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katerlouis

How does sending digital audio from Helix to USB-interface work?

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Please forgive the probably trivial questions, but I am a sound rookie.

 

Quick background:

I love my iPad Pro 11'' and use Helix as an audio interface over USB-C into the iPad and loop with the app "Quantiloop" (hiiiighly recommended, reaaally) – I control record/play/stop etc. with MIDI from the Helix (command center, sending notes from footstomps, nice!) – Using the Helix as an interface has it's quirks, which I won't go into now, because now that I want to add a microphone and the pocket synthesizer op-1 to the mix, I probably have to go through an audio interface anyways.

 

But, as far as I understand: When I use Helix line out to the interface, my audio is converted to an analog signal, and then converted back again to a digital signal from the interface to the iPad. That feels like I should avoid that, if possible. Plus: I'd lose the different outputs (usb1+2, 3+4 ... etc.)

 

Researching on how to to chain interfaces I stumbled upon many things, like ADAT, S/PDIF, AES/EBU etc. pp. 

 

Apparently the Helix can send it's audio digitally. Great! There was some discussion if this was only for L6-Link devices; but according to @phil_m the L6 Link connector also works with AES/EBU. 

 

Now. I am considering this particular interface from Focusrite, the Clarett 2Pre USB: https://focusrite.com/usb-c-audio-interface/clarett-usb/clarett-2pre-usb

It claims to have 10 inputs, alhtough there are only 2 physical inputs. So the rest comes in through ADAT. 

 

So, to the questions:

  1. How would you connect the Helix via ADAT (oh boy, how I probably misused that abbreviation :D) to the Clarett? What cable Would you use etc.?
  2. What exactly gets send over there? Only the main output? Or all 4 usb stereo outputs? Or something else entirely?
  3. Could the Clarett level the incoming audio somehow or does the leveling have to happening inside the Helix? Does the `Main` Output volume knob affect it?
  4. How would the signal be available in DAWs and other software? The usual `USB 1+2` etc.?

 

Bonus Question:

5. What I also like about this interface is that it can be powered via USB-C (if my iPad gives enough juice for that is another question, let's just assume it does) – does powering through USB still work when using the digital inputs?

 

 

Really appreciate if you could go in detail on the capabilities and even more importantly: the quirks and caveats that await me.

 

 

Thanks!

 

Louis

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21 minutes ago, katerlouis said:

1. How would you connect the Helix via ADAT (oh boy, how I probably misused that abbreviation :D) to the Clarett? What cable Would you use etc.?

Clarett probably has Toslink input switchable between SPDIF and ADAT protocols. There are some SPDIF RCA to SPDIF optical converters on the market. In case of LT you would need AES/EBU to SPDIF optical. 

 

25 minutes ago, katerlouis said:

2. What exactly gets send over there? Only the main output? Or all 4 usb stereo outputs? Or something else entirely?

Multi Output or whatever is assigned to Digital Out. AES/EBU and SPDIF are two channell only protocols.
 

 

26 minutes ago, katerlouis said:

3. Could the Clarett level the incoming audio somehow or does the leveling have to happening inside the Helix? Does the `Main` Output volume knob affect it?

I don't think Clarett could level the incoming digital signal. You can set Hx digital output level either in output block volume or global settings. As far as I remember Hx Volume knob affects what you set in Global Settings, likely only analog outputs. (2.71 firmware state).
 

 

39 minutes ago, katerlouis said:

How would the signal be available in DAWs and other software? The usual `USB 1+2` etc.?

Yes. usual input representation. ;)

 

40 minutes ago, katerlouis said:

5. What I also like about this interface is that it can be powered via USB-C (if my iPad gives enough juice for that is another question, let's just assume it does) – does powering through USB still work when using the digital inputs?

Should work but I would check the manual or Focusrite forums.

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3 hours ago, katerlouis said:

Using the Helix as an interface has it's quirks, which I won't go into now, because now that I want to add a microphone and the pocket synthesizer op-1 to the mix, I probably have to go through an audio interface anyways.

 

Hi,

O.K. you have a Helix and you want to add a mic and a synth - what’s the problem? Helix certainly has enough ins and out to cope. My Helix replaced my Focusrite Saffire as an interface three and a half years back - FireWire was no longer any good to me.

 

3 hours ago, katerlouis said:

But, as far as I understand: When I use Helix line out to the interface, my audio is converted to an analog signal, and then converted back again to a digital signal from the interface to the iPad. That feels like I should avoid that, if possible. Plus: I'd lose the different outputs (usb1+2, 3+4 ... etc.)

