I/O limits without "32 inputs/outputs"

If you don't enable "32 Inputs/Outputs", the manual doesn't say what the limits are then. It seems that without that checked, I get 8 outputs, but only 4 inputs, not 8. I tested with Steinberg UR44 which has 6 inputs and 4 outputs, and Focusrite Scarlett 18i20 (3rd gen), which has 18 inputs and 20 outputs. If this is really the limit, it seems a bit arbitrary. Maybe it's based on the MPC X hardware's limitations, which is 4 x Input, 8 x Output? I'd like to connect a reasonable setup to the Scarlett 18i20 and keep it connected, so now I have to use "32 Inputs/Outputs". The manual says that enabling 32 Inputs/Outputs increases CPU consumption - I wonder what the impact on CPU is, and what is the cause of that.

By the way, when you initially unbox the Focusrite Scarlett 18i20 and connect it to your MPC or Mac or whatever, you won't see MIDI ports! It is in MSD i.e. Mass-Storage Device mode, and instead of giving you MIDI ports (or higher than 48000 Hz sampling rates), it gives you a USB disk which has an HTML file telling you to go and register your device in order to get out of this crippled mode. Nice? You buy a product, it is crippled by default. Ha ha! This might be a bit baffling.
- https://www.reddit.com/r/Focusrite/comm ... ableton_9/
- https://www.thegearpage.net/board/index ... e.2115159/
- https://linuxmusicians.com/viewtopic.ph ... 2&start=75

In the manual (which the majority of users never read or even find), a procedure is given, which should enable you to override the default crippled mode:

In order to force your Scarlett 18i20 out of MSD mode without first registering it, hold down the 1-4 48V button while disconnecting and reconnecting the USB cable, and then continue to hold the button down for a further five seconds.

The only problem is, that does not work. As noticed by some users in the discussions linked above.

With some trial and error, I found the correct procedure at least for the 3rd Gen model to be:

1. Unplug the USB cable
2. Power OFF the Scarlett 18i20
3. Push and hold down the 48V 1-4 button
4. Power ON the Scarlett 18i20
5. Wait 5 seconds
6. Release the 48V 1-4 button
7. Connect the USB cable

--> Now the USB drive stops showing up, and you get your MIDI ports working, in Ableton Live, MPC One, etc.

Maybe I should have posted this with the title "Focusrite Scarlett 18i20 testing". I'm getting random audio dropouts, small clicks but bigger hickups as well. Randomly, maybe it plays for 30 seconds, maybe 40 seconds without at least a small hickup, but not a full minute. Only playing a simple audio track with a string pad, nothing else in the project. Connected directly with a USB cable, no USB hub in between.

It seems that saying that an audio interface "works" or "doesn't work" is a very simplistic model. There's a gradient of non-working in subtle ways.

For comparison, Mac Ableton Live 9 works with buffer size 32 samples, no glitches. And no drivers installed, running class compliant.

I updated the 18i20 from version 6.0b to 6.1b with the Focusrite Control application, but it didn't have any effect on the random dropouts. :/ What are Apple and Akai doing differently? One of them can get glitch free audio working.

I must conclude that the Class Compliant list thread is harmful, because it claims that something "works", even though the people have not even done proper thorough tests. None of the reports are credible, until complete video evidence is posted, showing the interfaces operating glitch free for a long period of time.

I can’t seem to get my MPC to register that my Steinberg UR44 is hooked up via usb. How did you manage to get the mpc to work with the UR44 with out installing the interface drivers?

Did you check that it's in Class Compliant mode?

I believe I made sure it was turned on. Turned the 32ins/outs on and off to see if that would fix it. Just checked the firmware on the UR44 too, to see if it was up to date. I’m stumped.

HouseWithoutMouse wrote:I updated the 18i20 from version 6.0b to 6.1b with the Focusrite Control application, but it didn't have any effect on the random dropouts. :/ What are Apple and Akai doing differently? One of them can get glitch free audio working.

is your 18ii20 the v3?

Yes, 3rd gen. It also works glitch-free in Linux (tested on an old i5 PC), even with mixer support with geoffreybennett's drivers https://linuxmusicians.com/viewtopic.php?p=133221

(BUT you need a new kernel version for all that to work, I compiled it from source to get it working)

The latest news is (see that thread) that the support is included in Linux kernel 5.14+. Great work.

Visualization of mixer possibilities:
https://linuxmusicians.com/viewtopic.ph ... 34#p136134