Hello n shalom everyone,
Im designing a pre amp,bandpass filter and power amp.At first of my project,im constructing a ECM pre amp using TS974.It work well(with some help from this forum esp Audioguru).Then i combine it with power amp using TDA2822M which then fed to 32ohm earphone with 90mW power rating.They work well with total gain 10000(80dB).
Then,next thing i had do is to design a bandpass filter(200-20kHz) which require me to use 4th order sallen key filter due to its simplicity and sharpness.I test the filter.It work well as in simulation.
Then,i place it as you can see on my post diagram(between pre amp and power amp).Then,i inject 0.5mV input with 100Hz ferq.,as i measure output of the power amp,the ouput is about approx. 0.15V,which mean im still can hear the sound at 100Hz.I thought my bandpss filter doesnt work well.After several days spend on time thinking of it,i just realize that the signal was amplify at pre amp about 100 gaind,and been attenuate at bandpass filter then amplify again at powere amp which indicate that there nothing much happen on my bandpass filter.
I want reduce,in other way to silent the sound at outer freq. of my bandpass.How do i want to achieve this?My idea are to place the bandpass filter
i)after TDA2822M or
ii)before TS974.
**My first idea seem to be impossible since the TL071 will not able to drive 32ohm earphone.If i want to move on with my 2nd idea,the problem that i thought i will face is mismatch impedance.
Does anyone can help me in this prob?
-elnino wesbo-
Im designing a pre amp,bandpass filter and power amp.At first of my project,im constructing a ECM pre amp using TS974.It work well(with some help from this forum esp Audioguru).Then i combine it with power amp using TDA2822M which then fed to 32ohm earphone with 90mW power rating.They work well with total gain 10000(80dB).
Then,next thing i had do is to design a bandpass filter(200-20kHz) which require me to use 4th order sallen key filter due to its simplicity and sharpness.I test the filter.It work well as in simulation.
Then,i place it as you can see on my post diagram(between pre amp and power amp).Then,i inject 0.5mV input with 100Hz ferq.,as i measure output of the power amp,the ouput is about approx. 0.15V,which mean im still can hear the sound at 100Hz.I thought my bandpss filter doesnt work well.After several days spend on time thinking of it,i just realize that the signal was amplify at pre amp about 100 gaind,and been attenuate at bandpass filter then amplify again at powere amp which indicate that there nothing much happen on my bandpass filter.
I want reduce,in other way to silent the sound at outer freq. of my bandpass.How do i want to achieve this?My idea are to place the bandpass filter
i)after TDA2822M or
ii)before TS974.
**My first idea seem to be impossible since the TL071 will not able to drive 32ohm earphone.If i want to move on with my 2nd idea,the problem that i thought i will face is mismatch impedance.
Does anyone can help me in this prob?
-elnino wesbo-
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