On Wed, Jan 08, 2014 at 05:04:38PM +0100, Robin Gareus wrote:
On 01/08/2014 04:43 PM, Fons Adriaensen wrote:
On Wed, Jan 08, 2014 at 03:51:41PM +0100, Robin
Gareus wrote:
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.
O dBu ? So you measured the line inputs, not the mics ?
I don't think I did. I used an unbalanced jack (out from a 4th
soundcard) -> balanced XLR (pin 2,3) to calibrate.
Then a XLR plug with a resistor between pin 2,3 for the noise measurement.
I just checked the calibration data for mu UA-5, which as far
as the analog part is concerned, is similar to the UA-25 (apart
from having separate line inputs which do not pass via the mic
preamps).
At max gain, the required input level for 0 dB digital is around
-42 dBu, fairly normal for a mic input. To produce -18 dB digital
with 0 dBu input you'd need 60 dB less gain. Maybe that's possible
with the gain pots just above the minimum, but anything measured
with that setting wouldn't be very representative.
Ciao,
--
FA
A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)