Jim Aikin Posted September 7, 2001 Share Posted September 7, 2001 Here's a technical question I'm researching: In a digital audio recorder, what's the difference between signal-to-noise ratio and dynamic range? Craig's 1988 book The Electronic Musician's Dictionary gives definitions for the two terms that, while not worded the same way, are pretty straightforwardly equivalent to one another. Some engineers I've spoken to, however, feel that in a digital system s/n should be measured with reference to a "nominal signal level" of -18dB rather than with reference to 0dB (full code). The trouble with measuring s/n this way is that in a 16-bit system, you're throwing away 3 bits, leaving your recorder with what would appear to be only 13-bit resolution. Thus the manufacturer may prefer to reference s/n to 0dB, as this spec will put the 16-bit recorder in a better light. We can get off into a rant, if you like, about how digital specs are sometimes deceiving. An actual 24-bit record/playback system, for instance, simply can't deliver 144dB of dynamic range, no matter what anybody tells you. But that's really a separate thread. I'm hoping to hear from people who really know this stuff and can nail down the difference (if any) between dynamic range and s/n in a digital system. Thanks! --Jim Aikin Link to comment Share on other sites More sharing options...
Ethan Winer Posted September 7, 2001 Share Posted September 7, 2001 Jim, > In a digital audio recorder, what's the difference between signal-to-noise ratio and dynamic range? < Excellent question. The [i]only[/i] thing that really matters is total dynamic range - from the loudest signal that can be recorded down to the residual noise. Anything else is just marketing and obfuscation. With old analog tape recorders you can set the meters to read "0" just about anywhere. So there too, all that matters is maximum signal versus residual noise. --Ethan The acoustic treatment experts Ethan's Audio Expert Book Link to comment Share on other sites More sharing options...
Anderton Posted September 8, 2001 Share Posted September 8, 2001 ...except with analog tape recorders, measuring distortion went hand in hand with measuring dynamic range or signal to noise ratio. With distortion starting to kick in around -20 dB, you had to specify how much distortion you were willing to tolerate for a given amount of dynamic range. But getting back to your original question, the two terms are interchangeable when applied to electronic systems. However, dynamic range can also refer to the difference between maximum and minimum levels with something like a live symphony orchestra. Although I suppose you could think of people coughing or people rustling in their chairs as "noise," people traditionally don't associate the dynamic range of an acoustic phenomenon as being related to a noise floor. After thinking about how your question relates to digital, now it's my turn for a question. With digital, do we now have to specify how much distortion we're willing to tolerate at LOW levels? In other words, are the last few dB of a 16 bit system REALLY usable, or do they sound as bad as tape overloaded to 10% distortion? Remember, with digital we've entered the bizarro world where signals get more distorted as they get softer, not louder. I'm scratching my head. Any comments?!? Craig Anderton Educational site: http://www.craiganderton.org Music: http://www.youtube.com/thecraiganderton Twitter: http://www.twitter.com/craig_anderton Link to comment Share on other sites More sharing options...
D. Gauss Posted September 8, 2001 Share Posted September 8, 2001 [quote]Originally posted by Anderton: [B In other words, are the last few dB of a 16 bit system REALLY usable, or do they sound as bad as tape overloaded to 10% distortion?...I'm scratching my head. Any comments?!?[/B][/quote] isn't that a whole new can or worms? i mean isn't overloaded tape rock and roll? (think early 50's distorted tunes or those farty roy thomas baker cars/queen drums), but low level digital crap is just that... -d. gauss Link to comment Share on other sites More sharing options...
Ethan Winer Posted September 8, 2001 Share Posted September 8, 2001 Craig, > With distortion starting to kick in around -20 dB, you had to specify how much distortion you were willing to tolerate for a given amount of dynamic range. < Good point! Which makes the difference between dynamic range and signal to noise ratio even less relevant in today's digital world. --Ethan The acoustic treatment experts Ethan's Audio Expert Book Link to comment Share on other sites More sharing options...
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