Building my own Cross-overs. NOW WITH WRITE-UP!!!

[KenC]

Just to let you know the Human ear can hear those frequency but, most people can not hear them due to a variety of things.

ask any doctor and he will tell you that our range of hearing is considerably smaller. I have a HF hearing loss in my left ear that prevents me from hearing anything above 6k Hz. and it sucks. I see a hear specialist every year to keep track of it so it doesn't degrade anymore.

20-20kHz is definitely an idealization. As the ear ages, the range gets smaller.

[KenC]

EMAIL ME FOR PICTURES

Write up:

1. Determine the crossover frequency that you desire.

Usually you can go to a car audio manufacturers website and find crossover frequencies. I went to MB Quart's website and saw that they use 3000Hz for their 6.5" woofers. Since I don't have tweeters in the back, I decided to make the cutoff a bit higher (~3200Hz).

2. Determine the components you will need.

I chose to make a second-order crossover (12db/oct) for two reasons. First, MB Quart uses second-order crossovers (not sure about the top of the line ones though, they MIGHT be 4th-order). Secondly, because of costs. Since the 4th order crossovers use twice as many inductors and capacitors, they would have been nearly twice as much to make.

There are several websites with cross-over calculators on the web. One such is http://www.ajdesigner.com/crossover/crossoversecond.php. You just imput the tweeter and woofer impedence (usually 4 ohms for car audio), and then the desired frequency for the crossover.

Here is the schematic drawing of the crossover itself:

C=capacitor
I=Inductor

I chose to make a Linkwitz-Riley type crossover (my friend suggested it over the Butterworth).
Here were the values of the components that I needed:
C1 = 6.0968137254902E-06 farads
C2 = 6.0968137254902E-06 farads
L1 = 0.00039007352941176 henries
L2 = 0.00039007352941176 henries

Since I was making two crossovers I needed two of everything.
I needed 4 capacitors of 6.1microfarads, and 4 inductors of 0.4 millihenries (weird units, I know).

I bought my parts from http://www.partsexpress.com. With the components that they had available, the closest I could get to 3200Hz was 3264Hz.

3. Determine how you want to design it.

This is the aesthetic portion of the design. I wanted both crossovers on the same board. Thus the crossover for the right and left channel are on this single board. I wanted mine to be fairly small so this was the design that we came up with:


4. Start Building

Here is what we basically started with:


I used a piece of plexiglass to mount all of the components on. It was only about $5 for the piece that I bought at Home Depot. We kept the plastic on the plexiglass and marked on the plastic where we wanted to drill holes and such.

After the holes were drilled, I decided to paint the backside of the plexiglass so that the wiring under would be hidden. I used some dark metallic blue paint because that's what I had sitting in my garage. I think it turned out pretty good.

The next step was to attach all of the components to the board. The copper-coil aircore inductors were very heavy (.5-1 lb each), so I used black zipties to hold them on. The polypropylene capacitors are very light so they weren't attached to the board, the simply stay on by sticking the wire through the hole and bending it.
Here is a crappy picture of the inductors attached to the board:


Then it was time to solder! Neither of us had very much experience with soldering, but it's not rocket science. I think it turne out well. For all of the internal wiring of the crossover I used MonsterCable ZX Series speaker cable ($1/foot).

*We soldered the wires according to the wiring schematic above.

Here is the finished product after all of the soldering was done:




Then we attached the output screw-terminal to the plexiglass and then drilled the holes for the wires to come up through from the underside.


I used spades to connect all of the wires into the screw terminal:


Then I connected the input terminal to the board and drilled holes for the wires to come through (the two inputs for the right side were paralled and same for the left channels):


Then the wires were brought through and connected with spades to the terminal:


The crossover is fully functional now.

I then decided to use slightly larger piece of wood (painted black) to mount the plexiglass to. This will give the heavy crossover some stability.

I found a piece of poplar at Home Depot and cut it to size. Then I traced where the crossover would go and then drilled holes where the plexi glass would mount to it.


Then I drilled holes in the corners of board where the mounting holes would be.
Then I painted it black:


Then threaded metal inserts were hammered into the mounting holes:


Then it was coated with black paint again to cover the silver threaded inserts:


I put a 'protective cover over the xover too:



Finished product!!:



(Disregard the flowery sofa; it was free.)

Feel free to ask any questions. I hope that this will help some one else undertake this satisfying task.[/b]

[bimmerphile]

now, how does it sound? :-D

[boricuabimma']

Damn it Ken... that thing looks wonderful, how did that work of art improved the sound?

[KenC]

I haven't hooked it up yet. It got too dark. Most likely tomorrow. I still am not sure where I'm going to mount it either.

How should I rearrange my amps and such to fit it? The entire thing is probably 4x as big as one of the RF crossovers below the Alpine amp. Any body want to do a ROUGH photoshop of where I should move everything?

[bwanac]

That thing looks real nice. My only concern is that it is HUGE! :shock:

Aren't x-overs when you buy speakers a lot smaller?

And by the partsexpress.com, they totally rock! Have great stuff that you would never know you needed. So much great electrical, audio, visual geeky stuff! They own! Sorry for all my yelling. :oops:

[BMW BMXER]

Ya its big. But its badass.
Can I be your friend?

[KenC]

That thing looks real nice. My only concern is that it is HUGE! :shock:

Aren't x-overs when you buy speakers a lot smaller?

And by the partsexpress.com, they totally rock! Have great stuff that you would never know you needed. So much great electrical, audio, visual geeky stuff! They own! Sorry for all my yelling. :oops:

Yes, most factory x-overs are much smaller. But keep in mind that the one I built is actually 2 x-overs.

The xovers that come with the top of the line a/d/s/ components are about as big as mine. Probably because they're 4th-order ones.

Each of those air-core inductors (the coils) will take 500watts rms :twisted: .

[bwanac]

500 watts! :shock:

That would be a killer system. Do they even make car speakers that can handle all that power? Even the stereo in my room, is limited to about 150watts. And they aren't some crappy pair of Sony's either.

[KenC]

500 watts! :shock:

That would be a killer system. Do they even make car speakers that can handle all that power? Even the stereo in my room, is limited to about 150watts. And they aren't some crappy pair of Sony's either.

All of the components in the x-over are made for home audio.

[KenC]

I just hooked them up for a bit (no complete install until I move everything around and have room for it all.
They sound fucking sweet! It cut out all of the really high frequencies from the rears and they sound much much better now!

[spencers]

Ken, what model blaupunkt tweeters are in the corner pods in your car?

[KenC]

Ken, what model blaupunkt tweeters are in the corner pods in your car?

VC10

They'll handle 100 watts RMS and 200 Peak.

[CiLK WuRM]

My god, that looks amazingly basass! Well done.

[KenC]

My god, that looks amazingly basass! Well done.

Thanks!

I just hope that this write-up will inspire/assist some one to build a set of their own. I'd love to see some other peoples creations.