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811B Horns


bluesboy

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I have a pair of corner horn speakers that I built myself. The crossovers are ALK designed.The speakers are currently equipped with K-401 horns and K-55 drivers.I am thinking about switching to Altec 811B horns and 808 8A drivers.Can I do this without modifing the crossovers? I'm also thinking about replacing the T-35 tweeters with Beyma CP-25s.

DIY Corner Horns,McIntosh C-26,McIntosh 2505,Micro-Seiki DD-40 TT with Grado reference master,Pioneer RT-909 reel to reel

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No for the reason above. You can't crossover the LaScala or Klipschorn that high. I say LaScala, or Klipschorn because you say 400 horn.

What bass horn cabinet are you using?

Altec horn numbers give you a hint to the low frequency cut off of the horn.

811 is 800Hz, 511 is 500Hz, 311 is 300Hz.

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Q-man and Rick are both excellent resources on this subject.

The Beyma CP-25 is reputed to be a hands-down improvement over the stock EV T-35 tweeter. I know Al K. is using them on his Belles for sure.

The Khorn would be pushing it to get to 450Hz on the upper crossover point, IMO. I know that the new 2004's are rated at having a 450Hz crossover at a 6db slope, but previously, the "accepted" value was 400Hz or a bit lower like 375Hz.

DM2.gif

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Guys,

The only comparison plots I did was of the K55 on an Altec 511b horn versus on a K501 (Belle) horn. It was to prove that the 511b would go below 500 Hz down to 400. It will!

Yes, I use JBL 2426h drivers on 811b horns in my Belles. I do NOT recommend that combination. The JBL driver has a continuous roll off. I had to "eq" the tar out of it just to get it to go flat up to 7500 Hz where I crossed it over to the tweeter. I still think the best driver for the Khorn is the later K55V or K55M. For the Belle you can do better. I suggest a new Altec 902 from Great Plans Audio. They are making new ones for original Altec tools. The original K55 is still good enough though. The weak point is that K501 and K401 horn itself!

Al K.

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On 1/20/2005 8:40:10 AM Al Klappenberger wrote:

Guys,

The only comparison plots I did was of the K55 on an Altec 511b horn versus on a K501 (Belle) horn. It was to prove that the 511b would go below 500 Hz down to 400. It will!

Yes, I use JBL 2426h drivers on 811b horns in my Belles. I do NOT recommend that combination. The JBL driver has a continuous roll off. I had to "eq" the tar out of it just to get it to go flat up to 7500 Hz where I crossed it over to the tweeter. I still think the best driver for the Khorn is the later K55V or K55M. For the Belle you can do better. I suggest a new Altec 902 from Great Plans Audio. They are making new ones for original Altec tools. The original K55 is still good enough though. The weak point is that K501 and K401 horn itself!

Al K.

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Al,

While you are on the subject......

Been using 511b/902-16a on top of 75' Cornwall bins. I just got hold (next week) of some ALK B X-overs. I would like to try a K-55/511b combo running them down to 400 Hz. Would the mod to your boards be tough?

Thanks,

Terry

Still using the K-77......

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On 1/20/2005 11:02:47 AM Al Klappenberger wrote:

Rick,

Take heart, there will soon be an answer to the WAF and the horn upgrade!
2.gif

That is all I'll say for now!

Al K.

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Tease!9.gif

I am interested in mating my K55M to an Altec 511 but have been having trouble finding them. What are the physical dimmensions for the horn. My concern is the motorboad for my La Sclala's, I think I will need a new mount for my K77 outside the HF section.

Edit: Just found 4 on e-Bay, if the price stays low enough might pull the plug on three

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Regarding the 511 change I have a split center, I think I am going to by a single horn and build a new HF box for it to A/B and decide from there. I am reluctant to make a change I cannot undue other than refinishing my La Scala cabinets in new veneer. As far as the JBL/Beyma tweeters go, I am less certain about that. I have never been a fan of aluminum or titanium tweeters. My experiences have found them a little too bright and crisp. While the K77 does not extend as far as the aforementioned tweeters, it is a little more toned down/mellower by comparison? Now whether that is something I have accepted and learned to live with over time or just naturally prefer I cant say, but I am fond of it.

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