First speaker design (crosscover)

[Richie V6]

Hi, I am a noob at speakers but i figured id give it a try. I am looking to build something for my computer. I am planing to use 2 Vifa midbasses in series and a Dayton tweeter.
Vifa Midbass
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=299-495
Dayton tweeter
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=275-030

I looked at the Vifa's response graph and saw that response graph dropped off around 800Hz. This is where I set the crossover point. I used a online calculator and calculated the capactior and inductor values for this frequency.

Given:
RH = 6 ohms
RL = 12 ohms
f = 800 hertz
Solution:
Linkwitz-Riley: C1 = 1.6583333333333E-05 farads
C2 = 1.6583333333333E-05 farads
L1 = 0.00238725 henries
L2 = 0.0047745 henries
Bessel: C1 = 1.9E-05 farads
C2 = 9.5E-06 farads
L1 = 0.002067 henries
L2 = 0.004134 henries
Butterworth: C1 = 2.34375E-05 farads
C2 = 1.171875E-05 farads
L1 = 0.00168825 henries
L2 = 0.0033765 henries

I than ran these values in a ORCAD simulator to see the crossover.
http://www.geocities.com/newsrichie/crossover_files/crossover.html
After looking at all 3 simulation I have no idea which one is better.
I was just wondering if you guys could give me some pointers and tell me if I am on the right track or not.
Thanks
-Rich

 

[pinkmouse]

For a start, looking at the specs of the tweeter, its Fs is about 1.8Khz, so you really want to crossover way above that, possibly around 3.6K. 800Hz is far too low...

 

[Richie V6]

Is that a bad tweeter choice?

 

[Ron E]

Well, you obviously made a mistake in your L-R calculation - the two legs should be symmetrical and should cross at -6dB or 10V.

First, you need to cross over higher as the others said - the recommended minimum for a 3/4" tweeter is typically 3kHz or 2X the resonant frequency - -whichever is higher.

Which crossover you should use depends on the drivers - you really can't build speakers with textbook crossover formulas because the electrical filter cascades with the natural roloff of the drivers to give you your total crossover slope. Linkwitz-Riley makes a good target response in a crossover optimizer because it sums flat - do a trace with the sum of the lowpass and highpass slopes to see for yourself.

Try looking at speaker workshop and the various accessories you will need. If you have the patience to use the program, you can make truly excellent speakers.

 

[Richie V6]

thanks for the advice guys. i know formulas arent great, but i am just trying to get my feet wet. i like how my 2 Vifa's sound just wire in series on my desk how does this updated version look?
http://www.geocities.com/newsrichie/crossover_files/revisedcrossover.GIF

 

[Richie V6]

BUMP anything else before i place my order?