What could be causing this spike at 60Hz?

[FargateOne]

I have a 2010 Asus laptop and a miniDSP Umik-1 since 2015. All worked well with REW and Dirac 3.0 for my thousands of measurements done since then. Yesterday, during the night so in a completly silence environment ( during the day Dirac mic level reads -48issh dB but last night in a more silence room mic level was -41dB) this 60Hz appeared every where. It is NOT a Hummm. My Arcam AVR-21 is dead silent even if I push the main volume at 90 (usually 55-62). With one point measurement only the spike is in all channel but surround left and sub right. In a 9 point measurement withthe help of the propagation window, the spike is in all channels.
I know I can check with REW (need to find a moment for now)but in the mean time what is a probable cause? usb cable? mic itself? Dirac software? or worst of all my receiver?
Fronts

Center

Surrounds

Subs

 

[Todd Anderson]

That's weird. And you're sure your UMIK-1 microphone was selected as the input source, and not the laptop mic?

I would definitely do RTA with Room EQ Wiz.... see if that spike is still there.

Was something in your home running? A dishwasher? A Dryer?

 

[FargateOne]

That's weird. And you're sure your UMIK-1 microphone was selected as the input source, and not the laptop mic?

I would definitely do RTA with Room EQ Wiz.... see if that spike is still there.

Was something in your home running? A dishwasher? A Dryer?

As usual I put all 60Hz sources to off, the to off, the clim and the heating of the house to off.No neon light. And that night it was past midnight. RTA confirm the spile at 60Hz to any channel choosed. I took my son's laptop and RTA showed the same spikes. It makes no sense that it would be the cable remains the Umik-1 isn't it?

 

[FargateOne]

I've found this old thread https://www.avsforum.com/threads/rew-background-noise.1950217/page-2
and I have the same exact problem. This is noise floor only. I ordered a new mic hopefully it will fix the issue and it is not the AVR...

 

[JStewart]

If you’re thinking it might be the umik you could try REW with the laptop mic.

 

[Todd Anderson]

That’s not a bad idea @JStewart.

I have a hard time believing it’s a cable… though, at 60hz, it seems like it would be audible… or, at least, minority noticeable!

I’d follow J’s advice and see if the laptop mic pics it up. And If that test passes, I’d order another mic

 

[Todd Anderson]

Actually… did you try an RTA measurement in a different room (or outside)?

Seems like that’s the easiest way to identify the mic as an issue

 

[FargateOne]

Actually… did you try an RTA measurement in a different room (or outside)?

Seems like that’s the easiest way to identify the mic as an issue

If you’re thinking it might be the umik you could try REW with the laptop mic.

Thanks to you two guys for your great advises. Purple is Umik-1 in the most silent chamber in the house (see the spike) and green is the laptop mic.
It is fair to say that my Umik-1 is broken isn't it?

 

[JStewart]

Thanks to you two guys for your great advises. Purple is Umik-1 in the most silent chamber in the house (see the spike) and green is the laptop mic.
It is fair to say that my Umik-1 is broken isn't it?
View attachment 87618

Looks that way. I don’t understand what might cause it though.

 

[JStewart]

@FargateOne , thinking a little further, was the laptop on battery power? And did you try measuring with the Umik on a different usb port?

 

[JStewart]

Here I just asked ChatGPT about the usb causing it and it indicated it was possible. This is the response:

Spoiler

Yes — a laptop’s USB port absolutely can cause or transmit a 60 Hz hum (or a harmonic of it) into a USB microphone cable or audio path.

Here’s what typically causes it and how to diagnose/fix it:




Common Causes

1. Ground loop through the laptop power supply
   • When your laptop is plugged into AC power, its power brick connects the system ground to the building ground.
   • The USB mic’s ground (via its shield) ties into that same ground.
   • If another piece of gear (like external speakers or an interface) is also grounded differently, a small current flows through the USB shield → 60 Hz hum.
2. Noisy USB power
   • The 5 V power rail on laptops can have ripple or switching noise.
   • Some USB mics draw power from that rail, and if the mic’s internal filtering isn’t great, that noise can appear as hum or buzz.
3. Poor shielding or long/unfiltered cable
   • A damaged or poorly shielded USB cable can pick up electromagnetic interference from AC adapters or nearby power cords.
4. Laptop fan or display power circuits
   • Internal components (especially in thin laptops) can inject low-frequency noise into the USB ground plane.

Ways to Troubleshoot

Test​	What it tells you​
Unplug the laptop and run on battery	If hum disappears → ground loop from AC brick.
Try a different USB port	Some ports share noisy power lines with other components.
Try a powered USB hub (with isolation)	Good powered hubs can “clean up” the 5 V rail.
Use a USB isolator	Breaks ground path while maintaining data; removes hum if it’s a ground loop.
Try another computer	Confirms whether your laptop’s port is the source.

Solutions

• If hum disappears on battery:
  → Use a two-prong power adapter (if safe for your laptop) or a ground loop isolator on the USB line.
• If it’s still there on battery:
  → Use a USB isolator like the iFi iDefender+, Behringer HD400 (for analog paths), or an audio-grade USB hub with clean power.
• Always use a short, well-shielded USB cable for mics.

Key takeaway


A 60 Hz hum from a USB mic isn’t usually the mic’s fault — it’s often ground noise or power ripple from the laptop’s USB port. Running on battery, isolating the USB connection, or adding clean power almost always eliminates it.



Would you like to describe your setup (e.g., laptop brand, mic model, and how it’s connected)? I can pinpoint exactly where the 60 Hz is likely coming from in your case.

 

[FargateOne]

@FargateOne , thinking a little further, was the laptop on battery power? And did you try measuring with the Umik on a different usb port?

I read your ChatGPT answer.
The graphs above are on my son's like new laptop and on battery power in a silent room. I tried in my old laptop the 2 usb ports and also the 2 usb ports on the new laptop.
It appeared all of a sudden 2 nights ago without any change in any outlet or devices plugged in or anything else in the living room.

It would be a huge hazard that 2 laptops have 4 defective usb ports or power supplies problems.
Remain the cable or the mic
iFi iDefender+ = 99$CAN
Anker usb 3.0 7 port hub = 59$CAN
Total 160$
New Umik-1 = 135$CAN
I will try a new mic with my old laptop (also I will try the old mic with the new cable) to see if it is the mic. If not, I can return it and order a new cable somewhere and those 2 devices.?

 

[Todd Anderson]

Your Mic is 10 years old… very possible that it’s had some sort of failure.

If I were betting here, I’d put money on the new mic not showing a spike