SoNic67 Posted September 9, 2013 Share Posted September 9, 2013 I see no active filters on their PCB (OpAmps). Just one big multifunction chip with three crystals (USB/Ethernet/DSD). Link to comment
SoNic67 Posted September 12, 2013 Share Posted September 12, 2013 Where is the rest of the thread? I just posted something and disappeared... Oh well... And yep, there are definitely active filters on there--it's just the opamps are really, really tiny, since they are MSOP packages. If you're looking only at the front of the board, you won't see 90% of what's going on--take a look at the back of the board at schiit.com/products/loki Now I see: AK4396 - probably in pure DSD more - and one AD OpAmp (ADA4004-4 quad since you have differential outputs?). That's nice (could be probably nicer), but you could probably leave the PCM 'in' with the same costs. Marketing strategy I guess... Why not, if that's what DSD purists ask for? Personally I think that the AKM multibit D-S approach to DSD sounds better than their 'direct DSD', but... if it sells, it sells... Link to comment
SoNic67 Posted September 19, 2013 Share Posted September 19, 2013 Since the DAC chip has different kind of analog filter optimal for PCM and DSD, making a proper PCM+DSD version of the DAC would mean double analog stages and relays to switch it. Neah, some just filter the crap out of PCM and DSD, at 30kHz and they are set... Link to comment
SoNic67 Posted September 20, 2013 Share Posted September 20, 2013 They seem to have quite steep analog filter in their 'DAC' product, based on their white paper it is around 36 dB/octave and starts to cut right after 20 kHz, this way they get enough attenuation by the first image frequencies around the PCM1704 DAC chip sampling rate. (their amplifiers also have quite steep low-pass filter right above 20 kHz, but not as much) That's why most of people decided to do OS, to push those analog filters a little 'further' away. PCM1704 at least doesn't generate a lot of ultrasonic noise like the newer D-S chips. I assume that sending DSD and PCM signal to the appropriate circuitry wouldn't require rocket science. Like I said, 'DSD only' was IMO 100% a marketing decision. Absolutely their right to do it, and our right to vote with our wallets... Link to comment
SoNic67 Posted September 20, 2013 Share Posted September 20, 2013 It's easier to filter out the first 352.8kHz than right at the 20.05kHz... Link to comment
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