dpac996;167121 Wrote: > In the datasheet for the PCM1748 it states this device offers some post > DAC low pass filtering internally, but it is not enough to attenuate > out of band noise (artifacts from DAC process), and the recommendation > is to employ additional low pass filtering.
that is true, but the multi-pole active filters usually prescribed in app notes are selected not for best sound quality, but best measurements (freq response flatness, S/N, etc.)... you can usually get away with just a simple first-order filter, there is even a BB app note (in broken english) illustrating it. possible side effects of HF noise do need to be considered, but anyone with the competence to perform tweaks *properly* should be able to account for those in the context of their own system. obviously this stuff is "at your own risk." i should add i am not a big proponent of unbuffered "direct DAC" out though... done that on multiple occassions, and unless you have a really benign upstream load with really short interconnects (tubes anyone?), the sound becomes anemic. a properly designed opamp buffer will usually sound better, despite its failings... > This reminds me of the modders who remove the muting circuits in cd > players...yeah those annoying clicks are real fun... it's one of the first mods i do, but only when the underlying circuit will tolerate it. modern DAC's have muting built in so the clicking is minimal in use. i usually modify the power supply as well, to keep the analog stage always on, so i only have to worry about power-on transients when i plug it in. of course, if i were giving the cd player to my dad or a friend, i would leave the mutes in for safety... but the problem is often that they are not even relays (which are fine by me), but shunt transistors which have non-linear behavior in the off state... those will definitely degrade sound quality. > I would love to hear what the SB3 engineers are saying about the dudes > who reroute traces and clip this line and that and just remove parts > that "seem" like they are in the way. no offense to the SB3 engineers specifically, who i'm sure are perfectly competent, but a lot of so-called "engineers" who make this stuff for a living are pretty clueless... an engineering degree (which i have), some spec sheets and layout software do not always yield a well-design product... > I guess it is fun on some level (kind of like those dudes that pimp out > honda civics), but you have to trust the designer on another level too! if they're deserving of it, sure... i'm actually not as cynical as i might sound. i like sound engineering and a well-designed industrial product, and i agree a lot of "audiophile" tweaking going on out there is misguided and silly. most people (myself included) do not really know what we are doing most of the time. that said, you have to keep in mind the most prevalent design goals for mass-produced electronics: minimal manufacturing time/labor, maximum parts availability/reusability at miminal cost, simple packaging, low failure rate, etc. etc... in the end, tweaking is an attempt to overcome some of the obvious compromises made during the initial design and production of a component. that does not mean all tweaking is good - a lot of tweaks actually make things sound worse - but with judicious and knowledgable application you can get some nice gains in musical enjoyment. but yeah, the moral still is, you have to know what you are doing... -- dorkus ------------------------------------------------------------------------ dorkus's Profile: http://forums.slimdevices.com/member.php?userid=3373 View this thread: http://forums.slimdevices.com/showthread.php?t=19822 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
