Traktor Kontrol S4 Mk3: add 4 effect units by ronso0 · Pull Request #14895 · mixxxdj/mixxx

ronso0 · 2025-06-03T23:17:59Z

Uses Mixxx' standard effects mapping, supports effect focus mode.
https://manual.mixxx.org/2.5/en/chapters/effects#controller-effects-mapping

This is an attempt to merge the midi-components effect unit into the S4 one.
Bonus: the previous effect focus state is restored

I've been using a minimal, hacky version of this since.. a week after I got the S4 ; )
and finally I managed to backport this and clean it up!

Features / Extras

In addition to the standard fx mapping

Shift + ⯇/⯈ assign buttons do assign unit 3 / 4
focus state from last session is restored (it's already stored in mixxx.cfg but wasn't used)
...

Breaking changes, due to switch to Mixxx standard mapping:

new control order, L->R:
Meta knobs 1 | 2 | 3 | Mix knob
Effect toggles 1 | 2 | 3 | Focus button
(before it was X | 1 | 2 | 3)
there is no Main assign switch anymore, rightmost button is now the focus button
(we may find a way to integrate that, but this had no prio for me)
rightmost button does not toggle all effects anymore

TODO

add optional auto-show/hide parameters (from midi-components)
update mapping documentation Traktor Kontrol S4 Mk3: document new effects mapping manual#777

for mixxxdj/mixxx#14895

acolombier

Couple of surface comment, haven't tested it yet!

res/controllers/Traktor-Kontrol-S4-MK3.js

acolombier · 2025-06-18T07:43:35Z

res/controllers/Traktor-Kontrol-S4-MK3.js

-            shift: function() {
-                this.group = this.unit.group;
-                this.outKey = "group_[Master]_enable";
-                this.outConnect();
-                this.outTrigger();
-            },
-            unshift: function() {
-                this.outDisconnect();
-                this.outKey = undefined;
-                this.group = undefined;
-                this.output(false);
-            },


This feature, which allows to enable post fader FX seem to be entirely lost. Could we move it so it can still be used somewhere? (e.g shift+long press)

Ah, that was the intention.

Then it would be good to make it a quick toggle / powerwindow button, ie. act on press.
And the other function (switch effect unit?) could be the longpress function as it's not time-sensitive.

Yes, sounds good!

res/controllers/Traktor-Kontrol-S4-MK3.js

acolombier · 2025-06-18T07:48:05Z

res/controllers/Traktor-Kontrol-S4-MK3.js

+            // onShortPress: function() {
+            //     // TODO dummy impl to avoid "Unknown control [EffectRack1_EffectUnit1], "
+            //     // TODO seems this slips through in Button -> defaultInput()
+            //     // console.warn(`focusButton shortPress`);
+            // },


Is this needed?

Well, I saw that warning being logged.
But I'll test again.

Uses Mixxx' standard effects mapping, supports effect focus mode. https://manual.mixxx.org/2.5/en/chapters/effects#controller-effects-mapping

acolombier

Sorry for coming back so late to this! I am planning to test this in the coming days! Feel free to prepare the manual update already :)

acolombier · 2026-01-03T16:10:22Z

res/controllers/Traktor-Kontrol-S4-MK3.js

+            console.warn("ERROR! new S4Mk3EffectUnit() called without specifying any unit numbers!");
+            return;


How about throwing an exception? Otherwise, this will log the failure but will carry on the execution in a "broken" state.

acolombier · 2026-01-03T16:10:38Z

res/controllers/Traktor-Kontrol-S4-MK3.js

+        if (numbers.length > 2) {
+            console.warn("ERROR! new S4Mk3EffectUnit() called with more than 2 unit numbers!");
+            return;
+        }


Same here - exception instead?

