CHOW Tape Model by Jatin Chowdhury

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Izak Synthiemental wrote: Tue Jan 28, 2020 1:31 pm
TIMT wrote: Tue Jan 28, 2020 4:58 am
Izak Synthiemental wrote: Thu Jan 23, 2020 8:38 pm Hi Jatin and community,

I really accustomed myself to using Chow Tape Model, great sound overall !

So, yesterday I played with some percussive material. When I played a Chimes sound, Chow Tape did not really like it! It seems that the hysteresis model is breaking when confronted with this kind of material. Can anyone test it (use any kind of chimes or closely related sound). On Chimes It sounds overly distorted even at relatively moderate settings, when the hysteresis is barely noticeable on more mid and low frequency kind of material. I guess it has to do with the interaction between the high frequency transients in the chimes and the model.

I'm using v2.0 of Chow Tape, Windows 64 bit VST, Ableton Live 10.1

Info to the mods: can you please move thread to "Effects" section?
I don't get what you did specifically to do this but i'm getting nothing that could be considered high frequency distortion on transients approaching nyquist with ChowTapeModel.what i do get though is some really bizarre but surprisingly useful intermodulated noise.maybe that's what you meant by distortion?cause im not hearing any clipping/waveshaping of any sort nor is there any visible in SPAN or an oscilloscope.i even made a similar "chimes"patch with a really long release just to see if this distortion would show up in the release of the harmonics and i came up with nothing other than what i mentioned above (intermodulated noise) :shrug:
I think you got hung up on my ambigious use of the term "distortion" initially. It's indeed rather some sort of noise in the lower to low mids segment of the frequency spectrum, not clipping, even though I wouldn't agree on your impression that this sort of noise was "surprisingly useful". Useful in what context and in what function? Definitely disagree on that, as much as I love the general sound of Chow Tape Model on most audio material.

Already added a more thorough issue report on GitHub that I would like to refer you to (just seen: Jatin has already responded):

https://github.com/jatinchowdhury18/Ana ... /issues/14
i didn't get hung up on anything.you specifically said "high frequency distortion"now you are saying that the "distortion"is broadband,hence why i didn't think you was referring to the noise and was looking for what most people other than yourself would consider distortion.yano,clipping,wavefolding,quantization distortion and the like

I don't care that you don't agree with what i saw a context for.there was no point you even commenting on that :tu:,but since you are curious,i'll indulge you kitty cat.one thing i like to do is add a kind of bed of instability to rather simple synth sound patches (like chimes for instance)to accomplish this i feed a highpassed copy into a multiplier or a dynamics plugins sidechain with the envelope settings set to almost waveshape that input.usually i have some crazy audiorate stuff on the patch to bring it on the periphery of noise(FM,feedback,AM etc),but not straight white noise.because the noise that is produced from the Hysteresis model in ChowTape seems to be extremely program dependent,it tucks under the dry sound nicely when used as a sidechain trigger so the two blend quite seamlessly and i can imply the dynamics being played softer or harder by riding the volume of the duplicate with ChowTapeModel on it and i can have this occur in the transient or the decay and release stages with the SC input patches volume ADSR amongst other stuff linked to release velocity.not really conventional use of the thing,but you did ask :P
I

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I have a stupid question: is it the tape or something else that suffers from hysteresis? If it's the tape, then wouldn't hysteresis apply to each segment of the tape separately, while it's under the recording head? If this is the case, then it would seem that hysteresis would only be relevant assuming a previous signal already recorded onto the tape. Yet from the paper that the plugin is based on, I get the impression that we are computing hysteresis as if we were constantly recording to the same piece of stationary tape. What am I missing here?

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@TIMT Again, I would refer you to my issue report at the corresponding Github page. For the rest of your derailment attempt: please stop uncalled for personal attacks on other forum members. No need to get all passive-aggressive and nervous about a bug report!

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With all the controls this plugin has, I have a question (that I think many other will have later):

What does each control do? Is there a manual of some kind?

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^this!
If it were easy, anybody could do it!

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In my perception this is in the first place an academic exercise, so the fact that Mr Chowdhury created a realtime audio effect from this can be seen as an extra.

