Trouble Recording DI via S/PDIF with Focusrite Scarlett 8i6 and Pro Tools on PC

[bvaughn84]

Hey Everyone,

I've looked everywhere and I can't find an answer to my problem. I'm not sure if I'm doing something wrong or if recording Wet+DI tracks simultaneously is just impossible with my interface in Pro Tools using a PC. I have the AXE 3, a scarlett 8i6 3rd Gen and Pro Tools (newest version). I have 2 S/PDIF cables connecting the axe and the scarlett so each is going to and from each other and I plug my guitar into the front of the axe and plug headphones into the scarlett. It's a very simple setup. I can record the wet signal over S/PDIF fine and it sounds great but for the life of me I can't figure out how to get a dry signal in there also.

1. What settings I need for Focusrite Control?
2. What settings do I need in Pro Tools to route things the correct way?
3. What settings do I need in the AXE itself?

If someone could help me out with some very specific instructions I'd be very grateful and I think it would be a great piece of information for the forum.

Thanks!

P.S.
Regarding the USB method, it was giving me lag after a certain number of tracks were being used in a song so I opted to start using a dedicated interface.

 

[Riccardo Ros]

https://forum.fractalaudio.com/threads/axe-fx-for-the-recording-musician.177592/
(layout 5 should cover your need... you connect the guitar to the audio interface and use spdif to edit the DI sound)

Another way: you should send an OUT for the wet sound (as you're doing now) and another OUT for the dry sound... through the SDPIF only one of them can pass.. you can use an analog cable for the wet sound and SPDIF for the dry one (to avoid conversion) but if your soundcard has 'good' inputs the method written by @GlennO is the more efficient

 

[bvaughn84]

Unfortunately, I already tried layout 5. I can only get the dry signal when plugging a guitar into the interface or conversely just the axe fx wet signal when plugging into the axe. In layout 5 instructions, it says to use your interface's software to route the guitar to both the computer via USB and to the AXE via S/PDIF and I don't see a clear way to do that in the interface's software or in protools I/O settings. Also, I would like to avoid going through a pre amp because it colors the sound. My goal is to get the axe's unfiltered sound over S/PDIF if possible.

I included some pictures of my settings on the axe, the scarlett 8i6, my protools inputs, outputs and buses, and lastly some info about scarlett's Input and Direct routing capabilities. It seems like I might need the rack version to do what I'm trying to do because there's an exclusive feature in the rack version that is for S/PIDF in and out... Can anyone confirm this?

 

[Riccardo Ros]

I think you're overthinking (no pun intended).
Over SPDIF you can have only 1 output.

So if you want to input the guitar on the Axe and use the Scarlett as audio interface you need to have 'physically' 2 outputs from the Axe to the interface:

• OUT1 for wet (spdif or analog)
• OUT2 for dry (spdif or analog)

Then in your DAW you'll have 2 separated tracks (this is Reaper but it's almost the same)

 

[GlennO]

Regarding the USB method, it was giving me lag after a certain number of tracks were being used in a song so I opted to start using a dedicated interface.

First, I would use USB before resorting to using spdif. USB will be much simpler for what you're trying to do. This lag problem you're describing is not normal behavior, can you provide any details?

Second, if you're determined to use spdif to record wet and DI, see the instructions for configuration #5 in the recording guide. When using configuration #5 to record both wet and DI, there is no special setup to be done on the 8i6 to record the DI. Simply arm and record a track in PT for the 8i6 input that you're plugged into. In Focusrite Control, to route the audio to your Axe-FX, set the spdif output source to the analog input you're plugged into. That configuration definitely works, so if you’re having trouble getting signal to the AxeFX, I’d suspect the problem is something simple, like a bad cable.

 

[bvaughn84]

First, I would use USB before resorting to using spdif. USB will be much simpler for what you're trying to do. This lag problem you're describing is not normal behavior, can you provide any details?

Second, if you're determined to use spdif to record wet and DI, see the instructions for configuration #5 in the recording guide. When using configuration #5 to record both wet and DI, there is no special setup to be done on the 8i6 to record the DI. Simply arm and record a track in PT for the 8i6 input that you're plugged into. In Focusrite Control, to route the audio to your Axe-FX, set the spdif output source to the analog input you're plugged into. That configuration definitely works, so if you’re having trouble getting signal to the AxeFX, I’d suspect the problem is something simple, like a bad cable.

You yourself posted a whole thing about this being a problem last February. I understand the buffer size issue was fixed but as of last summer I was experiencing this issue in a project.

