Audio Interfaces Under Linux


(J Rigg) #41

“General rule of thumb is if you have to depend on behringer, always carry two for when it breaks.”

Yep. A lot of the Behringer gear sounds pretty good for the price and is ok for light home studio use, but using it in a pro live sound situation is inviting failures. I have some of their stuff but I’m under no illusions about how long it would last in a commercial venue or touring PA. It does have the advantage of being cheap to replace if it gets filled with beer :slight_smile:


(Aklinbail) #42

only Behringer thing I would stand by on dependability is the BCR-2000… MIDI controller . Possibly the BCF-2000 as well (mine never died, but I’m not so sure how good those faders were)

I bought a very old (serial number is in 100’s) BCR 2000, with a broken encoder and 2 of the LED rings not working (no big deal for me)…

Pulled it apart with a mate to replace the broken encoder… Wow, that thing has supports and reinforcement coming out of every point and so many screws.

These have a reputation of being able to throw in the back of a van and take to bush doof, and they won’t break… (unless you happen to snap the encoder)… I can see why…

On the compressor front… Yeah, I had 1 channel die in a quad compressor after a couple of years of light studio use.
I don’t think they are all bad, I think they have bad batches…


(Seablade) #43
On the compressor front.. Yeah, I had 1 channel die in a quad compressor after a couple of years of light studio use. I don't think they are all bad, I think they have bad batches..

@allank

My example was just one out of many over the years I can give:) Bad batches doesn’t cover it really.

   Seablade

(Apeterson) #44

I often see affordable audio interfaces with many inputs and outputs – one product from (name redacted) boasts 18 inputs – then come away disappointed when I note that eight of those are ADAT Optical.
I cant speak for myself, but what are the chances that someone building out their first or second personal recording space is going to have an ADAT anything at their disposal? IMO, it really is something of a useless feature for anyone seeking a nice multi-input/output standalone audio interface.


(Paul Davis) #45

Actually, there’s a solid argument to the contrary.

Splitting up your gear enhances long term viability and expandability. Putting D/A-A/D into a separate box and running ADAT between it and the computer interface is a smart way to ensure that a failure on one circuit board/box doesn’t kill your entire signal processing chain, and allows you to upgrade both the channel count and quality of the converters in the future if you decided to.

Much better idea to buy separate converters and run them to a cheaper interface as your initial purchase.


(J Rigg) #46

“what are the chances that someone building out their first or second personal recording space is going to have an ADAT anything at their disposal?”

I’d say quite high. You can pick up a used RME HDSP9652 PCI card for 200.00 USD/Euro these days on ebay (you need a PCI slot of course) and if money is tight use something like the Behringer ADA8200 8-channel preamp/converters until you can afford something better.


(Anahata) #47

Well, I got a minidsp USB-Streamer B (https://www.minidsp.com/products/usb-audio-interface/usbstreamer-box - a neat little thing, just USB, ADAT in and ADAT out) and a Behringer ADA8200 hooked up to a laptop as an 8 channel mobile recording system at a pretty good price.

But I also have in the studio an RME Multiface II with 8 Analog inputs and another 8 channels of input via ADAT, and I can use the same Behringer ADA8200 for channels 9-16 on the rare occasions when I need more than 8.


(Admin) #48

I just got the U-Phoria UMC1820 - works out of the box with Ardour, I’m ALSA only on my install, so I can’t comment on JACK, I also have not done extensive testing, and I would not feel comfortable commenting on quality - although it sounds great to me. What I can say is, sound goes in and out, and I got it for a ridiculous price. No SPDIF tests and I haven’t got any ADAT gear here. No affiliation with Behringer.


(Risbyvej43) #49

Hi 8p8c

Behringer writes " … up to 96 kHz" some places, other places they write "… 96 kHz " without reservations. What is your experience? If you can run at 96 kHz without xruns that certainly initiates some deliberations …


(Admin) #50

I just had a quick test, mono input (bass guitar, no DI, PAD on, ALSA, no JACK) I tried 64 and 128 samples I managed to generate xruns and a couple of crashes on 96 kHz, tried 256 samples at 2.7ms on 96 kHz and all seems well. No xruns, seems solid, so how well it would cope with multiple audio streams in a full session…? I think it’s comparable to my 1010LT, which is damn good, next I’ll try MIDI.


(Admin) #51

This is on a Dell T5400, 8 cores at 3.0GHz, 8Gb RAM 128GB SSD stripped down XFCE installation.


(Crime) #52

TASCAM US-800 (8-input) works.

At least for audio. MIDI does not work. Don’t know why; Linux sees it as a device but doesn’t receive MIDI signals.

(I am in fact the person who figured out how to make it work, when that was difficult. But the last few years of kernel builds no longer panic at its misenumerating, so as long as you plug it in after the machine has booted you’re good. And they’re dirt cheap on eBay.)