 

Your audio is only converted to analog when it leaves the digital domain. As long as it travels back and forth via the Helix USB it remains digital plus you have all 8 channels of audio and full MIDI communication. You would have a pointless AD/DA conversion going on if you use the inputs on the Clarett 2, although it does have an Optical connection on the rear panel. 

 

3 hours ago, katerlouis said:

It claims to have 10 inputs, alhtough there are only 2 physical inputs. So the rest comes in through ADAT.

 

This is quote from Clarett the user manual:

 

OPTICAL INPUT – a TOSLINK connector carrying eight channels of digital audio in ADAT format at 44.1/48 kHz sample rate or four channels at 88.2/96 kHz. These are simply additional inputs to the Clarett 2Pre USB. This input is disabled at 176.4/192 kHz operation. This input is also capable of accepting an optical S/PDIF source.

 

I would add that if you haven’t done so already - download and read the manual:

 

https://customer.focusrite.com/sites/customer/files/focusrite/downloads/32407/clarett-2preusb-user-guidev1.2.pdf

 

3 hours ago, katerlouis said:
  • What exactly gets send over there? Only the main output? Or all 4 usb stereo outputs? Or something else entirely?
  • Could the Clarett level the incoming audio somehow or does the leveling have to happening inside the Helix? Does the `Main` Output volume knob affect it?
  • How would the signal be available in DAWs and other software? The usual `USB 1+2` etc.

 

I’m going to lump all this into one! The quote is from the manual once again.

 

Focusrite Control is the software application used with the Clarett 2Pre USB. It allows you to create a custom monitor mix for each musician, and also to specify the routing of all audio signals to the physical audio outputs. All sample rate selection, digital syncing and buffer size settings (Windows only) are available from Focusrite Control. 

 

 

3 hours ago, katerlouis said:

Bonus Question:

5. What I also like about this interface is that it can be powered via USB-C (if my iPad gives enough juice for that is another question, let's just assume it does) – does powering through USB still work when using the digital inputs?

 

 

Not according to the manual:

 

The Clarett 2Pre USB must be powered using the supplied AC adaptor (PSU). Connect the PSU to the rear panel socket and turn the unit on with the power switch.

 

It’s just my opinion, but I really cannot comprehend why you want to go down this complex route when all you need to do add a mic and a pocket synth is plug them into your Helix.

 

Good luck spending your money for the wrong reasons - now that’s what I would call quirky!

 

 

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1 hour ago, datacommando said:

It’s just my opinion, but I really cannot comprehend why you want to go down this complex route when all you need to do add a mic and a pocket synth is plug them into your Helix.

 

There are two main reasons to do this:

  1. My Helix moves around a lot but my monitors stay connected to the audio interface 24/7.  I don't want to have to take my Helix out of the bag just so I can have sound from my computer.
  2. A lot of my presets use all four paths.  No room left for mic paths or anything else.

Using the Helix as a mixer/audio interface is a compromise.  It is convenient and useful but if I want to mix things together I would rather have the flexibility of a mixer/audio interface.

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1 hour ago, jonandtice said:

 

There are two main reasons to do this:

  1. My Helix moves around a lot but my monitors stay connected to the audio interface 24/7.  I don't want to have to take my Helix out of the bag just so I can have sound from my computer.
  2. A lot of my presets use all four paths.  No room left for mic paths or anything else.

Using the Helix as a mixer/audio interface is a compromise.  It is convenient and useful but if I want to mix things together I would rather have the flexibility of a mixer/audio interface.

 

Damn!
 

Now I see.
 

That threw me - for a moment there I thought that your comments were a reply from the OP.

 

Well in your situation that's the way to go, considering your monitors are tethered to another audio interface and you have used all available paths - fine. I have no issue with that and there's no need to patch in your Helix simply to listen to your computer beeps. Although I don't think that is exactly what's being discussed here. The thing is, that when you read the comments made by the OP,  they appear to be somewhat confused by the whole thing of what signals take what paths and wether there would be enough "juice" in an iPad to power the USB. Er.. No! 

 

The addition of an essentially 2 channel USB interface with a few more via ADAT is a pointless expense and may become even more mind boggling for the poster.

 

But - hey if someone wants to do that - well that's entirely their choice - not my concern.

 

I feel certain that I did state, "It’s just my opinion" - oh, yes, I just re-read it and I did.

 

 

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6 hours ago, datacommando said:

O.K. you have a Helix and you want to add a mic and a synth - what’s the problem? Helix certainly has enough ins and out to cope. My Helix replaced my Focusrite Saffire as an interface three and a half years back - FireWire was no longer any good to me.

Two reasons: Reason 1: I fiddle around with a lot of patches (haven't found my tone yet), preparing each patch for mic and op-1 is bothersome and 2. sometimes not possible, because I've used up all 4 paths.

