Focusrite Scarlett 18i20

[cowboystitching]

Hi guys, I don't post on here very much but I just got a new Focusrite unit and I thought I would share my thoughts and also ask a few questions if anybody who is a bit more technically knowledgable than me can answer them.

So, I've had the 2i2 ever since it first came out, and have had nothing but good times with that little guy. Been doing alot of tracks at 96k, buffer size set to 256, and no xruns on my Thinkpad. Obviously I'm not running a pro studio or anything, but I've had a good bit of gear over the years, and I have been really impressed with the quality of make and most importantly SOUND that Focusrite has offered. But 2 inputs is a little limiting; so I decide to go all out and get the "flagship" model of the series: the 18i20. This thing is advertised as class-compliant, as was the 2i2, so I figure this should be a piece of cake, just plug it in, and it will be the holy phrase of end-userdom: "It just works."

Oh man....have I ever been wrong. I plug it in, type "lsusb" in the terminal, and what do you know? It lists Novation EMS. Jack has no problems starting at my settings; I run Catia and ALL 18 ins and 20 outs are recognized! So when I go to play a few songs I've done in Ardour 3, I notice a faint "clicking" on the playback. "Was that there all this time?" I ask myself. I go to try and play some more music, this time from Youtube and song files in Banshee. The same little crackling, clicking kind of noises start to appear. I plug the 2i2 back into the computer, and restart Jack. No clicks, no pops. Uh oh.

So, I start to troubleshoot. Maybe the firmware on the unit is bad, or it needs to be reset. I spend a whole evening getting Windows running in Virtualbox and use the Mixcontrol software Focusrite provides to attempt to update the Firmware. After I assume I complete a factory reset, I boot back into Linux and try it again. What do you know? The same clicking as before! I start to panic, wondering why this thing isn't working. I do all the usual troubleshooting, try different USB ports, try different cables, try different buffer sizes, everything, but still the crackling persists. I send a hurried e-mail to the mailorder store. "I think this unit is defective." I send a hurried e-mail to Focusrite. "Just get back to us with what Focusrite says," the store guy replies.

The next day I go over to a friend's house who has a Macbook, and we boot into his DAW. No clicks, no pops. Now I'm thinking this has something to do with the driver, so I start looking around online for people who have a similar issue. I end up on this blog post: http://focusritedevelopmentteam.wordpre ... -products/ and there went 3 days of my life trying to recompile ALSA with these guys' patches. After alot of work I still haven't been able to get that stuff working, but last night I got frustrated and tried running Jack at 48k, and voila! It works. Playback is fine, no crackling, all ins and outs are still recognized, so I am in the clear as far as functionality.

My question is; what is making the crackling at 96k? Is it clock jitter or something else? My friends Macbook has 8gb of RAM whereas mine is only at 4gb, would this make a difference? I'm not experiencing xruns so I don't know why it would? Is there some big difference in USB ports I've never known about (And yes, I've been using it off of USB 2.0 ports, so don't even ask) that the ones on the Mac would run at a higher sample rate than the ones on my Thinkpad?

Like I said before, the thing works great at 48k, and I've been meaning to just start working in 48k again anyway so I can use more soft synths and plugins. What bugs me is why can the 2i2 do 96k just fine but it's bigger brother can't? Any takers? Anybody?

-A.

[CrocoDuck]

My question is; what is making the crackling at 96k? Is it clock jitter or something else? My friends Macbook has 8gb of RAM whereas mine is only at 4gb, would this make a difference? I'm not experiencing xruns so I don't know why it would? Is there some big difference in USB ports I've never known about (And yes, I've been using it off of USB 2.0 ports, so don't even ask) that the ones on the Mac would run at a higher sample rate than the ones on my Thinkpad?

A clock jitter is the first thing that came up in my mind. It could be possible, check the clock source of the card. A little mismatch form clock in the card and clock in the computer can give those bad results. Speaking about USB stuff, repost the output of:

Code: Select all

lspci -vnn

I had an audio trouble with a new usb driver included in the latest kernels. Lets see what driver you are using. USB on laptop is prone to give some issue. That is because on a laptop thare are a lot of devices routed through the USB bus and a lot of hubs. Have you ever try to disable-turn off all the devices that use the USB bus?

I think that 4Gb of Ram should be adeguate for audio production... I mean, I did 48kHz with 512Mb for 10 years... but just 2 channels, however.

