KISS DAC PT.2
Jul 10, 2006 1:13:16 GMT
Post by rickcr42 on Jul 10, 2006 1:13:16 GMT
So this is getting weirder and weirder.
First.Why do USB switches cost so much ? I have looked at schemos so I KNOW these devices are not only fairly easy builds but could be made even better than those cheesy ass overpriced craptacular devices commonly available.
Second.For no reason I can explain in a direct head-to-head "non optimised/non scientific" subjective evaluation the old PCM2702 simple USB DAC beats the more complex PCM2704 (either line level OR SPDIF to external DAC) and PCM2706 (line,spdif to dac,I2S to dac).
comparing the three on the TI Grid the only difference I see is a slightly better S/N ratio but that does not explain the sonic difference so something else must be going on here.The price of the three is also a hint (02 most expensive) but again does not give an answer that satisfies as to the "why" of it
The test set up (again podged together and not optimal) :
1-cheap ass Radio Shack 4-to-1 USB switch,borrowed
2-line level audio selector using a silver contact rotary switch
3-USB from computer to USB Switch
4-USB Switch to one of the three DACs based on the above chips
A-PCM2702,line out to Audio Selector
B-PCM2704,Line out to audio selector,SPDIF out to DITB
C-PCM2706,line out to Audio selector,I2S out to DIY AD1865 DAC
All of the above are simple perf board builds using adapter boards for the USB chips and not optimised layout so the results may vary with a properly designed DAC though each being equal at least on the "non optimal" part direct head to head comparisons still I think valid.
Somthing just came up and I have to finish this later,be back...........
First.Why do USB switches cost so much ? I have looked at schemos so I KNOW these devices are not only fairly easy builds but could be made even better than those cheesy ass overpriced craptacular devices commonly available.
Second.For no reason I can explain in a direct head-to-head "non optimised/non scientific" subjective evaluation the old PCM2702 simple USB DAC beats the more complex PCM2704 (either line level OR SPDIF to external DAC) and PCM2706 (line,spdif to dac,I2S to dac).
comparing the three on the TI Grid the only difference I see is a slightly better S/N ratio but that does not explain the sonic difference so something else must be going on here.The price of the three is also a hint (02 most expensive) but again does not give an answer that satisfies as to the "why" of it
The test set up (again podged together and not optimal) :
1-cheap ass Radio Shack 4-to-1 USB switch,borrowed
2-line level audio selector using a silver contact rotary switch
3-USB from computer to USB Switch
4-USB Switch to one of the three DACs based on the above chips
A-PCM2702,line out to Audio Selector
B-PCM2704,Line out to audio selector,SPDIF out to DITB
C-PCM2706,line out to Audio selector,I2S out to DIY AD1865 DAC
All of the above are simple perf board builds using adapter boards for the USB chips and not optimised layout so the results may vary with a properly designed DAC though each being equal at least on the "non optimal" part direct head to head comparisons still I think valid.
Somthing just came up and I have to finish this later,be back...........