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Thread: Recommendations on maintaining precise SpectraStrobe control for given audio content?

  1. Default Recommendations on maintaining precise SpectraStrobe control for given audio content?

    Hey all,

    New Kasina owner/user here. FWIW I'm an experienced media/lighting/electronics engineer. I purchased the Kasina with a specific interest in creating my own music with SpectraStrobe component, as well as experiencing what others have achieved.

    Creating my own has been a little challenging, as a lot of the software instructions seem to be somewhat out-of-date, but I managed to reverse engineer things to an acceptable level, and I've now moved into the stage of attempting to create content.

    Here's the challenge I'm running into: I'm used to working with, and designing, audio/visual systems that give me complete control of all of the various signal chains (in their own lanes, so-to-speak). I understand the cleverness and convenience of encoding the LED controls into the frequency space of the audio content, but I'm finding that it is very unstable, not very precise, and full of "noise". For example, I setup a sample project that has the all of the SpectraStrobe tones, 18.2khz reference, with square wave LFO panning hard right/left @ 20hz, and then color tones at 18.7khz/19.2khz/19.7khz. The suggested tone level for best dynamics and headroom using the Audacity plug-ins seems to be about -39.483 db according to my calculations. When I run this project through the Kasina, all works as expected, it's detected as a SpectraStrobe signal and if I vary the volume of the color tones, the LEDs adjust output accordingly. Sweet!

    Now I move on to adding some musical content. I'm simply adding a deep bass tone as a sine wave, at or below 200 hz. When I do this, and get the bass tone into the correct volume level, the LEDs shut off. I have a sharp 8th order Butterworth lowpass filter on the bass track to make sure I'm minimizing frequency bleed. I've also experimented with putting sharp bandpass filters on each of the respective SpectraScobe tone channels/tracks to try and minimize frequency "bleed". I've also removed all filters as well just to see. It seems as though even though the bass track isn't anywhere close to the SpectraStrobe frequency range, it's loudness is overpowering the signal and whatever filters are being used to pull out the SpectraStrobe content (FFT, IIR, frequency decoder IC - I'm not sure what's under the hood here) can no longer recover a stable enough frequency so the LEDs shut off. If I increase the volume of all of the respective SS tracks, they come back. But now I'm in a cat-and-mouse battle with the overall loudness and frequency content of the music itself relative to the SS tracks and signals. I haven't even begun to add any more musical content yet and my initial findings are not great based on what I was hoping I would be able to achieve.

    Obviously there is some great music-based SS content out there. But now it's starting to seem probable that in order to achieve relatively clean SS control, within the scope of custom audio tracks or music, that some deep compromises are going to have to be made. Does anyone have any "best practices" or pointers on how to achieve this fine balance? I mean, even when I have no musical or audio content other than the SS reference tone, with all color tracks volume set to -INF db, I still get some flicker from the red channel (which red LEDs have a lower forward voltage so it sort of makes sense they would be the first one to go on based on "noise" in the signal) - but the only noise at this point is the SS ref tone track itself.

    I guess it makes sense by choosing to encode the control signal in the audio there is going to be some noise and lack of precision... but having to relatively adjust overall tone volumes based on what the audio track is doing is pretty daunting. And look, I've got about as steep of a filter as I can get on the low frequency sine wave bass track, my spectral analysis shows clearly that it is only producing content in the low frequencies, and the SS ref/tones are quite isolated in the upper bands, and yet I'm still running into this issue.

    For others who have successfully achieved a desired level of precision and control to their own music when making AS/SS tracks:
    • First, is it possible to achieve and maintain precise SS control over dynamic audio?
    • Second, what compromises to your music do you make to maintain enough control over the SS LED signals, or do you just sort of accept the audio signal is going to interfere with the SS signals and treat it as a "feature and not a bug"?
    • Third, is it advisable to just keep musical content to a particular frequency space and and db level and/or not overly complicated? It seems like trying to master an SS track would play all sorts of havoc to it.


    Looking for any guidance from those who have found the proper techniques to have creative freedom around the audio, but also precise (enough) control over the SS signals. I'm testing using the Kasina as a USB audio device, which has to be digitally transferred so there should be no "noise" on the line.

    Thanks in advance for any tips or suggestions you have. I'd really like to find the balance to achieve my creative vision with this awesome tech!

