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-   -   Crossovers for Dummies... (http://www.diyaudio.com/forums/multi-way/53974-crossovers-dummies.html)

sdclc126 21st March 2005 11:18 PM

Crossovers for Dummies...
 
Hi All,

I'm sure all this has been covered in previous threads (feel free to provide links if you know them), but I hate searching threads as they take forever to find and weed out...

Anyway, I need to know where to begin learning about designing and building crossover networks, as I know next to nothing about them. I don't know what the components are, what they do, the terminology, etc., so everything I read about them on these pages just goes over my head (among other things, but we won't go there).

Are there books, websites, etc? Also, am I correct in assuming that I will want software for testing/listening, etc? Any suggestions on that too? And where can I buy top end crossover components?

Thanks for your help!

BAM 22nd March 2005 12:38 AM

Order the Great Sound Stereo Speaker Manual from PartsExpress.com and read it. It is a good one.

mike.e 22nd March 2005 12:42 AM

Quote:

but I hate searching threads as they take forever to find and weed out...
Exactly!

There are a number of issues that crop up with playing around with crossovers. If your not able to do all the study and understand phase and radiation lobes,then you can stick with the simple stuff.


Simplest
http://www.bcae1.com


Harder
http://www.sound.westhost.com/articles.htm
http://www.linkwitzlab.com/
http://www.woodartistry.com/linkwitzlab/sb80-3wy.zip

Even Harder
http://www.geocities.com/kreskovs/John1.html
http://www.geocities.com/kreskovs/CrossoverdocN.html

Quote:

Any suggestions on that too? And where can I buy top end crossover components?
Depends on what top end means,if it means expensive components that you think sound better,im sure there are many sites around if you search for 'hifi audiophile capacitor' etc

Passive crossovers will require higher spec components than many cheap systems have.

Active crossovers consist of opamps and components that are less critical and often have good specs anyway.

Note that audiophiles will debate the ability of some of these components and their distortion,but Ive never seen a well carried out ABX test prove it.

sdclc126 22nd March 2005 05:47 PM

Order the Great Sound Stereo Speaker Manual from PartsExpress.com and read it. It is
 
Can you provide a link? I couldn't find it on their site.

sdclc126 22nd March 2005 06:12 PM

How About Some More Details?
 
I guess I need to buy a book to get started, but let me ask this: What are the basic parts of a crossover (passive) and what do they do? How do you set crossover frequencies?

Here's an actual application I have: I have an older set of a/d/s 3-way x-overs - one has a .47 mh inductor (I figured that one out myself, but I still don't know what it does) broken off, so I need to replace it. Obviously I want to use the same .47 mh value (?), but what would happen if I changed it? Just curious. And, should I use wire (which it has) or foil? And should I use air core (which it has) or solid (hardwood)? How would this change the performance? (Yes if I make changes to one I'll do the same to both.)

Bill Fitzpatrick 22nd March 2005 06:26 PM

Why do you feel the need to trash the broken .47mh inductor?

sdclc126 22nd March 2005 07:04 PM

"Why Do You Feel the Need to Trash the Broken Inductor?"
 
AAAAARRRRRRRGGGGGHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!!! !

Timn8ter 22nd March 2005 07:29 PM

That's funny. :D

Basic passive crossovers are made up of capacitors and inductors. Capacitors are high pass filters meaning they allow high frequencies to pass but not low ones. The actual frequencies will depend, mostly, on the value of the capacitor.
Inductors are low pass filters meaning they allow low frequencies to pass.
The idea is to use the correct value cap and inductor (using a two-way speaker as reference) to allow the highs to go to the tweeter and the lows to the woofer AND have a smooth transition at the crossover point (the point where both drivers are reproducing the same frequencies.
I second getting David Weems book to start out.
http://www.amazon.com/exec/obidos/AS...790192-7685742

BTW, I think Bill was pointing out that's it may not be necessary to trash the inductor if all that's missing is a very short length of wire. Inductors don't really wear out with age like caps. You may be able to reattach it with no audible change in the speaker.

sdclc126 22nd March 2005 08:03 PM

Yes thank you sir for some useable information, and I WILL get that book.

I don't mean to be rude to the other poster, but the answer was in the question: "broken." The inductor actually broke at the lead lines, so re-soldering it to the board would be problematic - there was nothing coming out of the inductor to work with.

Plus, he just didn't answer any of my real questions. Part of my post was about possibly replacing it with something "better" - i.e., a higher quality inductor like a foil, etc., if such a change IS actually an AUDIBLE improvement, which opens up a whole new can of worms.

I've read so much about the lengths people go to to build these things (and believe me I salute you guys), but I've really been wondering if all these incredible crossovers I've seen and read about actually make an AUDIBLE DIFFERENCE in the sound of a loudspeaker - not to a microphone or a graph on a computer monitor, but to THE HUMAN EAR.

And the only way to really test this is by doing it BLINDLY: one system, two identical speakers, then fiddling with crossovers and parts, and asking a BLINDED listener to see if he/she can hear any subjective difference when a change is made, but not even being told when or if or what kind of change has been made.

This is how pharmaceutical drugs are tested - it's called a double-blind study - and it should work for anything else. If you spend $100 to replace a part that cost $10, you're probably gonna hear a difference, because you WANT to - but that is subjective, NOT factual. The person who built the system and spent the money is probably not the best person to test for improved performance!

It goes back to the arguments I've seen about loudspeaker cables - jeez you can spend tens of thousands of dollars on these things, and when they were actually properly tested, people couldn't tell the difference from one to the other.

So I'm wondering if the same thing happens with crossovers - I'm sure there are differences, but there must be some point at which further changes (read: spending more money) ceases to make an audible difference. I guess that's one thing I'm trying to get a grasp of here.

Anyway, I dither. Perhaps now that I know a little bit more about a few of the components, you can go on to tell me how to pick various values to achieve desired crossover frequencies? And what's all this first, second, and fourth order stuff, and how do you do THAT?

Timn8ter 22nd March 2005 09:00 PM

Yes, there are definitely different quality components the biggest difference of which is going to be materials. You won't find many people on this forum that will use eletrolytic caps. More often they will use film and foil and the sonic differences can be very apparent. Perhaps less noticeable is inductors and that can be caused by magnetic saturation. Most will try to avoid iron/steel core inductors except for large values. Air core inductors with low DC resistance are probably the most common used here.
As for the rest of your comments/questions: Beauty is in the ears of the beholder and on occasion approaches the level of religion. I'm not going to go there.
Orders of crossovers:
The idea is to cause the driver to be less responsive as it approaches a certain frequency. This happens gradually and when measured appears as a slope, not a brick wall. The rate of the slope is measured in decibels relative to octaves.
First order = 6db per octave.
2nd order = 12db
3rd order = 18db
4th order = 24db.
As to which is best, that depends on the drivers being used and the designers goals. There are advantages and disadvantages to each and as in all speaker design, the goal is to have the least number of compromises.
Happy reading!


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