noisy outputs with usb

[maceasy]

Hi there,

I find that the main outputs are very noisy when the USB cable is plugged into the XT from my Dual 2.0 G5. Soon as I unplug it is fine. The question is whether this is peculiar to my system (some sort of f ground loop issue) or have others found this? thanks

[Dan Tyrant]

Same here. I also got noisy output when using the TOSlink output. I've resorted to using the analog outputs and only plugging in the USB connection when I need to transfer samples/patches.

[maceasy]

That's interesting - does it mean a fault with the XT,or is it just a few of us? Should I take it back and check out another one, or learn to live with it (bit of a pain, always unplugging the USB)?

[ArghBlarg_]

I have noticed that outputs get noisy with USB plugged into my V-Synth or Fantom-X. I think the noise we're all hearing is coming from the PC itself, through the USB cable.

I'm currently tearing my hair out trying to eliminate noise on my external USB audio interface (an ESI WaveTerminal U24).

When the hard disk moves its heads, or a menu is displayed by the video card, pops of up to -48dB are induced on the analog audio inputs of the U24. Totally ruins an otherwise -85dB noise floor. I have captured the proof in Sound Forge, and it's pretty ugly.

Blame it on sh*tty design, on the part of nearly every PC motherboard manufacturer, and the audio interface makers. The USB ports need to be isolated from the electrical activity of the rest of the motherboard. Really, a few optoisolator ICs wouldn't cost that much..

I have done some research, and there are only two solutions out there:

BB Electronics' "UISOHUB4", weighing in at $279.95 USD:
http://www.bb-elec.com/product.asp?SKU=UISOHUB4

Opticis M2-100-x optical USB extensions, $169 USD and up, depending on length:
http://3dotvideo.com/opticis/usb.html

If anyone can find a cheaper solution, please let me know.

Grr. It ticks me off so much that these manufacturers quote their lovely S/N ratios, but hide the fact that your average PC is going to inject so much noise over the USB cable as to make their audio interface useless without expensive opto-isolation.

Error 144 - Reboot? Y/N

[anti_pulse]

I feel the V functions better with regular midi than usb- especially with the whole arpegio sequencing problem... I only use it for transfering stuff. Just makes lif easier. Especially considering I spent 600 on a 1616m with two midi ins and two midi outs- I got to use them with something.

http://www.myspace.com/11505663

[BobTheDog]

Hi ArchBlah,

There may be a cheaper sollution:

1. Make sure that the usb card that your machine is useing is not sharing an irq with any other device.

2. Try it with only the V-Synth connected via usb, remove all other devices does this help?

3. Try reducing the load on the roland usb driver by setting the Audio Buffer Size to max in the control panel, does this help?

4. Use a tool like "PCI Latency Tool" to take the pci latency of your video card down to 64, does this help?

Cheers

Andy

[ArghBlarg_]

I'll try those things BobTheDog, thanks. I did disconnect all other USB devices, all other keyboard from their power and the mixer, etc. to avoid any other equip. causing the noise. I also tried a self-powered USB hub, and an internal PCI USB expander (which did help, every so slightly -- seems they isolated their USB plugs a bit better than the mobo manufacturer) -- I will try fiddling with the PCI latency.

Error 144 - Reboot? Y/N