Suggested change

if (numbers.length > 2) {

console.warn("ERROR! new S4Mk3EffectUnit() called with more than 2 unit numbers!");

return;

}

if (numbers.length !== 2) {

throw Error("S4Mk3EffectUnit() constructed with more or less than 2 unit numbers!");

}

acolombier · 2026-01-03T16:13:32Z

res/controllers/Traktor-Kontrol-S4-MK3.js

+        let numCount = 0;
+        for (const num of numbers) {
+            if (typeof num === "number") {
+                numCount++;
+            }
+        }
+        if (numCount < numbers.length) {
+            console.warn("ERROR! new S4Mk3EffectUnit() called with array that contains other types than numbers!");
+            return;
+        }


Suggested change

let numCount = 0;

for (const num of numbers) {

if (typeof num === "number") {

numCount++;

}

}

if (numCount < numbers.length) {

console.warn("ERROR! new S4Mk3EffectUnit() called with array that contains other types than numbers!");

return;

}

if (!numbers.every(num => typeof num === "number")) {

throw Error("S4Mk3EffectUnit() constructed with array that contains other types than numbers!");

}

res/controllers/Traktor-Kontrol-S4-MK3.js

acolombier · 2026-01-03T16:17:34Z

res/controllers/Traktor-Kontrol-S4-MK3.js

-            shift: function() {
-                this.group = this.unit.group;
-                this.outKey = "group_[Master]_enable";
-                this.outConnect();
-                this.outTrigger();
-            },
-            unshift: function() {
-                this.outDisconnect();
-                this.outKey = undefined;
-                this.group = undefined;
-                this.output(false);
-            },


Yes, sounds good!

acolombier · 2026-01-03T16:18:09Z

res/controllers/Traktor-Kontrol-S4-MK3.js

+            // empty 'key' is not considered in Button/PowerWindowButton
+            onShortPress: function() {},
+            onShortRelease: function() {
+                // console.warn("focusButton shortRelease");


Comment cruft

Suggested change

// console.warn("focusButton shortRelease");

There is a bunch of them in the file, and they seem to have been added for a one off debugging, so I don't think it make sense to keep them, are you happy to remove them?

ronso0 · 2026-01-05T02:10:16Z

Sorry for coming back so late to this! I am planning to test this in the coming days! Feel free to prepare the manual update already :)

Thanks for taking the time to review.
I didn't use this for long, just my personal implementation, so I think I might need to take another look at this and double-check the UX.

The manual is here mixxxdj/manual#777

acolombier · 2026-01-10T17:27:55Z

Tested this mapping and unfortunatelly, I was unable to get the effect 3 and 4 to work as expected.

acolombier · 2026-01-10T17:28:32Z

I think I might need to take another look at this and double-check the UX

Are you happy to make that PR a draft till you get a chance to look into this?

ronso0 · 2026-01-10T18:44:30Z

Sure.

github-actions bot added the controller mappings label Jun 3, 2025

ronso0 added a commit to ronso0/manual that referenced this pull request Jun 4, 2025

Traktor Kontrol S4 Mk3: document new effects mapping

581e624

for mixxxdj/mixxx#14895

ronso0 mentioned this pull request Jun 4, 2025

Traktor Kontrol S4 Mk3: document new effects mapping mixxxdj/manual#774

Merged

acolombier reviewed Jun 18, 2025

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ronso0 mentioned this pull request Jun 20, 2025

Traktor Kontrol S4 Mk3: document new effects mapping mixxxdj/manual#777

Draft

ronso0 mentioned this pull request Aug 13, 2025

S4 Mk3 screen support #13653

Merged

4 tasks

ronso0 added 2 commits September 25, 2025 00:09

Traktor Kontrol S4 Mk3: add 4 effect units

030d6de

Uses Mixxx' standard effects mapping, supports effect focus mode. https://manual.mixxx.org/2.5/en/chapters/effects#controller-effects-mapping

trace logging, disabled

a2ddfa3

ronso0 force-pushed the s4-4effect-units branch from 4618da8 to a2ddfa3 Compare September 24, 2025 22:11

acolombier reviewed Jan 3, 2026

View reviewed changes

ronso0 marked this pull request as draft January 10, 2026 18:44

		console.warn("ERROR! new S4Mk3EffectUnit() called without specifying any unit numbers!");
		return;

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ronso0 commented Jun 3, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Features / Extras

Breaking changes, due to switch to Mixxx standard mapping:

TODO

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ronso0 Jun 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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ronso0 commented Jan 5, 2026

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acolombier commented Jan 10, 2026

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ronso0 commented Jun 3, 2025 •

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