  2. Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    Just a quick update that I'm starting to get things dialed in a bit better. One of the "noise" bugs I was dealing with (weird clicks and glitching LEDs) is related to the audio USB driver. If I reinitialize the USB audio device/driver the clicking will go away - until it comes back, but then I can just repeat the process and get it to go away for a bit of time. I've got tight bandpass filters on all of the SS tones in their respective frequency range. I've raised the volume of all reference tones quite a bit past their recommended level from the tutorials and I seem to be having much better results. The LEDs still get some bleed and turn on when they shouldn't, but overall it's not terrible. The red is still the worst offender, due its lower forward/activation voltage but it's reasonably dim, not perfect, but workable.

  3. #3

    Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    What happens if you create an audio file and play it directly from the Kasina's drive: is there a difference in response? I wonder if there’s a sample rate mismatch happening somewhere that’s creating noise/distortion.

    How about audio into Kasina using it’s Aux input?

    Your method makes sense to me. If playback from a file on the Kasina is good that may point to the usb driver/interface causing the issue.

    My feeling is music in Kasina sessions or even any meditative experience to be distracting. I like colored sweeping noise or similar nature sounds that don’t call attention to themselves. But that’s just me, obviously many people want a different experience.

    I experimented using Ableton Live in the beginning but never followed through, I realized I would need to do a lot of trial and error to see what works best. Neuroasis (Scott Wilson) was the expert but he dropped out of site. Search on the forum, there have been some technical discussions a few years ago.
    Last edited by dougdi; 04-12-2019 at 02:44 PM.

  4. Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    I plan on experimenting with both, but my personal craft is all about sound scaping (I guess you could call it music, it has musical elements, but it's more ambient music if anything) + purposefully created lighting component. My creation is going well now, I think I've cleared most of the hurdles. Putting tight bandpass filters on each tone further helped remove some LED flicker. I upped the SS reference tone by about 12 db and it seems like as long as the other tones are all brought up to match the reference tone db level, then the brightness is relative to the reference tone and so there's not this brightness mis-match issue I was seeing earlier, so I *think* that solves the issue. The clicking/noise issue is definitely a USB audio device driver thing. All I have to do is change my sound device off of the Kasina, and then back to it (in my DAW), and the clicking/noise goes away for a good bit and then comes back. It's definitely some sample-level mismatch in the audio signal that shows up as maybe the sample buffer having some bad samples in it, hence clicks and pops, but they make the LEDs flash given the frequency I guess. Either way a quick "reset" of the USB audio driver and I'm back to the races with a clean signal until it happens again (maybe somewhere every 10-30 minutes), not the best, but also not terrible and I can live with that. I'm fairly certain since I can now get clean playback via that workaround, that it should work well directly on the Kasina, but I haven't tried it yet. But given the evidence I'm feeling pretty good about it.

  5. #5

    Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    Hi Cymatic,

    welcome to the forum! I appreciate your effort.

    Well, our SpectraStrobe encoder uses precisely tuned and steep band pass filters to avoid interferences among RGB channels and the reference channel. Plus we filter the audible audio by a low pass filter which starts to cut at about 13 kHz and cuts practically everything off above 17 kHz, before adding the SS signals.

    You are right regarding the 'color tone' and ref. signal frequencies. Just the width of the ref. signal pulses is 1/8, i.e. 12.5%. They are rectangular but filtered by the precise filter. Signal levels of the RGB color tones representing 100% brightness are -24 dB, and standard ref. signal level is 1/4 of the color tones. Presence of the ref. signal make it quite flexible and adaptive but the above mentioned values are SS standard.
    Without using the precise filters, fast edges of pulses or modulation generate overtones / noise which often 'leaks' to the other SpectraStrobe channels.

    Hope it helps you. :-)

  6. #6

    Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    Tomas- that’s great info, thanks for the details.
    Cymatic - good to hear you’re on the right track, I’m interested in your experimentation, please keep us updated.

  7. Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    Thanks guys. I feel like I've got a pretty good system going now. I was using the Audacity plug-ins/tutorials as a starting point. They're a bit out of date and the instructions don't work as-is, but I figured out what changed and looked at the plug-in code to reverse engineer the rest. Now I'm using my own favorite/obscure DAW and it's going well. I was basing the tone db levels off of what the plug-ins kick out by default which is closer to -39db, but that ends up being a bit low when other frequency content gets in the way. I'm a little sad to filter out audio content from 13khz - 17khz, I don't know about you guys, but my ears definitely hear the difference - but so far that hasn't been an issue, good to know that is also a used best practice should it come to it. The reference tone volume increase and putting steep bandpass on each tone track seems to have done the trick + the USB audio driver work around.

