Just a Suggestion

pedro quiroga once ask about some replacement tweeters. I made the remark that any tweeter will work as long as it has a good crossover attached to it.

I currently need to build a crossover for some tweeters. While I have gone overboard, this is something that anyone can do.



Printing your own circuit board is easy, your local Radio Shack has all the stuff you need. Your local electronics wholesaler has all the caps and coils that you will need.

Hooked to this crossover even a no-name tweeter will sound really great.



And yes, that is my first initial in the PC Board. The PC Board has not been drilled yet. I will finish it this weekend.

OK, I have about $100, invested. About $35 for all the caps, coils and resistors. Less than $30 for the pair of cheap tweeters. And around $30 for everything I need to print circuit boards.

It will sound fantastic. Now a crossover does not need to be this extreme. It can be as simple as the one I made for my DX3000's in my truck
http://www.caraudiotalk.com/audio-forum/car-stereo-speakers/5809-need-new-tweets.html

anyway, anyone can do this.

 

The crossover frequency on this one will be 6000Hz and the slope is 18dB per octave. I really like for tweeters to be slightly out of phase. Less directional that way.

The resistors add a level of complexity that I have not dealt with before. Not only does it limit audio slightly (I'm only dealing with a 1/2 ohm) but they also interact with the caps.

Midbass requires that the speaker is mounted solidly. Any vibration that is transfered to the panels that the speaker is mounted to, is absorbing sound. The only crossover that I might add, would be a single cap between 199 and 265 microfarad. This would prevent sub-bass from reaching the speaker so that it doesn't waste time with those frequencies that it cannot reproduce anyway.

 

"OUT OF PHASE" this concept is a little hard to understand. So lets see if I can keep from messing this up.

If we take one speaker from a pair and reverse the speaker wires, it is 180-degrees out of phase in relation to the other speaker. Now if we reverse the leads on the other one, it will be 180-degrees out of phase. But now the speakers are in phase with each other. In other words, if both speakers are wired right or both are wired wrong, there is no cancelling effect. If both are wired wrong, they are out of phase when compaired to the original music source.

Now to crossovers, and we are talking about passive only. Even order filters (crossovers), 12dB/octave, 24dB/octave are examples of even order filters. These filters will either be 180-degrees out of phase or in-phase. In any case, we can fix the problem (if one exists ) by reversing the speaker leads. No problem. With tweeters there is usually no problem. If a tweeter is out of phase with the Mid Bass driver, then it just becomes less directional. Its harder to tell exactly where the sound is coming from.

Odd-Order filters are either 90-degrees or 270-degrees out of phase. This cannot be corrected, Except by using odd order filters on all your speakers so that they are in-phase in relation to each other. Both 6dB/octave and 18 dB/octave are examples of odd order filters. While the 6 dB/octave is classified as an odd-order filter, its out of phase characteristics are typically not a problem. Without getting into the properties of caps and coils (and I wanna keep this simple) it takes both a cap and a coil to make a true out-of-phase condition. In a 6 dB/octave we only have a cap, no coil (or the reverse, one coil and No Cap).

Did this help or make it worse?

This out of phase stuff can be useful. My wifes car has both front and rear speakers. At higher volume levels all the sound seemed to come from the rear speakers. I simply reverse the wires on the right rear. I still retained all the volume of 4 speakers, but now the sound seems to be coming from the two front speakers. Can you tell me what happened?

 

Thats mostly right, It affects the rears only because of their proximity to each other. The fronts are too far away to be affected. The fronts, as you said, are in unison (I like that word chioce) so they tend to be noticed. The two rears are out of phase with each other, there is a cancelling effect but only between rears. The fronts are too far away.

The sound from the rear is still there, but because of the out-of-phase condition there is no directionality. Try it, you'll be amazed, it really works.

 

If both rears were wired out of phase (reverse the speaker wiring), then in relation to each other they would have been in phase.

Now in relation to the front they would have been out-of-phase. Doing both rear speakers that way typicallly will reduce the mid bass output slightly, but because the rears are in phase with each other, directionality might be restored.

Told you this subject was a little hard to grasp.

 

The completed crossover, now I will take it to work and hook it up to my test bench Monday.



Again this is something that anyone can do, it aint rocket science

 

First you need an etching solution (Radio Shack) and a single sided copper clad board (any electronics parts wholesaler) Radio Shack only has double sided board, too hard to work with.



Now we need patience and some Krylon Spray Paint.

Make a stencil of how the board will look. Put the stencil on the board and paint it. Whatever is painted will not be removed. Put in the etching solution for about 30 min to 1 hour. Your done. Rince with cold water. Remove the paint with Lacquer Thinner or steel wool, provided you didnt use 3 or 4 coats.

A magic marker will also work for fine lines, but eventually the etching solution will go through it if it remains in the solution too long.

The Etching solution is an ACID, wear latex gloves and I use tweezers to remove the board.

 

Yes I did. Thanks

 

And I'm still not sure why that might work. I'll need to look it over later today. The only real problem I have with it is the 3 microfarad cap. We would need to pass a little more audio than that. A 5.6 or a 6.8 would be much more reasonable.