This is your post below:

[ Update on June 3, 2022: As of AxeFX III DSP firmware version 20, you can now reliably change the USB buffer size in the I/O -> Audio page on the Axe-FX. Setting this value to 16 will give most people good audio alignment when recording. There are some new latency problems when using DSP firmware version 20 that hopefully will be fixed soon, but simply setting that parameter to 16 is a good fix for the recording alignment problem in many cases.



If you've tried to use your Axe-FX (or FM3/9) as an audio interface for recording, you've probably noticed there is an issue that causes recorded audio to play back late. You might record your guitar perfectly in time, but when you play it back, your guitar will lag behind other tracks in your song.

I believe I've found the source of the problem, but first here's a description of this issue:


The Problem
-----------

There is an inevitable latency that comes with computer audio. This latency will be present when you record your guitar into your DAW. However, all DAWs are smart enough to deal with this and apply a latency compensation so your guitar audio is aligned properly with tracks you are listening to, for example drums, while recording. Unfortunately, the amount of compensation that is applied when recording an Axe-FX is incorrect. The result is your recorded guitar audio will be delayed in relation to other tracks in your project. This lag is substantial, often in the 10-20 millisecond range (far greater than the internal processing latency). That is enough of a lag to make any recording sound sloppy. This problem does not occur with other audio interfaces, only the Axe-FX.


The Cause
---------

I believe I've found the cause of the problem. The Axe-FX has an internal usb buffer (actually 4) with a selectable size. The size of this buffer affects the latency. However, the latency reported to the DAW does not match the size of this buffer. This will introduce an error in the compensation applied by the DAW, resulting in misaligned tracks. In my experiments, it is only correct if the buffer size is set to 16. (Strictly speaking, the latency reporting is probably delegated to the driver, but that doesn't matter. As long as it doesn't match the actual latency, there will be a problem.)

This means there's a straightforward solution. The buffer size just needs to be set, preferably automatically, to a value that matches the reported latency, the DAW will compensate correctly, and your recorded tracks will be aligned properly.


The Workaround
--------------

I sent details about this last week to Fractal Audio. Unfortunately, there is nobody available to work on this at the moment, so there won't be a fix soon.

What can you do in the meantime? The details above suggest that if you could adjust the buffer size to match the reported latency, that would fix the problem. Alas, it's not so simple. The problem is there's a bug with the usb buffer size parameter that makes it exceedingly difficult to set it to 16 (or whatever value will match the reported latency).

Whenever you reboot your Axe-FX, the buffer size will reset to 128. Do not believe the size that is displayed on the I/O Audio page. It will show the value you most recently set, but it will actually be 128.

Ok, that's simple. All you need to do is set that to 16 whenever you reboot your Axe-FX, right? Well, unfortunately there's another problem that makes it difficult to set the size to 16. If you set the size within 5 minutes of a reboot, it will not adjust correctly and the latency will be off by as much as 100 samples.

Ok, that's simple. All you need to do is wait 5 minutes after a reboot before adjusting the buffer size, right? Well, unfortunately, it's not just a reboot that will require you readjust the size. You'll also need to do this after doing a number of other things, including unplugging/plugging your usb cable or quitting your DAW app, or importing a preset.

If that sounds like a hassle, you're right. Fortunately, there is another workaround. You can use manual compensation in your DAW.



A final note on expectations. If you make this change to the buffer size, a recorded DI track will be aligned very nicely. For wet tracks, this will eliminate most of the error, taking it down from over 11 ms, where it's a significant problem, to about 2 ms, where it is virtually imperceptible. In other words, it's an effective fix for most people. If you want a wet track to align more precisely however, you'll need to do a manual compensation in your DAW for that remaining 2ms.

Note: AlbertA reported some of these same findings 4 years ago.

 

[GlennO]

This is all explained at the top of the recording guide. The latency reporting problem was fixed since last summer. Just update your usb firmware (that's different from the usb driver) and the latency reporting will work fine. The post I wrote that you quoted has been locked, so I can't update it with the latest information on this subject. Note however, that information is still relevant for FM3 users since the problem has not been fixed on the FM3.

 

[bvaughn84]

I think you're overthinking (no pun intended).
Over SPDIF you can have only 1 output.

So if you want to input the guitar on the Axe and use the Scarlett as audio interface you need to have 'physically' 2 outputs from the Axe to the interface:

• OUT1 for wet (spdif or analog)
• OUT2 for dry (spdif or analog)

View attachment 117297


Then in your DAW you'll have 2 separated tracks (this is Reaper but it's almost the same)

View attachment 117298

I tried this and I wasn't getting any signal for the DI. I was using Output 3 though because I was using just a TS cable from out 3 of the axe to input 1 of the scarlett. So are you suggesting I use a balanced xlr from output 2 to Input 1 of the Scarlett? Would I then use Line instead of analog on the scarlett? And how would I route that in protools?

