About crossover

[rulezzz]

This crosover which i posted is 300-400Hz lowpass with
-2db on <400Hz and -10 on >400Hz i dont realy know is that true.Maybe somebody could post,or give a link of passive crossover WITHOUT induction (i have problems with it can't make it correctly) which would be like this :<80Hz <-2db (or less but not lower than -8db) lowpass and - 40db(could be lower but not higher than -35d) >120Hz.
Any information would be very helpfull.
Or if u can post active crossover like that with lowpass <80Hz and -40db >120Hz.And can u please write the microshem which to use for the amplifier because i found crossover like this but there is no microshem number only "amplifier"i tried to use lm358 and it didn't worked ,maybe i connected input and output not right ,don't know .
Thank you.

[dokter dB]

are you serious?
there is enough info on that everywhere on the net.
But if you want 40dB supression in a half octave, i suggest you do some reading about things. And search this forum.

[Stu]

Here is the response of the crossover that you posted - but I'm not sure you understand how crossovers are expected to work, so I've drawn how it appears that you think it works (-2db for all frequencies below 400 Hz and -10db above it) in blue.



If I'm wrong, I apologise, but if it is how you think they work, it is important to understand that it is not the case - crrossovers are not that sharp, and continue to decrease in response as you change the frequency (like the red line).

As for whether what you are thinking of doing is possible passively, it's realistically impossible to get even a first order low pass filter without an inductor, yet you seem to be asking for a at least a 12th order (I haven't done the maths, but it is a very high order you are after). If you want to do it passively, you need an inductor.

Actively, what you may want is a fourth order linkwitz-riley crossover, described here:

http://sound.westhost.com/project09.htm

This doesn't give the response you are after, but I still feel you might misunderstand what you need, and it does still give a relatively sharp roll-off (it will be about 48 dB down at 400 Hz). I don't see why you would need any more than this.

[rulezzz]

Ok Thx.

[sreten]

- crrossovers are not that sharp, and continue to decrease in response as you change the frequency (like the red line).

There are a class of filters called Elliptic or Caeur filters with very
sharp cutoff's (100dB/octave active) that are do not monotonically
decrease in response in the cutoff region.

The whole area is far too complicated to deal with here,
a filter design reference text / manual is required.

But the basic pricinciple is cascading a second notch filter
with a more normal filter, or cascaded notch filters. (a bit
like the opposite of an underdamped high/low pass filter)

Transient response / group delay is unsurprisingly very poor.

sreten.

[rulezzz]

i made this crossover but it didn't worked maybe microchem is not for this crossover??What is wrong?

[Stu]

sreten

Good points, I wasn't aware of any such filters being used in audio, but I was thinking it would probably be better to stick to conventional designs in this instance.

rulezzz

Do you mean microsim? I'm not familiar with that, but it is a well tested design (with one or two errors in your schematic - get rid of r3 [open] and r4 [short] and make c2 44 nF and it should be good), you shouldn't have any troubles with it if you wire it correctly.

Maybe someone else with more experience can comment if you still feel the need to simulate it.

[sreten]

The Joseph Audio line of loudspeakers has so called Infinite Slope Crossovers, which I believe is a variation on elliptic filters.

http://www.stereophile.com/loudspeak...15/index8.html

sreten.

[rulezzz]

I searched the internet and found these 2 passive crossovers they are >340 Hz and >600 Hz ,but i need <80-70 Hz.Maybe somebody know the formula how to calculate the capacitors and resistors for crossovers like those ,or if you know a link ,please post

[dokter dB]

guys, already made this earlier today but my router needed a update and it took me sooo long

but, you mean someting like this maahn