mswlogo;543939 Wrote: > The SqueezeBox test as I read it says the degration is HUGE !! 4bits of > attenution (Volume 20 is 24dB) drops to 75dB dynamic range. Nearly > 4bits lost for 4bits of attenuation. It's practically behaving like a > 16bit DAC, that the low 8 bits don't even exist !!! It's behaving like > a 16.5bit DAC. > > If I did have a "Perfect" 16bit DAC. And attenuated 4bits. And there by > lost every I attenuated by, I'd get 72dB dynamic range (that's absolute > worse case), right? SqueezeBox gets 75dB. You can't get much worse. > > I agree other DACs will do better. But people keep referencing this > squeezebox test in defense as showing all is fine and it's showing it > couldn't be much worse. mswlogo, Where do you get 4 bits of dynamic range lost from? Volume 20 is 25db down (slightly more than 4 bits in fact) and 19.4db less dynamic range (which is far nearer to 3 bits, isn't it?)
Much more importantly I suggest you look at the detail - the degradation is not linear! darrenyeats;543576 Wrote: > I think I see where you're coming from. > > If you look at the tests volume 30 is 12.5db of attenuaton but the > result is only 7.1db reduction in dynamic range from 40 (max). This is > noticeably different to stepping from volume 30 to volume 20, a further > 12.5db attenuation but which results in a more expected 11.7db reduction > in dynamic range. > > Why is the initial drop off nowhere near 12.5db decibels? > > I'm not an engineer but I do know this test was performed on a > Squeezebox which has an SNR of "over 100db". Perhaps someone can step > in and explain why the initial drop off is less than 12.5db. Perhaps it > is to do with the DAC noise being a further 4db or so lower than -96db > (compared to a digital 0db signal)? > That's why I'm betting better DACs will do a lot better - in the Squeezbox test I see the difference between going from 0db to -12.5db (7.1 db dynamic range lost) and going from -12.5db to -25db (11.7db dynamic range lost)...the effect is markedly different. I note that the gap between 12.5db and 7.1db is about the difference between 96db and the SNR of the Squeezebox (a bit "more than 100db"). Maybe someone can explain if this is a real connection or not. But it's not as simple as you say. Better DACs will degrade very slightly to begin with, I think. Darren -- darrenyeats http://www.amazon.co.uk/gp/richpub/listmania/byauthor/A3H57URKQB8AQO/ref=cm_pdp_content_listmania/203-7606506-5721503. (Inguz bass EQ'd) SB3 -> (pre bypassed) Krell KAV-300i -> PMC AB-1 (caps bass EQ'd) Desktop -> Genius Slab SW-flat2.1 700 Sennheiser HD 25-1 II ------------------------------------------------------------------------ darrenyeats's Profile: http://forums.slimdevices.com/member.php?userid=10799 View this thread: http://forums.slimdevices.com/showthread.php?t=77725 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
