Need USB audio interface

[ThatJackElliott]

You'll not be surprised to learn that in the US, over-the-air (terrestrial, radio) broadcast loudness is not regulated. As long as you don't exceed 100% modulation of the transmitter, you are free to make it as aggressively loud-sounding as you wish. So, that's one Stereo Tool doing that processing.

But on the other hand, for the stream, what might sound good in a car when competing against stations with US$5000+ dedicated hardware processors, like Orban Optimods and such, would sound terrible at home listening to the stream. Also, all our live shows are recorded for archiving and rebroadcasting and we don't need them over-processed, either. So that's a second copy of Stereo Tool doing that processing.

-23LUFS per EBU R 128 doesn't fly here -- our "station standard" loudness is -11LUFS.

Anyway, sort of a sidebar discussion there. BACK TO BUSINESS!

I unearthed and dusted off a Scarlett 18i8 that I used to use for producing and streaming live music to the station for broadcasting from local concerts here in town. It only has one stereo output bus, but I'll hook it up and see what ALSA makes of it. A learning exercise.

[j_e_f_f_g]

An 18i8 has only 1 stereo output bus???

As far as I know, the scarlett series right from the start has always been usb audio class compliant. So all of them should work with linux... well at least for being able to set the sample rate, and have at least one stereo out buss that all linux audio software can mix to. Now as far as making use of any additional stereo busses, that would depend upon:

1) You can assign (route) the inputs and outputs via the (hardware) knobs on the scarlett itself.
2) If not #1, the factory default setup provides you with a second stereo buss that is setup as you need.

Otherwise, if you need to run some Windows app to configure the hardware for your needs, that ain't gonna work on linux.

[ThatJackElliott]

Yep, a 2014 18i8 with only one stereo pair (labeled 1 and 2) of 1/4' output jacks. I'm looking at it. The photos online of the current model show four output jacks (2 stereo pair). They must have added the second pair after I bought this one.

[ThatJackElliott]

UPDATE:
This is an older model of the 18i8 with only two line-level output jacks, or one stereo pair. My goal is an audio adapter with four line-level balanced outs.
Even so, this device has four mic and four line-level inputs so I thought to see whether ALSA detects all the Capture inputs, because if it does then a similar device might expose all its Playback devices to ALSA.

But no, only one hw:x,y shows up:

Code: Select all

$ arecord -L | more
null
    Discard all samples (playback) or generate zero samples (capture)
default
    Playback/recording through the PulseAudio sound server
samplerate
    Rate Converter Plugin Using Samplerate Library
speexrate
    Rate Converter Plugin Using Speex Resampler
jack
    JACK Audio Connection Kit
oss
    Open Sound System
pulse
    PulseAudio Sound Server
upmix
    Plugin for channel upmix (4,6,8)
vdownmix
    Plugin for channel downmix (stereo) with a simple spacialization
usbstream:CARD=Generic
    HD-Audio Generic
    USB Stream Output
hw:CARD=Device,DEV=0
    USB Audio Device, USB Audio
    Direct hardware device without any conversions
plughw:CARD=Device,DEV=0
    USB Audio Device, USB Audio
    Hardware device with all software conversions
sysdefault:CARD=Device
    USB Audio Device, USB Audio
    Default Audio Device
front:CARD=Device,DEV=0
    USB Audio Device, USB Audio
    Front output / input
dsnoop:CARD=Device,DEV=0
    USB Audio Device, USB Audio
    Direct sample snooping device
usbstream:CARD=Device
    USB Audio Device
    USB Stream Output
hw:CARD=Generic_1,DEV=0
    HD-Audio Generic, ALC897 Analog
    Direct hardware device without any conversions
hw:CARD=Generic_1,DEV=2
    HD-Audio Generic, ALC897 Alt Analog
    Direct hardware device without any conversions
plughw:CARD=Generic_1,DEV=0
    HD-Audio Generic, ALC897 Analog
    Hardware device with all software conversions
plughw:CARD=Generic_1,DEV=2
    HD-Audio Generic, ALC897 Alt Analog
    Hardware device with all software conversions
sysdefault:CARD=Generic_1
    HD-Audio Generic, ALC897 Analog
    Default Audio Device
front:CARD=Generic_1,DEV=0
    HD-Audio Generic, ALC897 Analog
    Front output / input
dsnoop:CARD=Generic_1,DEV=0
    HD-Audio Generic, ALC897 Analog
    Direct sample snooping device
dsnoop:CARD=Generic_1,DEV=2
    HD-Audio Generic, ALC897 Alt Analog
    Direct sample snooping device
usbstream:CARD=Generic_1
    HD-Audio Generic
    USB Stream Output
hw:CARD=acp,DEV=0
    acp, 
    Direct hardware device without any conversions
plughw:CARD=acp,DEV=0
    acp, 
    Hardware device with all software conversions
sysdefault:CARD=acp
    acp, 
    Default Audio Device
dsnoop:CARD=acp,DEV=0
    acp, 
    Direct sample snooping device
usbstream:CARD=acp
    acp
    USB Stream Output
hw:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    Direct hardware device without any conversions
plughw:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    Hardware device with all software conversions
sysdefault:CARD=CODEC
    USB Audio CODEC, USB Audio
    Default Audio Device
front:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    Front output / input
dsnoop:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    Direct sample snooping device
usbstream:CARD=CODEC
    USB Audio CODEC
    USB Stream Output
hw:CARD=USB,DEV=0
    Scarlett 18i8 USB, USB Audio
    Direct hardware device without any conversions
plughw:CARD=USB,DEV=0
    Scarlett 18i8 USB, USB Audio
    Hardware device with all software conversions
sysdefault:CARD=USB
    Scarlett 18i8 USB, USB Audio
    Default Audio Device
front:CARD=USB,DEV=0
    Scarlett 18i8 USB, USB Audio
    Front output / input
dsnoop:CARD=USB,DEV=0
    Scarlett 18i8 USB, USB Audio
    Direct sample snooping device
usbstream:CARD=USB
    Scarlett 18i8 USB
    USB Stream Output

The other two USB devices -- "CODEC" and "Device" are a couple of cheap-o audio adapters I have connected for testing.