    I think I'm nearing completion of my first SS track. Specifically I'm using a Subpac as an added low frequency transducer to add a tactile element to the experience. The subpac is amazing and can go pretty low (below 10 hz for sure). So far it's been quite nice to have say an LED LFO @ 20hz matched with a low bass tone felt through the transducer on the subpac also @ 20hz. Adding this third dimension of vibration/tactility to the track, and designing it with that in mind, has been pretty compelling and satisfying so far. I haven't really done much with isochronic/binaural/monaural yet, but I'm looking forward to weaving that in. The subpac is interesting in that it can reach inaudible frequencies that are felt... it seems to taper off around 5-7 hz for my tests. Either way maybe putting tactile monaural beats through it as a 3rd dimension (light, sound, tactile) will add an interesting new sensory cue for entrainment and experience. I would guess others have already played with this, but it's all new to me.

    I'll post updates if anyone's interested.

  8. Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    Quote Originally Posted by Cymatic View Post
    Hey all,

    New Kasina owner/user here. FWIW I'm an experienced media/lighting/electronics engineer. I purchased the Kasina with a specific interest in creating my own music with SpectraStrobe component, as well as experiencing what others have achieved.

    Creating my own has been a little challenging, as a lot of the software instructions seem to be somewhat out-of-date, but I managed to reverse engineer things to an acceptable level, and I've now moved into the stage of attempting to create content.

    Here's the challenge I'm running into: I'm used to working with, and designing, audio/visual systems that give me complete control of all of the various signal chains (in their own lanes, so-to-speak). I understand the cleverness and convenience of encoding the LED controls into the frequency space of the audio content, but I'm finding that it is very unstable, not very precise, and full of "noise". For example, I setup a sample project that has the all of the SpectraStrobe tones, 18.2khz reference, with square wave LFO panning hard right/left @ 20hz, and then color tones at 18.7khz/19.2khz/19.7khz. The suggested tone level for best dynamics and headroom using the Audacity plug-ins seems to be about -39.483 db according to my calculations. When I run this project through the Kasina, all works as expected, it's detected as a SpectraStrobe signal and if I vary the volume of the color tones, the LEDs adjust output accordingly. Sweet!

    Now I move on to adding some musical content. I'm simply adding a deep bass tone as a sine wave, at or below 200 hz. When I do this, and get the bass tone into the correct volume level, the LEDs shut off. I have a sharp 8th order Butterworth lowpass filter on the bass track to make sure I'm minimizing frequency bleed. I've also experimented with putting sharp bandpass filters on each of the respective SpectraScobe tone channels/tracks to try and minimize frequency "bleed". I've also removed all filters as well just to see. It seems as though even though the bass track isn't anywhere close to the SpectraStrobe frequency range, it's loudness is overpowering the signal and whatever filters are being used to pull out the SpectraStrobe content (FFT, IIR, frequency decoder IC - I'm not sure what's under the hood here) can no longer recover a stable enough frequency so the LEDs shut off. If I increase the volume of all of the respective SS tracks, they come back. But now I'm in a cat-and-mouse battle with the overall loudness and frequency content of the music itself relative to the SS tracks and signals. I haven't even begun to add any more musical content yet and my initial findings are not great based on what I was hoping I would be able to achieve.

    Obviously there is some great music-based SS content out there. But now it's starting to seem probable that in order to achieve relatively clean SS control, within the scope of custom audio tracks or music, that some deep compromises are going to have to be made. Does anyone have any "best practices" or pointers on how to achieve this fine balance? I mean, even when I have no musical or audio content other than the SS reference tone, with all color tracks volume set to -INF db, I still get some flicker from the red channel (which red LEDs have a lower forward voltage so it sort of makes sense they would be the first one to go on based on "noise" in the signal) - but the only noise at this point is the SS ref tone track itself.

    I guess it makes sense by choosing to encode the control signal in the audio there is going to be some noise and lack of precision... but having to relatively adjust overall tone volumes based on what the audio track is doing is pretty daunting. And look, I've got about as steep of a filter as I can get on the low frequency sine wave bass track, my spectral analysis shows clearly that it is only producing content in the low frequencies, and the SS ref/tones are quite isolated in the upper bands, and yet I'm still running into this issue.

