DIY 3.5mm TRS MIDI breakout for Expert Sleepers

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elisha_gray
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DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by elisha_gray » Tue Jan 22, 2019 6:02 pm

Homemade Hack™
Quad Midi Jacks module

Image
Disting Mk4 cabled to two of the Quad MIDI Jacks


I have two Expert Sleepers modules that have MIDI headers. I read a suggestion from Os that a homemade breakout module would be straightforward to build.

I wanted to keep it small, so I used 3.5mm TRS connectors instead of 5-pin MIDI connectors. My homemade module has four jacks in 1U x 8hp.

It turns out there is a standard for 3.5mm TRS MIDI, but the standard didn't happen until after several different companies had several different pin-outs. I chose what I believe is the MMA standard, with MIDI pin 5 to tip, and MIDI pin 4 to ring. Korg and others use this wiring.

Each General CV and Disting Mk4 module has one four-pin MIDI header:
  • - Header pin 1 is MIDI out pin 4 (Quad MIDI Jacks gray wire to TRS out ring)
    - Header pin 2 is MIDI out pin 5 (Quad MIDI Jacks blue wire to TRS out tip)
    - Header pin 3 is MIDI in pin 5 (Quad MIDI Jacks yellow wire to TRS in tip)
    - Header pin 4 is MIDI in pin 4 (Quad MIDI Jacks red wire to TRS in ring)
Parts list:
  • - Intellijel 1U x 8hp blank cover
    - Tensility 54-00081 panel-mount female 3.5mm TRS jack, solder connectors (qty 4)
    - Samtec IDSD-04-D-10.00 eight-conductor ribbon cable with 4x2 header, 10" (25 cm) long (qty 2)
    - Rapco Horizon MIDI-MINI 3.5mm TRS to 5-pin MIDI cable, 15' (4.5m) long
    - Rapco Horizon MIDI-MINI-6 3.5mm TRS to 5-pin MIDI cable, 6' (1.8m) long
I also made an Arturia-to-MMA cable that handles the 3.5mm TS (not TRS) wiring on my Beatstep. Standards are wonderful things...

Image
MIDI header on General CV

Image
Rapco Horizon TRS-to-MIDI cable
Attachments
Disting Mk4 cabled to two of the Quad MIDI Jacks
Disting Mk4 cabled to two of the Quad MIDI Jacks
Quad_Midi_Jacks_and_Mk4.jpg (152.8 KiB) Viewed 255 times
MIDI header on General CV
MIDI header on General CV
General_CV_Header.jpg (68.7 KiB) Viewed 253 times
Rapco Horizon TRS-to-MIDI cable
Rapco Horizon TRS-to-MIDI cable
rapco-horizon-6ft-trs-midi.jpg (26.11 KiB) Viewed 254 times

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os
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Post by os » Wed Jan 23, 2019 3:40 am

:party:

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soon_come
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Post by soon_come » Wed Oct 23, 2019 9:35 pm

Love this. I’m thinking about a 0hp solution myself.

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soon_come
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Post by soon_come » Sat Nov 02, 2019 12:40 pm

Os, would something like this work fine for a DIY expander if I wire the pins to 3.5mm TRS connectors?

Uxcell 4 Pin 4 Way 24AWG Female IDC Flat Ribbon Cable 2.54 mm Pitch 20 cm 5 Pieces

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os
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Post by os » Sun Nov 03, 2019 4:22 am

Should be fine.

seta666
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Re: DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by seta666 » Tue Mar 10, 2020 12:46 pm

Can you share the wiring diagram? I would like to something similar in the plate holding my korg sq1...lots of free space in there.

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Zijnzijn Zijnzijn!
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Re: DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by Zijnzijn Zijnzijn! » Sat Jul 11, 2020 4:54 pm

Bump, would also love the schematic for this! Wanna make a floating one

ldezem
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Re: DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by ldezem » Thu Aug 06, 2020 2:57 pm

Zijnzijn Zijnzijn! wrote:
Sat Jul 11, 2020 4:54 pm
Bump, would also love the schematic for this! Wanna make a floating one
+1 for this. Made a 0hp midi-connector but I'm having a hard time with it. I attached Disting mk4 PIN 3 to Ring and PIN 4 to TIP. Bind the TRS jack sleeve to the case rails but I cant get it to work with a 16n faderbank controller.

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soon_come
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Re: DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by soon_come » Thu Aug 06, 2020 3:03 pm

Is it possible you did TRS B instead of TRS A (switched polarity or something like that, I believe)? I haven't done this yet but I bought some ribbon cable and TRS adapters to try to hack one up myself. One of these days I'll get to it.

ldezem
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Re: DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by ldezem » Thu Aug 06, 2020 3:24 pm

soon_come wrote:
Thu Aug 06, 2020 3:03 pm
Is it possible you did TRS B instead of TRS A (switched polarity or something like that, I believe)? I haven't done this yet but I bought some ribbon cable and TRS adapters to try to hack one up myself. One of these days I'll get to it.
Actually, just after posting this I noticed that the 16n faderbank can send different CC values for the USB and TRS outputs. Toggled 16n settings and now it's working as a controller for Disting mk4. So... I guess a 0hp midi-trs-jack is doable by following tips from the first post but grounding the signal with a wire to the case chassis is fiddly. Luckily the faderbank is a Berlin modular PCB variant and it can be powered from the rack, so they can share the ground. The TRS A/B reality feels borderline unfair to debug. Looking forwards to the ribbon cable controller thing!

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Re: DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by soon_come » Thu Aug 06, 2020 3:33 pm

FWIW Retrokits makes an inline switch that converts between the two formats.

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os
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Re: DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by os » Fri Aug 07, 2020 2:00 am

You don't need to ground the shield of a TRS MIDI plug, nor do systems need to share ground. That's the joy of MIDI - it's opto-isolated.

ldezem
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Re: DIY 3.5mm TRS MIDI breakout for Expert Sleepers

Post by ldezem » Fri Aug 07, 2020 4:06 am

Oh! Yes, thank you. So.. Technically this 0hp floating midi TRS is a TR connection. Feels fiddly to have a loose jack sticking from a panel crack but it works and offers good control over parameters. Thank you!

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