1 Topic by therealmadonna (edited by therealmadonna 2021-03-18 20:27:18)

  • Registered: 2021-03-18
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Topic: USB Stereo Mode Different Implentations

Hi,

I purchased 2 RME devices with the intention of using them to record 2-channel audio on iphone video. ADI 2 PRO and FF UCX I have an analog signal chain and really only need the RME devices for ADC at the end of the chain. Totalmix on the UCX is a bonus.

Before purchasing them I spoke to tech support at RME and I was told that the UCX has a usb stereo mode that will make it compatible with ios apps. From my testing as a user, I see that the implementation of "stereo mode" in FF UCX differs from that of the ADI 2 Pro. Can someone confirm my understanding?

ADI 2 Pro: When you select stereo mode, this requires creating a new connection to the computer. When stereo mode is enabled and a connection is made, the computer/ipad recognizes the adi 2 pro as a 2 channel usb device. It only sees those two channels.

Documentation: In the ADI 2 Pro manual look at pages 37ff (17.4 USB). It outlines stereo vs multichannel mode. In "Class Compliant Stereo mode", it is recognized by a computer as a 2-channel device. In "Class Compliant Multi-channel mode" it is recognized by a computer as an 8-channel device.


FF UCX: When you select stereo mode, there's no need to reconnect usb. It seems like there is some simple routing magic that allows all of the channels to be summed and routed to usb channels 1 & 2. In this case, the ipad recognizes the ff ucx as a multichannel device but audio is only going to 2 channels. When I open Garage Band, for example, I see that all the channels are available to be selected, although the signal is only being routed to 1 and 2. This is a clever implementation to allow a user to record all the channels in a single stereo track. However, there are cases where ios apps refuse to record audio if a multichannel audio input is detected. The camera app and many other video recordings apps reject the FF UCX unfortunately.

The Fireface UCX also has a "Stereo mode" that is not in the documentation. To access it, open the ios totalmix app, go to Settings > RME Interface settings > Output Channel count req. It will show two options: "Stereo", "Multichannel".

My simple question is: is there a way for the FF UCX be "be seen" by my iphone as a 2-channel device rather than a multichannel device with all audio routed to 1 and 2? If not, are there any plans to make this available or is it impossible given the constraints of the hardware design?

2 Reply by ramses (edited by ramses 2021-03-18 19:33:13)

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Re: USB Stereo Mode Different Implentations

As you say "analog signal chain" .. both devices, ADI-2 Pro and UCX make an A/D conversion.
I want to say by this, your analog signals will always be converted to digital.

Otherwise sorry, I have problems to understand your signal chain a drawing might help what you intend to build.

If you have a computer then I would 1st of all connect the UCX via USB to that computer, so that you have all the benefits of TM FX routing as a basement.

At this point you could connect your camera or video device surely also analog to the UCX .. it has several analog ports ....

If you WANT to get an ADI-2 Pro additional, then you would integrate it into the setup like I described in my blog article here:
https://www.tonstudio-forum.de/blog/ind … our-Setup/

In this szenario it is not required to connect the ADI-2 Pro through USB .. it simply runs in stand-alone mode.

And then you can connect the external devices to the analog ports of either ADI-2 Pro or UCX as you want ..

The advantage of having the ADI-2 Pro additionally is that you have all of its very nice unique features and a perfect phones preamp and preamp for your monitors, switchable at that unit and with a very nice slow ramp-up of volume (and all the other cool stuff like auto reflevel, dynamic loudness, PEQ, etc ...).

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13

3 Reply by therealmadonna (edited by therealmadonna 2021-03-18 19:50:47)

  • Registered: 2021-03-18
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Re: USB Stereo Mode Different Implentations

Thanks for the reply.

By analog chain I mean that I have mic -> tube preamp -> tube eq -> tube compressor -> adc -> iphone device.

I am not looking to use both RME devices in combination, I purchased both to see if they could solve my use case. I see your article and I considered doing something like that, but I am trying to find a one-device solution. If the FF UCX stereo mode operated similarly to the ADI PRO 2's stereo mode, then my problem would be solved.

I appreciate the setup recommendation as well, but I am only interested in additional setup recommendations if the answer to my question is that the FF UCX doesn't support a stereo operation like the ADI 2 Pro's. I understand that I could probably solve my problem by using the ADI 2 Pro's AES EBU for DSP mixing and effects. I could just plug my line level signal into the ADI 2 pro and send/return to the FF UCX for the totalmix capabilities.

Further clarification:
- by computer I meant a generic term for consumer computing device: laptop, iphone, ipad.
- my camera is my iphone. It does not have analog ports. I am using the RME device as adc to send my audio data as 2 channels to the device.


To keep it simple, I am just looking for clarification on whether or not it is possible for the UCX to be recognized as a 2 channel device rather than a multichannel device with all outputs routed to channels 1 / 2.