So my take-home is that just because something like an 18i8 has several input and output connectors, that doesn't necessarily mean that ALSA can find them. The manufacturer's bespoke driver/software is needed to configure it. And manufacturers aren't very helpful with any kind of in-depth information nor do they have much interest in the Linux world . . . so that's why I am hoping someone here can recommend a audio interface that has at least one stereo pair of inputs and at least two stereo pair of outputs, which show up in ALSA as one Capture device, and two Playback devices.

[merlyn]

arecord tells you the cards that are available. To see the inputs and outputs use alsamixer from a command line or I think in Ubuntu Studio there is an app qasmixer which is a gui for alsamixer. I'm pretty sure ALSA will see all the inputs and outputs, including S/PDIF.

[j_e_f_f_g]

arecord` tells you the cards that are available.

Not only that, but I think it's listing only the inputs. He should be using aplay (not arecord) to list the outputs.

ThatJackEliott, try this:

Code: Select all

aplay -L

I just find it hard to believe an 18i8 has only 1 stereo output (unless the rest of them are all digital like ADAT).

[Linuxmusician01]

Hey, thanks guys for the info.

"99% of all usb audio interfaces will work with linux.

In my experience 99% of 'm need a special driver (Windows or Mac) and/or software to configure 'm. Depends on who you ask how well Linux is supported nowadays by hardware manufacturers.

Maybe you should do a lil research yourself at the alsa web page for example."

A reasonable suggestion! But it doesn't seem to be very well maintained, and doesn't address some of my questions. Like, balanced analog ins and outs? More than one output DAC, and do the ADCs and DACs share one clock? Perhaps all of these are a given and I'm being too fussy, but I don't want to buy a thing and find it's not gonna work. OTOH, I don't want to be that guy who pesters the forum with questions that have obvious answers. A thin line to walk!

Indeed, the ALSA website ain't the place to go, unfortunately. They made internet forums for these sort of questions and to exchange experiences, if you ask me. So, to me at least, you're not "that guy" who pesters the forum with questions that have obvious answers. I too would like an updated list w/ USB audio interfaces that work without special software in Linux.

Now about those balanced in- and outputs on an audio device... Behringer is not gonna cut it for you I think, but I always thought that Focusrite was a bit more "professional". What audio device do you use now? Does that have balanced in- and outputs? Cheapest solution for now is to try out that Focusrite that you already have. Maybe it'll fit your needs anyhow.

[merlyn]

... Now about those balanced in- and outputs on an audio device... Behringer is not gonna cut it for you I think, but I always thought that Focusrite was a bit more "professional". ...

The Behringer UMC404HD does have balanced inputs and outputs.

XLRs are always balanced. Outputs that use a TRS jack, i.e. three conductors are also balanced.

[j_e_f_f_g]

The Behringer UMC404HD does have balanced inputs and outputs.

Yeah, but he also has to make sure that they're independent stereo busses. I've seen products that simply have dupliicate jacks attrached to a single bus.

He really needs to see if that manual contains a signal flowchart. That's really the only way he can find out for sure what the story is with those jacks (short of testing the device himself)/.

I'm gonna wait to see what aplay says.

[merlyn]

We're maybe getting a bit confused here. Jack has a Focusrite 18i8 gen 1. Yes, it only has one stereo pair as an output called 'monitor out'.

The Behringer 404HD does have more than two outputs. Yes, the main out is available on XLR or TRS jack, but it would be downright bonkers, not to mention a waste of money to put six jacks on the back that all do the same thing. I think it has six outs.

Where the 404HD is not that 'professional' is the rather weedy +3dBu output. I've had a loan of one, and the output is lower than other gear , but it wasn't a problem -- I simply turned the gain up on my mixer.

[j_e_f_f_g]

Every Behringer product I've bought has broken down well before it should have. I don't recommend them. Of course, the focusrite scarlett line isn't exactly high-end. But my 2i4 has lasted longer than any behringer I had.

Had a MOTU Ultralite. I liked it. But I used it on windows only. The overwhelming majority of MOTU's product line is troublesome (at best) on Linux. I don't recommend any linux user wade into that minefield.

[merlyn]

Actually, thinking about it the clue is in the name -- 404. Four ins, four outs. The reason there is also a main out is that the main out can be used to monitor the input -- zero latency monitoring, so called. There is a mix control on the front of the 404 that blends the input with the playback from the computer. It's not really zero latency monitoring, is it? It's monitoring through the interface.

[j_e_f_f_g]

I think that when focusrite name a scarlett device, the first number is the total number of inputs, and the second number is the total number of outputs. So we have:

SPDIF Out = 2 channels
Main Out = 2 channels
Headphones = 2 channels

We're still 2 channels short. Maybe a loopback pair? <Still waiting for aplay results>

[GMaq]

Wait!?

Are you guys collaborating in this thread..?

[j_e_f_f_g]

you guys collaborating in this thread..?

I made a deal with MattKingUsa. I promised to behave in exchange for his promise not to ban me. And matt is a male escort who keeps his word.