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Hello to everybody. My first message here.
I was using USB galvanic isolator which is usb 1.1 12M compliant only and i was happy with output quality of my hardware rack synths (such as Waldorf Blofeld connected to USB ports on galvanic isolator). All my usb connected synths were sounding digital noise and artifacts free. Yesterday I upgraded my amateurish pci xpress audio card to external Tascam 6 channel interface to record 6 channels simultaneously. Unfortunatelly this unit won't work on USB1.1 mode. It requires USB 2.0 high speed 480M. When i bypass the isolated hub, and connected to my PC directly i can hear digital noise artifacts and even movements on my mouse! History repeats itself. When connected to isolator, unit won't show up at all and its USB connection led wont turn on.
How can i solve this? High speed galvanic isolators are way much expensive than my previous usb1.1 isolator and i do not think i can afford a new one.
1- There are usb data transfer dongles. I saw one on amazon com. Will these kind of products ok for usb 2.0 high speed protocol?
2- Will usb over ethernet dongles work?
3- Is this digital noise related to switching power supply of my PC? If yes will a linear power supply such as a LAB power supply eliminates the main problem?
4- Is there any way to isolate signal from USB cable and power the USB connection with my powered hub again? Tascam is powered externaly using an adapter attached to mains.
Any comment is highly appreciated. Thank you in advance.
Dogan
Follow Ups:
Your case is extreme. I haven't heard such noise from a USB connection since about 2002.
You are assuming that Tascam DAC is being affected by noisy on the USB cable. That might be the cause or it might be from something else.
Possible sources of the noise:
- A very noisy PC. It might be sending noise down the USB cable or through the air. What is the PC? How old?
- A video cable connecting the PC to the video display monitor. Try moving the DAC.
- The monitor itself might be radiating and that is picked up by the DAC or by the USB cable to the DAC. Try moving the DAC.
- A ground loop often produces a hum but it can be source of noise of other kinds.
I'd try to do some experiments before I spent money. For a start, try connecting the USB cable to different posts on the PC.
my blog: http://carsmusicandnature.blogspot.com/
Thanks for suggestion but a seller on Aliepxress asks for USD209 for high speed isolator. I do not want to spend that money on isolator. I need to solve the main problem.
I tried #4, tascam wont turn on USB connection without 5volt supply on usb cable even it is connected to mains and turned on.
Dunno how handy you are with a soldering iron, but I would try to make a USB cable that allowed me to supply the 5v from elsewhere. The problem is usually the extreme dirtiness of the 5v power coming from the USB port. Rather than trying to filter out that crud, I'd try to obtain a good clean 5v elsewhere and pipe it into the device using a custom cable.
my $.02
Your best bet is a USB isolator capable of high speed
A couple are listed here
http://www.thewelltemperedcomputer.com/HW/USB_Isolator.htm
The Well Tempered Computer
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