You could use an old AT style KVM switch and just use the keyboard ports for MIDI.

Looks like a 1 to 4 / 4 to 1 switch can be had for $20 shipped.

http://www.ebay.com/itm/Manhattan-4-Way-VGA-M … x-/270750499123

I used to have 4 devices daisy changed, plus an analogue mixer and audio switch box. There were so many cables. In the end I just ended up with one set of leads and I just plug in whatever unit I need at a time.

cyclone3d wrote:

You could use an old AT style KVM switch and just use the keyboard ports for MIDI.

Looks like a 1 to 4 / 4 to 1 switch can be had for $20 shipped.

http://www.ebay.com/itm/Manhattan-4-Way-VGA-M … x-/270750499123

Interesting idea! Has anyone actually tried this?

I'd almost want to make adapters to run the audio through the VGA ports too, so that I could switch the audio along with the MIDI... Or maybe just take the VGA ports out and replace them with RCA jacks if the internal wiring is amenable.

PhilsComputerLab wrote:

I used to have 4 devices daisy changed, plus an analogue mixer and audio switch box. There were so many cables. In the end I just ended up with one set of leads and I just plug in whatever unit I need at a time.

Thanks. I could probably get by that way, although I really need to break open the SC-88 and re-solder the RCA jacks because they're already pretty spotty sometimes.

The wiring on those switch boxes is pretty straightforward. You could easily make adapters for the VGA to RCA or replace the VGA with RCA.

Those old switch boxes are really horrible for video and give really bad ghost images because the wiring inside doesn't have enough shielding, but it will work fine for audio and midi.

You can always put in some more shielded cables for audio, but I'm not sure it would make any difference for that type of setup.

HunterZ wrote:

Buy some kind of MIDI selector box. This would probably be expensive, as it would be seen as pro musician equipment.

Just get one of these: http://www.midisolutions.com/prodqth.htm

They're not particularly expensive, especially if can find a used one. I have one and use it with my MIDI modules; it works great.

Shponglefan wrote:

HunterZ wrote:

Buy some kind of MIDI selector box. This would probably be expensive, as it would be seen as pro musician equipment.

Just get one of these: http://www.midisolutions.com/prodqth.htm

They're not particularly expensive, especially if can find a used one. I have one and use it with my MIDI modules; it works great.

Or if you want to go with pro audio equipment, look for a non-programmable MIDI patchbay. Should be around 30-50 bucks secondhand.

NO!
quadra thru boxes are crap, don't get it!
get a midi thru box with an active power supply input instead

From the website of that product:

The Quadra Thru is MIDI-powered, and requires no batteries or power supply to operate with most MIDI products

My initial thought is how can that work, as the MIDI specifications do not really allow or make powering devices possible in any way.

But then I read from their FAQ:

If a device won't provide power to a MIDI Solutions product because it is not operating at the original MIDI standard 5V then no simple modification can be made to enable the device to power the MIDI Solutions product.

So they are sucking parasite power from the transmitting MIDI device which is something the standards have not taken into account, and if their device does not work, they blame the transmitting device not being according to original MIDI standards?

No wonder if they don't always work. You just can't drive four MIDI inputs from a single MIDI output, not directly anyway. They must have some energy harvesting/storing solution so that when data comes in at relatively low duty cycles, the device has enough energy to drive that to four outputs.

Grande finale:

In other cases the reason a product does not provide power is because pin 2 (the center pin) of the MIDI output has not been connected to ground as indicated in the MIDI specification

OK, now it's all clear to me. They use the fact that usually MIDI output connector pin 4 has 220 ohm resistor to 5V and pin 2 is grounded for shielding.

Midi specification quote:

One output shall drive one and only one input

keropi wrote:

NO!
quadra thru boxes are crap, don't get it!
get a midi thru box with an active power supply input instead

I've been using the Quadra Thru for years both with full-blown synth gear as well as various sound modules. Never had an issue.