 

[bvaughn84]

This is all explained at the top of the recording guide. The latency reporting problem was fixed since last summer. Just update your usb firmware (that's different from the usb driver) and the latency reporting will work fine. The post I wrote that you quoted has been locked, so I can't update it with the latest information on this subject. Note however, that information is still relevant for FM3 users since the problem has not been fixed on the FM3.

Good to know. I'll give it a shot. Obviously, USB is much easier. But in that case, when I'm using the AXE as an audio interface could I run into problems if I have a bunch of virtual instruments and plugins running? Do you happen to know when using the axe as an interface if it uses the computer's processor and ram to process audio in real time or does it use its own processing power? Also, I don't have the option of setting the axe to 16. I can do 32, will that work ok?

 

[GlennO]

Good to know. I'll give it a shot. Obviously, USB is much easier. But in that case, when I'm using the AXE as an audio interface could I run into problems if I have a bunch of virtual instruments and plugins running? Do you happen to know when using the axe as an interface if it uses the computer's processor and ram to process audio in real time or does it use its own processing power? Also, I don't have the option of setting the axe to 16. I can do 32, will that work ok?

An Axe-FX is a perfectly capable audio interface, it uses its own cpu, and it won't have any effect on the number of plugins you can use. The best buffer size for you depends on your cpu and what plugins you're using, but a size of 32 is usually plenty low. You may even prefer a higher size.

 

[bertwarbutton]

I have a Focusrite 8i6 and FM9.. Use spdif to the Focusrite to process the wet signal via output 2. Digital settings changed in GLOBAL I/O for spdif clock and output etc. Added an output 3 block linked directly after input 1 block. Output 3 block is analog output to the input on the Focusrite. Thus Output 3 sends the dry signal (with gate) to Focusrite.. Both are recorded in Reaper.

Also have used FM9 USB to Reaper directly, bypassing the Focusrite and this works fine as well.

 

[mr_fender]

SPDIF only carries two channels of audio, so the only way to get both wet and dry at the same time over SPDIF is if you split the stereo channels and use one for wet and the other for dry (dual mono). USB is much easier like GlennO said and you have 8x8 channels instead of just 2.

 

[bvaughn84]

I have a Focusrite 8i6 and FM9.. Use spdif to the Focusrite to process the wet signal via output 2. Digital settings changed in GLOBAL I/O for spdif clock and output etc. Added an output 3 block linked directly after input 1 block. Output 3 block is analog output to the input on the Focusrite. Thus Output 3 sends the dry signal (with gate) to Focusrite.. Both are recorded in Reaper.

Also have used FM9 USB to Reaper directly, bypassing the Focusrite and this works fine as well.

I'm not sure I follow. So specifically:

1. What are my settings in focusrite control
2. what are my physical connections (as in where do I plug the guitar in, and are there any other connections between the axe and the focusrite other than spdif?
3. What are my settings in axe edit both for the patch and for setup>audio?

 

[bertwarbutton]

1. Focusrite Control...

Settings:
Sample Rate: 48kHz
Clock Source: Internal

Inputs:
Analog 1-2 set to Line (48V phantom power is off; although makes no difference)

Output Routing:

Monitors 1-2: I have set to Playback 1-2 (this will take signal from Reaper Main Mix Feed); you can set this to Hardware - SPDIF 1-2 if you want to get the spdif feed from the FM9, directly

SPDIF Outputs 1-2: I have set to Playback 5-6 which could then be used for reamping if need be... Note the DI channel in Reaper would need to be routed to output bus 5-6. Not needed for just recording...

2. FM9...

Global Settings...

Go to Home - Setup - I/O - Audio and set...

World Clock: SPDIF
Digital Input Source: SPDIF if you want to reamp using SPDIF
SPDIF Output Source to the Output Block you use in your Preset. Block 1 or in my case, I added an output block in Parallel to Output Block 1, Output 2, and I have sent this as the SPDIF output block.
Input configuration: Set to Analog on all sources... If you want to reamp you need to set this Digital and the signal will then come from the DI channel in the DAQ (Reaper)...

