[LAU] Portable Digital Recorders

Kevin Cosgrove kevinc at cosgroves.us
Mon Feb 1 16:10:03 EST 2010


On 1 February 2010 at 21:58, fons at kokkinizita.net wrote:

> First of all, all these numbers should have a minus sign in
> front of them, and for them to be informative at all I'd want
> to know if they are dBu or dBV.

The Zoom spec sheet listed their numbers to be in dBm, which
requires usually requires an impedance.  They didn't give an
impedance.  But, they did define "0dBm=0.775Vrms" which lets one
calculate all that's needed.  Then again, Zoom didn't spec noise,
other than to say "very low noise and no distortion".  Hmm, how
can they say "no distortion"?

In my world dBFS (dB with respect to full scale, i.e. maximum
amplitude) would be more common.

> 99 and 106 are *very bad* - how does one design a mic preamp to
> be that bad ? Use a 714

741?

> wired as differential amplifier ? Things start to be
> interesting around -125 dBV and below.

Cheers....

--
Kevin





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