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DIY Speaker Help (Crossover?)

post #1 of 27
1/30/10 at 2:00am
Thread Starter 
So lately I have been feeling that my Logitech speakers on my desk have been really lacking. So I started looking at speakers. I wanted something cheap that would give me good sound for the money. Plus I of course wanted them to look good. So I started looking around, I found a few I liked, most over $200. So I thought hey why not DIY.

I have decided to try and build these. I am only confused about one thing. The whole crossover thing. I have tried to look for sites that can help explain that but most have just made me even more confused. Can someone help put this in a newbies language. Thanks!
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post #2 of 27
1/30/10 at 2:22am
I'm in the middle of building the sr71 kit from zaph. The crossovers basically force one driver to reproduce one set of frequencies and the other driver to reproduce the other ones. In a two channel, obviously, the tweeter does high freq and the woofer does low. Here's a wiki that will help.

It's part science and part art. You need to understand the performance of the drivers and then figure out the best way to blend them together. Then there's other variables like the room, the cabinet, vented or sealed, etc. Zaph has some stuff on his site that explains some of this too.

For you, basically, you just need to wire the crossover as explained and connect the inputs and outputs. You can also buy kits with crossovers pre-assembled. Madisound, for example, provided my crossovers so I just need to solder on the inputs and outputs.
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post #3 of 27
1/30/10 at 2:23am
Search this specific forum (under threads I've made)...I've made a set and have a build thread. What do you want to know about Xovers? Inductor placement? Schematic? Layout? Construction?

http://www.head-fi.org/forums/f6/beg...highlight=zaph
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post #4 of 27
1/30/10 at 2:24am
One more thing, try not to make it out of solid wood.
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post #5 of 27
1/30/10 at 2:43am
The crossover network is a set of simple filters.

Ignore for the moment the concept of sending different signals to different drivers.

Tweeters are really good at treble but if you send bass to them they may cook. So you have a high-pass filter on the tweeter that blocks the bass.

midranges are really good at mids but a lot of them get louder and more distorted as the frequency gets higher, so you pick a midrange that sounds good at the lowest frequency your tweeter can sound good at, and you design a low-pass filter network that keeps the treble away from the speaker that sounds terrible when it plays treble.

There are many variations, and i haven't bothered to cover woofers, or zobel networks, but, does that make more sense?

that's what made it make more sense for me.

As for how passive filter networks work, that's an issue for physicists. Just know that they do in fact work.
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post #6 of 27
1/30/10 at 2:48am
If you need some help getting up to speed on reading a schematic, there are a number of books out there. You might even be able to find one at the library at Pete Millett's DIY Audio pages.

You'll need to order the various parts - there are resistors, capacitors and inductors in there. You'll be able to find those at various sites and even a local electronics store if you have one.

One stumbling block is finding a way to connect them together. You can find terminal strips at Radio Shack and order them from several sites, too. You'll connect each component to the terminal point and solder it. If a resistor is supposed to be connected to a capacitor, you'll also connect a wire between where those ends are on the terminal points and solder them.

I'm not sure if I'm describing it well, but I wish I could just show you. It'd only take a few minutes for you to "get" what is going on. Then you'll see how it goes together.

I can't recommend one specifically, but you might want to search for soldering videos at YouTube. There must be several showing how the pieces go together. You'll see and you'll realize that it isn't that difficult.

Warning: once you figure it out and build something that works you'll end up building more.
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post #7 of 27
1/30/10 at 2:38pm
Thread Starter 
Yeah I know how to solder. I made this cable about a week ago. Turned out great. I plan to make a lot more, I already have 2 people asking me to make them one.

But that clears some things up. I found a book but it was ridiculous expensive for a book. It is called Loudspeaker Design Cookbook. I did some searching on this site and HTForum and that helped a little more. I now understand the science as to what it all does but as far as which components go to what I am still a little clueless.

For instance I read that designing and making your own speakers is more fun. As in just starting from scratch. But I don't understand how to design/decide what I need for the parts for a crossover for that specific speaker. I was wanting to build some nice little desktop speakers that sound well and are relatively cheap (~$100 for both). That may be too small of a budget but we'll see. I have looked at partsexpress and madisound and found some crossovers that are pre-built. The ones at partsexpress are pretty cheap, but if I were to do that for my first speaker I do I know which one to get?

Thanks for all of the help guys!
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post #8 of 27
1/30/10 at 2:43pm
TBH, you should really follow Zaph's schematics...it'll work (and sound!) much better than prebuilt ones because those aren't tailor made to that specific speaker.
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post #9 of 27
1/30/10 at 3:09pm
Quote:
Originally Posted by unl3a5h3d View Post
But that clears some things up. I found a book but it was ridiculous expensive for a book. It is called Loudspeaker Design Cookbook. I did some searching on this site and HTForum and that helped a little more. I now understand the science as to what it all does but as far as which components go to what I am still a little clueless.
The Loudspeaker design cook book is pretty beefy interms of math and technical info, not a beginners book. Single drivers loudspeakers are quite popular because of the lack of a cross over and the performance they offer.

They can be very easy to build and fun a good place to start I think.
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post #10 of 27
1/30/10 at 4:38pm
Pre-made crossovers should not even be sold. You would need very well behaved drivers to get a pre made crossover to work, and even then it would just be blind luck.

Are just having problems understanding how to follow the schematic? If thats the case I can probably help you with that. Or you can post on the HTGuide or PE boards and someone will help you. I know I couldn't make heads or tails out if at first and complex crossovers like the Modula MT still scare me.

*edit*

Also you might want to consider the Zaph ZA 5.2 MT, its not that much more than the ZMB4 but is a true reference level small 2 way. It would blow away the ZMB4, the crossovers are pre-built for you, and the drivers are also much sexier looking in my opinion.
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post #11 of 27
3/3/10 at 11:16pm
Thread Starter 
If I were to make the ZMB4's would they need an amp to power them? I am really thinking about making them. I would do the ZA 5.2 MT but I don't want to sink that much money into my first DIY speakers. I am thinking that if I make the ZMB4's I will be addicted like I am now to making cables and I will be making another pair of speakers soon. I will probably then do something more extravagant, maybe floor standing?

But another question, what do you mount all of the cross over parts to? I have seen pics of people having them on a piece of peg board? Then were at in the speaker is that mounted? Thanks.
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post #12 of 27
3/3/10 at 11:51pm
Yes you do...a simple Chipamp or a receiver will do.
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post #13 of 27
3/3/10 at 11:56pm
Thread Starter 
Okay cool. But now about the cross over mounting?
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post #14 of 27
3/4/10 at 1:22am
As long as it doesn't move, it's GTG. Whether it's screwed down or glued down or slides into a slit etc...
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post #15 of 27
3/4/10 at 1:32am
Thread Starter 
Okay cool.

Well after a lot of reading tonight, about 2 hours worth. I think I am just going to save a bit more and go for the ZA 5.2's. I think they will be better in the long run.

Now the question is should I go with the sealed or ported design? What are the pros and cons of each? I can't seem to find much.
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