At Superbooth 2018, RetroKits gave us a quick overview of their line of MIDI solutions, which include cable, hub and hosts for connecting a variety of MIDI devices.
Their MIDI solutions include the RK-002 Cable, which is a MIDI cable that can manipulate MIDI data on the fly; the RK-004 6-channel MIDI merger/splitte/clock processor; and the RK-005 MIDI hub.
See the RetroKits site for details.
Nice ideas.
Don’t think it is very nice and correct of Retrokits to keep excessive hammering on their site on not using the MIDI Solutions Quadra thru box. The remark they make. in that one should not use the +5V pin of a MIDI out plug for powering anything else than a MIDI input port, is correct. However that remark applies in general and not only to any brand of MIDI thru box. It very likely applies to their own boxes as well should their inputs be connected to their RK-002 cable.
Oh, and specifically about that cable: currently it comes “only for the Korg Volca series” MIDI inputs, and what it effectively does is putting the synth that is controlled in Omni On mode. Not very spectacular. But, as said already, some nice ideas in their other boxes and gadgets.
MIDI doesn’t have a 5V power pin. MIDI has a ground pin, and two pins comprising a current loop that transmits the serial data. Current is on or off in this loop and when on it must push at least 5mA . The other two of the MIDI pins are to be unconnected. This is the MIDI hardware standard and MIDI devices must conform with it.
In the past there were some rogue devices that did strange things with the other two pins, from power to two way communication. Such cables and devices do not conform to the MIDI standard and can not legally be called MIDI devices. They can also cause damage to other rogue devices in some circumstances.
Modern MIDI powered devices combine very low power circuitry with a circuit that parasitically draw a small amount of power off the current loop in order to power a processor, and the optocoupler, and drive the next device. As long as these devices are able to supply at least 5mA to the next device, and don’t do anything with the unconnected pins, and don’t connect the ground at both sides, and optically isolate the data signal, they are within scope of the standard.
On one of their devices they mention a customer got a fried device by connecting their device with some other. That means someone is doing something wrong. This should be looked into much more closely and figure out what the problem is (and whose side the problem is on). That would be better than a mysterious warning.
If your MIDI cable has 5V power on some pin, it is not being used as a MIDI cable because that is way outside scope.
Well Ad, the RK-002 is definitely not for volca only, we have a whole ecosystem on our site called the RK002/DUY Exchange portal which allows you to download any firmware into the ‘cable’ and even design your own with help of the free Arduino IDE. There are already numerous fixes/additions available (arps, filters, note scales, polymux, chords,…, … ) for a LOT of devices.
About the Quadra thru warning; This is the only box which harvests ánd stores power inside it for midi thru replication which seems to pose an extra risk on the RK-002. Working with non-powered thru-splitters (headphone splitters and such) is certainly not lethal but not recommended either because you are dividing power through multiple devices which deteriorates the signal. The Quadra Thru is unique in this power harvesting. By own means: Text alterations which clarify this unique case without naming it are welcome. Mag ook in het Nederlands.
this covers a big market gap. I want to run a DAWless rig and I have ran into problems that these devices will solve with an acceptable cost. congrats!
First the positive – these utility tools look really handy.
On the other hand part of their reason d’etre is to fix problems created by the introduction of USB midi, wonky design decisions, and now the introduction of midi on mini plugs by Korg and Arturia, and various implementation of synchronization. And don’t get me started on mobile phone chargers as power supplies. Manufacturers – proper five pin midi and decent power connectors please.