WEM MIDI information sought on accordion

[Martin L]

I purchased a secondhand Vignoni Ravel IV acoustic accordion back in 2020. It has an early WEM MIDI fitted. I am seeking information on the interface.

The WEM MIDI connector is a 6 PIn DIN connector (5 pins in a 270 deg arc and pin 6 in the middle). There are 4 wires connected as follows:

Pin 1. Red
Pin 3. Green (also connected to connector shell)
Pin 4. Blue
Pin 5. Brown
(Pins 2 and 6 not connected)

I understand that WEM MIDI can be used with a Musictech interface/power supply. The standard MIDI connector for an accordion is a 8 Pin mic style connector secured with a threaded collar.

I am hoping someone on the forum can help me with the following information

The function of each coloured wire (power +, Power -, MIDI out, MIDI out earth. Etc)

The correct supply voltage. ( I assume current drawn is relatively low)

I am unsure if this old MIDI has any special key combinations to change its function. I assume there is no “MIDI in” wire.

I was an electronics engineer before retirement and happy to change the connector and make up cables etc.

Prior to lockdown I had not played any instrument or read music so learning the accordion is a new challenge for me.

I would like to test the Installed MIDI on someone else’s MiDI interface/PSU and expander to ensure it works before investing in my own MIDI kit. (I have an offer already but need to ensure the connections are 100% correct beforehand)

I have read the posting by William Bell on this forum from 2014 - he appears to have the same MIDI installation as myself

Many thanks

 

[JerryPH]

If there is just one connector, it looks like all you have is one of the older and very basic MIDI out setups. To hear anything from this unit you will need some kind of expander unit and that unit has to be connected to a source like a mixer/amp to hear the results of your playing.

This kind of older MIDI normally has no advanced features like bellows control, and simply transmits on 3 channels right hand complete, left hand bass and left hand chords. You will likely have a battery somewhere that will need to power the unit, or it may draw power from pin #4. Hard to say... I am far from a MIDI expert on all things MIDI, I just know enough to make it work for my needs.

 

[boxplayer4000]

Martin:
Your description of the pins used on the MIDI connector states 4 pins are being used.
On your picture of the connector on the grille it appears to show only 3 pins being used (or is there a 4th wire which is not clear in the photo?)
I'm quite familiar with power supplies for the most basic Musictech MIDI systems and they only use 3 pins of a standard DIN plug/socket.
The basic Musictech systems use 5 volts but what I remember of WEM's own 'Partner' Expander it supplied 9 volts for the MIDI system.
Using more than 3 pins MIGHT suggest that a foot control was involved.
At the main connector on the PC board across the treble keys it's likely that the voltage being used is marked.
Any identification marks at the PC Board might be helpful as there are still people around who are familiar with WEM systems. I know of some who installed there own WEM systems.

 

[JerryPH]

A fast google netted me this:

MIDI Interface Details

Details and instructions for WEM MIDI Interface

www.accordionexpanders.com

 

[boxplayer4000]

JerryPH: A good find! I remember those publications. Dates? Maybe 1990s. Charlie Watkins (founder of WEM, Watkins Electronic Music) was a very innovative person and developed massive PA systems for the Beatles, Rolling Stones etc. in their early days not forgetting his magnetic tape based echo machine (The Copy Cat) which was an industry standard for many years. Amid all that he kept a soft spot for the accordion and would play 'Blaze Away' at the drop of a hat.

 

[Giovanni]

JerryPH: A good find! I remember those publications. Dates? Maybe 1990s. Charlie Watkins (founder of WEM, Watkins Electronic Music) was a very innovative person and developed massive PA systems for the Beatles, Rolling Stones etc. in their early days not forgetting his magnetic tape based echo machine (The Copy Cat) which was an industry standard for many years. Amid all that he kept a soft spot for the accordion and would play 'Blaze Away' at the drop of a hat.

All so very true a great guy i met him and his wife June many times they also raised a lot of money for charity ...............and yes he loved playing Blaze away !!!........................When I play it on my litle gigs I always think of Charlie........................

 

[Giovanni]

I have two suggestions. 1 ) contact Watkins electronic music speak to June Watkins .
2) contact elmat speak to John Farlowe

 

[fogman25]

I had a similar issue with a hohner morino club with midi of about same vintage 1980's. With help from members of the melodeon forum I was able to build an interface box which solves the problem. Two pins are for an external 9 volt power supply. Wires from these pins go to a voltage regulator inside accordion which changes it to 5 volt to power the midi system. The other two wires are for midi out. There are no midi messages for bellows pressure.

 

[bruce1530]

There were several versions of the Watkins midi.
The one I have is as described in http://www.accordionexpanders.com/wemidi6.htm

There's a cable runs from the accordion (usually on a 5 or 6 pin DIN - the 240 degree variant, not the same as the midi cable) to an external power supply box.

There are no special electronics in that box, it's just a 9V power supply, midi breakout, and maybe connections for 1 or 2 foot switches. Look at the wiring on the PCB at the accordion end to be sure, but on mine, we have:

5 pin DIN 240 degree:

pin 1 V+ (9V)
pin 2 optional - foot switch
pin 3 0V (and cable shield)
pin 4 Midi -
pin 5 Midi +


Note that the pins on the 180 degree (as used by midi) and 240 connectors are numbered differently. The 240 is 12345, the 180 is 14253. (the original 180 degree connector was 3 pin, numbers 123, they then added two extras, so it became 14253, so 123 still in the same place)

So you want to take pins 4,5 on the 240 plug and connect them to a standard midi cable, and connect a 9V supply across 1,3.