On 01/08/2014 02:41 PM, Fons Adriaensen wrote: > On Wed, Jan 08, 2014 at 05:05:48AM +0100, Robin Gareus wrote: > >> I can't confirm neither directly. But I think it works these days: >> >> http://focusritedevelopmentteam.wordpress.com/2012/04/23/linux-and-focusrite-novation-products/#comment-104 > > Interesting. > >> The reason I lost interest is that I think the device is crap. >> >> The volume dials don't latch. I set a gain on the Focusrite 18i6 and a >> minute later it's off by +-1dB. > > The 'rubber controls' effect. > >> Compared to the other two USB audio-device that I have, the [preamps of >> the] Focursite 18i6 is the noisiest. Measured with a 200 Ohm >> termination and jnoisemeter: ~-72dBFS (Flat, RMS) -- the Edirol UA-25 is >> at -81dBFS and the Presonus 1818VSL at -84dBFS. > > Those numbers by themselves mean nothing, you need to consider the gain > as well. If e.g. the 18i6 has 9 dB more gain than the UA-25 then they > have the same input noise. I had calibrated -18dBFS on all of them to the same source (a 1KHz sine, which I believe to be 0 dBu). That's how I found out about the rubber controls effect in the first place. I also did two another measurements, setting the gain-dial of each devices at minimum and maximum. The 18i6 still came out worst.. but that is not too unexpected. The gain range of the 18i6 is about -10dB .. +30dB (per specs it should be -10..+36), while on the other two it's -20dB .. +20dB. I also have one of them each. So maybe I was unlucky to get a bad/good device. I also did not have access to pro-equiment to calibrate & measure them, but identical equipment was used to evaluate all. >> That make we wonder which award those 'award winning' preamps of >> Focusrite actually won :) > > A marketing award ? > >> It has gain labels from 0..10 -= other comparably priced devices have >> latched dials properly labeled and calibrated with dB. > > If you can trust those dB marks is another matter... right. They don't need to be exact to the degree but at least give an indication. "About +5dB" is more useful that just a number, IMHO. > I'm enquiring about this for a friend who needs an USB card to be > used with the RPi, with 4 mic inputs. Application is environmental > noise monitoring AFAIK. All suggestions welcome ! The form-factor of the 18i8 is probably a bonus in this case. Skimming over http://wiki.linuxaudio.org/wiki/hardware_support the only comparable device would be the Alesis iO4 (unless you also consider more expensive equipment with more than 4 inputs). for environmental noise measurement, the devices do not need to be sample-sync, do they? You could probably use two stereo USB1 devices. best, robin _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