(Admin) #53

I hooked up an ADA8200 to the UMC1820, and - no input, checked alsamixer, only one fader visible. Hmmm. Rechecked the clock setting on the back - all good, two TOSLINK cables, hooked up to a Mac, and the faders were down on the interface, ran Ardour - no problema. Back under XFCE on Linux, tried sudo apt-get install xfce4-mixer, yep - faders show up but are not persistent. Ok, tried Qastools, all components installed via Synaptic, and - yes - the mixer settings are there and persistent. So if this happens to you - install Qastools components and check the faders there.


(Crime) #54

USB chipsets may matter.

I’m going to drop in here that USB chipsets used in the host appear to matter, possibly a lot, even (particularly?) in the USB 2.0 world. This may explain a lot of performance various people have seen in USB audio devices.

I did a bunch of research late last week into USB host behaviours and found that there are two underlying architectures, one of which (UHCI) uses the CPU to drive most of the work of running the bus (independent of things like transfer speeds) and one of which (OHCI) puts most of that work onto dedicated hardware in the card.

The result is that UHCI hosts (cards) put a lot more interrupts on the system bus, which for our purposes, is very bad. They also consume more CPU, though that’s not as big a factor I don’t think. Mostly, as linuxmusician tuning pages will tell you, you want to keep as many interrupts off your system bus as you can.

(There’s also a matter internally of synchronous NAK vs. asynchronous NAKs, and OHCI wins there too. The tldr if I understand it right is that OHCI can respond more quickly to packet failures; UHCI has to wait until the start of the next frame. Also, OCHI can queue multiple packets (n<4 I think? unclear) at a time, UHCI can queue only one at a time. But I am not that kind of hardware hacker and was gleaning what I could from the Linux USB driver mailing list and developer FAQ.)

I just moved from a UHCI Intel USB host card to an OHCI NEC USB chipset host card, system otherwise unchanged, and my minimum usable buffer setting dropped from 256 samples to 32 (3 frames in each case because USB), with buffer latency dropping from 30ms to 0.7ms, and actual measured round-trip Ardour latency dropping by an order of magnitude. On the UHCI cards (Intel chipset, VIA chipset, tried both) a setting of 128 samples would fail even just at playback, every time; on the OHCI card (NEC chipset), at a 32 sample buffer, I have now made a small number of successful test recordings against multitrack existing recordings, two channel input, without any XRUNs.

This is a big deal if you are running on USB 2.0 or 1.1, particularly on kit like the Presonus 1818vsl, where you don’t have access to hardware monitoring on Linux.

I talk about this more extensively here:

http://crimeandtheforcesofevil.com/blog/2016/07/25/so-hey-usb-chipsets-totally-matter/

And before that, discuss OHCI and UHCI here:

http://crimeandtheforcesofevil.com/blog/2016/07/24/usb-2-0-chipsets-digital-audio-workstations-and-linux/

(In USB 3.0, of course, chipsets on both ends matter, because the big deal with 3.0 isn’t so much the raw speed, though that’s nice; it’s that 3.0 is introducing FireWire-like data streaming. Before now, all USB data has been packeted; 3.0 provides a whole new transfer mode, apparently.)


(Anahata) #55

Those latency figures are impressive for a USB connection, but I’m puzzled. A quick search seems to show that OHCI is for USB low and full speed only (12Mbit*), also that EHCI is better than either of the others for higher speeds.

  • so “full speed” wouldn’t get you more than 8 channels at 24/48.

(Crime) #56

Yes, EHCI is the top layer for USB 2.0, and needed for USB 2.0 functionality. But EHCI loads and uses the 1.1 drivers underneath it. On linux, you can see this if you cat /proc/interrupts.

And regardless, if the card has protocol support in the hardware (required for OHCI), EHCI is going to use that hardware support, either directly or indirectly. And if the card doesn’t have protocol support in the hardware (not required - or present - in UHCI cards), it’s going to hand those duties to the CPU, and generate more interrupts.

Either way, you are going to get the same result, even with EHCI. The hardware is either present in the card, or isn’t. OHCI cards have the protocol handling in the hardware, UHCI cards don’t. If it’s not there, you have more interrupts and more processor handling of Stuff, even in EHCI.

All of my posted new results are EHCI running atop OHCI, vs the old results which were EHCI running atop UHCI.


(Dsreyes1014) #57

@solarbird: May I ask which card did you purchase specifically?


(Bjboydmusic) #58

FYI - Last night I set up my Steinberg UR22 (MK II) with Ardour. I am running Ardour in Linux Mint 17.3. In my audio set-up I set up UR22 as my input and output. I just plugged the interface in and it was recognised. I recorded guitar and it worked a treat. However, as yet I have been unable to get it to work when I use Ardour in Elementary. I am running Linux on a late 2011 macbook pro.


(Crime) #59

dsreyes1014: Syba SD-PEX20019 PCI Express USB 2.0 interface card. Mostly because the documentation specifically mentions that it uses standard OHCI drivers with no additional software needed, and on some digging, I found out it uses a NEC chipset.


(Crime) #60

Also it would be neat to see if this kind of improved performance shows up for other people as well, so post your results if you decide to try it.