[cowboystitching]

Ok, here is the output of that command

Code: Select all

00:00.0 Host bridge [0600]: Intel Corporation Core Processor DRAM Controller [8086:0044] (rev 02)
	Subsystem: Lenovo Device [17aa:2193]
	Flags: bus master, fast devsel, latency 0
	Capabilities: <access denied>
	Kernel driver in use: agpgart-intel

00:02.0 VGA compatible controller [0300]: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 02) (prog-if 00 [VGA controller])
	Subsystem: Lenovo Device [17aa:215a]
	Flags: bus master, fast devsel, latency 0, IRQ 43
	Memory at f2000000 (64-bit, non-prefetchable) [size=4M]
	Memory at d0000000 (64-bit, prefetchable) [size=256M]
	I/O ports at 1800 [size=8]
	Expansion ROM at <unassigned> [disabled]
	Capabilities: <access denied>
	Kernel driver in use: i915
	Kernel modules: i915

00:16.0 Communication controller [0780]: Intel Corporation 5 Series/3400 Series Chipset HECI Controller [8086:3b64] (rev 06)
	Subsystem: Lenovo Device [17aa:215f]
	Flags: bus master, fast devsel, latency 0, IRQ 44
	Memory at f2827000 (64-bit, non-prefetchable) [size=16]
	Capabilities: <access denied>
	Kernel driver in use: mei_me
	Kernel modules: mei-me

00:19.0 Ethernet controller [0200]: Intel Corporation 82577LM Gigabit Network Connection [8086:10ea] (rev 06)
	Subsystem: Lenovo Device [17aa:2153]
	Flags: fast devsel, IRQ 20
	Memory at f2600000 (32-bit, non-prefetchable) [disabled] [size=128K]
	Memory at f2625000 (32-bit, non-prefetchable) [disabled] [size=4K]
	I/O ports at 1820 [disabled] [size=32]
	Capabilities: <access denied>
	Kernel driver in use: e1000e
	Kernel modules: e1000e

00:1a.0 USB controller [0c03]: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller [8086:3b3c] (rev 06) (prog-if 20 [EHCI])
	Subsystem: Lenovo Device [17aa:2163]
	Flags: bus master, medium devsel, latency 0, IRQ 23
	Memory at f2827800 (32-bit, non-prefetchable) [size=1K]
	Capabilities: <access denied>
	Kernel driver in use: ehci-pci

00:1b.0 Audio device [0403]: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio [8086:3b56] (rev 06)
	Subsystem: Lenovo Device [17aa:215e]
	Flags: bus master, fast devsel, latency 0, IRQ 41
	Memory at f2620000 (64-bit, non-prefetchable) [size=16K]
	Capabilities: <access denied>
	Kernel driver in use: snd_hda_intel
	Kernel modules: snd-hda-intel

00:1c.0 PCI bridge [0604]: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 1 [8086:3b42] (rev 06) (prog-if 00 [Normal decode])
	Flags: bus master, fast devsel, latency 0
	Bus: primary=00, secondary=02, subordinate=02, sec-latency=0
	Capabilities: <access denied>
	Kernel driver in use: pcieport
	Kernel modules: shpchp

00:1c.1 PCI bridge [0604]: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 2 [8086:3b44] (rev 06) (prog-if 00 [Normal decode])
	Flags: bus master, fast devsel, latency 0
	Bus: primary=00, secondary=03, subordinate=03, sec-latency=0
	Memory behind bridge: f2400000-f24fffff
	Capabilities: <access denied>
	Kernel driver in use: pcieport
	Kernel modules: shpchp

00:1c.3 PCI bridge [0604]: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 4 [8086:3b48] (rev 06) (prog-if 00 [Normal decode])
	Flags: bus master, fast devsel, latency 0
	Bus: primary=00, secondary=05, subordinate=0c, sec-latency=0
	I/O behind bridge: 00002000-00002fff
	Memory behind bridge: f0000000-f1ffffff
	Prefetchable memory behind bridge: 00000000f2900000-00000000f29fffff
	Capabilities: <access denied>
	Kernel driver in use: pcieport
	Kernel modules: shpchp

00:1c.4 PCI bridge [0604]: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 5 [8086:3b4a] (rev 06) (prog-if 00 [Normal decode])
	Flags: bus master, fast devsel, latency 0
	Bus: primary=00, secondary=0d, subordinate=0d, sec-latency=0
	Memory behind bridge: f2500000-f25fffff
	Capabilities: <access denied>
	Kernel driver in use: pcieport
	Kernel modules: shpchp

