Tpa3118 output filter values

[Jasper1702]

Hi all I was hoping you can help !
I've been looking at getting the filter setup to filter out above 22khz
I'm using 15uH inductors and 1uf cap at the moment but it's starts filtering at 45 + kHz is it better to go to 22uH or 33uH to get it to 22khz ????
Hope you can help
Thankd

 

[nigelwright7557]

Are you getting any of the carrier (PWM) frequency on the output ?
If yes then use a 22uh.
If not I would leave it as it is.

 

[Jasper1702]

Yep I'm using the amp with a radio fm/Dab and getting a rejuced signal
I was hoping to get the filter as low a possible to help
I'm using 4ohm speakers with about 5" wire.
If i put my class b amp in signal is all good so its definitely the class D amp.
Thanks

 

[nigelwright7557]

Changing the output filter wont increase level.
You need to change the input resistor of the amplifier.
Or use a pre amp.

 

[Jasper1702]

Sorry i don't mean db gain off the amp ,I ment radio reception is rejuced so picking up less stations
Thanks

 

[Jasper1702]

Are these values good ????
On BTL
22uH and 1uf = 33khz cutoff
33uH and 1.5uf = 22khz cutoff
I used a online calculator for a 4ohm speaker
Thanks

 

[Jasper1702]

I've redone my tpa3118 circuit with a new output filter ising 22uH inductor and 1uf cap smd.
With my fm/dab radio next to it i get lots more stations
So a big improvement on the 15uH inductors.
As for the sound quality off the amp its as good as before
Hope this helps anyone with similar problems

 

[jfetter]

I've redone my tpa3118 circuit with a new output filter ising 22uH inductor and 1uf cap smd.
With my fm/dab radio next to it i get lots more stations
So a big improvement on the 15uH inductors.
As for the sound quality off the amp its as good as before
Hope this helps anyone with similar problems

thanks good info.

one of my china boards has 33uh / 0.68uf

-

 

[Jasper1702]

Thanks
It looks like your China board is for 8ohm speaker if its BTL
Or 4 ohm in SL
I,m going to try 33uH and 1.5uf when thay are delivered next week
I'll report back then.

 

[hifix]

Jasper1702, How far was the tuner from the amp ?

 

[Jasper1702]

The radio was about 6" max away and i moved it around a bit .
All was good fm and dab and im not in a good area for signal
Hope this helps