/operator with preenFM2? That is: Say, you have an LFO and use this to slowly modulate the frequency of an oscillator. The result normally will be a smooth transition from factor 1.0 over 1.1 over ... to a factor of -- say -- 4.0. Is it possible to leave out the fractional parts? So, that wathever the LFO-Value is, the resulting frequency-ratio of the oscillator is strictly non-fractional? (It should ramp up and down in octaves... and BTW I chose an LFO in this explanaition but this is not my primary intention. I would like to use velocitly or the free-env as input-source for this...)

Many thanks,

preenfm2 and preenfm3 / Basic waveforms with FM
« on: July 11, 2019, 02:03:30 PM »
Hello all,

so I am the proud owner of a preenFM2 now... And I try to get accommodated with its FM-synthesis (this is not the first FM-capable synthesizer I use, btw...), so I thought it would be fun to do what I have done on many FM-synths before: creating baisc waveforms with FM (saw, tri, square, pulse) to get an understanding of it's parameter-range and response...

But whatever I try I can not even come close to a synthesized 2-OP approximation of a sawtooth-waveform?!? hmm,... The spectrum looks right, so I guess there is some sort of phase-delay inside the operators, maybe?

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

many thanks,

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