How to i create a passive line-level 90hz high pass filter? I want to be able to filter off the low end limit of my speakers (90hz) before it goes into the (class d, tpa*) amps.
How would using a headphone output from a device affect the passive filter?
Or a audio isolator before the passive filter?
there's designs using resistors and caps but where there other passive circuits that used other components like err was it inductors??? :/
I’ve tried days of researching but a lot of what i find is for electric guitars or doesn't answer my question of what resistor and caps(?) to use for a line level or headphone input. Im a newbie that is trying to make my first understand of these related subjects and could do with a meaningful to me example , like this question to help me get started in making sense of it all
How would using a headphone output from a device affect the passive filter?
Or a audio isolator before the passive filter?
there's designs using resistors and caps but where there other passive circuits that used other components like err was it inductors??? :/
I’ve tried days of researching but a lot of what i find is for electric guitars or doesn't answer my question of what resistor and caps(?) to use for a line level or headphone input. Im a newbie that is trying to make my first understand of these related subjects and could do with a meaningful to me example , like this question to help me get started in making sense of it all
What speakers are they? What order filter do you need/want? A first order filter, that is one that attenuates at the rate of 6dB per octave, would comprise a capacitor in series with a resistor to form a potential divider, the resistor could simply be the input impedance of your amplifier TLS.org | Passive Line-Level Crossover
One Option for High Pass Filter
Hello cacao ambiance,
If I understand your question correctly, I had a similar issue a while ago. Due to room placement, my right speaker had a bit more low bass output than the left speaker, so I wanted to tame down the one with more output. My solution was to insert a capacitor between the output of my preamp and the input of the power amplifier for the right channel. I worked up a little spreadsheet to calculate the capacitance needed for the known input impedance of the power amplifier.
The first figure shows the simple schematic and the calculations for determining the -3dB frequency. The second figure calculates and plots the response curve.
In my case I used a pair of 0.1 MFD MusicCaps in series to get 0.05 MFD or 50 nF, which I thought was close enough to the calculated 47 nF for this application. This solution worked fine to tame the low bass output so the two speakers were better matched.
I hope this will be of some help.
Cheers,
ceulrich
Hello cacao ambiance,
If I understand your question correctly, I had a similar issue a while ago. Due to room placement, my right speaker had a bit more low bass output than the left speaker, so I wanted to tame down the one with more output. My solution was to insert a capacitor between the output of my preamp and the input of the power amplifier for the right channel. I worked up a little spreadsheet to calculate the capacitance needed for the known input impedance of the power amplifier.
The first figure shows the simple schematic and the calculations for determining the -3dB frequency. The second figure calculates and plots the response curve.
In my case I used a pair of 0.1 MFD MusicCaps in series to get 0.05 MFD or 50 nF, which I thought was close enough to the calculated 47 nF for this application. This solution worked fine to tame the low bass output so the two speakers were better matched.
I hope this will be of some help.
Cheers,
ceulrich
Attachments
If you know the input impedance of your power amp, you can calculate it according to the formula
C = 1/2pi(Zin)(f3) where
Zin = amplifier input impedance in Ohms
f3 = desired -3dB cutoff frequency in Hertz
C = series capacitor in farads (NOT microfarads)
(This equation is a simplified derivation of above equation.)
Example Zin = 47K, f3 = 90 Hz, C = 1/2pi(47,000)(90) = 38 nF.
If the amplifier has an input capacitor, then remove it and replace it with your series capacitor.
Output impedance of driving device needs to be much lower than the input impedance of the amplifier. Typical mobile devices have an output impedance ranging from a few ohms to around 40 ohms, which would not affect the performance of the circuit. Typical preamps have an industry standard of 47 ohms output impedance, but again this varies.
So you need to know the input impedance of your amplifier to design this circuit.
C = 1/2pi(Zin)(f3) where
Zin = amplifier input impedance in Ohms
f3 = desired -3dB cutoff frequency in Hertz
C = series capacitor in farads (NOT microfarads)
(This equation is a simplified derivation of above equation.)
Example Zin = 47K, f3 = 90 Hz, C = 1/2pi(47,000)(90) = 38 nF.
If the amplifier has an input capacitor, then remove it and replace it with your series capacitor.
