On 05/15/2012 06:10 PM, Fons Adriaensen wrote: > On Tue, May 15, 2012 at 12:07:36PM +0200, Robin Gareus wrote: > >> It has only balanced outputs but otherwise fits the bill. > > Usually you can use them as unbalanced. In some cases this > requires a special cable, but that's unlikely. > >> What seems weird with with this box: it has a word-clock out but no >> word-clock input. > > Not a real one, but it will sync to SPDIF or ADAT. Excuse my newbie question, but I'm not experienced with SPDIF. Can one [word-clock] sync two devices using SPDIF or ADAT and still use the analog I/O on both? -- Is that hardware specific or is there a standard for that? I assume the master-device will need to send a signal via SPDIF. I'll check later if the 1818VSL can do both: output to SPDIF and analog at the same time. but I don't know if I can do that remotely. What I do already know is that the clock-source for each input can be configured individually. but I'm still waiting for Brian to connect the device. my ssh login already works.. >> What is not clear to me is >> if the balanced I/Os are [or can be] ground-lifted. > > Better not. Ground lifting can damage your inputs unless > > 1. the inputs are physically isolated by a transformer > (not the case), > > 2. the common mode voltage (the difference between the two > grounds) is small. > > Unless you have transformer isolation, you need a more or less > common ground. And then, if the inputs are really balanced and > you use balanced cables, there is no need to lift the ground. Here it mainly concerns the outputs: In my case there's a ground loop between my Screen (Asus VE278) and the active speakers when connected via computer and an USB UA-25 (not UA25-ex which features a ground-lift switch) -> 1/4inch TRS -> B2031A speakers. Disconnecting either the screen or the speakers (and using headphones) works, otherwise there's a hum on the system; luckily no sparks, no x-runs, either :) A multimeter shows a constant 1mA current and ~3-4mV AC potential. (measured between the USB-shielding of the PC and the disconnected USB-cable of the UA25) when the screen is connected. Both the screen as well as the speakers (and computer) are connected to the same power-stripe and share the ground. Fun-fact: When disconnecting the screen the potential between USB and PC goes up to ~150mV (IFF the computer is not battery powered otherwise it's 0) but the current drops to nil. /me is pondering to cut the ground-wire from the screen.. but I have so far refrained from doing that. Anyway at some point the interface may end up on stage somewhere and ground-lifting may be required for the inputs, too. Although in that case I'll likely have some ground-lifting DI-boxes around. robin _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
