# Non-altering, reactive elements, signal frequency division, in a 3way audio speaker

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#### PatrickMalarkey

Joined Oct 2, 2021
120
A series reactive element will change the waveform of any non-sinusoidal signal, because of the maximum rate of charging, set by the series resistance, always present in any non-superconducting medium. Therefore, it is desirable to use shunt reactive elements for the crossover network in an acoustic speaker system; the attached photo/sketch is an arrangement for a 3-way system.

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#### BobTPH

Joined Jun 5, 2013
7,507
So if we send at square wave at, say, 100Hz to the woofer through a crossover, the signal at the woofer should still be a square wave, right?

Bob

#### crutschow

Joined Mar 14, 2008
32,841
The series resistance of any reactive crossover components will have little effect on the waveshape to the speakers at audio frequencies.

Your circuit has the serious disadvantage of having series resistors which will significantly reduce the signal amplitude to the low impedance speakers, waste power, and kill the low damping factor of the amplifier which is needed to minimize overshoot and ringing in modern speakers.

#### PatrickMalarkey

Joined Oct 2, 2021
120
So if we send at square wave at, say, 100Hz to the woofer through a crossover, the signal at the woofer should still be a square wave, right?

Bob
Bob if you're replying to my post of a 3-way crossover network, no I'm certainly not trying to convey that. A square-wave isn't a sinusoidal waveform and will be changed from a square-wave to a sinusoidal waveform, by either a capacitor or an inductor in a series circuit with a resistance. If you'll recall your first term book on AC/DC theory, consider the RC or LC time-constant and the limits on the charging rate presented by the combination of reactance and resistance.

#### PatrickMalarkey

Joined Oct 2, 2021
120
The series resistance of any reactive crossover components will have little effect on the waveshape to the speakers at audio frequencies.

Your circuit has the serious disadvantage of having series resistors which will significantly reduce the signal amplitude to the low impedance speakers, waste power, and kill the low damping factor of the amplifier which is needed to minimize overshoot and ringing in modern speakers.
Yes it will lessen the sound from the drivers and waste power, but conservation of minor amounts of power aren't what this shunt system tries to overcome. Unadulterated sound quality is, and to me it's permissable to waste a little wattage.

#### BobTPH

Joined Jun 5, 2013
7,507
You said a series reactive element will change the waveform, therefore using shunt elements is preferable.

This implies that using shunt elements will not change the waveform. Which, of course, is not true.

A filter, by definition, must change the waveform. So I have no idea why you think that shunt elements are better than series elements.

You may well have a valid point , but you have not conveyed it,

Bob

#### ci139

Joined Jul 11, 2016
1,874

#### crutschow

Joined Mar 14, 2008
32,841
Yes it will lessen the sound from the drivers and waste power, but conservation of minor amounts of power aren't what this shunt system tries to overcome.
Your resistor is wasting a lot more than a minor amount of power, as well as reducing the damping factor, which will likely have more detrimental effect on the sound then the change in the filter.
You perceived improvement in sound quality has no basis in fact.

If you really are that concerned about the passive effects of the crossovers on the sound, then then usual way is to use a bi-amp (or in this case tri-amp) system with a separate amp to each speaker, and the filters being active Linkwitz–Riley crossover filters at the amp inputs.
That way you get near perfect crossovers with none of the possible problems of passive filters, or the change in speaker impedance with frequency that also affects a passive crossover response.

#### MrChips

Joined Oct 2, 2009
29,194
Did the TS have a question?

It would be better understood if loudspeaker crossover networks were analyzed from a frequency response perspective. The purpose of the crossover network is to pass high frequencies to the tweeter, middle frequencies to the mid-range speaker and low frequencies to the woofer.

#### BobTPH

Joined Jun 5, 2013
7,507
Except that he also believes capacitors distort the signal in an amplifier so they would , presumably, havr the same bad effect in a signal level crossover network.

Bob

#### BobTPH

Joined Jun 5, 2013
7,507
Did the TS have a question?
No, just showing off his superior knowledge, as usual.

Bob

#### Ian0

Joined Aug 7, 2020
8,361
Neither capacitors or inductors Distort the signal anywhere near as much as a loudspeaker does.

#### BobTPH

Joined Jun 5, 2013
7,507
Yep, that is why I look forward to the DBI (direct brain interface) for audio. It also gets around my hearing loss.

Bob

#### PatrickMalarkey

Joined Oct 2, 2021
120
You said a series reactive element will change the waveform, therefore using shunt elements is preferable.

This implies that using shunt elements will not change the waveform. Which, of course, is not true.

A filter, by definition, must change the waveform. So I have no idea why you think that shunt elements are better than series elements.

You may well have a valid point , but you have not conveyed it,

Bob
I differ about shunt reactive elements, because for an acoustic signal there are non-sinusoidal qualities that aren't passed by series reactive elements. They are rejected by reactive elements; and, therefore rejected by shunt circuited elements. And in the picture of a crossover network, those qualities are passed to the drivers. Except maybe the midrange, it's kept from a too low overall impedance system by those resistors.

#### Ian0

Joined Aug 7, 2020
8,361
A tweeter that is across the full bandwidth amplifier output with only a 4Ω series resistor will soon be a dead tweeter.

#### LowQCab

Joined Nov 6, 2012
3,446
On this subject there is only 1 winner, hands-down ..........
Modern Digital-Active-Crossovers provide extremely high-performance
that can't even remotely be touched by ANY Passive-Crossover.

If You still want to putz around with Passive-Crossovers,
I suggest You look into a Series-Connected, First-Order-Crossover.
They're very forgiving of Impedance-mismatches, and Frequency-miscalculations,
but not so great for ultimate Tweeter-protection.
They're very easy to get an excellent result with,
and have a sort-of "self-adjusting" quality,
and make a great up-grade to a cheap set of "Book-Shelf" Speakers.
.
.
.

#### Ian0

Joined Aug 7, 2020
8,361
A bass unit already has series inductance. If you find one with a reasonably smooth hf roll-off (no big peaks or dips in response) it can be used without a crossover, as its own series inductance will prevent the impedance getting too low when it is placed in parallel with the tweeter.

#### Ya’akov

Joined Jan 27, 2019
8,146
Have you characterized the distortion you are trying to eliminate? What does it look like?
I also wonder what the output of your alternative filter looks like. Do you have any idea?

#### Ian0

Joined Aug 7, 2020
8,361
I also wonder what the output of your alternative filter looks like. Do you have any idea?
That's not going to be easy! - the series element in the filter is the inductance and resistance (and all the mechanical resonances) of a loudspeaker.

#### Ya’akov

Joined Jan 27, 2019
8,146
That's not going to be easy! - the series element in the filter is the inductance and resistance (and all the mechanical resonances) of a loudspeaker.
I suppose the bestone could hope for is a comparison into a pure resistance.

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