Surge XT

Hi Paul @baconpaul , is it intentional that there is NO visual feedback on the LFO x EG module ? When I connect cv to the MOD1 etc there is no movement on the screen.

The freq and the saw are moving, but nothing from the LFO does.

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Oh ha no I simply forgot to code the display to the modulated values

I will add an issue for xt2.1 (issue 664)


Cool, I was going ask same. Visual feedback ftw.

5 posts were merged into an existing topic: Surge XT Patching

Conversation about patches made with Surge XT at Surge XT Patching

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I have a question about, and at least one feature request for the polyphonic Tuned Delay module.

What should the polyphonic behavior be if pitch CV is polyphonic, but audio input is monophonic?

Currently it ignores all but the first channel of the pitch CV, giving monophonic output. I’m thinking it ought to replicate the mono input to match the pitch CV channel count. Depending on how you look at it, this could be a design fix or a feature request.

And for a straight ahead feature request, can you please provide CV control over the V/Oct Offset parameter? This would provide for most of the capabilities of the wonderful Sckitam Waveguide Delay, but with the huge benefit of polyphony!

For me there are two wonderful use cases:

  1. Much like what can be done with the Waveguide Delay, perform “through zero FM” (actually phase modulation) on any oscillator output, except now with full support for polyphony!

  2. Easily generate multiple phased signals of the same source audio/CV. This would especially be handy if you replicate monophonic input to match the polyphonic channel count of the V/Oct Offset CV. I’m thinking this would be equally handy for audio and LFO inputs.

You could take the module over the top by adding attenuated L/R feedback inputs. I’m not sure if a single attenuverter should apply to both L and R feedback, or if each input should get its own attenuverter. One can certainly accomplish this with a pair of small mixer modules like VCV CV MIX, but having the feedback input built in would be extremely handy.

Tuning polyphony; I fixed that this morning when I realized it when patching it myself over in the patching thread! I am not updating the nightlies while I wait for the library drop but it’s fixed in my next branch which will be a nightly once the library builds run. I might do a fairly soon 2.0.2 cleanup release with it and a few other fixes too.

The mono audio poly voct though is a case I don’t handle and should.

As to the cv control of the offset: the delay time is just cv in + knob. So in this simple module If I added another cv in it would be just another item in the sum. (The integer offset seems like you would not want to modulate it due to it being a function of graph length)

But I like the idea of having a “wider” version of this simple module with a mod matrix and as well as a core offset, a modulateable offset for both the left and right channel. Or perhaps an offset and spread. Could add a few other things like a gain while in there for some vca like capabilities. Let me tag @steve here and we can think about that panel. (Of course right now you could just use two of these modules and use the mod matrix to adjust the voct signal but agree it could be more compact)

I can write all that up as GitHub issues. Good ideas. (Edit - issues 646 and 647)


@baconpaul Do you plan to release Surge XT on Cardinal too?

The Surge XT code is all GPL3-or-later, is all on our GitHub, is tagged with both a branch and a tag for release, and is made available in binary form as a nightly. We are an open contribution project for tested PRs which retain compatibility with prior versions.

I have shared the git hash of our first release tag with the library team also.

I think that’s all anyone would need to repurpose Surge into other forks or contexts, and the license allows them to as long as they share any changes they make and, if those changes are tested, compatible, etc… ideally upstream them (although upstreaming is not a requirement)

The only binary distribution I have any control over is the one in our GitHub actions linked above.

Hope that helps.


After I updated to Rack 2.2.0 on Windows 11, my patches failed to find the Surge XT beta modules. Reinstalling from the most recent Surge XT nightly build fixed everything up.

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We were using an API which Andrew wanted to remove in 2.2 and so older nightlies won’t work. I was hoping that the library with the fix would be shipped before 2.2 came out but we are still in the hopper. So if you want to run XT in rack 2.2 you need to grab the nightly, which is the new 2.1 beta, or wait until the library process runs. (Every other module built overnight but surge hasn’t yet. Don’t know why).


last nightly runs peachy, but yeah, was also looking for it to pop up besides the other updates done overnight

There’s a new module called EGxVCA in the nightly. Fair warning - It’s very much an alpha / work-in-progress with plenty still to be done on it (including everything in the display area) - but it does basically work as an ADSR envelope and VCA.


I was wondering about that, too. Thought maybe the graphics won’t be open source. Super nice that you put out everything for free to use everywhere!

I am a happy Rack Pro user, but it still always makes me happy when powerful music software like this is free for everybody!!! Surge has been my favourite synth VST for some time now, and this is even better!

:sparkling_heart: :sparkling_heart: :sparkling_heart:


First tests with this look and sound good, replacing the ADSR and VCA’s in Paul’s Tuned Delay example patches.

Let’s not use this thread for 2.1 alpha testing. I’ll start a new one outside announcements later on. I merged everything for my 2.1 fixed assuming 2.0 would be in library though - so current nightly is ahead of first release.

Anyway I’ll start another thread now


I just updated Rack to 2.20 and Surge has disappeared. I’m not EXACTLY sure where you are supposed to put these plugins that don’t come in there own folders like the ones you get out of the library but I had this in the Documents/plugins and also just in the general Rack 2 folder and it was working 10 minutes ago before I updated. Comments?


Yes if you have an old XT nightly it won’t work with 2.2. Grab the newest and it will. Install like any other plugin.

I had hoped we would be in the library by now but we aren’t, so you get to get the 2.1 beta rather than the 2.0 release :slight_smile:



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Just copy that file to the Rack plugins folder and Rack will handle it.

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