High Pitched Tone in Studio Monitors...

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Rusty K

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I figured that I'd have to take my monitor amp into the shop but there is something weird about the tone. There is a spot right in the middle where the tone almost goes away. If I move my head in either direction left, right or back the tone returns. Could this be a phase issue?

Also when my Mac screen dims the tone changes.

????:confused:
 
Rusty K said:
I figured that I'd have to take my monitor amp into the shop but there is something weird about the tone. There is a spot right in the middle where the tone almost goes away. If I move my head in either direction left, right or back the tone returns. Could this be a phase issue?

Also when my Mac screen dims the tone changes.

????:confused:
Click to expand...

I had this same problem a couple of years ago. I tried everything to get rid of it. Finally, I replaced a USB cable, and bingo, it went away. I've also heard of Firewire cables inducing this as well. Balanced cables also seem to hava a positive effect. But, that's only one of about a thousand reasons this could be happening. Change your refresh rate on your monitor and see if that has any effect. Also, try lowering the brightness levels from the monitor's software control panel, not on the monitor itself.
 
Thanks TB...I'll check the usb cable from my mbox. The screen brightness issue I'll look into as well. Do you think any of this has to do with close proximity between amp and monitor/computer? My amp is right under the computer but separated by a 1 inch shelf.
 
Rusty K said:
Thanks TB...I'll check the usb cable from my mbox. The screen brightness issue I'll look into as well. Do you think any of this has to do with close proximity between amp and monitor/computer? My amp is right under the computer but separated by a 1 inch shelf.
Click to expand...

It shouldn't be an issue if you're using balanced cables between the DAW and amp. I guess the test would be to move the amp and see if the problem persists. It's a hard problem to pin down....could be a cable, could be the covering coming loose from the winding on a transformer in monitor/amp/comp power supply (least likely).
 
TeyshaBlue said:
It shouldn't be an issue if you're using balanced cables between the DAW and amp. I guess the test would be to move the amp and see if the problem persists. It's a hard problem to pin down....could be a cable, could be the covering coming loose from the winding on a transformer in monitor/amp/comp power supply (least likely).
Click to expand...

Well, it could be a ground loop if you are using balanced cables and there is a potential difference between either the grounds of the interface / DAW / amp.

It could also be from your screen's backlight or transformer and not the speakers. Try turning the backlight brightness up to 100% and disable any auto-dimming. Dimming the CCFL backlights in most monitors is usually done using pulse-width modulation ( http://en.wikipedia.org/wiki/Pulse-width_modulation ) which can cause humming/vibrations.
 
Update...

Sorry for the long absence...I forgot which forum I posted this in and I haven't been getting notices on it.

I think I've eleminated the USB cable as a possible cause but I haven't moved the amp yet...hassle. I'll do that next and report.

Thanks for the suggestions.
 
Update!

Moved my amp away from my computer monitor...no difference. Any time I open an audio program and engage the Mbox soundcard the tone is back. It has to be something to do with the audio interface between the mbox and the mac. :mad:
 
The reason that the tone sounds louder or disappears when you move your head is because of the physics of sound.

XXXXX
XXXXX
XXXXX
XXXXX

Imagine the sound like that in a way, there will be points in your audible space where the wave (i'm assuming its a sine wave) coming out of both your monitors will be in unison with each other, and thus amplifying what your hearing, and also in, where the gaps are, the waves almost cancel each other out hence causing the you to think that the sound isn't there.

I know what i mean, its very hard to explain!!!!
 
Oh, and you might want to do a bit of debugging too.

Check its not your amp and stuff, don't power on your pc, just turn your monitors, pc monitor, amp, everything like that on so you can either omit or point the finger at something in your pc.
 
moresound said:
Do you have florescent lighting ?
Click to expand...

Nope...recorded in this room for 5 yrs. and didn't have this tone. Also there are audio spikes when I preform certain functions like snapping to zero point for playback, and when my puter's been asleep...when it wakes back up. I could turn off "sleep" but I'm not always at the computer when I have my audio programs up and running.
 
Update

I wanted to finish this thread but had forgotten about it.

I wound up dumping Mbox and their core drivers and replaced it with Apogee Duet. No noise! I don't know about older versions of Apple OS but 10.6.2 doesn't get along well with Mbox. Tired of waiting for a fix. I'm sure Apple was counting on that. :rolleyes:
 
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