Hi Thanks for reading. I’m building a three-way crossover.
Concerning the mid and tweeter filter, I am using a capacitor in series with the drive unit and an inductor across the drive unit to form a second-order filter.
Can I use a cheap ferrite core inductor across the drive unit, or does it have to be a good quality air core, to achieve the best sound quality. My thinking is: Since I will never hear the sound signals that pass through the inductor, not matter what the inductor does to those sound signals, it should not affect the sound coming out of the speakers. Is this true?
Or does the inductor affect the end sound that will come out of the speakers
Concerning the mid and tweeter filter, I am using a capacitor in series with the drive unit and an inductor across the drive unit to form a second-order filter.
Can I use a cheap ferrite core inductor across the drive unit, or does it have to be a good quality air core, to achieve the best sound quality. My thinking is: Since I will never hear the sound signals that pass through the inductor, not matter what the inductor does to those sound signals, it should not affect the sound coming out of the speakers. Is this true?
Or does the inductor affect the end sound that will come out of the speakers
The Voltage that appears across the driver which represents the signal to it, is the same Voltage that the inductor has formed across itself in combination with the speaker.
This is incorrect and a common misconception.
In a second-order filter, both elements play essentially an equal role in affecting the sound.
A series element divides voltage. A parallel element divides current. Both affect the final current through the driver’s voice coil.
If you have a voltage source (most audio amps are voltage sources), then the only time a parallel component (or block) doesn’t affect the rest of the circuit is if it is wired across the entire voltage source. In that case, it simply causes more current to be drawn from the amp. This, still, may slightly affect the sound depending on the amp.
But if the component is in parallel across the driver, and there are any other components in series (as is the case in a 2nd order filter) then the component certainly IS part of the signal path.
This is easy to hear. Take an 8ohm driver. Put a 4ohm resistor in series with it. You’ve attenuated it slightly. Now put a 1mH inductor across the driver. You’ve now high-passed it at 636hz. Any non-linearities or other non-idealness of the inductor will shine through and affect the sound.
Regarding how much inductor quality and type matter, there’s another recent thread on the topic. My personal approach is to get the largest awg air coils I can afford. And don’t bother paying extra for Litz or flat-wound.
My way of looking at it is that combining a capacitor and inductor in series forms a voltage divider.
In a voltage divider, the component with the largest opposition to the flow of current will have the largest voltage developed across it.
Now consider supplying a mixture of low and high frequency currents to a series capacitor and inductor combination:
Since the capacitor has the larger opposition to the flow of low frequency current, the low frequency voltages develop across the capacitor.
Since the inductor has the larger opposition to the flow of high frequency current, the high frequency voltages develop across the inductor.
The capacitor can therefore be used as a low frequency voltage source for a woofer and/or the inductor can be used as a high frequency voltage source for the tweeter.
To your question: If an inductor somehow distorts the high frequency voltages being developed across it, it will distort the sound from the tweeter.
In a voltage divider, the component with the largest opposition to the flow of current will have the largest voltage developed across it.
Now consider supplying a mixture of low and high frequency currents to a series capacitor and inductor combination:
Since the capacitor has the larger opposition to the flow of low frequency current, the low frequency voltages develop across the capacitor.
Since the inductor has the larger opposition to the flow of high frequency current, the high frequency voltages develop across the inductor.
The capacitor can therefore be used as a low frequency voltage source for a woofer and/or the inductor can be used as a high frequency voltage source for the tweeter.
To your question: If an inductor somehow distorts the high frequency voltages being developed across it, it will distort the sound from the tweeter.
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I made a little edit in line 3 above in the pursuit (hopefully) of clarity!
Thanks! What do you think of this inductor, would it be good for crossover use:
https://cpc.farnell.com/multicomp/m...nductor-40uh-20-2-pins/dp/FT01570?st=inductor
Does the former have an effect. The value i need is 40 uh
I'm leaning towards air core inductors Thanks!
https://cpc.farnell.com/multicomp/m...nductor-40uh-20-2-pins/dp/FT01570?st=inductor
Does the former have an effect. The value i need is 40 uh
I'm leaning towards air core inductors Thanks!
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Is lowest resistance always best?
We all know speakers are not resistors, but complex impedances. Unless impedance correction is made (which is not always done due extra cost and complexity), there will be interactions between x-over components and speaker impedance in a form of secondary resonances. For eg, they can manifest as bumps in response or notches in impedance curve.
From my experience, a bit higher resistance in coils is often beneficial to control those interactions, beacuse it controls the Q of secondary resonances.
The proof are nomerous occasions when people "improved" factory x-overs with lower resistance, thicker wire coils (and lower resistance foil caps instead of bipolar elcos) and then found tonal balance is messed up.
Example of achieving exactly LR2@1k with different coil resistances - 0, 1 and 3 ohms.
Clearly the latter.
What if I conjugated a real woofer to adjust the low end resonance damping to my liking. That would work?
What if I conjugated a real woofer to adjust the low end resonance damping to my liking. That would work?
That type of inductor is not suitable for loudspeaker crossover use!
40 microhenry (0.04 millihenry) seems a small value for use in a loudspeaker crossover. How did you arrive at that value?
I think you should show us your proposed crossover layout, complete with component values, so we can check it all out.
8I like the illustration of post 9. I can for instance show how one could make a mid pass band shape by balancing the low pass with high pass atenuation resistor and make a sligthy diving curve in spite of flat according the value of the high pass attenuation resistor (or cps ESR as well?)
And btw the same between the mid low pass spl level and the tweeter high pass to let continue a sligth rolling magnitude shape ?
And btw the same between the mid low pass spl level and the tweeter high pass to let continue a sligth rolling magnitude shape ?
@goodguys You are looking at the cpc site, so here's an example of a loudspeaker crossover inductor on that site:
https://cpc.farnell.com/unbranded/l...dp/TF00268?st=loudspeaker crossover inductors
You'll get a greater choice of inductors, both air core and ferrite core, from this supplier: https://wilmslowaudio.co.uk/inductors
https://cpc.farnell.com/unbranded/l...dp/TF00268?st=loudspeaker crossover inductors
You'll get a greater choice of inductors, both air core and ferrite core, from this supplier: https://wilmslowaudio.co.uk/inductors
Makes sense to have a sligthy 5 dB roll off between the low end and high end of the loudspeaker (Harmann Curve ?) ?
Is this possible as a low pass filter, in working practise i mean. Take a 4 ohm resistor and place in series with an 8 ohm drive unit. Then place a 10 uf cap across the drive unit. Crossover frequency should be something like 1khz.