00:1d.0 USB controller [0c03]: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller [8086:3b34] (rev 06) (prog-if 20 [EHCI])
	Subsystem: Lenovo Device [17aa:2163]
	Flags: bus master, medium devsel, latency 0, IRQ 19
	Memory at f2827c00 (32-bit, non-prefetchable) [size=1K]
	Capabilities: <access denied>
	Kernel driver in use: ehci-pci

00:1e.0 PCI bridge [0604]: Intel Corporation 82801 Mobile PCI Bridge [8086:2448] (rev a6) (prog-if 01 [Subtractive decode])
	Flags: bus master, fast devsel, latency 0
	Bus: primary=00, secondary=0e, subordinate=0e, sec-latency=0
	Capabilities: <access denied>

00:1f.0 ISA bridge [0601]: Intel Corporation Mobile 5 Series Chipset LPC Interface Controller [8086:3b07] (rev 06)
	Subsystem: Lenovo Device [17aa:2166]
	Flags: bus master, medium devsel, latency 0
	Capabilities: <access denied>
	Kernel driver in use: lpc_ich
	Kernel modules: lpc_ich

00:1f.2 IDE interface [0101]: Intel Corporation 5 Series/3400 Series Chipset 4 port SATA IDE Controller [8086:3b2e] (rev 06) (prog-if 8a [Master SecP PriP])
	Subsystem: Lenovo Device [17aa:2169]
	Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 16
	I/O ports at 01f0 [size=8]
	I/O ports at 03f4 [size=1]
	I/O ports at 0170 [size=8]
	I/O ports at 0374 [size=1]
	I/O ports at 1840 [size=16]
	I/O ports at 1810 [size=16]
	Capabilities: <access denied>
	Kernel driver in use: ata_piix
	Kernel modules: pata_acpi

00:1f.3 SMBus [0c05]: Intel Corporation 5 Series/3400 Series Chipset SMBus Controller [8086:3b30] (rev 06)
	Subsystem: Lenovo Device [17aa:2167]
	Flags: medium devsel, IRQ 11
	Memory at f2828000 (64-bit, non-prefetchable) [size=256]
	I/O ports at 1860 [size=32]
	Kernel modules: i2c-i801

00:1f.5 IDE interface [0101]: Intel Corporation 5 Series/3400 Series Chipset 2 port SATA IDE Controller [8086:3b2d] (rev 06) (prog-if 85 [Master SecO PriO])
	Subsystem: Lenovo Device [17aa:216a]
	Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 17
	I/O ports at 18a0 [size=8]
	I/O ports at 1894 [size=4]
	I/O ports at 1898 [size=8]
	I/O ports at 1890 [size=4]
	I/O ports at 1880 [size=16]
	I/O ports at 1850 [size=16]
	Capabilities: <access denied>
	Kernel driver in use: ata_piix
	Kernel modules: pata_acpi

00:1f.6 Signal processing controller [1180]: Intel Corporation 5 Series/3400 Series Chipset Thermal Subsystem [8086:3b32] (rev 06)
	Subsystem: Lenovo Device [17aa:2190]
	Flags: fast devsel, IRQ 19
	Memory at f2626000 (64-bit, non-prefetchable) [size=4K]
	Capabilities: <access denied>
	Kernel driver in use: intel ips
	Kernel modules: intel_ips

03:00.0 Network controller [0280]: Intel Corporation Centrino Advanced-N 6200 [8086:4239] (rev 35)
	Subsystem: Intel Corporation Centrino Advanced-N 6200 2x2 AGN [8086:1311]
	Flags: bus master, fast devsel, latency 0, IRQ 42
	Memory at f2400000 (64-bit, non-prefetchable) [size=8K]
	Capabilities: <access denied>
	Kernel driver in use: iwlwifi
	Kernel modules: iwlwifi

0d:00.0 SD Host controller [0805]: Ricoh Co Ltd MMC/SD Host Controller [1180:e822] (rev 01)
	Subsystem: Lenovo Device [17aa:2133]
	Flags: bus master, fast devsel, latency 0, IRQ 16
	Memory at f2500000 (32-bit, non-prefetchable) [size=256]
	Capabilities: <access denied>
	Kernel driver in use: sdhci-pci
	Kernel modules: sdhci-pci

