ralphpnj wrote: > i just finished reading a really poorly written review of Auralic's > Altair streaming DAC and in the review extensive coverage is given over > to the various filters in the unit. > > So my question is: > > How are these "filters" different from a simple graphic equalizer or > simple DSP or even, god forbid, tone controls? > > Note: the review is the March 2017 issue of Stereophile.
They are probably talking about the DAC 's reconstruction filters both the digital and analog part, the measurements side note did it have a lot of different impulse responses ? They are a necessary part of every DAC ( except some NOS DAC's but they are broken by design ) These are not really eq filters but the final stage in giving you a nice analog signal after the DAC process without ultrasonic gunk in the signal . The hot topic a couple of year have been these filters impulse response and steepness and resulting ringing fancy terms like "apodizing" is used . In some cases like Ayre DAC they even sacrifice the hf response a bit to get less ringing . And also how they are implemented in the chips or software is point in good DAC design . Not just the chosen filter topology but how you do it , for example the dreaded intersample overshoots you can get if these filters have no margins for very high levels in the signal and you are oversampling . It can be done better with floating point math in software instead of hard wired digital filters ? Or can it ? Some extrem setting can be "EQ like" in the highest treble , there is always some trade offs between frequency response phase response and ringing . The ringing in DAC filters has always been assumed benign as the frequency of it is above human hearing and you have pre and post ringing in these impulse response test . Which are just test this kind of signal is not present in music the DAC normally converts ( due to normal ADC filtering when recording) but a way to test one property of the filter . Meridian and Ayre and some others argue that apodizing aka no pre ringing sounds better even if it sacrifices performance elsewhere All in all usually very subtle differences if they are at all audible . In the old days a thing the DAC designer just decided for the design at hand . Now for good and bad it's a knob to twiddle on some DAC . And in software if you oversample with Squeezelite on PI based player you got the whole range of possibilities to twiddle with for yourself :) a real handful the SoX lib can any filter you like ? I'm testing it to remove my MeridianG98DH ovesampling of inputs by letting Squeezelite do it with the important diff of -3 dB attenuation to handle intersample oversshots -------------------------------------------------------------------- Main hifi: Touch + CIA PS +MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub. Bedroom/Office: Boom Kitchen: Touch + powered Fostex PM0.4 Misc use: Radio (with battery) iPad1 with iPengHD & SqueezePad (spares Touch, SB3, reciever ,controller ) server HP proliant micro server N36L with ClearOS Linux http://people.xiph.org/~xiphmont/demo/neil-young.html ------------------------------------------------------------------------ Mnyb's Profile: http://forums.slimdevices.com/member.php?userid=4143 View this thread: http://forums.slimdevices.com/showthread.php?t=106979 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
