Hi all,
I've been looking for the cheapest way to make myself a crossover and I learned about using RC filters for high and low-pass. (looking to split mono signal from an amp into two small-ish speakers: one for higher and one for lower frequencies)
From what I can tell, making RC crossovers is as easy as using a calculator to put your values into and playing around until you get your desired cutoff frequencies. Here's an example of one of these:https://www.trance-cat.com/electrical-circuit-calculators/en/rc-low-pass-filter-calculator.php
However, when looking around the web for the most optimal values for these RC filters, I couldn't find much info - this makes me think something is wrong with using these filters for audio... I see a lot about passive filters utilizing inductors rather than resistors, but to me it looks like they work pretty much the same.
My question: Is there a reason using RC filters for high/low pass is bad? The only negative I can think of is the fact that your resistor slightly lowers your output volume. I figured this isn't a big deal as long as you're using small resistors and whatever size capacitor gets you your desired cutoff frequency.
Bonus question: If I were to use RC filters as my values, does anyone have any recommendations on what cutoff frequencies I should use for a smaller boombox setup (~2" - 4" full range speakers)? What size/type of resistors and capacitors should I buy for my high/low pass?
I've been looking for the cheapest way to make myself a crossover and I learned about using RC filters for high and low-pass. (looking to split mono signal from an amp into two small-ish speakers: one for higher and one for lower frequencies)
From what I can tell, making RC crossovers is as easy as using a calculator to put your values into and playing around until you get your desired cutoff frequencies. Here's an example of one of these:https://www.trance-cat.com/electrical-circuit-calculators/en/rc-low-pass-filter-calculator.php
However, when looking around the web for the most optimal values for these RC filters, I couldn't find much info - this makes me think something is wrong with using these filters for audio... I see a lot about passive filters utilizing inductors rather than resistors, but to me it looks like they work pretty much the same.
My question: Is there a reason using RC filters for high/low pass is bad? The only negative I can think of is the fact that your resistor slightly lowers your output volume. I figured this isn't a big deal as long as you're using small resistors and whatever size capacitor gets you your desired cutoff frequency.
Bonus question: If I were to use RC filters as my values, does anyone have any recommendations on what cutoff frequencies I should use for a smaller boombox setup (~2" - 4" full range speakers)? What size/type of resistors and capacitors should I buy for my high/low pass?
I think this belongs in the multiway forum.
Using a passive RC crossover filter between the amplifier and the loudspeakers has several disadvantages:
-When the impedance level is very low, you blow up the amplifier, when it is somewhat higher, the damping of the woofer's response is seriously degraded.
-You can only make filters with noncoincident real poles with RC filters, which is jargon for very slow roll-off around the crossover frequency.
Using a passive RC crossover filter between the amplifier and the loudspeakers has several disadvantages:
-When the impedance level is very low, you blow up the amplifier, when it is somewhat higher, the damping of the woofer's response is seriously degraded.
-You can only make filters with noncoincident real poles with RC filters, which is jargon for very slow roll-off around the crossover frequency.
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A capacitor in series with an tweeter IS an RC filter, works, and has been used since forever.
It does what is expected from it: let highs through and cut lower frequencies.
Not the sharpest one but acceptable and efficient.
Now for the woofer you need the opposite, a lowpass filter, and an inductor in series with woofer is the equivalent, with all same considerations.
IF you want to avoid an inductor using an RC system, you need a big resistor, about same impedance as woofer (so you already start with a 6dB loss) which will also kill damping and to boot will dissipate as much as the woofer.
A lose-lose situation just to skimp on an inductor.
It does what is expected from it: let highs through and cut lower frequencies.
Not the sharpest one but acceptable and efficient.
Now for the woofer you need the opposite, a lowpass filter, and an inductor in series with woofer is the equivalent, with all same considerations.
IF you want to avoid an inductor using an RC system, you need a big resistor, about same impedance as woofer (so you already start with a 6dB loss) which will also kill damping and to boot will dissipate as much as the woofer.
A lose-lose situation just to skimp on an inductor.
Are you doing that thing that Sonus Faber likes to do? They have an interest in keeping their crossover as simple as possible, but this is difficult. They notice that their tweeter crossover, a resistor and capacitor in series with the tweeter, is susceptible to the impedance peak. The response goes up when it should be going down and leaves a response peak.
This wouldn't be an issue if the tweeter didn't see such a high impedance at these frequencies. They changed to an RL crossover, no capacitor in the tweeter circuit. Thus simple, but effective enough.
The inductor needs to be of especially high quality. With the right measurement equipment this shouldn't be a problem.
This wouldn't be an issue if the tweeter didn't see such a high impedance at these frequencies. They changed to an RL crossover, no capacitor in the tweeter circuit. Thus simple, but effective enough.
The inductor needs to be of especially high quality. With the right measurement equipment this shouldn't be a problem.
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