Basically these are the manuals:

http://dafx2019.bcu.ac.uk/papers/DAFx2019_paper_3.pdf
(Highly technical academic paper which requires some understanding of the underlying math and physics concepts - which I lack)

https://medium.com/@jatinchowdhury18/co ... eb2cd3e3f6
(Series of articles for Medium.com on modelling of complex nonlinearities in algorithms)

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In my perception, since this little gem is being generously offered to general simpletons like myself, a small non-academic manual would be highly appreciated.
If it were easy, anybody could do it!

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Does this model implement any type of compression?
rabbit in a hole

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Great idea guys! My apologies for not thinking of it sooner. Here's a first draft, let me know if any parts are confusing, or could be more elaborate: https://github.com/jatinchowdhury18/Ana ... ser-Manual

@autobot there is no direct compression algorithm contained in the plugin, however the nonlinear characteristic of the tape can effectively shrink the dynamic range of a signal much like a compressor would do (albeit with a bunch of distortion and other effects that you wouldn't normally find in a compressor).

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does the model attenuate DC offset?
-and is the smearing similar?
I have some experience of cassette tape

Thanks for your work and hope it continues to be recognised

by smearing I mean, magnetic distorsion(transient randomising,contiguous colouring)?

-in truth I was not sure this post is cool, but it can't hurt I guess
I love tape gotta try this

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chowdsp wrote: Thu Jan 30, 2020 4:55 pm Great idea guys! My apologies for not thinking of it sooner. Here's a first draft, let me know if any parts are confusing, or could be more elaborate: https://github.com/jatinchowdhury18/Ana ... ser-Manual

@autobot there is no direct compression algorithm contained in the plugin, however the nonlinear characteristic of the tape can effectively shrink the dynamic range of a signal much like a compressor would do (albeit with a bunch of distortion and other effects that you wouldn't normally find in a compressor).
Wow, you have to be the most responsive developer by far, looking at your track record of very quickly responding to user requests.Trust me, we don't this that for granted and some commercial audio developers could actually take note regarding that aspect.

One thing I would enjoy to see you elaborate on: how do changes in the playhead parameter categories affect the frequency spectrum? I observed that some of those parameters produce an increasingly narrower frequency spectrum if the distance gets increased (which is to expected I guess?), but I'm not entirely sure about the exact mechanism of action.

To me it felt (speaking from memory right now, since I'm not on my machine at the moment) like lows get more and more attentuated until only a small spectrum range in the upper mids remains. Effectively kind of a bandfilter that gets narrower as you increase the SPACING distance?

I guess higher IPS settings produce a fuller bandwith and more linear frequency response? The difference sounded rather subtle in my initial test, while some tape emulations produce a drastically different result when changing this parameter.

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Yes, there is a DC blocking filter that attenuates the DC offset. The smearing effect that you mentioned is modelled, but I've had an idea for the past 6+ months to include some allpass dispersion filters that I think will improve the smearing characteristics. Unfortunately this idea has proved pretty tricky to implement since I need hundreds of allpass filters to create the smearing characteristic that I want, and that can be pretty computationally expensive to implement in real-time.

The model is more optimized for reel-to-reel tape machine than cassette tape, but by tweaking the parameters, I'd bet you can get pretty close! For more cassette type sounds, I really like Sketch Cassette (https://aberrantdsp.com/plugins/sketchcassette/), which has the benefit of being more of a commercial product and less of a science experiment. I've spoken to the developers and they're definitely knowledgeable about this stuff as well (also super nice guys).

Some resources for allpass dispersion filters:
http://dafx.de/paper-archive/2006/papers/p_013.pdf
http://dafx2019.bcu.ac.uk/papers/DAFx2019_paper_49.pdf

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chowdsp wrote: Thu Jan 30, 2020 4:55 pm Great idea guys! My apologies for not thinking of it sooner. Here's a first draft, let me know if any parts are confusing, or could be more elaborate: https://github.com/jatinchowdhury18/Ana ... ser-Manual
:tu: :hug:
If it were easy, anybody could do it!

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Last edited by rbn777 on Wed Sep 20, 2023 8:42 pm, edited 1 time in total.

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Thanks! Just finished uploading builds for the "Bad Circuit Modelling" project. I have Windows and Mac available but haven't been able to test the Mac Builds very much. The Sallen-Key LPF and Diode Clipper are probably the most useful, since they contain most of the features from the other plugins. Still a work in progress, but any feedback would be much appreciated!

https://github.com/jatinchowdhury18/Bad ... master/Bin

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