Series Crossover Question

[jimiw]

Just wondering if I am understanding this correctly.
In a 1st order series crossover the inductor value determines the tweeter crossover frequency and the cap determines the woofer?

I ask because my speakers have this:

An externally hosted image should be here but it was not working when we last tested it.

112uF = 355Hz (Woofer)?
.86mH = 740Hz (Tweeter)?

Thanks

J

 

[eriksquires]

Try it with XSim it's free and will simulate that quite easily. 🙂

Erik

 

[speakerdoctor]

I second that motion Erik!

 

[rayma]

In a 1st order series crossover the inductor value determines the tweeter crossover frequency
and the cap determines the woofer?

Yes, the relative impedance of the driver and the shunt impedance across it determines how
the amplifier's output current splits between the two vs frequency. It works the same for
either the tweeter//L or the woofer//C. Connecting the two pairs in series results in a constant input impedance.

 

[jimiw]

Thanks!

And XSim is really cool!

An externally hosted image should be here but it was not working when we last tested it.

 

[rayma]

XSim is really cool!

With a first order crossover, the drivers are usually both connected with the same polarity.
Is the Magnepan really connected like that?

 

[system7]

Series filters are tricky beasts. Your simple one has no bafflestep bass boost, so is probably a wallmounter whatever the drivers.

You can do simple with smooth well behaved drivers and an efficient tweeter.

Here's a 8" bass design with 4 ohm woofer that is high inductance, so will sound reasonably bassy. The WLM La Scala reinvented by me. 😱

Next is a cool series filter by Cousin Billy. You can actually replace the red 8 ohm resistor with a fullranger for a three way. Genius.

Modelling required, of course. Downloads

 

[speakerdoctor]

Thanks!

And XSim is really cool!

An externally hosted image should be here but it was not working when we last tested it.

Did you use measured FRD and ZMA files or mfg. traced curves for those drivers? or just nominal values? Curves look too clean and XO point seems low for a 2-way.

 

[jimiw]

@system7, These are Magnepan MMGs.

@rayma, I double checked and that's what it looks like. the Woofer +, Tweeter + cap and coil are all wired together.

@speakerdoctor, I just used a generic 4 ohm ZMA.
10 4 0
10.1517 4 0
10.3056 4 0
10.4619 4 0
10.6205 4 0
... etc.

I was mainly just trying to determine the crossover point as I ripped out the junky crossover parts and am now bi-amping with miniDSP 10x10.

Thanks!

 

[wolf_teeth]

Guys- it's a Magnepan.
There won't be BSC because it's a dipole. At any rate, not the same method. My guess is the driver sensitivities will affect that the most here.
The large membrane can xover wayyyy lower than your average tweeter.
If he's running active, all he needed is the transfer function anyway, and the planar units are likely flat impedance. He's likely pretty close.

When I saw the 0.86mH, I thought that better be a wide-ranger or very robust tweeter xovering that low, but it's likely of no concern in this particular case.

Later,
Wolf