[akgfan]

I've just got a bit of frightening experience. I was listening internet radio through grubdac and connecting my printer through usb port. Suddenly, no sound. I tried connecting and dissconecting grubdac for a few times, checked fuse in my amp - nothing. It didn't work for a few minutes. Then it came back to life again! Uff...

 

[tomb]

Quote:

I've just got a bit of frightening experience. I was listening internet radio through grubdac and connecting my printer through usb port. Suddenly, no sound. I tried connecting and dissconecting grubdac for a few times, checked fuse in my amp - nothing. It didn't work for a few minutes. Then it came back to life again! Uff...

Yes - this is something I should perhaps document on the GrubDAC website.  Plugging or unplugging other items on the PC's USB buss will knock a GrubDAC offline - momentarily.  Most likely, if you simply waited instead of connecting/disconnecting, you would've found it "re-appear" as a connected USB device.
 
In any event, as you just saw - it's a completely harmless nuisance.
 
 

 

[hitman47]

WOOOOOHOOOOOO It's working!!! I reflowed some bad looking pins on the newly installed U1 (still can't believe I managed to replace it) and now everything works without a hitch! Thanks Tomb and everyone else for your help and merry christmas!

 

[tomb]

Quote:

WOOOOOHOOOOOO It's working!!! I reflowed some bad looking pins on the newly installed U1 (still can't believe I managed to replace it) and now everything works without a hitch! Thanks Tomb and everyone else for your help and merry christmas!

Merry Christmas to you!  Glad you got it working!

 
 

 

[akgfan]

Quote:

Yes - this is something I should perhaps document on the GrubDAC website.  Plugging or unplugging other items on the PC's USB buss will knock a GrubDAC offline - momentarily.  Most likely, if you simply waited instead of connecting/disconnecting, you would've found it "re-appear" as a connected USB device.
 
In any event, as you just saw - it's a completely harmless nuisance.
 
 

 
I normally plug other usb devices and it stops playing for just about half of a second. But this time I thought it is dead. I used different power plug for printer so I thought it has something to do with ground loops and I damaged it.
 
 

 

[mmcaleer]

Finished my DAC.  I am only getting output on the right channel and NO bass.  Any recommendations?
 
Thanks,
 
Mike

 

[tomb]

Quote:

Finished my DAC.  I am only getting output on the right channel and NO bass.  Any recommendations?
 
Thanks,
 
Mike

No bass may just mean you don't have both channels.  (Deep bass is mostly non-directional in stereo and depends on the combination of both channels for full response.  That's why single subwoofers work instead of needing pairs.)  Anyway,  for some reason this has cropped up at least three times in the last few days.  You can look in this thread a couple of pages back or check the right-most pins on the Wolfson chip.  The top pin on the right side (USB connector down) is the Left output for the DAC.  The bottom pin on the right side is the Right output.  If the particular channel pin is not actually soldered to the pad (this can be easy to miss) or is bridged to something else, then you won't get any sound out of that channel.
 
 

 

[mmcaleer]

Thanks Tom,
 
I will check that first.  I took the DAC to work and looked at it under a scope and did have two bridges on the TI chip.  I fixed those.  I will make sure I soldered the Wolfson completely.
 
Mike

 

[mmcaleer]

No luck.  I reflowed both chips with no luck.  I have one channel and it sounds like it is far away, in a tunnel and a "tinny" sound.  I will take it back to work tomorrow and look at it again under the scope and take close up photos.
 
Mike
 

 

[tomb]

Quote:

No luck.  I reflowed both chips with no luck.  I have one channel and it sounds like it is far away, in a tunnel and a "tinny" sound.  I will take it back to work tomorrow and look at it again under the scope and take close up photos.
 
Mike
 

Yep - I think we need to see some of those pics.  Hopefully, cobaltmute will look in as well.

 
 

 

[mmcaleer]

Here are the photos.  Anything pop out at you?  I checked every pin under a Mantis scope to make sure there were no bridges and that every pin was soldered securely. 
 

 

[tomb]

Quote:

Here are the photos.  Anything pop out at you?  I checked every pin under a Mantis scope to make sure there were no bridges and that every pin was soldered securely. 
 
 

Geez - the PCB looks pretty d*mn clean from here!  If you checked it with a Mantis microscope, too, then bridges are not the issue.
 
This may sound a bit ridiculous, but are you sure you wired the output connector correctly?  You can sometimes get the symptoms you describe on DACs or amplifiers, if the wires are crossed - ground with signal.  Also, the ground connection is only on the top of the PCB - where the ground plane is.  It looks like you may not have the best soldering on the output leads.  The ground leads, in particular, appear to have not wicked at all to the top of the board.  The holes are plated and that shouldn't be an issue, but I've had it happen on my own DACs - a Bantam and an Alien once.  In my case, they were never cased and the constant flexing because of that worked the solder joints loose.  I had a heck of a time trying to get the ground leads soldered back correctly.
 
You can check the output connector and wiring by placing your DMM probes on the connector and some part of the ground on the top of the PCB - away from where the ground leads are soldered.  You can try the pads on the bottom (along with the output connector) at the Wima's and V-D resistors for the signal wires.  You should be able to measure zero resistance when checking for continuity.
 
Anyway, those are some of my guesses for the time being.
 
 

 

[mmcaleer]

The problem was the stereo jack.  It was not the correct jack, it was a closed circuit jack.  I swapped it out and it sounds MUCH better now but lacking a LOT of bass. like almost none.  Highs are so high it almost hurts.  Besides that, the sound quality going through the DAC into the CMOY is night and day vs straight out of the computer.  What should I look for to solve the bass issue?
 
Mike

 

[akgfan]

Isn't that just your initial impression? I was thinking the same at first and searching forum. But no solution worked and then I got used to it. It just sounds so much clearer and have more highs than for example soundcard. However, when songs have deep bass, the bass is there.
 
Edit: If you are used to EQ or some bass boost function on your soundcard and forgot that you have enabled it, you may be surprised.

And you never know how your soundcard manipulates with sound.

 

[jdkJake]

Can you verify the values of C16 and C17?
 
R8 and R9 look to be correct (110R), but, I cannot see the WIMA caps well enough to verify they are the correct value.