🚀 go-pugleaf

My lab is seeking an amplifier to power a headphone driver in a closed
acoustic coupler for an auditory neurobiology set-up.  The driver has a
ten-ohm impedence, and reaches about 100 dB SPL with 1.5 volts applied to
it.  The problem is that we would like to get down to near 0 dB SPL, and
this implies less than 15 microvolts of noise on the output of the power
amp (unweighted).  Can anyone suggest a commercial product that meets
these requirements?  The closest thing I am aware of is the Crown D-75, but
I am only saying that because a Crown rep says it will do the job.  I have
not had the chance to measure one yet.  But the D-75 is a bit pricy (over
$500), and we would like to spend less, if possible.  Does anyone make a
high quality headphone amplifier that is this quiet?

A more complete spec:
   gain = 0 to 20 dB (we might even get by with some kind of unity gain buffer)
   output swing = 3 volts peak to peak, minimum, into 10 ohms
   output impedence = 1 ohm or less
   input impedence = 600 ohms or greater
   distortion = 0.01% THD or less, 50 Hz to 10kHz at any output voltage
        from 1.5 Vrms down.
   hum and noise = 100 dB below 1.5 Vrms at output, unweighted

If there is no commercial product that does this, we will have to roll our
own.  I would greatly appreciate hearing about any references to low
noise power amp or follower circuits that we could look up.

Thanks.
-- 
Julian Vrieslander     "Don't rush me... you'll get a rotten miracle."
Neurobiology & Behavior, W250 Mudd Hall, Cornell University, Ithaca NY 14853    
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