Newbie question. Mixing Poly and Mono in schematics?

[Spogg]

When I started with FS, about 8 years ago, I was in the same situation as you. I knew nothing about principles of digital production and processing of audio. In terms of synths, I came from an analogue electronics background which of course makes use of voltage and current as opposed to numbers. My fascination of this very different approach spurred me on to learn more and is still on-going. If you are equally as fascinated I reckon you’ll follow a similar path.

I’m trying to decipher what you mean but I wonder if you’re aware of the Wavetable prim duo? That system creates a set of waves based on a float array and the player prim selects from the tables based on the frequency. This is organised in such a way that at no time does the output go above nyquist, so you never run into aliasing. Each waveform in the tables is bandwidth limited, so higher frequencies have fewer high harmonics (which we wouldn’t hear anyway) to avoid aliasing.

And I wish you and everyone here a Merry Christmas too!

[R&R]

Precisely, the thing I was rambling and wondering about is very much like how the wavetables work according to your explanation. But at yet another abstraction layer down like a preference-system of interpolation at key frequencies and evaluation made per cycle at realtime. But such a would probably gobble every last bit of CPU
Probably wavetables are superior than any over engineered scheme would ever be

Looked at the wavetable prim only at a glance this summer. I actually wanted to use it initially but didn't understand it nor did I find an good way of importing for example generated wave data. Only point data from text files or internally generated (and... well... me and math ) etc.
There are really cool utilities out there that generate very nice morphing wavetable data, usually outputing wav files. Would have been nice to import some of that or record own. Well, I ended up right away (ADHD style) defaulting to using toolbox saw etc instead. Atleast for now

I came from an analogue electronics background

I also read some electronics in school, analogue circuits, logic circuits and opto-electronics.
Even made a few one-chip computer circuits using ASM. Aaaand... I remember zero of how. Unfortunately

Haven't worked with electronics professionally. Only made a few diy projects, speakers and some video filters back etc in the day...

[R&R]

I'll end this side of christmas by posting this comment from the code of christmas past... or was it ghost?

only-god-knows.jpg (56.41 KiB) Viewed 3820 times

[martinvicanek]

I've been experimenting with MVs and MyCo's oversampling... trying and using them with filters, some synced oscillators and the toolbox overdrive etc. With different results

[...]

I noticed that there is a drift between oscillators, when combining different oscillator for example the toolbox oscillators and other oscillators. This drift seems to be exaggerated when running thru oversampling, in particular the 4x... The 2x oversample-modules specifically the hard (rounding?) ones seem to suffer less from this but results differ between every oversample module and is dependent of frequency played and waveforms etc.
The drifting looks like, on a FFT, exactly like the comparison FFT between MyCos and MVs modules in their "Oversampling Kit". Bands creeping in from high frequency and moving downwards...

It would be helpful to have at least a basic schematic to see the issues you describe. Chances are we might even be able to fix something.

[R&R]

It would be helpful to have at least a basic schematic to see the issues you describe.

No need to fix if it ain't broken Probably just behaviour by design...
But I'll see if I can find the oscillator-pair I tried when experimenting. Perhaps it's an interesting thing if you like to ponder about the cause. I'll post it if I can find back to the particular combination with this drifting.

The goal is to fill every empty spot in the "osc module" dropdown-menu in my plugin with choices so, there will be
alot of experimenting

Chances are we might even be able to fix something.

I'm pretty much 800% confident you would be able to fix anything at this point. But I don't want to waste your time MV... until i'm a bit more up to speed on sound basics. I'm a dummy and need to learn
Btw Haven't even tried the velvet noise you made...

PS
I do already use your 2x and 4x oversample modules in several places. Now just recently also inside some osc modules. Pretty much anywhere I can get them work in the schematic and where I get a reduction of aliasing.

Was wondering...
Is the 4x oversample (Order: 6, Slope: soft) module adapted for the 2x (Order: 6, Slope: soft)... it is used with, or would the 4x oversample be messed up if used with higher/lower order (soft or hard) 2x inside?

