Working out X/O values using this online calculator

[Bill poster]

Just found this useful calculator

ERSE - Crossover Calculator - First Order 2 Way

when I input the impedance, should it be the overall rating of the driver (ie 8 ohm) or the impedance level of the driver at the point of x/over ( in this case, 7 ohm @ 350 hz) ?

[tinitus]

neither
there is no fixed impedance

mostly you will need to calculate with a lower xo point, resulting in bigger inductor
look at impedance above xo point
imagine what happens when the inductor 'meets' the rising impedance
a zobel takes care of some of those problems, but not all of it

low impedance, small inductor, big cap
high impedance, big inductor, small cap

[Bill poster]

Kind of understand crossovers are something I never got to grips with, hence going for as simple design as poss. Prob a good idea to get cheap caps first etc before splashing out on sonicap platinums etc

[PeteMcK]

the impedance level of the driver at the point of x/over - always

[AllenB]

Originally Posted by Bill poster

Prob a good idea to get cheap caps first etc

Some of us change our crossovers regularly over periods of months. Using the correct crossover components and values is far and away more important than how much you spend on a capacitor, provided you at least make sensible choices on the types of component you use.

The basic issue with crossovers is twofold. Firstly, although you want to shape the tweeter and woofer response so they match up, they are anything but even and flat to start with...so the needs of your crossover will vary depending on what frequency you are looking at.

Secondly, the drivers' impedance is anything but flat either, so the crossovers will behave differently depending on the frequency, and this may give unexpected results.

This usually also means that what the tweeter needs will not be the opposite of what the woofer needs. When designing a crossover using modern techniques, the rules may go out the window.

If you want, I will outline a simple but effective starting method for building a two way crossover using 8 components, which is useful for when you want to adjust it by listening methods.

[PeteMcK]

Allen, re:' I will outline a simple but effective starting method for building a two way crossover using 8 components' - please do... this is one of the most asked & misunderstood questions on this site. It would be a good idea to put it in Articles or the Wiki too....

[Cal Weldon]

AllenB,
Bring it to my attention, I will take the idea of making it a sticky to the back room. Please PM me when you have posted.

[pinkmouse]

And I'll remind him.

[AllenB]

Thanks guys, I'll start writing tonight.