I have been working on reproducing the DDJ-REV7’s Serato Stems workflow in djay Pro.
On the REV7, pressing the small Deck Pad HOT CUE and SCRATCH BANK buttons simultaneously normally activates Stems mode. Both buttons flash, and the four small pads above the platter control Vocal, Melody/Harmonics, Bass, and Drums.
The REV7 sends a dedicated MIDI message for this combination:
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Deck 1: MIDI channel 1 in conventional MIDI numbering, note 112
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Deck 2: MIDI channel 2 in conventional MIDI numbering, note 112
In the .djayMidiMapping file, where channels are numbered from zero, I added:
<dict>
<key>keyPath</key>
<string>turntable1.padModeUnmixer</string>
<key>midiChannel</key>
<integer>0</integer>
<key>midiData</key>
<integer>112</integer>
<key>midiMessageType</key>
<integer>1</integer>
<key>output</key>
<dict/>
</dict>
And the equivalent entry for Deck 2:
<dict>
<key>keyPath</key>
<string>turntable2.padModeUnmixer</string>
<key>midiChannel</key>
<integer>1</integer>
<key>midiData</key>
<integer>112</integer>
<key>midiMessageType</key>
<integer>1</integer>
<key>output</key>
<dict/>
</dict>
padModeUnmixer is djay’s internal name for its Neural Mix/Stems pad mode.
I also mapped the four MIDI notes produced by the small Deck Pads in the combined mode to the four Neural Mix stem toggles. The result is very close to the native Serato implementation:
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Press HOT CUE + SCRATCH BANK
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Both mode buttons flash
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The four small Deck Pads control the four stems
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The regular Performance Pads remain available for other functions
An important detail is the empty output dictionary. It enables MIDI feedback to the REV7. Without that MIDI Out feedback, djay receives note 112, but the controller does not remain in the special Stems bank. The double-button shortcut therefore stops working.
I also removed the Neural Mix actions assigned to the small pads when SCRATCH BANK alone is selected. Having both SCRATCH BANK and HOT CUE + SCRATCH BANK mapped to Stems caused inconsistent state changes when leaving and re-entering the combined mode.
There is still one limitation.
djay uses the same internal padModeUnmixer state for:
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Stems on the regular Performance Pads
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The new Stems mode on the four small Deck Pads
Because the note 112 mapping includes MIDI Out, selecting Stems on the regular Performance Pads also sends the Stems-mode message to the REV7. This automatically switches the four small Deck Pads to Stems as well, even if they were previously in Hot Cue mode.
I tried removing MIDI Out from the note 112 entries. That fixes the unwanted coupling, but it also prevents HOT CUE + SCRATCH BANK from activating the small-pad Stems mode at all. MIDI feedback is therefore required for the REV7 to latch this mode.
The current compromise is:
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HOT CUE alone: small pads operate as Hot Cues
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SCRATCH BANK alone: no Neural Mix actions assigned
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HOT CUE + SCRATCH BANK: small pads control Neural Mix/Stems
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Selecting Stems on the Performance Pads also switches the small pads to Stems
The final limitation appears to come from djay using one shared padModeUnmixer state for both pad sections. A completely independent implementation would probably require Algoriddim to add a dedicated REV7 Deck Pad Stems state to its native controller integration.
Even with that limitation, the mapping is very usable and gives djay Pro access to one of the REV7’s most convenient Serato workflows without requiring Bome MIDI Translator or another background application. That is particularly important for anyone who wants to use the REV7 with djay on an iPad.