Output impedance of driving device needs to be much lower than the input impedance of the amplifier. Typical mobile devices have an output impedance ranging from a few ohms to around 40 ohms, which would not affect the performance of the circuit. Typical preamps have an industry standard of 47 ohms output impedance, but again this varies.
So you need to know the input impedance of your amplifier to design this circuit.
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oow goodie help already!
was hoping for something generic that i can swap between amps.
I use tpa3116/8, irs2092,tpa3250, tas5611, tpa3255, tk2050. I mainly use the tpa3116 black board for these speakers. I have attached the 2 Input Impedance related pages from the datasheet for the tpa3116. next looks like i need to find out what gain resistors are used to know the Input Impedance, right?
next ill get photos of the speakers
was hoping for something generic that i can swap between amps.
I use tpa3116/8, irs2092,tpa3250, tas5611, tpa3255, tk2050. I mainly use the tpa3116 black board for these speakers. I have attached the 2 Input Impedance related pages from the datasheet for the tpa3116. next looks like i need to find out what gain resistors are used to know the Input Impedance, right?
next ill get photos of the speakers
heres the photos of my speakers and the amp i use with these ones, which is in fact YJ SMD version of tpa3116 boards:
Yuan Jing Audio - ON SALE! - TPA3116 Class-D 2.0 Stereo Amplifier Board + Anti-Pop - USD $14.99
I think these speakers are European or German - made or designed. there was very little info about them, think i remember.
Yuan Jing Audio - ON SALE! - TPA3116 Class-D 2.0 Stereo Amplifier Board + Anti-Pop - USD $14.99
I think these speakers are European or German - made or designed. there was very little info about them, think i remember.
Attachments
I”m not sure what i need. How do i work out how many *dB per octave i need?
I even wonder would a passive post amp speaker "crossover" (not really a crossover, just a freq limit filter.) is what i want? would be generic and work with any amp but i lose efficacy. The speakers don’t have cross over. the tweeter seams to have its own thing cus it was just wired in parallel with the mid/bass speaker.
I should mention come to think of it, these speakers where originally 100v ones but i removed the transformer to turn them into normal speakers. The transformer had a fat cap across it. i can get a photo of it? still got them laying around.
I even wonder would a passive post amp speaker "crossover" (not really a crossover, just a freq limit filter.) is what i want? would be generic and work with any amp but i lose efficacy. The speakers don’t have cross over. the tweeter seams to have its own thing cus it was just wired in parallel with the mid/bass speaker.
I should mention come to think of it, these speakers where originally 100v ones but i removed the transformer to turn them into normal speakers. The transformer had a fat cap across it. i can get a photo of it? still got them laying around.
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With passive you're pretty much stuck with 3 dB/octave. Otherwise go active.
Will probably require a large, expensive capacitor.
Will only be "generic" if the input impedances of your amps are the same.
Do you know the input impedance of your amplifier?
ok, thx. knowing that is quite helpful.
i could potently live with that.
nope. a prev post was about my efforts to try and see about working that out.
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Here is are photos of the original transformer from the speakers from when they where 100v ones. it had this 15uF kerpen cap and parallel 220R resistor in series with what i guess(?) was the ground of the user/installer connections to the speaker transformer.
Can this cap be used for a speaker side/post amp passive low freq filter? or did it do something else to do with it being a 100v line speaker?
Can this cap be used for a speaker side/post amp passive low freq filter? or did it do something else to do with it being a 100v line speaker?
Attachments
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Hello too, ceulrich
Do you have a copy of this spreadsheet? i would be interested in a copy please.
Thanks
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Spreadsheet
Hello cacao ambiance,
If you can work with Excel V14.7.0 for a Mac, send me your e-mail address off forum at dwpharma2@gmail.com and I will send you a copy.
Cheers,
ceulrich
Hello cacao ambiance,
If you can work with Excel V14.7.0 for a Mac, send me your e-mail address off forum at dwpharma2@gmail.com and I will send you a copy.
Cheers,
ceulrich
To block lows, 100-200uf non polar capacitor in series with speakers, if 8 ohm. Double that if 4 ohm. Should be $3 or so. 63volt or 100. 6 db high pass filter
I don't understand your question.
The amplifier goes before the speaker in the audio system.
Do you want to filter the signal going into the amplifier, or do you want to filter the signal after passing through the amplifier, i.e. at the speaker?
