Surge XT

Oh I see it’s the silly reply semantics. You were responding to the scope message from 4 months ago

Well still hope you are excited to learn about sparrows!


I sure am, I now know much about sparrows. thank you! You know - it seems often you think there is something sinister in my posts, but I don’t think so. your modules are great - I’ve always said so. You are super helpful to people. well, maybe some day…

Nah nothing sinister! Just thought it was the wrong thread :slight_smile:


Shout out to twist vco and string vco. The way you’ve opened up a Plaits clone in a original new way is amazing, And both of these can produce the most interesting percussive voices. Having a blast with these. Thanks for All the work.



True story - one of the very first modules I wrote was “KSPoly” in the “BaconPlugs” collection which did a tuned delay line string. It had loads of problems (linear interpolation of the delay line being one of them) but the evolution of that code and testing it in rack because the String oscillator in surge, which we then ported back to rack!


Just curious - was the linear interpolation making the delay lines go slightly out of tune?

Not noticeably (although zoh definitely does). but it had some edges on the smooth waveshapes

Now we have one fractional delay line class with a small window sinc interpolation we use most places and it works fine. We’ve talked about that right? Plus the 2x or 4x over sample can really help

I think we probably have discussed that.

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Slightly OT but I was thinking about how good Nimbus is yesterday, and wondered if a polyphonic Rings would be possible too?


Rings is cool but also a bit odd for surge the instrument - is it an oscillator a filter an effect? The answer is kinda yes. It also overlaps with a few components we have way more than plaits and clouds. So right now we have no plan to bring it to the surge universe

Ah no problem Paul. Don’t ask, don’t get! The answer to the question of whether it’s an oscillator, filter or effect is of course all three. I use it a lot to process external audio, but I don’t see that very often. I have a few patches where I’ve split a signal out to 16 Rings, and a poly module wouldn’t sound any better - it’s just easier to patch and adjust. Have to admit that’s a fairly unusual scenario, so don’t worry about it :wink:

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It’s not quite the same but both the string oscillator and combulator effect in xt could do maybe some of what you want as well?


Yep good shout. I also discovered the Surge filter can be a resonator in comb filter mode, and with the modulation on full range it changes the pitch in tune. Feeding it quantised pitch CV can make similar sounds to what I do with Rings.


Yeah the combulator is just a stack of three such combs. And the string is a bit different with the filter in feedback loop but not a lot. These are all related indeed

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Not sure if this is a bug or possibly just the way I have this patch setup, but whenever I load this patch the REVERB 1 module seems to put out some massive noise which totally blows out the audio.

The input is a 3 channel poly cable from the Macro Oscillator 2.

Its not always the same channel that has the noise, the input looks normal so I can only guess this reverb algo is doing something off at patch load time?

You don’t specify which platform, but I just tried the following (going by your description) patch and reloads fine, no noise whatsoever. MacOS arm64 version of Rack 2.4.1.

NoNoiseXTReverb1.vcv (2.1 KB)

Ah sorry, Windows 11, VCV Rack Pro 2.4.1

Here is the patch (I’ve put in a button VCA combo to prevent the noise from destroying speakers)

reverb-massive-noise.vcv (6.9 KB)

This is the background image, pretty sure this isn’t part of the issue, but in the interests of full replication

And this is the list of modules used in the patch:

VCV: VCV Pro (
VCV: VCV Free (
    Random Values
    Audio 2
Surge XT: Surge XT (
Squinktronix: Squinktronix
Little Utils: Little Utils (
Impromptu: Impromptu (
DanT: DanTModules (
    Bright Idea
    Seizure Trigger [Purfenator Expander]
Count Modula: Count Modula (
    Cable Palette
chowdsp: ChowDSP (
Bogaudio: Bogaudio (
Audible Instruments: Audible Instruments (
    Bernoulli Gate
    Liquid Filter
    Macro Oscillator 2
Alright Devices: Alright Devices

Edit: So to try to reproduce the issue, download the patch and image, open the patch, set the audio module for your system, reload the image in Purfenator, make sure Clocked is running and the VCAs by the audio module are off, then save the patch. Now close and reopen Rack, when it loads mouse over the Reverb1 output to see if the values are crazy

did my little patch repro this as well? If not, then likely some other module might be the culprit. Then eliminate one after the other to see where the noise disappears. Just trying to help narrow things down…

I had to change your patch a bit because i dont have the grande module?

But yeah, it does repro

file a bug on the surgeXT git. seems a win issue by the looks of it. The grande modules I use way more often than the stock ones, as they are small and also have a 4 merge 4 split one, which is perfect for many things :slight_smile: