Quote:
Originally posted by Vadim
Jan,
Now, the question is what happens when we want to attenuate the signal? I must say that I do not know how to accomplish such an operation without affecting the resolution of the signal. Attenuation must result in a bit reduction of the digital word. Because when we scale down the signal we also are attempting to scale down the noise, but the noise being stochastic (non-deterministic) in nature will resist that and its amlitude will (or perhaps should) remain the same.
So, I think a dithering technique is in order here if we were to attempt to accomplish amplitude reduction without any significant bit reduction. I somehow doubt that Behringer programmers did that.
Now, that although the A/D section is 24 bit capable, we naturally do not get the 24 bits if the signal originates at the analog outputs of a CD Player. Also, I am sure that there is no way for that 24 bit A/D converter to actually do 24 bits in a real world environment. Perhaps, if we were to place this converter inside a Faraday box (a completely electromagnetically screened metal enclosure), then maybe we can measure 24 bits, - and that is a much stretched ‘maybe’. Inside your equipment rack you will get 16 bits at best out of this 24 bit internal architecture.
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With all this in mind I still think that we cannot afford to do any digital attenuation. I need to go back to my DSP books and look at exactly how to do digital attenuation. So I am not 100% sure that I am right about this, but …
Vadim
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I suggest that you read up on floating point operations. Your signal stays very close to the original resolution throughout the process. As long as you utilize the full dynamic range of the D/A your output will have the same resoultion as the input (extreme processing algorithms/cases exempt of course). And just to reiterate one more time, S/N and digital resolution are related but are not the same.
Also, on another note, the need for dither can be eased up somewhat by the presence of analog noise floor above the theoretical A/D converters resolution. It's not the optimal noise shaping but can be often "good enough".
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