Active Crossover Schematic

[deriver23]

Could anyone supply me with a schematic for a 2-way(highpass/lowpass) active crossover?

[Lothar34]

You sure you want an active crossover? Usually you buy an active crossover, and build a passive one.

[pinkmouse]

Originally posted by Lothar34
You sure you want an active crossover? Usually you buy an active crossover, and build a passive one.

Not at diyAudio. We build everything!

There are many threads discussing active crossovers over in the Loudspeaker area, and you could have a look at Rod Elliot's site.

[Lothar34]

Originally posted by pinkmouse


Not at diyAudio. We build everything!

There are many threads discussing active crossovers over in the Loudspeaker area, and you could have a look at Rod Elliot's site.

I checked his profile and it said "noob diy in car audio" so I assumed he wasn't going to build an active one. I've been wrong before though...

[v-bro]

Maybe this will help making things easier, good functioning and deadcheap:
http://www.t-linespeakers.org/tech/f...ssiveHLxo.html

To maybe make things a little easier to understand from the start:

Resistor in series capacitor parallel cuts the highs, capacitor in series resistor parallel cuts the lows(same values, same x-over frequency).

Increasing values lowers x-over freq.
Decreasing values rises x-over freq.

With only two components per channel you can create a 6db's decreasing per octave filter!

With only four components per channel you can create a 12db's decreasing per octave filter!

Choise of component quality in order of preference:
Capacitor:"peanutbutter oil soaked paper-foil caps" (joke) "MKP","MKC","MKT".
Resistor:at least "metalfilm"

[deriver23]

v-bro i would prefer to build (or buy) a 4th order(24 db/octave) Linkwitz/Reily active x-over because of the superior sound quality.
i think that i am up to it i am thiking about building the one on rod elliot's website. if you know of any relatively inexpensive or easy to build x-over like this of these please let me know (less than $50 ??)

[v-bro]

"Active" has nothing to do with "superior soundquality", 24db/octave slopes can be usefull for speakers that behave badly outside their freq-range, so look at this:http://www.marchandelec.com/xm46.html

The circuitry and component count in a device like this is extremely minimal (thus easy to build), this simplicity improves soundquality dramatically (when compared to most cheap active op-amp based x-overs).

[deriver23]

does active have anything to do with the x-over frequency? because some of the active crssovers have a 300hz x-over frequency? what x-over frequency do you reccomend? If there is no quality difference between active x-over and passive then why ever use an active one? I want to biamp (with one amp parallel bridged) does this affect what crossover i would use? if i built the one you sugested i would have to use more than one correct?
is it possible for a modification to be mad so that it will go doawn to 20hz?

on a side note on the link you provided for x-over information this is a direct quote "you can live with the insertion loss ... beyond 2nd order the drawbacks become overwhelming. "

[v-bro]

Provided the higher freq driver can handle it I would recommend an x-over freq as low as possible. Active x-overs have 1:1 in-output volume, passive ones have slight insertion loss (fixeable when using enough power/good eff. speakers).

Indeed you use more than one, it's much like the passive loudspeaker filters that use much larger (l-c instead of r-c) components. Only passive loudspeaker filters become very expensive when filtering lower freqs because of the immense components needed. Passive line level filters though need only very small components and therefore can be built relatively cheap.

Making it go down to 20hz is possible in many ways (using a bandpass enclosure for instance, or filtering away a lot of the efficiency (notch filtering) in order to create deeper roll-off).

[v-bro]

I should add that I am experimenting a lot on this type of filtering at the monent and have noticed some filters give only little insertion loss and some alot.

Quality of the components seems pretty important, also found in the pricelist from marchand elecronics a kit for one filter for 65 dollars, the loss would be only -1 db at 24db/oct!

I think I will order one soon to figure out how it works...