The filters for these two alternative duties are very different !
yes, i’m (now) interested in both.
When i started this thread i was just thinking about passive before amp filter. then i started to think and remember about a post amp, internal to speaker passive filter as i would then not have to match the amp impedance for a before amp line level passive filter. So later in the thread I ask about speaker post amp passive filter.
Sorry for the confusion. i should really start a new thread regarding post amp passive filters, in a more correct forum category...
If you want to do the high pass before the amp, this should be very helpful.
TLS.org | Passive Line-Level Crossover
If you want to do it after the amp, you'll need large value caps for a 90Hz high pass. There are many online calculators, this is a good one.
2-Way Crossover Calculator / Designer
TLS.org | Passive Line-Level Crossover
If you want to do it after the amp, you'll need large value caps for a 90Hz high pass. There are many online calculators, this is a good one.
2-Way Crossover Calculator / Designer
ok i think i finally understand it. in the speaker crossover calcs. Even-though the high pass cap is intended for the treble speaker, i just put the cross over at 90hz 4ohm for both treble and bass speakers and use the cap it calculates for treble speaker for my mid,bass speaker! i always thought the high pass cap was only for the treble speaker for some reason! arr at last.
so i have extracted some 100v+ 100uF,330uF,470uF caps and been playing around with them seams to do they job.
Interestingly i think there is some distortion in the base with the bigger values still... but 100uf while on its own is ok, compared to 330uF i hear how much bass im losing and in a open bigger space, i suspect ill notice more. i wonder how 200uf would sound... need to find a cap...
I wonder if maybe i damaged the speakers for driving them on the hard side, with low freq they where not designed for. :/ I tried quite a lot, to not over do it... but i guess its hard not too...
next is to pop these caps into online calc to see what the high pass filter freq is with each one. need to find the track list for my freq test cd too kinda hard to tell which freq is which from the test cd without it! or ill use gnu/linux cli SOX software to generate new test freq files. maybe even dare to approach learning hot to use scope to see whats happening...
also wondering how a 2rd order high pass would affect things? cus when i turn the bass more than i normally would to see what happens it distoruts in a unpleasant bad PA way and so i wonder if that is something to do with the sharp cut off?
Thank you all!!! Huge Help
Im still have an interest in trying out passive line level pre amp filters... after i face up to working out how to find out amp impedance. Looks like i will end up using post amp speaker filters for there genericness, efficiency wise my problem is putting to much power into them so i can live with a few % loss. I can put the caps on the spare speaker terminals so i have future choices of with and without
so i have extracted some 100v+ 100uF,330uF,470uF caps and been playing around with them
seams to do they job. Interestingly i think there is some distortion in the base with the bigger values still... but 100uf while on its own is ok, compared to 330uF i hear how much bass im losing and in a open bigger space, i suspect ill notice more. i wonder how 200uf would sound... need to find a cap...
I wonder if maybe i damaged the speakers for driving them on the hard side, with low freq they where not designed for. :/ I tried quite a lot, to not over do it... but i guess its hard not too...
next is to pop these caps into online calc to see what the high pass filter freq is with each one. need to find the track list for my freq test cd too
kinda hard to tell which freq is which from the test cd without it! or ill use gnu/linux cli SOX software to generate new test freq files. maybe even dare to approach learning hot to use scope to see whats happening...also wondering how a 2rd order high pass would affect things? cus when i turn the bass more than i normally would to see what happens it distoruts in a unpleasant bad PA way and so i wonder if that is something to do with the sharp cut off?
Thank you all!!! Huge Help
Im still have an interest in trying out passive line level pre amp filters... after i face up to working out how to find out amp impedance. Looks like i will end up using post amp speaker filters for there genericness, efficiency wise my problem is putting to much power into them
so i can live with a few % loss. I can put the caps on the spare speaker terminals so i have future choices of with and without
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Good, glad you figured it out. I didn't mention that part about using the tweeter section as your woofer high pass, hoping you would figure it, and you did. 
A 2nd order just rolls off the bass twice as fast.
What kind of caps are you using? For speaker crossovers you'll need to use non-polarized caps, since the signal is AC.
A 2nd order just rolls off the bass twice as fast.
What kind of caps are you using? For speaker crossovers you'll need to use non-polarized caps, since the signal is AC.
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