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Old 17th November 2006, 01:05 AM   #1
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Default How do you design a crossover??????

for me, it just about seems impossible. how do you choose all the parts and stuff? could someone "fill me in" on this?
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Old 17th November 2006, 01:34 AM   #2
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Frog,

Crossovers are complex. It takes years to get good at making them. You can't be just "filled in." It's like asking "can someone fill me in on how to tear down an engine?"

Here's an XO calculator. It also shows you how to do box sizes etc. That should help.

http://www.mhsoft.nl/spk_calc.asp
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Old 17th November 2006, 02:09 AM   #3
heater is offline heater  Finland
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This "filling in" could take some time not to mension expense.

I suggest you first read this: http://sound.westhost.com/lr-passive.htm

Then, if you are like me, you might decide that going active might be easier. As for example here http://sound.westhost.com/lr-passive.htm

Then when you have understood all you can you start experimenting and probably come back here to discus why things don't work out as planned

Still, nothing ventured, nothing gained.
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Old 17th November 2006, 02:09 AM   #4
Daveis is offline Daveis  United States
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Prototype first using multiple amps and an active crossover.
Once you are satisfied with the sound, design the passive crossover using software like Xover Pro, etc. Or pay/commission someone at Madisound or online to build you one.

Multiple amps, a volume control solution, and a Behringer DCX2496 and 15 minutes can result in a passable solution.

Dedicating a PC as crossover can also work. This is expensive.

Main thing is to have the box dimensions right. For the beginner (me included) I stay away from vented boxes. I just use an oversized sealed box. Amazingly, a sealed box that's too small will only make your bass roll off prematurely. It won't necessarily sound bad.

But if you want a sure thing look for Jon Marsh, Zaph, etc and build with a proven winner.
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Old 17th November 2006, 02:30 AM   #5
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Quote:
Originally posted by heater
Then, if you are like me, you might decide that going active might be easier. As for example here http://sound.westhost.com/lr-passive.htm
Did you mean http://sound.westhost.com/biamp-vs-passive.htm?
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Old 17th November 2006, 07:20 AM   #6
heater is offline heater  Finland
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What I actually meant was the 24db/octave active c/o project itself:http://sound.westhost.com/project09.htm

Your link is Rods excellent introduction.
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Old 17th November 2006, 09:22 AM   #7
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Quote:
Originally posted by Cal Weldon
Crossovers are complex. It takes years to get good at making them. You can't be just "filled in."
Indeed!

I ended forgetting the calculator's and spreadsheets and just setup a test mic and sweepgen and breadboarded until I got it right, both on screen and sound wise.
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Old 17th November 2006, 11:07 AM   #8
Pano is offline Pano  United States
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Black Magic is best - or Voodoo. (Unlike speaker cables where HUNA is best.)

Before you begin - be sure to lay in a good supply of chicken lips, toad ears and bat feathers. These will greatly aid your calculations.

There are software crossover calculators available, but they work best by the light of the new moon. Burn a green candle, if you don't have new moonlight.

Components made of cryogenically treated unobtainium can really simplify your calculations and curses, as they tend to receive and transmit ethers and ectoplasm extremely well. Your ears will know the difference!

But don't expect results overnight. And of course - YMMV. IMHO.
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Old 17th November 2006, 03:43 PM   #9
hermanv is offline hermanv  United States
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Default Re: How do you design a crossover??????

Quote:
Originally posted by legendaryfrog
for me, it just about seems impossible. how do you choose all the parts and stuff? could someone "fill me in" on this?
Designing a crossover is a complex operation. Many do their own design, it can be learned.

The following is very general, it is meant to provide a birdís eye view of the process rather than being an instruction guide. (Hopefully, I got it right).

Item 1. You need to decide on the crossover order, i.e. 1st order, 2nd order, 3rd order or 4th order. Each order increases the slope of the attenuation past the crossover point by 6 dB per octave. i.e. 1st order is 6 dB/octave, 2nd is 12dB/octave etc.

How is this decision made? The driver behavior out of band mostly determines this. The newer ultra stiff exotic coned drivers tend to have very bad out of band break-up characteristics and usually work best with steeper crossovers. These crossovers steeply reduce any out of band energy reaching the driver. On the other hand gentle slopes are usually preferred if a phase flat or wide dispersion design is your goal. Low order designs use the fewest parts.

Item 2. You need to decide if a Linkwitz-Riley or conventional crossover (usually Butterworth) is preferable. This is important because conventional crossovers have a phase of plus and minus 90 degrees at the crossover frequency which means the crossover point must be 3dB down, whereas Linkwitz-Riley crossovers have a plus and minus phase of 180 degrees at the crossover point which means the crossover frequency point needs to be 6dB down. Likwitz-Riley crossovers have very good phase characteristics and are often preferred for 1st and 2nd order designs, the advantages decline as the order number increases.

At the crossover frequency both the lower and higher frequency driver each contribute Ĺ of the acoustic output. Summing the two acoustic signals requires the correct phase for each driver. Depending on crossover style and order(slope) chosen, the drivers might be connected in phase (+ to +) or out of phase (+ to -).

Once these decisions are made any number of component value calculators are easy to find on the internet.

The Loudspeaker Design Cookbook by Vance Dickerson describes most of these points in fine detail. Many have learned the craft from this book.
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Old 17th November 2006, 04:34 PM   #10
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Quote:
how do you choose all the parts and stuff?
It might help if you have some electronics knowledge...

You can do a search on the web for capacitors and resistors etc.
And there are a few threads on here where people recommend components.

There are also lots of websites with tons of info about crossovers...Search for butterworth or Linkwitz Riley.
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