0d:00.1 System peripheral [0880]: Ricoh Co Ltd R5U2xx (R5U230 / R5U231 / R5U241) [Memory Stick Host Controller] [1180:e230] (rev 01)
	Subsystem: Lenovo Device [17aa:2134]
	Flags: bus master, fast devsel, latency 0, IRQ 11
	Memory at f2500400 (32-bit, non-prefetchable) [size=256]
	Capabilities: <access denied>

0d:00.3 FireWire (IEEE 1394) [0c00]: Ricoh Co Ltd R5C832 PCIe IEEE 1394 Controller [1180:e832] (rev 01) (prog-if 10 [OHCI])
	Subsystem: Lenovo Device [17aa:2136]
	Flags: bus master, fast devsel, latency 0, IRQ 19
	Memory at f2500800 (32-bit, non-prefetchable) [size=2K]
	Capabilities: <access denied>
	Kernel driver in use: firewire_ohci
	Kernel modules: firewire-ohci

ff:00.0 Host bridge [0600]: Intel Corporation Core Processor QuickPath Architecture Generic Non-core Registers [8086:2c62] (rev 02)
	Subsystem: Lenovo Device [17aa:2196]
	Flags: bus master, fast devsel, latency 0

ff:00.1 Host bridge [0600]: Intel Corporation Core Processor QuickPath Architecture System Address Decoder [8086:2d01] (rev 02)
	Subsystem: Lenovo Device [17aa:2196]
	Flags: bus master, fast devsel, latency 0

ff:02.0 Host bridge [0600]: Intel Corporation Core Processor QPI Link 0 [8086:2d10] (rev 02)
	Subsystem: Lenovo Device [17aa:2196]
	Flags: bus master, fast devsel, latency 0

ff:02.1 Host bridge [0600]: Intel Corporation Core Processor QPI Physical 0 [8086:2d11] (rev 02)
	Subsystem: Lenovo Device [17aa:2196]
	Flags: bus master, fast devsel, latency 0

ff:02.2 Host bridge [0600]: Intel Corporation Core Processor Reserved [8086:2d12] (rev 02)
	Subsystem: Lenovo Device [17aa:2196]
	Flags: bus master, fast devsel, latency 0

ff:02.3 Host bridge [0600]: Intel Corporation Core Processor Reserved [8086:2d13] (rev 02)
	Subsystem: Lenovo Device [17aa:2196]
	Flags: bus master, fast devsel, latency 0

Not even seeing the interface with that command. Alsa is 10.25. Kernel on my laptop is 3.11 low latency; Kernel on my desktop is 3.8 lowlatency, and I also had a 3.2 low latency kernel on my laptop as well. How do I check the clock source on the card? There doesn't appear to be any hardware control for that. I've also tried this on my Lenovo Thinkcentre with the exact same results, so I don't think it's a laptop issue. I'm also running absolutely nothing on my laptop off of USB when I'm using the unit.

I totally agree with the 512 RAM at 48k, that's what I worked with for years with lots of plugins back when I used Logic Pro. I remember the jump to 2gb being mind-blowing. Maybe it's the huge amount of outputs messing up on playback?

[CrocoDuck]

Yep, we don't expect to see your interface with lspci, since lspci lists all PCI devices. It was to understand who deals with the USB controllers on your system, that all deal with pci bus. I see that the driver being in use in your system is ehci-pci. The first time I installed a kernel with that driver I had headaches trying to have a decent setup using a 2 channel 16bit/48kHz cheap usb sound device. I ended up installing a kernel with the older uhci_hcd driver. However, I updated my kernel some days ago and I have back the ehci-pci driver, that actually seems to work good now. My feeling is that ehci-pci may still have some bad performance. Maybe things will get better with new updates. Here a thread where my problem was discussed http://bbs.archbang.org/viewtopic.php?pid=23279 .

From the specifications of your sound card (http://us.focusrite.com/usb-audio-inter ... ifications) I can see that there is an internal clock (no suprise), but seems like you can't synchronize with an external wordclock. Also, I can see that clock jitter is said to be <250 ps. However, I can't see what kind o measure they did so is impossible to make some calculation to understand if this value could be responsable for this... What about timers in your system? Try to read this http://wiki.linuxaudio.org/wiki/system_configuration , the section about hardware timers. I also sospect that the reason for the issue may be in some weird clock/timer precision/jitter combination between the soundcard and the rest of the system.

