Hello.
Could anybody help please?
I wish to connect my laptop (USB to USB), to an rCam DAC.
Going direct, as you can imagine, the background noise is horrific!
I had an isolator from Brown Bear (Denmark), but it gave up the ghost after a few hours use.
When it worked it was very good.
I'm now using Wireless connection, but a USB cable would be useful on occasion.
Any suggestions greatly appreciated.
Thank you, Tom M.
Could anybody help please?
I wish to connect my laptop (USB to USB), to an rCam DAC.
Going direct, as you can imagine, the background noise is horrific!
I had an isolator from Brown Bear (Denmark), but it gave up the ghost after a few hours use.
When it worked it was very good.
I'm now using Wireless connection, but a USB cable would be useful on occasion.
Any suggestions greatly appreciated.
Thank you, Tom M.
Hi,
looks like there is already an internal isolator see attached u101.
Have you tried contacting Arcam for their solution? maybe some issue with grounding DAC wall wart or laptop AC/DC power brick. Use laptop batteries or SPDIF and/ or optical.
need more trouble shooting w Arcam in the loop.
> maybe try a new higher DC supply for this DAC try ~ 9V DC instead of theirs which is only 6V. also add or take away an earth ground?
looks like there is already an internal isolator see attached u101.
Have you tried contacting Arcam for their solution? maybe some issue with grounding DAC wall wart or laptop AC/DC power brick. Use laptop batteries or SPDIF and/ or optical.
need more trouble shooting w Arcam in the loop.
> maybe try a new higher DC supply for this DAC try ~ 9V DC instead of theirs which is only 6V. also add or take away an earth ground?
Attachments
A galvanic isolation would not use the USB power supply and ground directly in the device. That IC is just an EMI filter and line terminator http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXyxuss.pdf
thanks for looking that part up. yes not a real isolator I should of known cause the 3.VDC connection on the input side and common ground.
6V shown on schematic seems low for 3T linear reg. ripple rejection, but probably measures higher in real life. need to use O-scope to check.
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actually no I cant imagine, like Pano I dont have this kind of experience of horrific noise, any half way decent modern USB implementation is pretty transparent, in fact its gotten ti the point where IMO it has left everything elsed behind. I suspect there is something wrong with the way you have connected everything up.
USB noise
A USB isolator will certainly fix this but another solution is a small mains isolating transformer applied before and in series with the laptop's "brick" power supply.
Farnell sell a USB isolator that I know works well with the rDAC -see USB-ISO - OLIMEX - BOARD, USB 2.0 COMPLIANT PORT | Farnell United Kingdom
HTH.
John Dawson (Arcam)
A USB isolator will certainly fix this but another solution is a small mains isolating transformer applied before and in series with the laptop's "brick" power supply.
Farnell sell a USB isolator that I know works well with the rDAC -see USB-ISO - OLIMEX - BOARD, USB 2.0 COMPLIANT PORT | Farnell United Kingdom
HTH.
John Dawson (Arcam)
That's true but so what? There is almost no material you can find that's recorded at higher sample rates and it's hardly easy to tell the difference between the same material recorded at say 192ks/s and then downsampled to 96ks/s. So, on balance,I suggest it is probably better to get rid of the noise from the computer PSU if it's troublesome ...
IMHO of course.
John Dawson
Do you have a headphone amplifier and headphones? Try the output of the DAC into headphones to see if you still hear noise. Go from there to track the source of the problem. If you don't hear the problem through headphones, then it is a loop somewhere down the line between the DAC and the speakers. If you do hear the problem through headphones, then try another USB cable, port, computer, etc. If the problem is persistent, it is likely that your rDAC is faulty and you should return it for warranty repair.
It is a trap to assume that any given connection is the source of noise in your system without testing to verify. You can spend a lot of time and effort attempting to correct something that is not the problem.
-Aaron.
It is a trap to assume that any given connection is the source of noise in your system without testing to verify. You can spend a lot of time and effort attempting to correct something that is not the problem.
-Aaron.
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