Hey all,
I have been very very happy with my Weiliang DAC7 (Wolfson WM8741 based) for years, besting many other DACs along the way.
I have finally decided to try Async USB (to get up to 24 bit 192k) and purchased a CM6631 daughtercard off the bay.
I have USB working, but have two issues:
I have a slight audible hum from this USB connection that was not there via COAX or TOSLINK. The same exact USB extension cable and computer connecting to another DAC via USB has no hum. This DAC7 via USB with different USB cable on a different computer has no hum. Something about this particular computer (or extension cable) and this DAC has hum...
Also, the installation of the 7 pin Daughtercard disables TOSLINK (COAX works fine via original switch). I asked seller about a switch to enable / disable TOSLINK/USB and he is saying switch all 7 pins. I don't think I need to switch all pins... any help on which pins to switch?
Also, before I connected the 7 pin daughtercard, there was a jumper on the empty Weiliang PCB USB connector - I think it was pins 5-6 (I don't remember) that someone advised years ago... what was it for and maybe I need to switch - enable TOSLINK? SPDIF to GND makes no sense...
And yes, I have Googled this already!! Thanks in advance....
I have been very very happy with my Weiliang DAC7 (Wolfson WM8741 based) for years, besting many other DACs along the way.
I have finally decided to try Async USB (to get up to 24 bit 192k) and purchased a CM6631 daughtercard off the bay.
I have USB working, but have two issues:
I have a slight audible hum from this USB connection that was not there via COAX or TOSLINK. The same exact USB extension cable and computer connecting to another DAC via USB has no hum. This DAC7 via USB with different USB cable on a different computer has no hum. Something about this particular computer (or extension cable) and this DAC has hum...
Also, the installation of the 7 pin Daughtercard disables TOSLINK (COAX works fine via original switch). I asked seller about a switch to enable / disable TOSLINK/USB and he is saying switch all 7 pins. I don't think I need to switch all pins... any help on which pins to switch?
Also, before I connected the 7 pin daughtercard, there was a jumper on the empty Weiliang PCB USB connector - I think it was pins 5-6 (I don't remember) that someone advised years ago... what was it for and maybe I need to switch - enable TOSLINK? SPDIF to GND makes no sense...
And yes, I have Googled this already!! Thanks in advance....
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Well it sounds like it works with another pc/cable, so the pins are likely fine, and it’s more likely some ground noise/impedance issue, or a disturbance on the a/c that’s lending the noise onto the ground. Maybe a monitor perhaps, might try turning things off that are on the same outlet, or circuit. Maybe even the cable, who knows.
I have that same board as well, have been using it daily for 6 years or so and feel it has been a great reference, am blown away every day! It is in a case along with a decent headphone amp, has an isolation transformer and some other line filtering as well on the incoming a/c. It had been modified to an early death during the first couple of years, then the mods were transferred to a fresh board, along with some burson op amps, expensive capacitors throughout.
Recently, I have put a simple linear power supply to replace the power that’s normally in the usb from the pc. The results were very positive just from a noise basis, there had been no humming, but maybe to try something like this with your noisy setup if nothing else works.
I am using an SA9023 usb board as I have no option for adding special drivers at this current location.
I have that same board as well, have been using it daily for 6 years or so and feel it has been a great reference, am blown away every day! It is in a case along with a decent headphone amp, has an isolation transformer and some other line filtering as well on the incoming a/c. It had been modified to an early death during the first couple of years, then the mods were transferred to a fresh board, along with some burson op amps, expensive capacitors throughout.
Recently, I have put a simple linear power supply to replace the power that’s normally in the usb from the pc. The results were very positive just from a noise basis, there had been no humming, but maybe to try something like this with your noisy setup if nothing else works.
I am using an SA9023 usb board as I have no option for adding special drivers at this current location.
I believe it was the extension cable that was giving me problems with this particular USB connection -
But I just don't understand why the Optical is dead with USB card installed - I may disconnect the 5V on the CM6631 card and see if the optical returns...
But I just don't understand why the Optical is dead with USB card installed - I may disconnect the 5V on the CM6631 card and see if the optical returns...
Definitely worth a try. Hope you get it working, should be nice.
It may need to power up with it connected perhaps.
It may need to power up with it connected perhaps.
Well, I snipped / added a switch on the 5v pin and OPTICAL now working when USB card 5v switched off...
Now all three connections work ... yeah!
Now all three connections work ... yeah!
Well, as luck would have it, if the 5v is turned off and usb connected (and to a computer), it gets the 5v from the computer and doesn't care about the switch...doh!!
Look like all I had to do was snip the 5v from board and then whenever usb connected it would disable the OPTICAL... why do I make things so complicated?
Anyway
Look like all I had to do was snip the 5v from board and then whenever usb connected it would disable the OPTICAL... why do I make things so complicated?
Anyway
And well well well, once I turn the onboard 5V off via switch and get power from computer via cable. no hum....odd, but now happy....