    For others who have successfully achieved a desired level of precision and control to their own music when making AS/SS tracks:
    • First, is it possible to achieve and maintain precise SS control over dynamic audio?
    • Second, what compromises to your music do you make to maintain enough control over the SS LED signals, or do you just sort of accept the audio signal is going to interfere with the SS signals and treat it as a "feature and not a bug"?
    • Third, is it advisable to just keep musical content to a particular frequency space and and db level and/or not overly complicated? It seems like trying to master an SS track would play all sorts of havoc to it.


    Looking for any guidance from those who have found the proper techniques to have creative freedom around the audio, but also precise (enough) control over the SS signals. I'm testing using the Kasina as a USB audio device, which has to be digitally transferred so there should be no "noise" on the line.

    Thanks in advance for any tips or suggestions you have. I'd really like to find the balance to achieve my creative vision with this awesome tech!
    Unfortunately the software that would allow complete control of spectratrobe lighting with ease is no longer available. I do have a copy of it on an old laptop. Maybe I will auction it off to the highest bidder

  9. Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    TomasC, thanks for this info, this is really helpful and definitely the type of thing I was looking for. I've mostly got it working cleanly now, although I do still get some flicker/bleed on the red channel when the only thing playing back is the SS reference tone @ 18.2 khz. I've basically been reverse engineering everything from the Audacity plug-ins because that was the most accessible information I found recording the specification of SS. When I look at the Audacity plug-in's code, I see that the reference tone generated is just a sine wave @ 18.2khz - are you saying it should be a pulse wave with a duty cycle of 12.5% @ 18.2khz instead or is that related to panning? It seems the SS reference tone needs to be panned by an LFO for the track to be recognized as SS vs AS, is that correct? The best I could find from the plug-in code was pulse wave at 50% duty cycle (so square wave) panned full to left/right @ 20hz. I noticed if I tried different panning LFO frequencies (say 10hz) there was a range in which it would work so there seems to be some leeway there, but I'm definitely about getting this as 100% correct as possible if I can. I'm guessing maybe a slightly incorrect reference tone implementation might be leading to this red flicker/bleed - and the brightness is definitely proportional to the reference tone db level.

    Would you mind clarifying the reference tone pulse width of 1/8th, is that the waveform of the tone itself (vs sine wave) or is that the panning LFO waveform, and if it is the audio waveform, what are the standards for the panning of the reference tone so I'm about as exact as the filters expect? Thanks a ton, I'm almost there!

  10. Default Re: Recommendations on maintaining precise SpectraStrobe control for given audio cont

    Well, I ended up scrapping the Audacity plug-ins and just wrote my own tone generator software and generated mono sine waves at the respective frequencies (1 second loops). Inside my DAW I setup a panning LFO on the SS reference tone track, square wave @ 20hz, 100% left/right. With steep 8th order Butterworth bandpass filters on each track in their respective frequency range. I'm happy to report I am now getting a clean signal. Apparently something about the tone generated from the SS reference generator plug-in for Audacity wasn't perfectly clean, as it was causing bleed into the red frequency range even with a tight bandpass filter applied. Just a guess but that's what the evidence is suggesting.

    For those interested, I'm taking the 1 second tones I generated as .wav files, putting a forward loop on them, and then I'm triggering them from a digital sampler in the DAW. From there I'm using envelop automation on volume/panning, volume/panning LFOs, as well as audio reactivity to get precise control. Without the bandpass filters on each of the respective tracks, I still get a bit of noise/bleed into the various colors, but with the filters it's appearing pretty clean/stable so far.

    Putting the tones into a sampler and triggering them with MIDI notes is nice because I don't have to work with huge bounced/raw audio tracks in the DAW for the duration of the track which keeps the file size way down (just 4x, 1 second mono loops in the sampler; my template project is only 164KB!).

    Also FWIW my testing with 44.1khz 16 bit .wav files on the Kasina results in the Kasina playing a nasty/loud burst of noise right as the file finishes playing. I'm on the latest firmware, is that a known issue? There's definitely nothing at the end of the file in terms of crazy samples, and on the computer and other playback devices it doesn't happen. If I take the same .wav file and export as 320 kbps MP3 I don't here the nasty noise. It kinda sucks because I was using it with the subpac and it results in: a super bright flash of the LEDs, really loud nasty noise on the headphones, and a loud pop on the subpac's transducer which could actually damage the thing (as well as listener's ears). MP3 it is!

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