Midrange horn drivers

[CIGARBUM]

I may be trying to build another pair of speakers. I know what I am going to do for the bass bin , so that leaves the midrange horn, that will be ALK tractrix, now what are the option for the drivers? I know you could use the stock K-55 or a Great Plains 16 ohm 902, I guess there are some JBL not sure of the number.

Does anyone have any other option or opinions that are not crazy ridiculous in price?

Tweeters, K-77, Beyma 25 other options, again not crazy ridiculous in price, Definition of crazy, anywhere north of $400/pr.

Thanks

CigarBum

[PrestonTom]

I assume the tractrix is a 1inch throat. Is this ultimately a 2 way or a 3-way system? What will be your crossover frequency and will you be crossing steeply?

[CIGARBUM]

Yes, 1" horn, 3-way system, not sure of the crossover points, I guess that may depend on the components selected. Can you explain what the basic differences would be for the different slopes?

CB

[PrestonTom]

As you go down in frequency the excursion on the diaphragm is increased since it needs to move a good deal of air. With a small throat (1 inch) the problem can be even more severe. At some point, the degree of excursion (volume of air being pushed) is so large that you will get distortion and the longevity of the diaphragm is also reduced.

This has several consequences. One, is the choice of material for the diaphragm (which can unfortunately also limit its high frequency response). Two, the first problem can be reduced if the mid-range is not crossed at too low a frequency and also if the filter is steep so the driver is not required to move a good deal of air. Since you are using a 3-way configuration, life is a bit easier. This is part of the reason that a two-way system can be so difficult to set up.

One possibility is to talk to the guy at Great Plains Audio. Let him know your crossover points (and steepness) etc and he can recommend the diapragm driver combination (the GPA 902). If you move to a larger throated horn (1.4 or 2 inch), a number of additional possibilities will open up

[Blvdre]

JBL's 2470 or 2420 drivers are also nice, and can be had for a reasonable price on e-bay if you're patient. I purchased a apir of 2470's that needed a bit of clean-up for $200, and am presently running a pair of 2420's that had already been cleaned up quite nicely, $200 as well (for the pair). I also had a pair of brand new GPA 902's previously in a two-way config. Very nice sounding combo, but had to be crossed a bit higher.

[JohnA]

Check out these, esp. the 475. They also make a nice series of 2" drivers

450pb_465pb_475pb.pdf

[oscarsear]

I don't know exactly what you plan to construct but Greg Roberts builds his V-trac Khorn modification that is similar to AlK's but will accept a 2 inch midrange driver. That opens up a lot more driver choices.

[sootshe]

If you're looking at constructing a heritage type system & you're going to use the ALK Tractrix, I don't think you can go past the K55 from the point of view that the Tractrix will open the sound of this driver up dramatically. It also has other advantages - it can be crossed over quite low (400Hz), is inexpensive & it is basically bullet proof. You hardly ever hear of anyone blowing one unless they do something stupid to it.

I'm currently waiting for delivery of my set of Tractrix horns from ALK & will be running this combo, plus the mods below.

For the top end - the Crites tweeter is also hard to beat. Very smooth, detailed & extended frequency range....once again at a realistic price.

For crossovers, you have to have the ALK Universals. Best investment I ever made. Having the ability to pad the midrange up or down is invaluable!

Best of luck.