Hi nn200.47 uF CAP and 22uH inductor is needed for LC low pass filter
I hope you know about dissipation and and HF components and sidebands of SPWM signal . and about response of your loud speaker . your speaker didn't design for such frequencies !I know cut-off frequency is above the standard frequency you have told, but they set these values that seems incorrect! maybe their ears could hear the ultrasonics!
Of course .ou prefer to limit the cut-off frequency for 200 hertz, assuming that the input frequency range of amplifier is below 200 hertz or not?
Of course .
But you should normalize the impedance of your filter . as you probably know such a filter has an out put impedance . you should design it for your desired range of impedance .
Do you know how to design it for a special impedance ?
best Wishes
Goldsmith
Hi againwhat you mean by output impedance? you mean load impedance which is speaker(s)? if yes , it's 4 ohms.
The best idea is using a filter to allow to pass all of the audio range in out put and then using a low power N order filter in your preamplifier ( before comparator )what's your idea about minimising cut-off frequency below 22 KHZ? this may put core on pressure to force to filter a high power bandwidth which may increase core losses and THD.
i have seen many class d subwoofer amplifiers in half or full bridge modes which their LPFs were designed for full range audio but input FREQ were filtered by an active low pass filter to reach the desired frequency response for driving subwoofers.
Do you know what issue will increase THD in a class D amplifier??! why you think so ?this may put core on pressure to force to filter a high power bandwidth which may increase core losses and THD.
I told you before ! you should design your filter to be able to support special value of out put load !I wrote the formulas in my previous post for calculating L and C for a specific load impedance(RL).
Hi again
I told you before ! you should design your filter to be able to support special value of out put load !
And it's design procedure is different ! ( consider value of zeta= 1 in your design process , then your filter will be normalized in your desired impedance ) .
Good Luck
Goldsmith
HiHi
could you tell me why you consider damping factor in calculation ? what if we consider quality factor? for instance quality factor of 1/√2=0.707 would be critically damped which is ideal for this type of filter but damping factor would be=0.707 !
but when we consider damping factor=1 , Q would be=1/2
now could you clarify what should I do for it?
A guidance about damping factor :but considering damping factor or quality factor was problematic for me
Hi again
now your filter is with good values , L=57uH and C= 900nF .
So , is your problem solved now ? any other question ?
Best Wishes + Good Luck
Goldsmith
Notice : Core selection has some limitations ! for example frequency of operation - loss - permeability - allowed magnetic flux and ... etc . how you are selecting your cores ? what are your criteria ?once I tried ETD 30 with 1mm air gap and it was nice. unfortunately it was dropped down and broken.
what about RM cores ? for example RM12?
what about Iron powder cores? like T157-2?
nn20
Notice : Core selection has some limitations ! for example frequency of operation - loss - permeability - allowed magnetic flux and ... etc . how you are selecting your cores ? what are your criteria ?
for being sure about linearity of an inductor , a gap space will guarantee it !(linearity or not)
I hope you know your sound or a music , isn't a sine wave ! according to the fourier series each un sinusoidal wave is consists gang of sine waves .because the output sound Sinusoidal waves' fidelity is important and as you surely know, no other harmonics should not be added to output sound, just this.
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