Remote midi over ethernet

[Tubetec]

Ive been thinking about creating a cheap and ultra simple controller that puts midi input and output at the end of a network cable from a host pc ,
forget the usual USB midi adapter which requires drivers and has a limitation of 5m plus the distance you run the midi cables ,

Instead a network to serial module to handle the long wire transmission element over any existing cat 5 network cable , then a serial to midi adapter , then a couple of small bits of software on the pc to provide a virtual midi device over Com port which the DAW readily interfaces with ,
Its beautifully simple , any extra remote relay switching requirements can easily be handled by serial command ,



ethernet Com port

Serial to midi , with opto isolator


The software to make it work,
https://www.tobias-erichsen.de/software/loopmidi.html
The Hairless MIDI<->Serial Bridge
and the article here
https://www.partsnotincluded.com/how-to-send-receive-midi-messages-over-serial/

 

[Tubetec]

The nice thing from my perspective is I dont need to look at a single line of code , its plug and play with idiot proof software config ui's,
bypassing the entire USB stack in favour of Lan connection for midi seems like a good plan , might give better latency performance at the expence of two tiny software applications/processes running in the backround .
I aready have the Lan module which costs 5 euro , the midi to serial is available locally for 25 euros in either the form I showed or in an inline cable to Db25 connector .Software is free and does exacty what it says on the tin with a super lightweight Windows control panel app to configure it .

 

[Tubetec]

The inspiration for this idea came from a vintage computing website ,
The old Comodore Amiga was always known for its faultless midi timing which in turn was fed from its serial port output .Adding Windows USB layer cake on top turns it to shit,
back to basics .

 

[Tubetec]

On your old fashioned USB to serial cable you dont often get all the pins connected ,
usually just 3 ,
The ethernet decoder board I showed before needs a micro attached to work , it also has a wifi modem on the sub board .
It provides all the needed terminals .

 

[ccaudle]

Just to be clear, this is about using Ethernet cabling to transmit standard MIDI messages, not MIDI-over-IP which encapsulated MIDI into UDP/IP packets so that it can be routed through Ethernet network switches?

 

[rob_gould]

What you are proposing looks a lot like this

https://www.midi.org/midi-articles/rtp-midi-or-midi-over-networks
It should work

 

[Tubetec]

No its not using RJ45 to transmit midi signals , its ethernet packets to cover the distance with a virtual device driver that allows it put out midi data over serial at the far end .
I tried it using a usb to TTL convertor and Im able to get Reaper to output a time code signal that registers in both Hairless and loop midi . Tomrrow I'll confirm output from the TTL with the scope .

There is examples of people sending midi over long distances but cable capacitance is bound to take the edge off the square wave to the point timing suffers , might work fine in some situations , could be a show stopper in others .

Yeah thats it Rob, RTP midi ,
Software | Tobias Erichsen

Looks like a good methodology for digital control of analog gear with precise timing , the abillity to sync to midi markers, cues or timecode/mmc is more or less native to any DAW and the people using them . Relieving the USB from having anything to do with midi can only be a good thing Im thinking .
Latency testing is also easily possible via recorded channels in the DAW ,either midi inputs to VST or audio triggered via midi from external modules .

 

[Tubetec]

I found this unit , does exactly what I was thinking of , appears under midi devices in the DAW via the RPT Midi software and supports USB host from keyboard as well as two pairs of midi in/outs over lan . Its just what you want in a studio situation .

https://www.doremidi.cn/h-pd-40.html
It must be a pretty simple box ,
It appears to have a browser webpage style config .
I might just grab one instead of randomly throwing parts together and spending lots of time pissing about with programming , at around 100 its good value,
In any case Im sure its the same basic components as found on ebay cheap as chips ,

Theres an Apple library for Arduino that turns it into an RPT to old style Midi in/out
https://www.arduino.cc/reference/en/libraries/applemidi/

 

[Tubetec]

I found this board by Doepfer ,
https://www.doepfer.de/pdf/MTC64_Out_manual.PDFenables 64 relays, solenoids or lamps to work via midi ,
Its discontinued now but it can still be found for sale .
They also have a 64 contact midi input module which translates switch contacts to midi messages ,

Theres also this unit ,
https://www.robot-italy.com/it/midi-relay-dimmer-output-module-8-relays-0-dimmers.htmlThe handy thing is it also has a USB connector and a programming software to set up the midi channels just how you want them .

One interesting thing this search has thrown up is the virtual church organ software , it works as a retrofit for any ancient air organ , uses a PC to generate the sounds via midi switching .
Hauptwerk – Virtual Pipe Organ
How cool would it be to rig up an old harmonium as controller for this .

 

[Tubetec]

Ive noticed the relay based audio attenuator/volume pcbs , normally with IR remote , they tend to sell for way over the odds
Below is an off the shelf 16 channel standard relay module , The Doepfer MTC64 will allow control of 4 of these pcbs via midi

How do I wire the relay contacts and resistances into an attenuator , lets assume 8 relays per channel , how many steps can I make ?
I know the relays below are big and clunky and way way over speced in terms of current rating , but it does make life easy , it only costs 12 euro and the screw terminal blocks should allow the resistance network be hardwired very easily ,


https://soundmovements.co.uk/diyaudio/Attenuator.htmlthis link seems to be pointing in the right direction ,

I have previously spoken about mini magnetic reed switches in conjunction with smd electromagnets to actuate them , Ive since lost the link to the part I had in mind , I posted a link here somewhere or other.

Acoustic noise from a magnetic reed switches in operation is of a similar order of magnitude to the tick of a wrist watch when you hold it close to your ear , theres also galvanic isolation between audio signal and the supply that energises the coil , your switch contacts live in a vacuum so wont tarnish , I'm not certain the mechanical lifespan of basic glass magnetic reed switches but its probably tens of thousands of times , The power required to energise such coils is also likely to be miniscule compared to a relay .

 

[Tubetec]

RPT midi looks like a rock solid way to integrate digitially controled analog audio equipment and DAW in near real time ,


It doesnt need the complexity of usb ,fireware,thunderbolt and the other proprietary audio networking systems when all it has to do is open or close a few switch contacts , the computer doesnt need talk to the tubes in the preamp to find out if they had a nice day or not , it doesnt need special software or flashy GUI's associated with it to work. Theres no proprietary interfaces ,formats or drivers going out of date to worry about .

 

[loopzilla6]

Keep us updated - this is cool.

 

[Tubetec]

With the help of this schematic I can visualise how 7 relays are combined to form an attenuator with many more steps ,

 

[Tubetec]

I took a look at Dil mini reed relays , costly things ,
they still need 100ma at 5v , they have a switching time of 1mS ,
They probably contain a glass reed switch and the electromagnetic coil and pole piece arrangement ,

I got a magnetic feild indicator along with some test equipment I bought ,
Magnet Stick , its a simple device , a glass reed relay at the tip wired to a led and a battery ,
The reed switch is very sensitive to magnetic fields , its only a tiny magnetic force required to actuate it ,
Your typical 3-5v microsolenoid draws 100-200 ma but provides several grams of magnetic pull, way more than we need to opperate the magnetic reed switch . Maybe the higher resistance 24v solenoid coils will still exert enough force with only 5v applied with lower
current draw , but there still a big ugly lump of a component
A flat low profile coil with less turns but much higher resistance due to diameter might be possible , the core might consist
of a flat strip of metal in a loop encompassing a pair of reed switches at either edge .

Making the attenuator in the form shown below allows great matching at the expence of the extra resistors in parralel , it requires a pair of contacts to switch it /out , not simply shorted out like the previous example .