^ I have read at least 3 people trying it with a ROLAND MPU + SYNTHS and everyone had issues, I think Phill's Computer Labs is one of them. IIRC it had trouble with SysEx messages, something important with the MT-32.
These boxes might work with other midi devices but with ISA PC cards they seem to have issues. Maybe "crap" was too harsh I admit it 🤣 , still it's not like they are cheap and worth a gamble. Better play it safe 😉

Jepael wrote:

From the website of that product:

No wonder if they don't always work. You just can't drive four MIDI inputs from a single MIDI output, not directly anyway. They must have some energy harvesting/storing solution so that when data comes in at relatively low duty cycles, the device has enough energy to drive that to four outputs.

A proper synthesizer keyboard with a beefy power supply can. Many modules and lesser MIDI devices can't, and that's why they also make a device that can be connected to a power supply for powering the MIDI bus. BTW, this manufacturer has a very good reputation in pro-audio circles...

keropi wrote:

^ I have read at least 3 people trying it with a ROLAND MPU + SYNTHS and everyone had issues, I think Phill's Computer Labs is one of them. IIRC it had trouble with SysEx messages, something important with the MT-32.
These boxes might work with other midi devices but with ISA PC cards they seem to have issues. Maybe "crap" was too harsh I admit it 🤣 , still it's not like they are cheap and worth a gamble. Better play it safe 😉

So then the other option is a MIDI patchbay, e.g. Kawai MAV-8 (cheap), Roland A-880 (programmable) and UM-550/UM-880 (programmable + USB starting with Win98), Akai ME30P/ME30PII/ME80P (all programmable, ancient but cheap), Ensoniq Mx8 (cheap), JL Cooper Synapse. Those are all 19" pro-audio gear, except for the Roland UM-550, and they should play fine with SysEx.

I just use old-style midi thru boxes, zero issues and zero config needed 🤣

both need external power supply to work.

I daisy chain mt32/sc88/emu. I also have + use Roland MPU-104 + MPU-105.

MPU104 is a 5x source input selector (I have my main workstaiton pc + two retro PC hooked to it)
MPU105 is 5x output selector. (Ive used it but I dont currently use it).

I like daisy chain all my modules, as I like to have sometimes all my GM modules playing same song, you get a richer effect!

all hooked to a stereo mixer so I can control each modules volume independently.

So I just found a 4-in, 1-out passive RCA stereo audio + S-Video + composite video A/V switchbox laying around in the garage that I forgot I had, so I rewired my synthesizers for independent audio switching to the PC line-in.

Unfortunately I still lack both MIDI and audio cabling to be able to connect up more than 2 synthesizers at a time, and I still have to run multiple synthesizers in some cases because I lack a MIDI switching solution.

Speaking of MIDI switching:

I looked at MPU-104's on eBay and they are overpriced due to now being vintage.

I found these two eBay actions for AT-keyboard switchers, but I'm not sure if they're safe for MIDI synthesizers:
http://www.ebay.com/itm/232330915260
http://www.ebay.com/itm/270750499123

I'm also somewhat thinking about modding the A/V switchbox I am using, because between the composite and S-Video connections there are enough signal lines for MIDI.

The keyboard switchers should be fine as all pins are active. Only two pins are active on MIDI cables, so MIDI DIN won't necessarily work for the AT keyboard protocol, but the other way around is fine.

Look for a MIDI patchbay such as the Kawai MAV-8 (4 IN, 8 OUT). Should be available for 30-40 dollars (preferably including power supply - but a cheap 9-12V DC power supply will also work), and since it's not programmable there isn't much that can break.

The only downside is that it's a 19" unit (but not a very deep one - it's about 50x5x15 cm).

Also, BIN prices ≠ going rate of regular auctions.

for that price you can get a smaller midi-thru box and call it a day , why get a rack mount bay and waste space?

keropi wrote:

for that price you can get a smaller midi-thru box and call it a day , why get a rack mount bay and waste space?

It depends on what you want to do with it. Personally I really like all of the routing options a MIDI patchbay offers, something my MIDI/computer interface doesn't (unless I keep my computer on and DAW open at all times).

Consider it as follows:
- Option A is buying tons of MIDI merge*/thru/split boxes, having to change the cables every time you need to change something in your configuration.
- Option B is a MIDI patchbay to which you more or less permanently attach your stuff, and you only need to push a button or change a switch position to choose a different routing.

* Note: not all patchbays offer merge, AFAIK only the programmable ones.