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A time-aligned top end - Part II


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Guest David H

Dave,

I think a couple of people are trying to tell you something! Idea

Al K.

Seems like it, but I am thinking a smaller horn designed to cross at 500 hz would be better than adapting.

Hope no-one is in a hurry.....Dave

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How about going all the way to a 1" adaptor and the Great Plains 902? (500 to 20,000+ Hz for La Scala and Belle owners)

Yeah! What he said. Brian

I could never get an answer but not all great plains are good to 500 more like 900. I don't care what they say. However they do sound great. I'd try another pair.

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Wow Al. the picture really sings a thousand songs in this case. I never really thought about it but the off axis response is restricted by the squeezing at the throat which is necessary to retain Tractrix expansion in an Edgar type horn. The Eliptrac on the other hand is not contrained in this manner and is evident from the picture alone. The conical throat I suspect is the key to retaining good off axis response.

I guess I should find a good driver to test the feasability of the Eliptrac 400 for 2-way operation.

The response plots look very promising, I am anxious to see the all encompasing results.

BTW, prototype horn #2 is on its way,

Dave

Would you be interested in trying a K-69 ?

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"I am thinking a smaller horn designed to cross at 500 hz would be better than adapting"

I agree, but a good reason to make it expandable is to allow for later upgrades. Even a 500 Hz elliptic horn could be designed for a 1 inch driver and separated at the 2 inch point where a flange would allow either a 2 inch driver or an adapter down to 1.4 or 1 inch to be bolted on. I found that there is no difference in the taper so long as the area from 2 inch diameter back to the smaller driver is round. The elliptic mouth can transition down to round at the 2 inch diameter point. The adapter could have a flange and bolt pattern exactly emulating a 2-inch driver. That would not be a compromise at all. It would be a true tractrix expansion all the way.

Another reason to make it expandable is to limit manufacturing costs. Only a single horn would need to be made for each cutoff frequency. It would be made for 2 inch drivers and adapters down to 1.4 and 1 inch offered separately. Start with the K55 on the 1 inch adopter and move to a 2-inch driver later by removing the adapter.

Al K.

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Guest David H

"I am thinking a smaller horn designed to cross at 500 hz would be better than adapting"

I agree, but a good reason to make it expandable is to allow for later upgrades. Even a 500 Hz elliptic horn could be designed for a 1 inch driver and separated at the 2 inch point where a flange would allow either a 2 inch driver or an adapter down to 1.4 or 1 inch to be bolted on. I found that there is no difference in the taper so long as the area from 2 inch diameter back to the smaller driver is round. The elliptic mouth can transition down to round at the 2 inch diameter point. The adapter could have a flange and bolt pattern exactly emulating a 2-inch driver. That would not be a compromise at all. It would be a true tractrix expansion all the way.

Another reason to make it expandable is to limit manufacturing costs. Only a single horn would need to be made for each cutoff frequency. It would be made for 2 inch drivers and adapters down to 1.4 and 1 inch offered separately. Start with the K55 on the 1 inch adopter and move to a 2-inch driver later by removing the adapter.

Al K.

I couldn't agree more.

Dave.

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Guest David H

Here is the Eliptrac 400 rev-b slightly modified for use in the ALK/Martinelli Trachorn frame.

I have made good progress in the stackable build technique, I am very pleased with this horn.

Dave

post-24405-13819635258456_thumb.jpg

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Guest David H

700Hz for La Scala and Belle and room for a JBL 2405 or JBL 2404?

Dreaming again?

I was thinking more along the lines of 500-600hz for Lascala and Belle and go 2-way or Coaxial. I'll have to take come measurements.

Dave

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Guest David H

Sounds good to me. May I request a 1in trought horn to replace my k400 in my LaScalas. PLEASE Brian.

You may however all of the Eliptracs wil be 2 inch with optional reducers from 2" to1.4" or 2" to 1"

Dave

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all of the Eliptracs will be 2 inch with optional reducers from 2" to1.4" or 2" to 1"

I want to point out again that this will NOT be a jury rig compromise like grafting a conical section on the square throat of an Edgar type horn. The extension will have a true and correct tractrix taper. It will simply be round from the 2 inch point back to the driver, but still a tractrix expansion.

AL K.

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55,

The problem with the 400 Hz crossover for the Belle is the size. It would require raising the top like I had to do to fit the Martinelli Trachorn 400 into the Belle. A smaller horn makes much more sense. The Belle and LaScala woofer has no problem going up to 500 or even higher. Why force a 400 Hz horn into it unless you only wanted to manufacture a single horn for everything. That is what I was doing.

Al K.

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Guest David H

Why not make it like the first... down to 400 ?

The 400hz horn is not going anywhere, this would be completely different horn better suited for Belle and Lascala.

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