Hello, I am thinking of building a bandpass filter for the mids in my car. I've got everything figured out except for the resistor wattage. What wattage resistors should I use?
Amp:90W RMS @ 4 ohm
Mid speakers: 50W RMS @ 4 ohm
Amp:90W RMS @ 4 ohm
Mid speakers: 50W RMS @ 4 ohm
The average power dissipated by the mid filter resistors will be low.
10W wirewound resistors are adequate for your application.
10W wirewound resistors are adequate for your application.
While searching for information, I saw that the most power is used at around 350 Hz. Will the 10W really be enough, and if so, mind sharing how you got that value?
Seeing that you posted in Analog Line-Level, indicating a filter position ahead of the power amp, chances are we're looking at 1/4 W metal film.
Mind sharing the filter topology you had in mind? If you do need something passive between power amp and speaker, be aware that crossover filter designs only tend to be using as much resistance as needed to match sensitivity between the drivers, otherwise they tend to be relying on LC filtering as much as possible - efficiency with RC filtering would be terrible. Speaker design software is advisable for good results, speaker drivers have a habit of not being terribly resistive in nature.
Mind sharing the filter topology you had in mind? If you do need something passive between power amp and speaker, be aware that crossover filter designs only tend to be using as much resistance as needed to match sensitivity between the drivers, otherwise they tend to be relying on LC filtering as much as possible - efficiency with RC filtering would be terrible. Speaker design software is advisable for good results, speaker drivers have a habit of not being terribly resistive in nature.
I want to connect the passive filter between the amp and the speakers, containing of two resistors and two capacitors( one of each for LPF and one of each for HPF). I thought of using this scheme: Screenshot-2018-12-15-14-01-27-476-com-android-chrome — imgbb.com
As sgrossklass mentions, RC filtering (as shown in your scheme) is inefficient.
You need LC (inductor/capacitor) filtering for maximum efficiency.
Investigate loudspeaker crossover networks - midrange band pass filter.
Band-pass filter 12dB per octave
Resistors are not normally required in an LC bandpass filter.
You need LC (inductor/capacitor) filtering for maximum efficiency.
Investigate loudspeaker crossover networks - midrange band pass filter.
Band-pass filter 12dB per octave
Resistors are not normally required in an LC bandpass filter.
The same as the impedance of the midrange speaker for which you are designing the band-pass filter.
(Assuming you are using one mid per channel - if more than one per channel then supply more detail.)
(Assuming you are using one mid per channel - if more than one per channel then supply more detail.)
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I'm thinking of using multiple speakers per channel. In that case I'd need to use the total impedance of all speakers (let's say 2 speakers in parallel, 4 ohm each would give a total of 2 ohms), right?
Yes, you would use the total impedance of the combination.
However, a total of 2 ohm is rather low and you would have to be sure that your amplifier can handle a 2 ohm load without fear of damage to the amp.
The alternative is to have two 4 ohm mids in series (8 ohm total) or two 8 ohm mids in parallel (4 ohm total).
However, a total of 2 ohm is rather low and you would have to be sure that your amplifier can handle a 2 ohm load without fear of damage to the amp.
The alternative is to have two 4 ohm mids in series (8 ohm total) or two 8 ohm mids in parallel (4 ohm total).
I can't give you a link to a page of assembled LC crossover boards, but if you go to Parts Express: Speakers, Amplifiers, Audio Parts and Solutions then click speaker components, then click assembled passive crossovers, you'll see a lot of them for sale. The lower power ones don't have a power rating, but the higher power ones do. This vendor is in the US.
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