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Hi
I need some good (low latency) midi splitter i have in my piano:
1x MIDI IN
1x MIDI OUT
No USB

For now im using one Roland interface UMONE MK2 but i'll need to have two MIDI-USB output, i know that i can buy midi extender but then i will need another midi to USB interface. Maybe someon know something that will extend my midi into two USB midi interfaces? And everything will be done in one device

I also know that i can plugin one to Computer and then output from computer to another device but i want to avoid this solution

I'm not sure what you're asking for, but one of these options is probably the answer:

A single MIDI OUT to multiple MIDI OUTS = MIDI Thru box

Multiple MIDI OUTs to a single MIDI In = MIDI Merge box

Multiple USB slave devices to a single USB host = USB hub

For the first two, for examples, see http://midisolutions.com/products.htm

Sounds like the request is for a device that lets two USB hosts receive the data from a single MIDI device. A hub won't help.

Anything reasonable you buy will just be two USB to MIDI adapters, like the UM-ONE MK2, and a MIDI "splitter", in the same box. Just buy the pieces separately, and stuff them all into one cardboard box.

A MIDI splitter can be made inexpensively with ~zero latency. Separate USB to MIDI adapters won't have additive latency, so there's no downside to this plan besides having to acquire a cardboard box.

MIDI (the good old round connectors) carry a serial signal that can be connected to a (similarily old) RS232 port. The signals on those MIDI-OUTs are one-way, you can duplicate them without any logic problems.

Find a MIDI cable with connectors that you can take apart, or buy ones from an electronics supply shop, or cut a cable into half and beep wires-to-pins with a multimeter. Lookup the MIDI connector pinout, identify GND and TX line on MIDI-OUT (and RX on MIDI-IN), and duplicate TX to 2x RX.

The added latency is 0 (zero).

Minor caveat: A potential problem (arr..hum!) is that you can involuntarily create a ground loop when you connect them to different equipments that are not strictly MIDI. All faithful MIDI-INs are supposed to be isolated, but RS232 ports and cheap china converter cables may not be. It won't be a problem in most cases, though. The worst case is to have a 50/60Hz hum in your speakers.

The logic levels of MIDI and RS232 are not compatible. If anything even remotely like this worked, your RS232 port was extremely forgiving.

This is what a reasonable MIDI to RS232 adapter would look like: https://www.compuphase.com/electronics/midi_rs232.htm

This could slowly and silently damage a poorly designed MIDI output, by drawing more current than it was intended to handle. Ideally the output can handle a complete short, but who knows. It's a violation of the specification, and shouldn't be suggested to anyone who isn't qualified to evaluate the ramifications themselves.

@lukasz-zsakul: What exactly are you trying to accomplish?

To be clear i need one MIDI USB to my laptop - VST And another one for led strip. So i belive i need only midi out for both. But im not sure if i can Connect only out in my midi-usb interface , i cant test it now. If it wont work then i ll need one MIDI splitter/thru and one midi merger, and two midi-usb interfaces?

Okay, I think I'm starting to understand. What you want to do won't really work, because the two USB devices you want to connect your MIDI keyboard to are not both Hosts, and unlike 5-pin MIDI which is peer-to-peer, USB differetiates between hosts and slaves, and you can't directly connect two slaves together without a host in the middle. A computer is a host, an LED strip would not be a host. You need to have a host between your keyboard and the LED strip. Since the computer is already there, the "solution you want to avoid" is the most sensible thing to do... keyboard and LED strip both connect to the computer, rather than to each other.

If you REALLY don't want to use the computer, you can go MIDI OUT of the keyboard into a MIDI THRU to turn the one Out into two, and then connect one of those two Outs to your UMONE (which will go into your laptop) and use the second Out to go to some other host (which will then go to your LED strip). That other host could be something like an iPhone/iPad, or a dedicated device like this one: https://kentonuk.com/product/midi-usb-host-mkii/

You just need a cheap MIDI Through (splitter) Box inbetween the piano and the Roland UM1 Mk2.
Piano's MIDI Out goes into the splitter box and passes straight out again through a MIDI Thru going to your Lighting controller MIDI Input (operating on one MIDI channel as defined from your piano) while another MIDI Thru socket can send the piano's keyboard musical MIDI data (on a different MIDI channel as defined from your piano) going straight into the Roland UM1 MK2 (whose MIDI Input connector cable you can just plug directly into the Thru box) going out of Roland's USB into your computer VST software.

Something like this will do the job for £34, although there's many similar products on the market, possibly even cheaper. Have a search around.
https://www.thomann.de/gb/miditech_midi_thru_filter.htm?sid=ebf516c2702bcd7d685f3a266de359e6

You're assuming the LED strip has a 5-pin MIDI input, but it sounds like it actually has a USB input, which I assume makes it a slave device as I described in the post preceding yours.

It might clarify things if the OP provided info on the make/model of this LED strip he's talking about.

What is an LED strip? How are LEDs tied to MIDI?

He wants to make led lights illuminate as he plays each note and he wants to drive this with a midi signal.

Aren't there device that do that using an audio signal? Those have been around for decades.

I suppose the idea is to map a specific note to a specific LED in the strip.

So, I again suppose that some sort of a mini computer like Raspberry Pi or Arduino is involved.

And then the main computer also needs the MIDI data to make some noise to go along with the lights.

Once again, I apologize for not specifying it.
Yes, my two devices are hosts

one is a computer for VST
and the second is a raspberry PI to which the led strip will be connected

So it looks like I need to buy a midi OUT splitter in my piano and a second UM1 MK2 cable - one for the computer, the other for the raspberry Pi ?

Ah, the LED strip is not a standalone USB device, but is connected to a raspberry PI! Yes, that's significant, since as you point out, the PI is a host (the LED strip itself is a slave, and of course, hosts and slaves have different wiring requirements). I was wondering about that, because while I've seen USB powered LED strips, MIDI was an unexpected twist there!

So yes... MIDI Out of your keyboard into a splitter (thru box), one UM1 to your computer, one UM1 to your PI, that's the way to send the MIDI Out to two USB hosts.

Why would a manufacturer of midi LED strips design them with a USB port to receive midi and not make it a host so that you could attach a midi keyboard and send midi to it to light the LEDs? Pushing the extra cost off on other stuff you need to get to make it work is not "designing to a price point".

I suppose (again) that nobody makes MIDI controlled LED strips, but strips that can be controlled with some other protocol.

So a mini computer like the Pi or Arduino is needed to take in the MIDI and to control the strip.