[dbooth]

Hi guys/gals,

Sandra report to follow....

I've had this problem for a while where both my pc and studio speaker monitors emanate a sawtooth-like 1kHz digital noise when the HDD is doing heavy lifting or even sitting at idol for that matter. The speakers - Yamaha HS-50M's - are connected to an M-Box Mini 3rd Gen, and whilst the sound does not end up in my final bounces inside PT10, it is a constant annoyance & hindrance to me being able to hear the mix clearly.

My set-up:
Win 7 / PT10 / M-Box mini 3rd gen / Balanced ¼” cables / Yamaha HS-50M Monitors

What I have experienced so far...

- Constant sawtooth 1kHz sound (with upper and lower harmonics sometimes) coming from PC Casing when HDD working or mouse moving or clicking on items.
- When speakers are on and connected to M-Box, the sound is amplified through the speakers louder than the general pc noise.
- Upon loading PT, the sound is much worse, then disappears until the session loading screen appears.
- While a session loads, it comes and goes, and comes back fully when the session is loaded.

What I have learned and tested thus far…

- Used a different usb cable to connect m-box (no difference)
- Moved the M-box to different usb ports (no difference)
- Disabled all the usb ports one-by-one (no difference)
- Used unbalanced audio cables to monitors (made it even worse/louder)
- Plugged Shure 840 headphones into headphone socket on m-box front (signal is clean)
- Plugged headphones into speaker outputs on back of M-box – both left and right channels (signal is clean in both cases)
- Unplugged speakers from M-box while still powered (noise disappears / clean signal)
- Plugged speakers into headphone output on M-box (Noise returns as before)
- Plugged power for speakers into separate power plug on wall (no change)
- Plugged power for speakers into the same power on wall as pc and everything else (no change)
- Used same M-box and speakers with Win 7 laptop running PT 8.0 LE connected to power (same noise)
- Used same M-box and speakers with Win 7 laptop running PT 8.0 LE running on laptop battery (clean signal)
- Used same M-box and speakers with Mac laptop running iTunes & Logic X connected to power (clean signal)

My conclusions…

There is some sort of power issue, especially with the USB power. Both the speakers and m-box appear to have no problems per se. They appear to work exceptionally well with a powered Mac laptop & and a battery powered Win7 laptop. The desktop is always powered and creates noise in the system, as does the powered Win 7 laptop, and I have to conclude that therefore this is a Windows pc based issue.

What low-cost measures or tests would people here recommend?

Should I try speaker cables with the ground lifted/removed from the path? Is this as dangerous as a power cable getting the ground pin removed? Are ground loop isolators going to help with this problem, or is this more than likely something caused from the PC power supply at the wall? I’d love to eliminate the pc casing noise too, but at the very least, I want to get rid of the speaker noise, as I can move the desktop to somewhere less annoying.

Also, is there something inside the PC casing that I can check for grounding, etc… and perhaps connect that to the casing of the speakers? How can I find this? What measures should I take?

Am I missing something critical? Please let me know.

Thanks,
Dan