 

If I'm missing something here and theres a nice and convenient way to just plug it in and it works, please enlighten me :).

Maybe there is a way to globally route AUX into master out without going through the whole patch, because I obviously don't want the OP-1 to get distorted, delay, reverb etc.

 

Oh, theres a 3rd reason! When the Helix goes into the iPad via USB and Headphones in Helix' headphone out, I hear the guitar sound from the Helix AND the monitoring / incoming sound from the Quantiloop app. When I now disable the monitoring it is a real pain to get Quantiloops output volume to match the Helix volume. When the Helix is connected to the iPad, the volume rockers don't do anything (just like on macOS, so it's a Helix thing, I guess?) - the only way is to level audio from iPad seems to be Helix' global settings, which is no fun because the discrepancy between Helix "internal" volume and the iPad volume seems to depend on the situation (using spotify, youtube, remix hd live, garageband, anytune etc.) :'(

 

Quote

Your audio is only converted to analog when it leaves the digital domain. As long as it travels back and forth via the Helix USB it remains digital plus you have all 8 channels of audio and full MIDI communication. You would have a pointless AD/DA conversion going on if you use the inputs on the Clarett 2, although it does have an Optical connection on the rear panel. 

Sorry if I wasn't clear; that's exactly what I meant. Going over USB keeps the signal digital, but when I want to use an audio interface for said reasons AND can't get the optical / SPDIF / AES/EBU / ADAT / xyzerioerjiklas way to work, then I'd have unnecessary D/A-A/D conversion, which I'd like to avoid. That's why I am asking 

 

 

 

9 hours ago, zolko60 said:

Clarett probably has Toslink input switchable between SPDIF and ADAT protocols. There are some SPDIF RCA to SPDIF optical converters on the market. In case of LT you would need AES/EBU to SPDIF optical. 

 

Unfortunately I understand only roughly 20% of what you're saying there :D - When SPDIF and AES/EBU can only cover 2 signals, how does Focusrite get the remaining 6 inputs into the interface? (It says 10ins and 4outs)

 

Do you mean a converter like this?

 Bildergebnis für xlr to optical

 

Well that would certainly be annoying and overkill :D

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My late mother told me that there would be days like this, so that’s it guys- this is getting into borderline insanity.

 

It’s all my own fault really.

 

Anyone wanting to run a Teenage Engineering OP-1 Mini through a Helix and into an iPad, with a mic and a Live Looper app should have been a big clue! 

 

What’s worse is the title of the thread should have made me run away screaming.

 

If some one asked you what not to feed a lactose intolerant cat, and you advised them what to avoid, don’t be surprised at the results when they go on to feed it milk!

 

I’m  outa here.

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11 hours ago, katerlouis said:

If I'm missing something here and theres a nice and convenient way to just plug it in and it works, please enlighten me :)

 

I decided to go the extra mile on this one, so here ya go, check these guys out - they may be able to help you.

 

The Line6 MIDI MAD SCIENTIST CLUB

 

https://www.facebook.com/groups/1149598418555545/

 

“This is for those of us who are looking into the HELIX as a hub for so much more. We start from the concept of the LINE6 dream rig and push forward for the most portable, dynamic, collapsible and modular solutions possible. This group is meant as a collaborative area where we can post and share solutions to both common and obscure connectivity issues. Everything from iOS apps to midi controllers, to lighting rigs, you name it, if you’re integrating new functionality into your rig, we want to hear all about the how and why.”

 

Edited by datacommando
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13 hours ago, katerlouis said:

When SPDIF and AES/EBU can only cover 2 signals, how does Focusrite get the remaining 6 inputs into the interface? (It says 10ins and 4outs)

10 inputs in case the optical input is used as ADAT lightpipe protocol (@44,1 and 48kHz). 4 inputs if used as SPDIF. 2 inputs if not used.

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3 hours ago, zolko60 said:

10 inputs in case the optical input is used as ADAT lightpipe protocol (@44,1 and 48kHz). 4 inputs if used as SPDIF. 2 inputs if not used.

 

That's really excellent!

 

Judging by the previous replies, now our friend is only going to be able to understand 2% of that.

 

Also, I have previously quoted great chunks of the Clarett Manual which explains this and it has either not be read by the OP or totally ignored.

 

What else can anyone do?

 

I despair!

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7 minutes ago, datacommando said:

What else can anyone do?


Look for some AES/EBU 96kHz to ADAT SMUX converter maybe? :D 

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33 minutes ago, cruisinon2 said:

Dogs barking can't fly without umbrella!

 

Whoopi, Jack!

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31 minutes ago, zolko60 said:


Look for some AES/EBU 96kHz to ADAT SMUX converter maybe? :D 

 

Overkill

 

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