This forum uses cookies
This forum makes use of cookies to store your login information if you are registered, and your last visit if you are not. Cookies are small text documents stored on your computer; the cookies set by this forum can only be used on this website and pose no security risk. Cookies on this forum also track the specific topics you have read and when you last read them. Please confirm whether you accept or reject these cookies being set.

A cookie will be stored in your browser regardless of choice to prevent you being asked this question again. You will be able to change your cookie settings at any time using the link in the footer.

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Noisy audio alarm output *SOLVED *
#1
Music 
Hi OP friends
I have produced a number of simple audible warning messages (sample attached) to be played via an OP over temperature action.
The problem is that there seems to be a lot of background noise in the Pi audio output.
I have tried both HDMI and analogue outputs as well as a USB audio dongle but all give the same background noise.
Ive also eliminated PSU noise by running on a 12v battery.

Anyone got any tips for cleaning up the audio output ?
Thanks
Steve


Attached Files
.zip   canopus coolant alarm.zip (Size: 387.96 KB / Downloads: 8)
Reply
#2
I just uploaded your mp3 to my pi 3 and played it through the 3.5mm audio jack, through a portable amplified speaker and it sounded fine. I used this command.

omxplayer -o local "canopus coolant alarm.mp3"

I also set a trigger in OP and it sounded fine. Is the background noise subtle? Something that I might miss?
Reply
#3
(2016-04-03, 03:25 AM)Vamonos Wrote: I just uploaded your mp3 to my pi 3 and played it through the 3.5mm audio jack, through a portable amplified speaker and it sounded fine.  I used this command.  

omxplayer -o local  "canopus coolant alarm.mp3"

I also set a trigger in OP and it sounded fine.  Is the background noise subtle?  Something that I might miss?

Thanks for checking. I just tried connecting my headphones and it was clear of noise. It seems that my speaker/amplifier combination is picking up the noise. I'll try shielding it better !

Edit: The RPI was putting the noise onto the DC supply to my amplifier. Running the Pi AND the amp on same psu - very noisy. Ran the amp off a separate battery - no noise. I added 12v DC power conditioner to clean up the DC supply to the Amp and, although it didn't remove the noise completely, it improved it a lot.
Reply
#4
Interesting. The speaker that I tested with, is a rechargeable bluetooth model that also has a 3.5mm jack, so my supplies were isolated. Any possibility that another peripheral is creating noise on the ground line? Have you tried disconnecting everything else. Many are using the Pi as a media center and I can't imagine this being a typical problem.
Reply
#5
(2016-04-03, 09:42 AM)affinite Wrote:
(2016-04-03, 03:25 AM)Vamonos Wrote: I just uploaded your mp3 to my pi 3 and played it through the 3.5mm audio jack, through a portable amplified speaker and it sounded fine.  I used this command.  

omxplayer -o local  "canopus coolant alarm.mp3"

I also set a trigger in OP and it sounded fine.  Is the background noise subtle?  Something that I might miss?

Thanks for checking. I just tried connecting my headphones and it was clear of noise. It seems that my speaker/amplifier combination is picking up the noise. I'll try shielding it better !

Edit: The RPI was putting the noise onto the DC supply to my amplifier. Running the Pi AND the amp on same psu - very noisy. Ran the amp off a separate battery - no noise. I added 12v DC power conditioner to clean up the DC supply to the Amp and, although it didn't remove the noise completely, it improved it a lot.
 
I just checked with a bluetooth speaker connected by cable - works fine and quality is great without disturbing noise. Have not managed to get the bluetooth connection setup though. Pairing und Trusted devise works but connecting I could not get working yet.
Reply
#6
Did you try disconnecting all other peripherals? Everything except the amp to make sutlre there isn't a poorly designed item plugged in somewhere?
Reply
#7
(2016-04-03, 09:36 PM)Vamonos Wrote: Did you try disconnecting all other peripherals?  Everything except the amp to make sutlre there isn't a poorly designed item plugged in somewhere?
Found it ...
It is the 12v-5v DC converter I'm using to power the Pi. (Must have some sort of switching circuit)
I tried powering the Pi from a separate PSU and its fine.
I think I need a ground loop isolator - just ordered. Will advise if successful Undecided
Reply
#8
For the benefit of others I solved my noisy Pi audio output using a cheap (£5) Ground Loop Isolator from eBay.
It connects between the Pi audio jack and my amplifier.See photo attached.

I can now crank up the volume and warn all my neighbours that my "Coolant temperature is high" without hiss and crackling the audio. Big Grin

Bye the way - yes I do plan to tidy up the cabling.


Attached Files Image(s)
       
Reply
#9
(2016-04-07, 10:14 AM)affinite Wrote: For the benefit of others I solved my noisy Pi audio output using a cheap (£5) Ground Loop Isolator from eBay.
It connects between the Pi audio jack and my amplifier.See photo attached.

I can now crank up the volume and warn all my neighbours that my "Coolant temperature is high" without hiss and crackling the audio. Big Grin

Bye the way - yes I do plan to tidy up the cabling.
is it possible to share your audio files  Wink
Reply
#10
(2016-04-07, 12:18 PM)snowboarder Wrote:
(2016-04-07, 10:14 AM)affinite Wrote: For the benefit of others I solved my noisy Pi audio output using a cheap (£5) Ground Loop Isolator from eBay.
It connects between the Pi audio jack and my amplifier.See photo attached.

I can now crank up the volume and warn all my neighbours that my "Coolant temperature is high" without hiss and crackling the audio. Big Grin

Bye the way - yes I do plan to tidy up the cabling.
is it possible to share your audio files  Wink

Happy to oblige. They are a bit "Mechanical" but are the best I could do.
Also happy to create any more that you might need (In English)


Attached Files
.zip   Openplotter audible warnings.zip (Size: 645.64 KB / Downloads: 15)
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)