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Built crossover for Avatar cab horn

LoveThatBass

LoveThatBass

Supporting Member
Jun 28, 2004
5,177
3,562
Dallas/Fort Worth Metroplex area of North Texas
#1
After discussing replacing the cap that comes with the Avatar cab with many here including Bill Fitzmaurice I decided to venture out and build my own. I used a crossover calculator Bill sent me via email. Previously I tried a 3K (12db)then a 3.5K (12db) crossover prebuilt. The 3K allowed the horn to distort due to the low end. The 3.5K was better but still a little honky and very slight distortion due to lows. I decided to go for 4K. I put the values in the calculator and and came up with a 3rd order Butterworth (18db). This smoothed the sound out. I used KimberKap audio capacitors from Parts Express. They are a bit pricy but not as much as some of the Pro Audio caps. This made the biggest difference in audio quality. I freely passed all the harmonics and tones of the bass strings that I had not heard till now. The components used are:
C1= 3.2mf @ 200 volts
C2= 10mf @ 200 volts
L1= .24mh at 800 watts
I used an epoxy glass circuit board from Mouser Electronics and wire ties to hold the components to the board.
I cannot stress enough what a good capacitor can do for you. When I compared it to the Dayton board with cheaper polyprophyline caps the Dayton sounded dull by comparison. The KimberKaps are soleful, clean, quiet with lots of clarity.
 
#5
Using high quailty caps isn't a bad idea, though most of the improvement you're getting is due to the steeper slope. But using a very high grade/wattage inductor isn't required, as it is only serving as a shunt to ground. A low wattage air core inductor such as the Parts Express 255-214 is adequate. High wattage solid core inductors are a necessity for low-pass filters.

In this particular application I'd use a 4th order Linkwitz HP filter crossed at 3kHz. The steeper slope would allow the tweeter to be crossed over lower to fill in the upper mids better. It also wouldn't hurt to have even a 1st order LP filter on the woofers to roll off the highs so that the woofer and tweeter outputs aren't fighting each other.
 
#7
Your theory that the 18db slope making more of difference in sound is incorrect. I tested a 2nd order design using kimberkaps. They are the big difference in tonal quality. The 3rd order did smooth things out though.

The B115H has an Eminence Kappa Pro LF.
it does not suffer tone loss
Good low end, excellent mids and highs now.
Yes, the Inductive coil rated at 800 watts is a bit overkill but was not much more expensive than a lower rated one so I went with it.
 
#13
I plugged the figures in for a 1st order filter at 4000 hz and came up with 4.9uf cap which is close to avatars Avatars 4.7uf cap.
Bill, your suggestion of a 4th order Linkowitz at 3khz might do the trick. I can tell you I get a tiny bit of distortion from the horn with bass up high enough. If I change the 10uf cap to 6uf and add another 1.10mh inductor it should put me at about 3.3khz. I may try this next week and see what it does.
And my comment about the 800watt inductor not costing much more was inccorrect. The 300 watt 18guage unit is $3.30 vs. $7.50 or so for the 800. Oh well it won't burn up any time soon. :hiding:
 
#14
By the way, before I started this, I put the figures in a crossover design calculator for the original Avatar cap and horn. It came out to aprox. 4khz with only a 6db slope for the 4.7uf cap Avatar used. I contacted Avatar as to the reason for 4khz instead of something lower and they stated the horn would work better (less distortion) and last longer at this crossover frequency. The horn does distort the lower you go toward 3khz. It looks like you would loose some mids here but my B115H puts out good tone so I am not going to worry about it.
 
#16
The reason Avatar crosses over so high is that the 1st order filter they use provides almost no protection for the driver. If that horn is being fed 50 watts at 4kHz, for instance, it's still getting 12.5 watts at 2kHz, and that's the source of the distortion. With a 4th order filter you'd only be getting 0.19 watts at 2kHz. The 4th order filter would allow you to lower the crossover point to the lower end of the driver's range at 3kHz to get all the useable response the driver is capable of without asking it to work at frequencies where it can't give anything but distortion.
 
#20
Here's a stupid question. If I keep my tweeter turned off all the time anyway, would I gain any highs by taking the crossover & tweeter out of the circuit, or do they only add highs?

Sorry to jump in with this, but it sounds like you guys would know the answer.

Thanks, Alan
 

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