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FINALLY DONE--210hz "KEVHORNS"-pics added 1-30


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I was gonna say....the "Stairway to Heaven" poster is perfect beside those babes.


Did you tell us in the other thread what networks you are using and what driver is on that tractrix tweeter?


I'm using GotHover's universal crossovers and Crites/ APT 50 driver for the tweeter.
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Those look really nice.

fyi and for what it is worth -- the network is Al's Universal Type A (ALK).

Dean, you are right, they are ALK's Universal design. I just wanted to give credit to GotHover since he builds them with parts he selects, not just building a ready-made kit from ALK.
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NOTICE: There are only two people authorized to build my network designs. They are Greg Roberts, for the original ALK Universal and Dean Wescott (DEANG), for special case designs. NO OTHERS! Anyone may build my designs for THEIR OWN USE and modify them as they like. HOWEVER, be very careful how you pick you “experts”. Most modifications to my designs are not improvements and are often steps in the wrong direction.

Several cases in point:

1-To add a switch selecting two different capacitor values in a 1st order network, like the woofer / squawker cross in my universal network clearly indicates a lack of understanding of 1st order filter. Changes in capacitor value will have no addable effect due to the sloppy response of this type filter. This is the very thing that makes it “universal”! To change the frequency requires a change in BOTH the capacitor and inductor. The ratio of inductor to capacitor values determine the impedance level of the filter.

2-To use an adjustable transformer to attenuate a driver (squawker or tweeter) without compensating for the rising impedance seen through the transformer as attenuation is increased serves to destroy the frequency response of the filter. Compensation must be by a swamping resistor, as I did in the squawker section of the Universal, or by synthesizing the filter element values to a new impedance level for EACH transformer setting. Various resistors values must be selected for each attenuation setting when low levels of attenuation, such as 2 or 4 dB, are used. This requires a 5-pole switch. 2-poles will not do.

3-The value of the inductor in the squawker filter of my Universal is .30 mHy, not .33. This is a minor error causing only minor degradation but is made totally illogical by selecting foil inductors which are far more expensive than Litz wire inductors and have higher loss at the 6000 Hz frequency of the squawker / tweeter crossover frequency. Foil inductors have their minim loss, or maximum Q at frequencies well above the audio range making them a poor choice for crossover networks. The .30 and .20 mHy Litz inductors peak right at 6000 Hz making them ideal.

Al K.

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Guest David H

Al, the crossovers you are talking about have only been seen by a few people, I sent a pair to Greg to test and a DIY set was built by another forum member. I understand you do not approve of these crossovers, and wanted to let it be known that I am not building and selling your crossovers, though I have built similar clones for myself and a few freinds.

Al, I respect your work, and reccomend your products regularly, and I apologise for the confusion.

Dave Harris

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Great job Kevin! I like the adjustable tilt mechanism.

So... Any first impressions of the trictrax tweeter horn?

Looks like another drive to Flint in the future for me.

I listened to the pair for the first time tonite, and I am very impressed. The tweeters sound different for sure. I think they have a wider soundstage than before, and I believe they blend in better with the mid also. They don't have as much up and down dispersion as the other horns. If you stand up, you can hear a difference in the tweeter. But then again, I built these to be directed at the listener while seated, and that it does very well. Come on down and have a listen for yourself!
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Can you post some close up of the tweeter horns. Do you have any specifications so I can build some for my lascalas?

If you have the tractrix calculator punch in these numbers: 727 for the flare frequency, 3.0 for the ratio, 2.53 for the throat dimension. That will give you a horn that is 3" tall by 9" wide by 4" deep. I just continued the the flare all the way out to make the riser look like one continious piece in front. I'll post some pics on Friday. -Kevin
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