tagger

I have considered the JBL 2404 -- it's a very nice sounding HF driver. It's not at the top of my list due to availability, cost and especially the 100 x 100 dispersion pattern. Perhaps I'm wrong, but I thought it best to more closely match the 90 x 40 pattern of the mid horn. In addition, my basement only has a 7.5 ft ceiling, and the tweeter will be approximately 4 ft from the ground. I'd think keeping the vertical pattern tighter would be preferable.

Has anyone here ever used a small format horn with a 902 driver? I also posed this question at the Lansing Heritage forum with no responses, so perhaps it's just not used in this application. I don't see why it couldn't though since the 902 (on paper) goes up to 20 kHz.

The RP 280F towers have dual binding posts to give you the option of bi-amping them (driving the high and low frequency drivers with separate amplifiers). Assuming that is not your intention, you can plug your speaker cable into either set. There should be a bar connecting each black and each red terminal together -- you would only remove that bar if you intend to bi-amp.

What is an appropriate horn to use with the Altec 902 as a tweeter above 4000 Hz? Typically with horns I go with bigger is better but I'm not sure that's necessary with the higher frequencies.

Would you add the foam to the throat slot only, or cut it to fill the entire horn?

I should have mentioned, I'm using ALK gentle slope 700 Hz for the low cross and will use ALK extreme slope networks at either 4000 Hz or 5800 Hz for the tweeter. I will be able to attenuate both the squawker and tweeter to taste. These are being used in my basement theater room which is set up for both 2-channel listening and watching movies in 5.1. I'm probably the only one who listens to music on this system, but a one seat sweet spot is never one of my goals.

As the title suggests, I'm looking for help choosing a tweeter. I built a pair of two-way Cornscalas with Crites 15" cast woofers and Altec 288 / MR594 horn mid-tweeters. I started another thread asking about the merits of changing it to a three-way by adding a tweeter to cover the very high frequencies. I'm now looking for suggestions on which tweeters I should consider. Chris A suggested the Beyma CP25 would mate well with the manta-ray mid horn crossing somewhere between 2.5 - 4 kHz. I currently have a pair of Altec 902's I could try, keeping the top section all Altec. I am also considering the B&C DE250 and B&C DE10. I'd like to hear opinions on these and any others I should consider. Also, is there a rule of thumb in matching dispersion patterns of horns covering different frequency ranges in the same system? Joe

I assume if I crossed at 4 kHz this would not be necessary? How would it be accomplished in the ALK networks if I instead crossed at 5800 Hz? How is it accomplished in general in a passive network?

The 288 is a 1.4" driver, and the MR594 was designed for Altec's 1.4" drivers. I haven't measured the horn slot diameter, but I doubt it would be 2" at the throat. What is "c" in that equation? EDIT: The Altec Lansing spec sheet shows a 1.406" throat diameter.

Tough to argue that. I'd put Joe Montana and Johnny U up there too, but can't say who edges out who.

My current ALK network is the AP12 700 Hz network. It is a two-way network that includes an output to an optional tweeter network. There are no changes to my existing network required to add one of his tweeter networks. Would that not also be the case if adding a different tweeter network design? I have the schematics for the AP12 network, but since Al no longer publishes it on his site I will not post it here. No need to risk that! I revisited his site and realized I missed that he also offers a 4000 Hz version. That's probably close enough.

First, thank you for the advise thus far! Now I'm thinking of performing some cabinet surgery to remove the top 5 inches above the mid horn to keep the tweeters closer to ear level. Do you have a suggestion on a 3.5 kHz tweeter network to add to my ALK 700Hz network? The ones Al builds start at 5800 Hz, but I'm not adverse to building a 3.5 kHz network myself if I have the plans. A different commercial solution would be fine too.

This is very interesting. Why is it a bigger problem with a steeper slope? I figured with the extreme slope network (~120 dB / octave) the frequency overlap would be sufficiently small enough to not be noticeable. I do have a Behringer DCX2496 active crossover I could play with to time align everything. I'm not sure it would be a good permanent solution since it's a pro audio unit. I suspect my Emotiva USP preamp doesn't have a high enough output voltage but perhaps I'm wrong.

I plan to use ALK extreme slope tweeter networks so I'm not overly concerned with time aligning them. Also, if I were to have the tweeters recessed on top of the cabinets, wouldn't early reflections off the top of the cabinet be an issue? As it is the 288 drivers are almost sticking out the rear -- the top section of the cabinets are open in the back -- so to physically time align them the tweets would need to be all the way in the back. As for the crossover point, my thinking is to allow the 288's to play to their strengths, which in my mind is from 1200 - 9000 Hz. The MR594's are constant directivity horns and are very well behaved in that range. Al K has 5800 Hz, 7500 Hz and 8500 Hz versions of his extreme slope networks, and I intended to go with one of the higher ones. However, I may be easily swayed otherwise.

The only problem with the Beyma is the size of the horn. The outside dimensions are 6.3" (L) x 5.3" (H) and needing a 4.72" (L) x 5.12" (H) cutout. I built the top sections of my Alcorns with enough room for a 5" (H) OD lens and no more than a 4.25" (H) cutout. My thinking was that I would use a B&C DE120 / Eliptrac HF horn combo up top. As such, I didn't leave enough room to experiment with a larger variety of tweeters, unless I rest them on top of the cabinet. I attached a photo -- the cabinets are still unfinished at the moment.