Midi interface question (Serial v USB)

[The Lone Rider]

Looking at a midi interface.

I've got a Roland percussion pad and a keyboard, as well as the i/o used on my guitar amp (to access more settings than it has knobs for).


Currently looking at a opcode stuido 64x, but I am way out of touch with what the "in" thing is.

Opcode has a 4 in 4 out interface via 9 pin serial port. Most of the other interfaces I've looked at are USB.

As far as sequencing I'm not doing much more than sending channel and on/off messages (keyboard) and channel, on/off, velocity, volume messages (pad).




Which will have better response and less latency?

[jim.cox]

I'm no expert on MIDI, but...

As I understand it , USB is serial - and with the current chipsets capable of doing very high speeds.

Also there aren't many computers now that have the old 9 pin serial ports

You can get usb <-> 9 pin converters - I use one to get my gps to talk to my laptop

I would think that USB would be the way to go

[The Lone Rider]

Hard to say. I know of people having problems with latency with usb. Nothing worse than pressing a key and hearing sound half second later.

[SMOKEU]

Hard to say. I know of people having problems with latency with usb. Nothing worse than pressing a key and hearing sound half second later.

It wouldn't be the interface itself that's causing the lag. USB mice and keyboards don't seem to lag.

[jim.cox]

USB mice and keyboards don't seem to lag.

Agreed - but plenty of drummers mention lag as an issue with midi.

Google USB and Midi and Lag and you will see what I mean

One good tip I have seen is to make sure you only use USB2 or 3 chips, drivers and devices. USB1 and 1.1 are significantly slower. Sticking a 1.1 device in a USB2 port can slow everything.

I suspect that the USB chip, the Southbridge chip and their device drivers are also significant

[Buyasta]

Hard to say. I know of people having problems with latency with usb. Nothing worse than pressing a key and hearing sound half second later.

Latency shouldn't be an issue, particularly if it's USB2 - the latency on USB1 is 1ms, while USB2 is 940ns.

USB does have a very slight CPU overhead - on a modern system, well under 1% CPU usage per device used - but unless you're trying to use it with a computer that's more than 5 years old and running CPU-heavy applications, that's extremely unlikely to be an issue.

[The Lone Rider]

but unless you're trying to use it with a( computer that's more than 5 years old and running CPU-heavy applications, that's extremely unlikely to be an issue.

pro audio multi tracking with many audio tracks running vst and vsti tracks via midi is heavy. I've previously always have had problems and had to offset audio to overdub then quantize. None of the professionals I know so far have said more than the opcode used used to be top of the line pro gear. Haven't seen anything comparable on usb other than cheapo $30 no name no spec units. Or the underwelming m audio units

[The Lone Rider]

Found this "On the other hand, USB 2.0 is capable of speeds of up to 480Mbps. That's 480 million bits per second. That's roughly four thousand times the maximum potential speed of a serial port clocking at 119200bps. However, the real speed of USB to or from any particular device generally depends on the device itself, other devices connected to the same bus, or other limitations on the host PC."

But I am still suspicious of midi via USB.

Wish I could try a unit before I buy it.