[cowboystitching]

From the specifications of your sound card (http://us.focusrite.com/usb-audio-inter ... ifications) I can see that there is an internal clock (no suprise), but seems like you can't synchronize with an external wordclock. Also, I can see that clock jitter is said to be <250 ps.

Checked out the back of the interface tonight and there's a word clock in; so maybe this is somewhat of a workaround?

What about timers in your system? Try to read this http://wiki.linuxaudio.org/wiki/system_configuration , the section about hardware timers.

Went through this evening and tried out all the changes to the system they recommend; but still, nothing. Same clicks and pops. I went ahead and ordered one of these http://artproaudio.com/art_products/aud ... t/syncgen/ so we will see if maybe slaving the Focusrite to an external clock fixes this. I'll make sure to post the results.

[eikakot]

Try turning off your wifi of the laptop. Few years ago I had that problem with usb sound card. some anoying pops and clicks when wireless was on

[CrocoDuck]

Checked out the back of the interface tonight and there's a word clock in; so maybe this is somewhat of a workaround?

It could be, but since we don't have accurate datas about timers in the computer and clock in the soundcard we can't understand if it will be sucessful. However, a better clock (and the ART looks better then the internal of your soundcard) is a nice improvement (and it will be lovely useful if you need multiple interface setup). Are you sure about the word clock in? In this shot I can see just an out: http://sonicfiber.com/images/product/Fo ... _18i20.jpg . Maybe you can slave the device through SPDIF?

Try turning off your wifi of the laptop. Few years ago I had that problem with usb sound card. some anoying pops and clicks when wireless was on

Yep. As I said, is worthwhile to disable all hardware running through usb when asking for high audio performances. On my laptop I must run this every time I make music to prevent xruns:

Code: Select all

#!/bin/sh

modprobe -r ppdev # I don't have a parallel port
modprobe -r lp # I don't use a printer when making music
modprobe -r uvcvideo # I don't use a webcam when making music
modprobe -r videodev # Ditto
modprobe -r ath9k # Wireless driver
modprobe -r r8169 # NIC driver
modprobe -r btusb # Bluetooth USB

killall modem-manager # I don't have a modem
killall wpa_supplicant # See the network stuff above

modprobe snd-hrtimer # Load the ALSA high res timer for my MIDI stuff
echo -n performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor # Set the CPU scaling governor to performance
TASKLETPR=76 # Define a variable TASKLETPR and set it to 76
ps -eLo pid,cmd | grep [t]asklet | awk '{ system("chrt -f -p '$TASKLETPR' " $1)}' # Do some greppy awky stuff and set the prio of the tasklet daemon

give it a try.

[cowboystitching]

Are you sure about the word clock in? In this shot I can see just an out: http://sonicfiber.com/images/product/Fo ... _18i20.jpg . Maybe you can slave the device through SPDIF?

Ohhh man...I have really got to stop trying to troubleshoot stuff when I'm half asleep after work.

It's not a total loss, apparently using that Mixcontrol application you can set the sync source to adat or s/pdif, and then save it to hardware; so hopefully I can get it working that way. We shall see.

I ran that bash script yesterday; but I'm still getting the clicks. I also went through and ran every command you have there in the terminal, but to no effect. Interestingly enough, Focusrite returned my email saying they think it's a USB bandwidth issue as well. CrocoDuck, you don't think possibly more RAM would help out? I noticed that Ipad users are complaining of the same issue at 96k, and they have much lower RAM than say; a Macbook Pro, which I did try this unit with when I was trying to figure out if the hardware itself was defective.

[CrocoDuck]

CrocoDuck, you don't think possibly more RAM would help out? I noticed that Ipad users are complaining of the same issue at 96k, and they have much lower RAM than say; a Macbook Pro, which I did try this unit with when I was trying to figure out if the hardware itself was defective.

Ipad for sure has less ram, but it could have different USB hubs, controllers and drivers as well, leading to the issue for USB bandwidth reasons. Probably the best idea is to test your system with a distro with the older USB controller driver using a bootable media. You can test it and see wether the audio issue is present. If I'm not wrong these distros use the older driver:

http://tangostudio.tuxfamily.org/
http://puppylinux.org/wikka/PuppyStudio
http://www.ap-linux.com/
http://www.dynebolic.org/
http://puredyne.goto10.org/
an older ubuntu studio release (before 12.04).

[cowboystitching]

I must confess, I haven't tried a downgrade of the USB drivers just yet, but I did manage to sync the clock to S/pdif after changing the settings to sync via S/pdif on the MixControl app (in VirtualBox) and it plays back audio just fine at 96k!