Physical Connections:

My set up...
1. Guitar in to FM9 Input 1
2. SPDIF Out FM9 to SPDIF IN Focusrite
3. SPDIF IN FM9 to SPDIF OUT Focusrite
4. I use Output 1 (Balanced) in my preset as my main output when playing live and this feed goes to FOH
5. I use Output 2 directed to SPDIF that goes to the Focurite. Note you can adjust the Output level in Block 2 to adjust needed level into Focusrite.
6. When recording a DI signal, I add a third output block in parallel, and linked to the IN Block FM9. So guitar in signal is routed directly to Output 3. I then take 1/4" cables and connect Output 3 L/R FM9 to the two front Inputs on Focurite. I then record these as Stereo in Reaper...

Thus Preset:

1. One input block
2. Three Outputs if recording guitar DI as well... other wise:
Block Out 1 is main FM9 output for FOH
Block Out 2 is SDPIF to Focusrite and wet signal
Block Out 3 is DI dry to Focusrite

I have utilized the wiki and FM9 manual as well as youtube videos for support... search youtube and you will find a number of videos on Fractal and SPDIF and also Reamping options...

 

[GlennO]

I have utilized the wiki and FM9 manual as well as youtube videos for support... search youtube and you will find a number of videos on Fractal and SPDIF and also Reamping options...

Just to let you know about an alternative worth considering, see configuration #5 in the recording guide. That has some advantages over what you're currently doing. For example it avoids those extra D/A/D conversions it doesn't require preset modification.

https://forum.fractalaudio.com/threads/axe-fx-for-the-recording-musician.177592/

 

[bertwarbutton]

Note that I had difficulty getting this approach to work with the Focurite 8i6... so need more testing on my part... my "quick" solution was to do the structure as I posted... it worked ... so more work when I have time...

 

[GlennO]

I know what you mean...I just thought I'd mention an alternative that has some advantages. FYI, I use configuration #5 with an 8i6.

 

[bertwarbutton]

Ok so back in my court to test further...

 

[bertwarbutton]

Ok tested further and all is working following configuration #5. I had to adjust a few channel routing Settings in Reaper and I out 1 FM9 set to digital instead of analog in.

 

[bvaughn84]

1. Focusrite Control...

Settings:
Sample Rate: 48kHz
Clock Source: Internal

Inputs:
Analog 1-2 set to Line (48V phantom power is off; although makes no difference)

Output Routing:

Monitors 1-2: I have set to Playback 1-2 (this will take signal from Reaper Main Mix Feed); you can set this to Hardware - SPDIF 1-2 if you want to get the spdif feed from the FM9, directly

SPDIF Outputs 1-2: I have set to Playback 5-6 which could then be used for reamping if need be... Note the DI channel in Reaper would need to be routed to output bus 5-6. Not needed for just recording...

2. FM9...

Global Settings...

Go to Home - Setup - I/O - Audio and set...

World Clock: SPDIF
Digital Input Source: SPDIF if you want to reamp using SPDIF
SPDIF Output Source to the Output Block you use in your Preset. Block 1 or in my case, I added an output block in Parallel to Output Block 1, Output 2, and I have sent this as the SPDIF output block.
Input configuration: Set to Analog on all sources... If you want to reamp you need to set this Digital and the signal will then come from the DI channel in the DAQ (Reaper)...

Physical Connections:

My set up...
1. Guitar in to FM9 Input 1
2. SPDIF Out FM9 to SPDIF IN Focusrite
3. SPDIF IN FM9 to SPDIF OUT Focusrite
4. I use Output 1 (Balanced) in my preset as my main output when playing live and this feed goes to FOH
5. I use Output 2 directed to SPDIF that goes to the Focurite. Note you can adjust the Output level in Block 2 to adjust needed level into Focusrite.
6. When recording a DI signal, I add a third output block in parallel, and linked to the IN Block FM9. So guitar in signal is routed directly to Output 3. I then take 1/4" cables and connect Output 3 L/R FM9 to the two front Inputs on Focurite. I then record these as Stereo in Reaper...

Thus Preset:

1. One input block
2. Three Outputs if recording guitar DI as well... other wise:
Block Out 1 is main FM9 output for FOH
Block Out 2 is SDPIF to Focusrite and wet signal
Block Out 3 is DI dry to Focusrite

I have utilized the wiki and FM9 manual as well as youtube videos for support... search youtube and you will find a number of videos on Fractal and SPDIF and also Reamping options...

Fantastic job on this explanation. I prefer this method because it provides the smoothest workflow for anyone using Pro Tools on PC because not only can you plug into the front of the AXE and avoid coloring your tone with preamps, you also can also use a separate computer to run axe edit to avoid the USB issue where Axe Edit crashes while using Pro Tools.