Another OT, but sound related

Dra

I have been using a laptop for over a year now for DJ work. MP3s.
I have notice the last 2 times (both in the same room), a very high pitched whine. The loudness of the whir / whine is not effected by gain going to the amp (I haven't tried the amps levels). It is only audible when there is no sound coming out of the speakers and the room is quiet. No oscilation evident, and no change of pitch either.
Laptop > USB out > Native Instruments Audio-2DJ interface > mixer > DR260 > PLX3102

My first thought was what I've heard from others is transport noise of the laptop. However, with the laptop off the sound is still present. Unplug the USB from computer, sound goes away. (Actually, killed power to amp, then unplugged the USB, then power the amp back on.) Recently I had the laptop in the house to test a recently repaired powered speaker. I don't recall the whir in that situation. I (think) I was running on battery power only. Could a PS for the laptop (even with the laptop shut down) cause such a thing. Why? What can be done?

Thnaks,
DRA

Gadget

Have you tried running the laptop on the batteries alone? does it still have the noise?
G

Dra

OK I found the noise. And it is actually several concurrent tones. It is the USB to serial connection to the 260. Got any Ideas?

DRA

Gadget

OK I found the noise. And it is actually several concurrent tones. It is the USB to serial connection to the 260. Got any Ideas?

Nolo..comprehende...sorry..

G

Dra

You know... Driveware ...GUI
Like it is the communication, but not chirping, just high pitched tones that don't change or break that I can tell.

DRA

Gadget

Have you tried running the laptop on the batteries alone? does it still have the noise?

Dra

Yes. Noise remain regardless.

DRA

Cory Cooper

Hey Guys,

USB whine is a well-known problem in the pro audio world. It is present mainly due to the design of USB, relating to the bus-powering of devices. There are a lot of reports all over the web, including Digidesign, M-Audio, etc. I too had the whine when my Mbox 2 Mini was connected to my MacBook Pro via USB. My solution was to move to a FireWire-based unit, the Apogee Duet. Of course, until Pro Tools 9 was released, there wasn't any support for non-Digidesign/M-Audio devices when using Pro Tools. A "higher grade pro audio" USB cable from Monster helped a little, as recommended by another user, but the whine still existed from what I remember. I believe I used a ground-loop isolation cable from the outputs, which reduced it to an acceptable level. I no longer use, nor have the Mbox connected. Some people have reported success to varying degrees using a powered USB hub between the computer and the USB device/connection.

Your original post shows the following:

Laptop > USB out > Native Instruments Audio-2DJ interface > mixer > DR260 > PLX3102

A later post shows:

It is the USB to serial connection to the 260.

If the noise is being generated by the first scenario, then a better grade USB cable, powered USB hub, or ground-loop isolation cable may help. If it is due to a USB-Serial connection to the 260, it would be much more difficult to isolate and correct. Are you using the serial connection on the 260? If so, is it via a null modem cable or a USB-Serial cable?

I will see if I can find any further troubleshooting steps to try and let you know. Gadget's recommendation of running the computer via battery only is a known fix that works in some instances, but unfortunately not yours as you stated.

Dra

Cory Cooper wrote:

Hey Guys,

Your original post shows the following:

Laptop > USB out > Native Instruments Audio-2DJ interface > mixer > DR260 > PLX3102

A later post shows:

It is the USB to serial connection to the 260.

If the noise is being generated by the first scenario, then a better grade USB cable, powered USB hub, or ground-loop isolation cable may help. If it is due to a USB-Serial connection to the 260, it would be much more difficult to isolate and correct. Are you using the serial connection on the 260? If so, is it via a null modem cable or a USB-Serial cable?

I will see if I can find any further troubleshooting steps to try and let you know. Gadget's recommendation of running the computer via battery only is a known fix that works in some instances, but unfortunately not yours as you stated.

Yes, the orignal post assumed that the whine was in the actual audio signal path, but it was not. With the 260 GUI control line unplugged it is dead silent.
Laptop USB > USB - serial coverter > null modem cable with XLR's in middle > 260.

Thanks for your input. Anything else you can come up with will be appreciated.

DRA

Gadget

I had the problem once.. but it was on a remote gig.. and I didn't have time to diagnose the problem.. I have to assume it was a cable...because that is the only time I have ever heard it...
G
Yo Coop! Hows it hangin?

Cory Cooper

Not sure if this would work, but may an opto-isolator:

http://www.rs232-converters.com/rs232_isolator.htm

Not too bad G...been around here lurking when I can. Hope you have been well and biz has picked up for you,

Dra

Thanks, Gary.

I posted the link on PSW. Maybe I'll get a hit.

DRA

Dra

Updated: The source (or at least the trigger) of the whine is the screen. When I close the lid and the screen turn off, the sound goes away.

DRA

Dra

Cory Cooper wrote:

Not sure if this would work, but may an opto-isolator:

http://www.rs232-converters.com/rs232_isolator.htm

Not too bad G...been around here lurking when I can. Hope you have been well and biz has picked up for you,

This did the trick. I got one (different brand) for $11 from CNC Specialty Store (dot com). I would assume that any and all would work for this problem.

Thanks,
DRA

Cory Cooper

Excellent. Glad it worked out.

Thanks for letting us know,

C