## Crossovers

Device/Module Wishlist

Original topic on PlanetZ: https://forums.scopeusers.com/viewtopic.php?t=9391

####

Posted: Sat May 31, 2003 11:56 am
by Music Manic
Are there anymore crossovers like the one Celmo did but with different types of crossover networks?
Thx

####

Posted: Sat May 31, 2003 3:19 pm
by Immanuel
Lo and Hi cut filters will do it.

####

Posted: Sat May 31, 2003 9:10 pm
by Music Manic
Will crossover give flat amplitude relative to the frequencies they crossover?
Thx

####

Posted: Sun Jun 01, 2003 5:18 am
by Immanuel
In general they are supposed to, but dedicated cross-overs will often i.e. dampen the tweeter, if it has a higher output, than the bass.
However, the idea is, that if the enclosures, you want to use are well combined, then you just cut highs from the bass, and cut lows from the tweeter (and cut lows and highs from the middle, if you use a 3-way system).
So, if you want the x-over frequency at 200Hz you basically just high-cut the bas at 200Hz and lo-cut the rest at 200Hz. The Cut frequency on high/lo-cuts is where the sound is dampened 3dB, but as both signals will be damped 3dB, the sum will be a flat signal. Start out with that.
The High and Lo-cuts are 12dB/octave. In the 2448 mixer, you will find steeper cuts in the EQ-section.
If you use software-x-overs, it is even more important, that you switch off/turn down your amplifier, while loading projects!

####

Posted: Sun Jun 01, 2003 10:59 am
by Music Manic
So if I want to crossover at 200Hz say wouldn't I need to cutoff at about 100 and 300 due to the -3dB passband frequencies.
The thing is how do I know the filters are that precise?

####

Posted: Sun Jun 01, 2003 12:39 pm
by Immanuel
Yes, in most cases, you will get the best result from setting the same lo- and hi- cut frequency. Not much to bother about in terms of calculations
About precision: you either trust digital to be acurate, or you use measuring equipment, wich will likely give you a faulty result at higher frequencies - unless you know what you are doing AND have a good room for the purpose. Personally I would trust the filters - not the grafics - cause they don't follow the numbers very well, but the numbers I will trust.
They will most likely be more aqurate than the matching of your speakers anyway

####

Posted: Sun Jul 06, 2003 11:51 pm
by jabney
Has anybody had a chance to compare their home-made sfp crossover with a touring-class hardware (but still digital) crossover e.g. BSS, XTA, EAW, etc?<p>If you don't <i>have</i> a home-made sfp crossover, why not?

####

Posted: Mon Jul 07, 2003 12:48 am
by j9k
if you try to make a crossover with a 2nd order hi pass lowpass combination you will create a notch at the center frequency due to phase problems. 4th order filters will cause the same problem but a little bump instead.
j9k