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diyAudio Member
Join Date: Aug 2003
Location: Santa Cruz, California
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Quote:
Originally Posted by withnail
Soooo... if you get cryogenic superconducting circuit (and we all know that for some people, the money they spend on hifis could easily accomodate this!), thus eliminating thermal noise from the DAC, amplify it, and then no more need for cryocooling! Since thermal noise doesn't depend on voltage, the thermal noise on the 50v stage is still about 1 microvolt, ie 1/3 of the signal resolution!
Cryogenising a circuit could be easily and silently done with a Stirling cryocooler. What do you think, am I mad or is there a spark of genius in it somewhere?  |
Oh dear, so complicated. Here's an alternative: preemphasize the digital signal before it hits the DAC, since high frequency noise is more audible than LF noise, and apply de-emphasis in the amplifier feedback loop. Voila! Your perceived DAC noise is reduced a bunch of dB, and internal amplifier noise is also knocked down.
This, by the way, is not a serious suggestion, although I'd like to find out the result if anyone tries the technique. Hmmm... It could be interesting for systems with digital volume control, actually, although the extra high frequency energy would work the reconstruction filters pretty hard and you'd lose some headroom depending on how much HF energy was in the source. Oh well, something else to work on in my copious free time.
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