On Tue, 11 Apr 2017 19:39:41 -0700 Patrick <[email protected]> wrote: > It's an ASI6514 that says Input Level -10 to +24dBu in 0.5dBu steps.
dbu is reference zero VU. VU is an analog standard developed many, many moons ago, derived from dBm. VU includes things like the weight of the needle in the meter, therefore the inertial dampening causing the ballistics, the rate at which that needle swings with a given applied voltage, the rate it recovers when that voltage is removed, etc. It's essentially meaningless except as a reference where the voltage is dynamic. A VU meter should respond approximately close to the way the human ear responds. Nearly logarithmic. One VU meter should behave exactly the same as any other. Should. 0 dBm is reference ( and being zero, equal to ) 1 milliwatt dissipated in a 600 ohm load. ( 600 ohms being the telephone analog standard ) 0 dBu is the voltage that would cause 1 mw to be dissipated in 600 ohms, but is actually reference the voltage independent of power or resistance, hence ~0.775V RMS. -10 to +24 dBu means anywhere between 0.245 VRMS and 12.277 VRMS. Obviously, in 600 ohms that's a lot more power than the same voltage level in the typical 10K card input. The up side is that since it's a voltage reference, the input R is irrelevant. "House standard" is whatever level has been chosen as the standard reference level in any given plant. For decades, it was zero dBm, until the Japanese decided to use 1V in 10K instead, which screwed everything up. Some plants are 0, some are +4, some are -10. Then, along comes digital, and some are 0, some are -12, some are -16. What level do you want your standard to be ? -- Cowboy http://cowboy.cwf1.com Dinner is ready when the smoke alarm goes off. _______________________________________________ Rivendell-dev mailing list [email protected] http://caspian.paravelsystems.com/mailman/listinfo/rivendell-dev
