USB Class Compliance: For Discussion of Issues & Bugs

HouseWithoutMouse wrote:Here's what the Focusrite Scarlett 18i20 audio dropouts look like:



In the test, I made the Odyssey plugin produce a constant steady waveform (by pressing down a pad and going to Preferences, which leaves the note unreleased and playing indefinitely), recorded the output with a Zoom H4n recorder, and loaded the wav file into Ableton Live for analysis.

There is a similar dropout every 40+ seconds, and each dropout lasts about 21-22 milliseconds, which is very close to 44100 / 2048. There was some variance in the interval between dropouts:

0:29:518
1:10:109 (+40.591)
1:50:459 (+40.350)
2:30:692 (+40.233)
3:11:193 (+40.501)
3:52:141 (+40.948)


In my Mac, the same audio interface works without any glitches like that.

MPC One version 2.10.0.
Focusrite Scarlett 18i20 version 6.1b.
Connected directly with the Focusrite supplied USB cable, no USB hub in between.
The MPC's "32 Inputs/Outputs" option was NOT enabled.
No MIDI devices were connected to either the Scarlett or the MPC.
Playback was not on. The MPC was in a stopped state. No MIDI I/O should have been happening, because nothing was connected and nothing was playing, except the one stuck Odyssey note.

I seriously hope Akai fix their stuff. The Scarlett 18i20 is an affordable and fairly popular audio interface. The Class Compliant "working/not working" list thread cannot be trusted, because people are apparently not actually testing the interfaces.

I have the second Gen 18!20 on my MPC one and didnt notice any dropouts, maybe its because of the type of my music.

Mine is a 3rd gen. It took me half an hour to figure out that something was wrong with the audio output. For comparison, I recorded 45 minutes of steady buzzing from Mac Ableton's Operator synth through the same Scarlett 18i20 unit and there were no dropouts. By the way, the letter between the numbers 18 and 20 is a lower-case i, not an exclamation mark.

a friend told me that the 3rd gen isnt fully CC anymore...

Disappointment

Certified Beatz wrote:So okay finally downloaded and installed the update .. I don't have time tonight to dive into all the features.. I did however try my audio interface Motu 828es first problem like others have mentioned it need 44.1k bitrate okay changed now I can see and use 32 outs but guess what like others reported less 6 bars drops outs and clicks and glitches.. I won't spend anytime finding out why I don't think this feature is full tested and I'll just go back to using my X the way I was before.. only way this will work of they open up the outputs in standalone using the audio interface built-in the MPC then send the outs to your audio interface.. oh well still love my MPC..

No matter what MOTUs arent going to work. MOTU says flat out class compliant only on the Mac, so no Windows, Linux, etc.. MOTU has been very vocal in the past about not being Linux friendly at all, they aren't going to budge on that any time soon.

Monotremata wrote:

Certified Beatz wrote:So okay finally downloaded and installed the update .. I don't have time tonight to dive into all the features.. I did however try my audio interface Motu 828es first problem like others have mentioned it need 44.1k bitrate okay changed now I can see and use 32 outs but guess what like others reported less 6 bars drops outs and clicks and glitches.. I won't spend anytime finding out why I don't think this feature is full tested and I'll just go back to using my X the way I was before.. only way this will work of they open up the outputs in standalone using the audio interface built-in the MPC then send the outs to your audio interface.. oh well still love my MPC..

No matter what MOTUs arent going to work. MOTU says flat out class compliant only on the Mac, so no Windows, Linux, etc.. MOTU has been very vocal in the past about not being Linux friendly at all, they aren't going to budge on that any time soon.

Thanks for the reply, I have talked to 2 reps saying different altho yes for ios it should still work with Linux. They state its on akai so back n forth game anyway .. if such is true when putting out the unbelievable update which I love they should have stated limitations.. I know I can use it in controller mode but who wants to load plugins inside of a plugin makes not sense when akai audio card sounds great and should be utilized.. my thoughts back to what I know works..

Yorgos Arabatzis wrote:

Dmcghee wrote:Yes, the MPC records the way it was designed to record. I only hope Akai implement 32 audio tracks of disk streaming in stand alone.

Ok let’s break it down to sections with examples..
Let’s say you have a 32 sounds drum program, can all be played and controlled simultaneously on the X32?Can you record it’s motorized faders action as the mix progresses?
On the inputs side let’s say you have a studio with a bunch of synths, drum machines, modulars etc. , can you record 32 input channels simultaneously on the MPC via X32?

Yes you can absolutely record 32 takes simultaneously back into your MPC X/Live/One from the X32.

