High pitched buzz a couple minutes into streaming

[14lionstudios]

I don't know if this is the proper place for this thread but when I start streaming my stream has no high pitched buzz but a couple minutes into streaming I can hear it. By my hard drive light it starts when that goes on but I have an SSD. Is there any way to fix this issue? There is also a Beringer x32 hooked up four our churches sound but when I mute the soundboard through obs the buzz is still there.

 

[AaronD]

Are you using the internal audio? That sits in an electrically noisy box, probably without a metal "can" over that part of the circuit board, and so it picks up that noise. Nothing you can do about that, except to use an external audio device that connects digitally to the computer.

And get a *good* external device! The cheap ones are just a wrapper around the same chip that is designed to sit inside the noisy box, and so their performance is not that great.

---

Even if you do use an external device, you can still have a ground loop. Digital is indeed (mostly) immune to that (if the ground loop noise gets really bad, digital "just doesn't work"), but if there's an analog part of the signal path *anywhere*, the analog noise will get in at *that* point.

I had a laptop that used the built-in USB connection of an otherwise analog sound board, and it had a high-pitched "warble" that depended on what the laptop was doing. Even moving the mouse was enough to change it.

Unplugged the laptop from the wall so it was running on battery, and it immediately went away. Plugged it back in, and it came back. Classic ground loop, even if it sounds different. It was picking up a switching power supply in the laptop, instead of the usual raw AC power and all of its "dirt", and getting into the analog output of the built-in USB sound card.

The solution was a USB isolator. NEVER BREAK A SAFETY GROUND!!!

I looked at off-the-shelf USB isolators, got sticker shock, and made my own custom circuit board around a chip that does that entire job. Problem solved!

---

Now I have a similar problem with a different rig. It's low enough to not be a pressing issue - easily managed with a noise gate in OBS - but I do have some 1:1 audio transformers to put on the analog side, once I finish a few other projects to replace the function that they're doing now. That rig uses the aux outs of an X32 to feed a USB line-in, because the X32's USB connection is tied up with the sound guy's multitrack.

 

[14lionstudios]

Are you using the internal audio? That sits in an electrically noisy box, probably without a metal "can" over that part of the circuit board, and so it picks up that noise. Nothing you can do about that, except to use an external audio device that connects digitally to the computer.

And get a *good* external device! The cheap ones are just a wrapper around the same chip that is designed to sit inside the noisy box, and so their performance is not that great.

---

Even if you do use an external device, you can still have a ground loop. Digital is indeed (mostly) immune to that (if the ground loop noise gets really bad, digital "just doesn't work"), but if there's an analog part of the signal path *anywhere*, the analog noise will get in at *that* point.

I had a laptop that used the built-in USB connection of an otherwise analog sound board, and it had a high-pitched "warble" that depended on what the laptop was doing. Even moving the mouse was enough to change it.

Unplugged the laptop from the wall so it was running on battery, and it immediately went away. Plugged it back in, and it came back. Classic ground loop, even if it sounds different. It was picking up a switching power supply in the laptop, instead of the usual raw AC power and all of its "dirt", and getting into the analog output of the built-in USB sound card.

The solution was a USB isolator. NEVER BREAK A SAFETY GROUND!!!

I looked at off-the-shelf USB isolators, got sticker shock, and made my own custom circuit board around a chip that does that entire job. Problem solved!

---

Now I have a similar problem with a different rig. It's low enough to not be a pressing issue - easily managed with a noise gate in OBS - but I do have some 1:1 audio transformers to put on the analog side, once I finish a few other projects to replace the function that they're doing now. That rig uses the aux outs of an X32 to feed a USB line-in, because the X32's USB connection is tied up with the sound guy's multitrack.

I am also using the avermedia gc570 to capture video from another pc and sound from the soundboard could something interfere with the capture card I have

 

[AaronD]

I am also using the avermedia gc570 to capture video from another pc and sound from the soundboard could something interfere with the capture card I have

Every signal needs a reference. The actual signal is taken to be the *difference* between the "signal wire" and that reference. If the reference is moving, then that's the same as the signal moving.

If all of the reference connections end up forming a loop, that loop becomes an antenna. That's a ground loop. The signal that that unwanted antenna picks up, makes the references move...

If you break that loop without also breaking the signal, then the antenna still tries to work, and its unwanted signal is concentrated at the break. MASSIVE noise at that point.

If you break *both* the reference *and* the signal, then all is quiet......and you need to find some other way to get the signal across that break.

Transformers do that by converting the electrical signal into a magnetic one and then back again. No electrical connection. Every good DI box has one of those, but it's probably 12:1 or something like that, so a weak line-level signal on stage can become a strong mic-level signal to drive a 100-foot cable run to the booth in back, where it gets amplified back up to a useful level.

The USB isolator that I used, is practically a complete bidirectional radio set all in one chip - oscillator on each side that gets modified for the signal, and a receiver on the other side that ignores everything except that *specific* "wiggle" and decodes it - but because it's all right there on the same chip, it doesn't need the antennas.