Now the real question is, why is the clock going out of sync? At some point I'm going to upgrade the ram in my Thinkpad to 8gb (which I had planned to do anyway), and had already planned to go back to 48k as my standard recording rate before even getting this interface, so this should not really crop up again. I also ordered a USB 2.0 expansion card for my desktop, so maybe we can find out running it on it's very own USB bus if it is in fact a bandwidth issue?

I will post more results in the not too distant future.

[CrocoDuck]

...but I did manage to sync the clock to S/pdif after changing the settings to sync via S/pdif on the MixControl app (in VirtualBox) and it plays back audio just fine at 96k!

Now the real question is, why is the clock going out of sync?

I think it is a hard question to answer, if not provided a lot of information about system timers accuracy, jitter, interaction between system and soundcard. I mean, a comprehensive view of the whole "apparatus" is needed to have a accurate picture of what is going on, but I think is not a thing you can gain with some command (for example, an accurate statistical plot of the events coming from timers could be needed). Probably the internal clock of the interface in the device is just not accurate enough for high sample rates when making data-comunication with your hardware-software combo (also, the rest of the hardware in the soundcard could pay a role). Sometimes manifacturers make very weird choices for the quality of the components, expecially for pro-sumer products (is even impossible to find state-of-the-art datas and specifications for most products, do I have to measure the devices by myself??? ... sorry for the outburst).

At some point I'm going to upgrade the ram in my Thinkpad to 8gb (which I had planned to do anyway), and had already planned to go back to 48k as my standard recording rate before even getting this interface, so this should not really crop up again. I also ordered a USB 2.0 expansion card for my desktop, so maybe we can find out running it on it's very own USB bus if it is in fact a bandwidth issue?

This should be a nice upgrade of the overall performances, let's see what happens! However, if the issue is related to the driver then it could be present even with the new card. Anyway, since you said that the playback is nice with the device slavered, I would suspect more timers and clocks to be the core of the issue at this point. Yeah, the issue was not present on another computer... I read somewhere that the internal timers of Apple computers are less accurate than others (if I'm not wrong they don't use HPET, I don't have infos about kernel timer). This could yield to some clock inaccuracy compensation... but I'm just speculating.

[marcos x]

sorry if this is a hijack but having similar problems on another 18i20

my "question" to the gurus is http://www.linuxmusicians.com/viewtopic ... 18&t=12079

[cowboystitching]

No hijack at all, I posted in your thread.

[cowboystitching]

Whelp. More interesting results...

I got a nice simple USB 2.0 PCI expansion card for my desktop, and I'm not getting continuous clicking, but I'm still getting occasional clicks. Then after a few minutes I start getting xruns like CRAZY and then jack crashes. Possibly some sort of issue with this card? This happens at 44.1, 48, and 96k. Works just fine off of the desktop's internal USB ports though. Also, when I run the ALSA -> Loop -> Jack bridge I get lots of weird sample rate glitching, but when I run the Pulseaudio bridge (this is all being done via Cadence, btw) to Jack everything runs just fine. Still have yet to try it with 8gb of ram on my laptop yet.

Anybody interested in working on getting the alsa patches developed by the guys in this thread (http://focusritedevelopmentteam.wordpre ... -products/) to add full support for the 18i20 and merged upstream to the main alsa driver? I would be willing to even put a fairly generous code bounty on it. And I'm being 100% serious here.

[CrocoDuck]

Sorry for the late reply... I'm having a crazy month...

I got a nice simple USB 2.0 PCI expansion card for my desktop, and I'm not getting continuous clicking, but I'm still getting occasional clicks.

Ouch! What about your PCI slots? Do you have both PCI and PCIe? If so, bandwith problems are expected when using PCI, since in this situation the PCI slot must transmit data through a bridge chip. If you have PCIe you should use a PCIe card. The issue could be also because the chipest... maybe is not a good supported one. Give again the output of lspci -vnn .

Anybody interested in working on getting the alsa patches developed by the guys in this thread (http://focusritedevelopmentteam.wordpre ... -products/) to add full support for the 18i20 and merged upstream to the main alsa driver?

A day I will start to contribute to the community with code... but up to now I can't find the time to learn and make actual things.

sorry if this is a hijack but having similar problems on another 18i20

my "question" to the gurus is http://www.linuxmusicians.com/viewtopic ... 18&t=12079

I have no idea what to do to help you...