I have never written USB device drivers, but I would suppose that if the device works with host X, all you'd have to do is put a USB analyzer between the device and host X, see how the host works, and make your own host's driver do the same? If all of the devices and hosts are supposed to implement the same public spec, you don't even have to guess and reverse-engineer what's happening, right? I mean, if you are a professional company, not some hobbyist who can't afford the tools? Something like this https://www.totalphase.com/products/beagle-usb480/

I could be wrong, that's just what I figured out from the web in a few minutes.

coffeesounds wrote:Arturia Audio Fuse rev2 working perfectly, including MIDI ports and integrated USB hub - I can control synths over USB midi and record via individual inputs.

Makes me think I should switch to AudioFuse Studio to get more physical controls

Does it also work for multitrack recording? Wanted to make sure since I'm about to purchase one.
And does it record with input gain faders on the interface or pre faders?
thanks

Selahl Tapes wrote:Hell! this evening I planned to fully test my Audient ID14 interface with the MPC 2.10 update in standalone, but some how got side tracked into the city and came home with a Roland SP-555!?! I was curious to see if the SP-555 worked with the MPC as the Roland had a USB port on the back, so I hooked everything up and what do you know!!! the MPC recognised the SP-555 as a interface.

Things I am able to do when the SP-555 & MPC One are connected via USB HUB and Roland is selected as the audio device.

Record inputs and outputs
Record SP-555 effects into the MPC
Record Plugins from MPC onto SP 555 pads with effects then back onto a MPC pad.

Main outs of MPC going through SP555 effects section for live jams.

Easily transfer sounds from SP555 pads to MPC pads via record inputs and outputs

Play MPC from SP555 pads via midi

All this over one USB cable, a potential monster of a set up MPC & SP555 but with one problem. It has crackle and pops in the audio on play back and recording that I think a lot of people are having when using the new 2.10 feature… this is a Akai problem and needs some optimisation before we get clean pop and click free audio with our chosen interfaces.

that is pretty cool, maybe it even deserves it's own thread.

Reply from focusrite support regards class compliance.
"In regard to your inquiry, the Scarlett 3rd Gen line is Class Compliant on macOS or iOS. For Windows the ASIO driver needs to be installed for it to work."

Compatibility issues are not at all solvable on the audio interface manufacturer side, because you can't get dozens of manufacturers to care about MPC. But it's still good to know what Focusrite etc. are saying. The issues are only solvable on the MPC side, which in practice means Linux device drivers, if I understood the architecture correctly. So if you want to get something working with the MPC, you basically have to get it working on Linux (which of course is a diverse world of components and versions on diverse platforms). Not sure if Akai are going to take part in this or if they just wait for the legendary Someone (tm) aka. the mythical Open Source Community to provide the fixes. This speculation could be wrong of course.

Orbitalgun wrote:2nd gen 18i20 Focusrite Scarlett and octo pre both work in stand alone and with the computer!

Are you experiencing any crackling when this setup is connected to the MPC? I'm hearing a digital artifacts hum coming from the 2nd Gen 18i20 Scarlett and OctaPre in my setup.

Thanks for the info. Cheers!

Pictures from recording a steady sine wave coming from the 18i20, or I don't believe it works. At least 15 minutes worth of perfect playback of a sine/triangle/sawtooth wave, recorded on an external recorder. I've been testing the 18i20 3rd gen also with Linux Mint 20.2, and getting constant microscopically tiny crackles like vinyl records. The crackling is so small, it isn't noticeable when playing music, only with a steady oscillator wave. But with the MPC, there are 21 ms silent gaps at varying intervals which change depending on the Scarlett's clock source, internal vs. SPDIF. With the MPC there's no vinyl style crackling, just the big 21 ms dropouts, which ARE noticeable even with music playback. With a 2014 Macbook Pro it works with no crackles or dropouts. With a 2011-2012 Macbook Pro and old OSX 10.7, there were tiny crackles as well.

I doubt all reports on this forum, until the playback has been shown to be perfectly clean and glitchless, with a synthetic wave playback test. Mind you, with a certain clock source the 21 ms dropouts come at over 5 minute intervals! Record an hour of the steady wave playing from an MPC, load it to Ableton Live, Warp it and check that Ableton detects 0 transients in the 60 minute recording. I got this with the less old Macbook Pro.

I own a RME Fireface 800. It is firewire only (400/800). I wonder if it's possible to daisy chain between the computer and interface to establish a connection. I really just want expanded I/O via an interface, and connecting directly to an interface is a brilliant idea in that it bypasses any AD/DA conversion you would normally have patching via analogue.

Very little information on the Akai Professional website regarding which interfaces are compatible, and the overall connectivity possibilities with this.