Peter Chubb <[EMAIL PROTECTED]>
Henry> Hello I am having a problem with the Yoga AD-100 (Virtual 5.1
Henry> Channel USB Adaptor) sold by Jaycar. When I plug it directly
Henry> into a motherboard usb port I get good clean analog stereo
Henry> audio. However when I plug it into a USB 2.0 powered Hub or USB
Henry> 2.0 repeater which is turn plugged into one of the motherboard
Henry> usb ports I get the audio overlaid with a very annoying random
Henry> continuous "tac-tac-tac" sound whose amplitude is not affected
Henry> by the player audio volume control. In other words the "noise"
Henry> is still there when the audio is off.
Sounds like unclean power to the USB hub. `still there when audio is
turned off' is a dead giveaway.
Interesting idea - but I am not so sure.
Note that the PBT UM201 unit produced no 'noise' under the same
conditions as the Yoga AD-100 - but that unit could have better power
conditioning...
The impression I get with the Yoga AD-100 is that it is to be connected
to headphones so it would not be drawing that much power. The two times
the problem occurs are:
1) Plugged into a 7 port Skymaster USB 2.0 powered hub which uses a 3
amp 5 volt plugpack (volts checked okay with multimeter).
2) Plugged into a 5 meter powered repeater (essentially a one port hub)
which gets its power from the host computer.
However in both cases having a hub introduces an extra time delay. I
read somewhere that noise could be a sign of missed or repeated data.
When I looked at usbview I saw something that made me wonder if the
hardware data buffer in the usb chip itself is smaller for the Yoga?
PBT UM201:
Maximum Packet Size: 1
Interval: 10 ms
Yoga AD-100:
Maximum Packet Size: 192
Interval: 1 ms
Decreasing the 'Period Time' (originally 50 ms) in the ALSA Advanced
Settings in xmms (which I am using to play audio files) had no effect.
What is really annoying is that this problem does not occur when the
AD-100 is plugged directly into a motherboard usb port. I could put then
quickly put it down to a 'non-standard' usb device and try to find
something else...
Henry
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