Filtered IR 60hz

[jdkoontz]

Why am I getting that ~60hz signal prior to the pulse? Is that a power coupling into the sound card?

 

[jdkoontz]

I'm using a Steinberg UR22 MKII USB Soundcard

 

[John Mulcahy]

Could be, difficult to say without the mdat file. You could check the spectrogram.

 

[jdkoontz]

The above graph was at our church.
At home, I still see the pre-pulse 60hz signal, but it's more in the 1% range.
I removed the USB charger that's powering the UR22 and usded only USB 5V for power and removed the Laptop charger and ran the tests on Laptop battery.
The pre-pulse ripple went down below 0.5%.
I'm headed back to the church this afternoon and will retest.

 

[jdkoontz]

Could be, difficult to say without the mdat file. You could check the spectrogram.

Thanks John, I'll try that.

 

[jdkoontz]

Spectrogram with 63hz filter.

 

[jdkoontz]

Spectrogram with no filter.

 

[John Mulcahy]

There are power line components at 60 Hz and 120 Hz, but they are fairly low. The main contributors are background noises at around 46, 50 and 55 Hz.

 

[jdkoontz]

There are power line components at 60 Hz and 120 Hz, but they are fairly low. The main contributors are background noises at around 46, 50 and 55 Hz.

View attachment 62805

Probably HVAC?

 

[jdkoontz]

Is there any way to use the RTA as a CAL file?
Measuring any room noise like HVAC and remove that from room tests?

 

[John Mulcahy]

No, noise isn't so easily removed I'm afraid.

 

[jdkoontz]

No, noise isn't so easily removed I'm afraid.

Understand. Thanks for the response.
The easy solution is just to turn off HVAC, but there are several banks of HVAC in the Church around the BroadcastStudio.
The AV director said we will ignore for now and wait for Fall when HVAC is turned off and reconfirm final tests at a later date.
The 60hz noise ended up being Earth Ground being non-consistant. We went from 15% to below 5%.
It also helped to run the Laptop and UR22 on battery during REW tests.
We will continue to improve 60hz noise during tests.