4 Reply by therealmadonna (edited by therealmadonna 2021-03-18 20:15:19)

  • Registered: 2021-03-18
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Re: USB Stereo Mode Different Implentations

waedi wrote:

No thats complete wrong understanding.
Your stereo signal is routed to channel 1/2 for recording.
Other input signals have their own channel for recording.
Every input signal will be recorded seperate.
The interface is not mixing all together.

What do you mean by "my stereo signal"? If I have 36 channels of input, which is the "stereo signal"? In my testing, I was able to route my signal from input 3 to usb channel 1 in Garage band. This seems to confirm my understanding that "stereo mode" in the UCX reroutes the output to channels 1 & 2. But I am not 100% which is why I was asking for clarification from an informed user or RME employee. Not sure if you fall into either of those categories.

waedi wrote:

This is absolutely unwanted.
If a 36 channel audio interface appears as two channel unit people would send it back for repair.

RME must be flooded with ADI 2 Pro returns from people switching from 8 channel to stereo mode on those devices.

waedi wrote:

You can record that stereo signal in perfect quality no problem at all.

No I can't. It's not compatible with several iOS apps that capture audio and video simultaneously.

waedi wrote:

The market has not a gap in devices that provides a stereo audio signal thru USB.

I also received a Sonosax M2D2. It was actually designed for what I'm trying to do. High quality ADC routed to 2 usb channels. It has some other limitations but its design is evidence that some manufacturers are trying trying to address a need that is not filled by other products in the market.

Why do you need to respond to my questions so belligerently?

  • Registered: 2021-03-18
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Re: USB Stereo Mode Different Implentations

I want thank the moderators for removing the abusive posts by another forum member.

6 Reply by waedi (edited by waedi 2021-03-18 23:19:04)

  • waedi
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Re: USB Stereo Mode Different Implentations

Please take my apologize, I was too harsh.
It was difficult for me to understand your problem.
But still, to keep it simple, no, there is no option to make the UCX a two channel device afaik.
Depending on the DAW you can select the desired input channels for recording.
And yes, lots of iOS applications have problems for connecting to interfaces.
It seems to be the case that there is not yet established a industry-standard protocol for iOS.
Too much change in iOS in short time and not enough request from the market for iOS as recording devices.
In most cases owner of iOS devices own a computer it is less complicated to record with the computer direct, without iOS involved.
In your case I have an idea now why you use the iOS.
You have those tube-units for the mic, I assume you have a room for singing and the computer is in another room, the office, and therefor it is more comfortable to connect quick the iPhone for a recording session spontaneously.
And with those interfaces it should be possible.
When you have one mic, then the recording should be a monotrack (can be a stereo-track).
Please tell your connections on the units and step by step it will come to the recording.

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue

7 Reply by MC

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Re: USB Stereo Mode Different Implentations

@therealmadona: You seem to have missed that the two options of CC-mode routing in the UCX are PLAYBACK ONLY, a simple routing thing, and not totally different operation modes as in the ADI-2 Pro. And it does not mean the other channels won't work anymore - they still do. It is only there for simplified monitoring:

-----------
C8: The iPhone/iPad playback channels 1/2 are copied to the phones output 7/8 and SPDIF/ADAT 1/2, channels 3 to 8 to ADAT outputs 3 to 8. Application example iTunes: Music playback with this 2-channel app happens only on the playback channels 1/2, therefore the headphone output could not be used. Thanks to the C8 option the iTunes signal is also available digitally via SPDIF/ADAT.

CA: 1:1 routing of all 18 playback channels. Application example djay: independent usage of main output and phones/PFL. Mode C 8 would always provide both signals at the phones output. CA is a typical DAW mode.
---------------

The Camera app has a different problem of being incompatible, it's not about multichannel or stereo RECORD. AFAIR it can take only mono as input source.

Regards
Matthias Carstens
RME

MC's Website

8 Reply by therealmadonna (edited by therealmadonna 2021-03-19 06:48:50)

  • Registered: 2021-03-18
  • Posts: 9

Re: USB Stereo Mode Different Implentations

Thanks Matthias for the clarification. I purchased the FF UCX under the recommendation from RME's tech support's suggestion that the "stereo mode" in the ios app would serve the purpose I was describing in a similar way to the ADI PRO 2's "stereo mode".

FWIW, The camera app has no problem recording stereo audio using the following sources that I've tried:

Steinberg UR22c
Focusrite Clarrett 2pre
RME ADI Pro 2
Sonosax M2D2

Those all have in common that they only route 2 channels of audio through usb. All other interfaces and adc that I have tried (which have in common that they route >2 channels) have failed. I'm not claiming that this is an exhaustive test, but it's not the case that the camera app sums audio to mono, either.