alvin1118 0 Report post Posted February 22, 2008 (edited) just done my USB DAC. Specification: DAC: PCM2702, 16Bits, Sampling Freq. 48khz Amp Stage: RA1 (Grado Clone!) Voltage Regulator: ROE Gold Cap, LM317337 Signal Cable: MOGAMI 2549 Overview: Voltage Regulator: DAC+RA1: Front: Rear: Running in now. i would say 999% better than built in sound card!! lol now i really enjoy music XD Edited February 22, 2008 by alvin1118 Share this post Link to post Share on other sites
heady 0 Report post Posted February 22, 2008 (edited) Sweet. Very nicely done. Well done. What power supply pcb did you use? Edited February 22, 2008 by heady Share this post Link to post Share on other sites
alvin1118 0 Report post Posted February 22, 2008 haha thanks XD power supply is full bridge rectifier + LM317337. PCB get from a taiwan friend. cheap and good for all application manz. but if you want to invest on power supply, there are other higher end type. $$$$ >< Share this post Link to post Share on other sites
chesterqw 0 Report post Posted February 24, 2008 that is a DIY USB DAC +amp!!?! holy mother. Share this post Link to post Share on other sites
wkwlb 0 Report post Posted February 24, 2008 nice case work!! Share this post Link to post Share on other sites
alvin1118 0 Report post Posted February 25, 2008 that is a DIY USB DAC +amp!!?! holy mother. yeah, USB DAC + RA1 GRADO CLONE AMP running in. didnt switch off for 72hours already XD nice case work!! thanks bro bring back to poly & drill holes. lol Share this post Link to post Share on other sites
heady 0 Report post Posted February 25, 2008 How did you do the square hole for the USB connector? TIA. Share this post Link to post Share on other sites
alvin1118 0 Report post Posted February 25, 2008 How did you do the square hole for the USB connector? TIA. eh? i drill a hole then use file slowly make it square the power inlet also the casing is thin, can easily file it Share this post Link to post Share on other sites
alvin1118 0 Report post Posted February 25, 2008 the transformer actually gives me a lot of troubles. HISSING SOUND!!!! the magnetic interference is terrible. very loud hissing noise when plug in high sensitivity headphone >< moral of the story: dont save cost on important part. i should have bought one "good transformer" instead of using an old VCD Player one. sad :lookdown: no choice now, i uses anti static aluminum foil to wrap around the transformer, and ground the chassis and usb connector to somehow reduces hissing noise. it does help a lot XD hissing noise is very low now but still audible when not playing music. maybe when free then change the transformer see how Share this post Link to post Share on other sites
heady 0 Report post Posted February 26, 2008 I understand that to shield electromagnetic effect of transformer, the shielding material need to be mild steel or something which a magnet can stick to. From your pics, I think one piece of mild steel between the power supply / transformer and the DAC board may be enough. Getting that piece of mild steel will be difficult, though. Using a SMSP and a small capacitor filter may be a better way to go, for a DAC. That is how I power my Monica3 DAC. Share this post Link to post Share on other sites
alvin1118 0 Report post Posted February 26, 2008 yah,now trying to look for mild steel. or rather just live with the low hissing noise. lol Good SMPS & cap filter would be a good solution for DAC as the power source is separated from the chassis. no more worry on electromagnetic interference.haha.. btw,DAC really sound a lot better. almost run-ed in. quite nice Share this post Link to post Share on other sites
chesterqw 0 Report post Posted February 26, 2008 soft iron to block out magnetic stuff Share this post Link to post Share on other sites
alvin1118 0 Report post Posted February 26, 2008 soft iron to block out magnetic stuff think i should isolate the problem step by step. 1st move away transformer, see is there any noise. 2nd, check on grounding loop. i suspect the noise actually comes from grounding loop issue Share this post Link to post Share on other sites
alvin1118 0 Report post Posted February 27, 2008 just bought a cheap and good sennheiser HD201. plug in and listen using my USB DAC, surprisingly, no hissing noise at all! wondering is it my DAC only suitable for this kind of headphone. lol Share this post Link to post Share on other sites
heady 0 Report post Posted February 28, 2008 Hmm, it probably means the headphones which had hissing is too sensitive. You will need to reduce the gain if you prefer that headphone. Share this post Link to post Share on other sites
