This may be very old news to the mastering engineers at this forum . More about intersample peaks .
The company TC electronics have some of their AES papers freely aviable . I'm not affiliated with them similar research may be aviable elsewhere . Please provide me with more reading in the tread if you have some god reading to suggest . http://www.tcelectronic.com/tech-library/mastering/ You get four different papers describing some consequences of brick wall audio at 0dFs especially with very artificial limits . Yes this is about intersample peaks or intersample overs as they are called . The one where they run borked signals trough consumer CD players are really interesting . A perverse consequence can be that really old school DAC can behave more benign when overloaded , such are the times we are living in . Benchmark audio has taken it into their design of their latest DAC . This has been discussed before on this forum http://benchmarkmedia.com/products/benchmark-dac2-hgc-digital-to-analog-audio-converter It's sales blurb ,but they actually added some headroom for this phenomena -3.5 dB Hydrogen audio forum have an ongoing discussion . I've read treads in this forum where members have had good results by actually lower the digital gain before the DAC or transporter with SoX . I was just surfing the web for good reading about this problem , hence sharing with you . Appreciate even better reading about it if you help out . Reflections so far , my thoughts . This is an understood and we'll known problem for at least a decade ( if not more )yet it s consequences has not changed much in mastering or consumer audio . Master engineers still use outdated methods to evaluate peak levels ( not considering the true signal level after reconstruction ). Equipment manufacturers and chipmakers does not seem to care much . Happily making a bad problem worse . Modern productions methods can easilly produce signals inside the "system" that violates the nyquist requirements . Perceptual coders are also suspectible in their filters mp3 and AAC OGG and all are not at all happy with this . (There is a reason for why Apples mastered for iTunes program suggest -1 dB and delivery as 24/96 before their conversion to 256kbs AAC .) This would not be a problem if all where as carefull as some old school sound engineers regarding levels . And finally a Squeezebox thought , if you are using a DAC or in my case a HT processor hence you untilise the digital output. Would it be a good idea to just pull down the digital volume a little bit prior to your DAC when listening to music with these "production values" . I think this is sufficient ? Or is it not . Or are more elaborate measures using SoX and custom-convert.conf really needed ? Configuring SoX in this case can have some potential problems done wrong you can run into the same problems as discussed in these papers ! The simple undithered 24 bit volume in a squeezebox simply move the bits down the "ladder" and they fall off at the end ( truncated ) harmless with 16 bit , a theoretical issue with 24 bit sources where maybe you should have used dither . The Pro people usually always suggest dither when changing bit depth , but a small volume change in a squeezebox does not really reduce the bits . Any suggestions . I will ofcourse I'll try at home in the weekend , the first thing a 16/44.1 input sees in my system is a sample rate converter to 24/96 then probably conversion to float before entering the DSP processes . -------------------------------------------------------------------- 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 (in storage 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=102378 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
