Sony MZ-RH1 mic input noise
by John Beale Dec. 2006


The MZ-RH1 mic input amplifier has a relatively low noise floor. In the highest gain setting, I measured my model (s/n 5041476) to have an input noise at -122 dBu (unweighted), with the input being a shielded 150 ohm metal-film resistor to ground on each channel, at 20 deg. C. When the internal memory buffer fills and the minidisc motor spins up to write out the data to disc, which happens approximately 6 seconds out of every 26 second period in PCM recording mode, it creates about 2 dB of additional noise. It looks more significant than it sounds in the left-hand illustration. In the expanded plot on the right you can see that the noise spikes are very short in duration, and audibly they sound like a faint sputtering noise.
   

Click on image below for larger view

RH1 input noise, amplified

noise, expanded horizontal scale

RH1 motor noise.mp3  (6 seconds off, 6 seconds on, 3 seconds off)
input: 150 ohm resistor to ground on each channel; shielded.


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