Haven't looked that close on the transient caused by the oversample... Is it's freq and amp completely relative to the incoming transients slope and amp, could it be cancelled out or would that in turn result in aliasing?
I try to avoid using oversample with the toolbox saw for esthetic reasons (it's upper harmonics) and I suspect it starts to become audible in such combinations, particularly with any reso applied, and layered/unison...

[R&R]

Ah ok. Don't know If this was the cause for the drift I saw before... But here is another observation.

I knew however early this one was happening all along. I just forgot about it. Maybe now a good time to try and fix it for my LFO, especially when controlling Amp. In other circumstances, even in my osc modules, a little drift doesn't bother me. I often use toolbox saw in my osc modules so there is not such drift, or rounding error.

Since I usually need both PW and Sync on my squares... I resort to DSP with an extra line for hard sync. Basically one of the DSP code versions of your (MVs) old saws.
Noticed that some of your saws (2.0 and maybe other newer and improved ones) doesn't suffer from this issue anymore, so I might just try and alter that DSP If I can get it to work. I seem to have better result in my LFO with only DSPs and toolbox oscillators so I think I'll stick to that... for the time being...

[martinvicanek]

Was wondering...
Is the 4x oversample (Order: 6, Slope: soft) module adapted for the 2x (Order: 6, Slope: soft)... it is used with, or would the 4x oversample be messed up if used with higher/lower order (soft or hard) 2x inside?

IIRC the 4x oversampling filter is balanced in some sense. I have designed more variants, basically for 60 dB, 80 dB and 100 dB stopband rejection with a softish transistion band, but not yet posted.

Haven't looked that close on the transient caused by the oversample... Is it's freq and amp completely relative to the incoming transients slope and amp, could it be cancelled out or would that in turn result in aliasing?
I try to avoid using oversample with the toolbox saw for esthetic reasons (it's upper harmonics) and I suspect it starts to become audible in such combinations, particularly with any reso applied, and layered/unison...

Good point about transients. Transient artifacts will be worse for the hard filters. And yes, there is no need to oversample the toolbox saw osc, as they are practically alias free.

[martinvicanek]

Yeah, the saw LFO was never meant to be used at audio frequencies, but either way the drift should not be there. Version 2.0 does not have this issue.

[R&R]

Hmmm seems you've done some additional magic with the ASM version of the osc 2.0... since the DSP code version of it seems to suffer the same drift

And yes, there is no need to oversample the toolbox saw osc, as they are practically alias free.

Not always aliasfree when I use them or should I say "how" I modulate them... lol. I seem to break eveything
But I can manage using your DSP and 4x upsample in some cases. Works just fine... drift or no drift.

Only the LFO to Amp usage that's bothering me somewhat now, since it becomes quite clear that the square starts creeping in and adding Amp when holdning a note after few seconds...

I'll try with your ASM synced saw (perhaps also made for LFO, but I use it as audiorate also ) and see if that works inside my LFO

[R&R]

Yeah, the saw LFO was never meant to be used at audio frequencies, but either way the drift should not be there. Version 2.0 does not have this issue.

Thought I'd throw your parabolic osc+saw at my LFOs... and some S&H (stepped) saws as well. Would be nice to fix the PW square drift at the same time. But still can't find any combination of osc that works. Syncing and oversampling the toolbox saws would work but the their upper harmonics is a problem for LFO.

You don't by any chance still have the original DSP for the sync-master oscillator of: http://www.dsprobotics.com/support/viewtopic.php?f=3&t=36471&hilit=sync+oscillator#p109371
?

I'm not sure I would be able to alter it, but atleast I have a sporting chance with a DSP
ASM however not so much... lol.
But that sync-master seems a bit different with it's sync-saw sgn? real numbers? you give me nosebleeds trying to even remotely understand what sorcery you're doing in your ASMs... and DSPs for that matter

I need to try and add a sync input, or rather a retrigger for the sync master ...so, some kind of reset for the sync-saw of the sync master.

A sync master reset might also open up for more elaborate use of your sync saws with alias suppression.
They are already used in the simplest form in my plugin (program 3 or Osc Module 4: Pitch n Sync) with some oversample
Not as gritty as raw hard sync of regular saws with just a DC block filter, but they are instead very low alias comparison