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Static after touching touch pad on laptop with USB cable?


JoshT

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When I use the USB out from the MacBook Air, I get terrible static for about 10 seconds each time I touch the touch pad. The static then suddenly disappears and all sounds fine. Sometimes the problem does not repeat itself after an hour or so of play time, but usually it happens each time I touch the touch pad. This does not happen when I stream to the AEx that is separately connected to my DAC by mini-Toslink to Toslink.

 

The DAC is a Music Hall DAC25.3 and I am using a generic USB cable.

 

Any thoughts on the source of the problem? I posted the same question over on the PC Audio forum at AA a week ago but received no responses.

 

Josh

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Josh,

 

It's just a long shot ... but if your DAC is on USB as well (sorry I don't know), any chance of using a different USB port for either ?

 

Although I never could proove any such "out of sync" thing, e.g. Chris has written about it sufficiently enough, so I guess it just can happen (on a Mac (only ??)) and then USB priorities would be "capable" of just mimicing this.

 

Your suggested trial would be about using two USB ports not being on the same internal hub. But I wouldn't know (again) whether such a thing (more hubs) exist on your Mac.

 

Btw, if all is "right", the time it takes to "reset" things will be the buffer size in use. Not that you can change that (I think).

 

Despite all the vagueness, I hope this helps you.

Peter

 

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Plug in an Ethernet cable that goes to a grounded router and see if that cures it.

USB Dacs powered by USB seem to have grounding problems with some laptops which don’t have an earthed power supply.

If that does cure it then adapt an Ethernet cable to ground only (no signal wires)

 

 

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This is last year's MacBook Air and it apparently has only one USB 2.0 port. There is another port that looks like a peripheral USB port (the "B" side?), but I think it's the DVI display port (whatever that is) based on looking at the specs page.

 

I think the only way to use ethernet is to use a USB to ethernet adapter in the same port.

 

I mostly stream to an Airport Express from my iMac anyway, and plan on getting a MacMini if I decide to go USB, so this isn't a big deal, but it's puzzling me. There are no drop outs from the USB, just about 5 to 10 seconds of bad static before everything clears up, and only after touching the touch pad.

 

 

Josh

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Not sure how to do a screen shot!

 

Here is some information. Is this what you're looking for?

 

 

USB Bus:

 

Host Controller Location: Built-in USB

Host Controller Driver: AppleUSBOHCI

PCI Device ID: 0x0aa5

PCI Revision ID: 0x00b1

PCI Vendor ID: 0x10de

Bus Number: 0x04

 

Apple Internal Keyboard / Trackpad:

 

Product ID: 0x0223

Vendor ID: 0x05ac (Apple Inc.)

Version: 0.73

Speed: Up to 12 Mb/sec

Manufacturer: Apple Inc.

Location ID: 0x04600000

Current Available (mA): 500

Current Required (mA): 40

 

IR Receiver:

 

Product ID: 0x8242

Vendor ID: 0x05ac (Apple Inc.)

Version: 0.16

Speed: Up to 1.5 Mb/sec

Manufacturer: Apple Computer, Inc.

Location ID: 0x04500000

Current Available (mA): 500

Current Required (mA): 100

 

 

USB Bus:

 

Host Controller Location: Built-in USB

Host Controller Driver: AppleUSBOHCI

PCI Device ID: 0x0aa7

PCI Revision ID: 0x00b1

PCI Vendor ID: 0x10de

Bus Number: 0x06

 

BRCM2046 Hub:

 

Product ID: 0x4500

Vendor ID: 0x0a5c (Broadcom Corp.)

Version: 1.00

Speed: Up to 12 Mb/sec

Manufacturer: Apple Inc.

Location ID: 0x06100000

Current Available (mA): 500

Current Required (mA): 0

 

Bluetooth USB Host Controller:

 

Product ID: 0x8216

Vendor ID: 0x05ac (Apple Inc.)

Version: 1.80

Serial Number: 90840DF3EFAD

Speed: Up to 12 Mb/sec

Manufacturer: Apple Inc.

Location ID: 0x06110000

Current Available (mA): 500

Current Required (mA): 0

 

USB High-Speed Bus:

 

Host Controller Location: Built-in USB

Host Controller Driver: AppleUSBEHCI

PCI Device ID: 0x0aa6

PCI Revision ID: 0x00b1

PCI Vendor ID: 0x10de

Bus Number: 0x24

 

Built-in iSight:

 

Product ID: 0x8505

Vendor ID: 0x05ac (Apple Inc.)

Version: 3.19

Serial Number: 8HA1504NE2DM3L00

Speed: Up to 480 Mb/sec

Manufacturer: Apple Inc.

Location ID: 0x24400000

Current Available (mA): 500

Current Required (mA): 500

 

 

 

 

Josh

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