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Thread 18i20 3rd gen randomly switching input assignments

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  • 3 participants
1 18i20 3rd gen randomly switching input assignments
Has anyone had this problem: we have a condenser mic on the guitar amp going into Input 1 and a condenser mic on the bass amp going into Input 2. We start the recording and at some random time the input assigned to the bass switches to the input assigned to the guitar. And I literally mean the XLR input on the unit switches. We can see the levels on both the front of the 18i20 and in the focusrite controller change to the new instrument. In other words, the XLR cable that is going into the first input is now being seen as the second input on the Scarlett, and the XLR running from the bass is now being seen as the first input on the Scarlett.

Okay, so we move the XLR inputs to 3 and 4. Same thing! Or I’ve got guitar going into the first input, bass going into the second input, piano going into the third input and voice going into the fourth. Then one and two switch and three and four switch. In Logic Pro X the tracks switch as well because I think they are getting the signal from input one, which was guitar and then is the bass, and so on.

We are using Logic Pro X on a Macbook Pro running 10.15.2 Catalina MacOS. I have tried deleting and reinstalling Logic Pro X and deleting and reinstalling the Focusrite controls, as well as restoring factory defaults in the focusrite controller. With restoring the factory defaults the input assignments go back to where they should be, but the switch happens randomly again. This happens on nine of ten recordings.

Is there any way to make the input assignments stable?
Hi there, sorry to not have any answers but I am glad to find someone else experiencing the same symptoms.

I have an 18i20 2nd Gen which has been randomly swapping inputs for some months now -- I assumed it was a particularly strange problem with my ADAT expansion since I'm using deprecated hardware over ADAT which happens to also need Firewire (Profire 2626 as a slave unit), but I recently acquired an OctoPre as a replacement for the 2626 and I'm still having the same problem.

I hadn't considered this until I read your post, but I think it may be a flaw in the firmware since the release of the 3rd Gen units. I didn't have this problem until I updated my firmware after the 3rd Gen had released.

For the sake of this being documented and hopefully solved, a full rundown of the symptoms: All pairs of analogue inputs will swap, meaning 1 will swap with 2, 3 with 4, 5 with 6, and 7 with 8. All other inputs seem to be immune. This will happen without prediction -- even in the middle of recording.
Hi, I'm so glad to read your reply. I was able to get an answer from Focusrite eventually. They do admit that it is a problem with their firmware for the 3rd generation, and they claim to be working on it. That was February 14th. I did notice that if I lowered the sample rate I was recording at down to 88 or lower it was more stable. If you write to focusrite at technical.support@focusrite.com, you can get after them to fix their firmware too.

Please keep in touch. I'll post any thing I find out here as well.

Kind regards, John

Also glad to not be having the same problem. My gen 2 18i20 is doing the same thing. Anything above 96000 sample rate causes input groups to reverse i.e. 1 and 2, 3 and 4 and so on. I sent in a support ticket 2 weeks ago along with a video and no response. Kinda driving me bonkers because I can't get the latency I want when tracking guitar and bass through an amp sim while my 9 year old presonus box works just fine. Kinda annoying to have to switch interfaces between tracking guitar and drums.

I'm on Ableton live 10, AMD ryzen based windows 10 system

[ Post last edited on 05/13/2020 at 20:59:04 ]

Hey Toucher, glad to see more people talking about this.

I did end up getting in touch with Focusrite support eventually, but it took so long for them to get back to me that I'd already resolved the issue at a level of my liking.

With input from @jrosebalt, I went ahead and decided to lower my sample rate. Combining the fact that I tracks 7 mics on a drumkit and he said it was "more stable" at 88kHz, I went all the way down to 48kHz -- the 48kHz solution lets me assign all my drum mic inputs to ADAT and ensures they will always be properly organized. I have had no problems since trying this.

I would like to recommend this temporary solution to you not just as someone who also records both drums and guitars, but as someone who is also now being formally educated in audio production. I was largely using 96kHz because I thought it would provide me with a distinct advantage over 44.1-88kHz; faster sample rate means faster transfer speed and higher resolution, right? Now I realize I was a little misguided with how a higher sample rate affected latency and resolution -- I'll get into that later. Scientifically there is an advantage (largely in that it maintains the shape of your transients), I have found that the "downgrade" to 48kHz has not negatively affected my recordings at all. I now can record my full kit on one slaved 8-preamp interface, and I have plenty of inputs on the master interface that I dedicate to a guitar mic, a bass mic, a vocal mic etc. with room for expansion.

Since your main issue seems to be latency, I'd recommend looking more at the Hardware Buffer size. AMD Ryzen is a wide range of CPUs, but as long as yours is a higher end model and you have enough RAM to handle the job, the lowest size HW buffer actually has a much larger impact on your latency.

Granted, you may already know this, and have made the 96+kHz decision being well informed. But in the event that you similarly are recording at a higher sample rate due to misguided reasons I feel the need to close with this to be as helpful as I can: unless you really really really really really know you need 96kHz or higher, I recommend just using 48kHz. I assumed I needed it, and I was wrong. As a multi-instrumentalist, the change to 48kHz has improved my workflow so much, since I don't need to have so much hardware to preamp every input.