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Dubravko

Open frame speaker (Heresy kind)

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Hi guys...

I am new in terms of building horn type of speakers. 
After some time/money I have in collection Eminence delta 12A, Atlas sound PD-4 and Electrovoice T35 
speaker units. PD4 do not have horn. My idea is to make open frame speaker (naked) system with low frequency 
driver based on Heresy speaker enclosure on the bottom of the mounting frame and PD-4 with Edgar Tractrix 
plywood horn for mids and on top will be T35 driver. Crossover design will be based on classic E type network. 
Woofer cabinet design is compresion type. I am not sure what will be better, to build some sort of Heresy 
speaker with all driver units in one enclosure or to pursuit idea of open frame - modular system. 
First one is great looking but second one gives flexibility.

 

Dubravko/Croatia EU
 

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Welcome.  

 

Are you making the plywood tractrix horns?  I’d start with the open design, which would allow you to time align the drivers.  You could always install the horns in the Heresy-type cabinets later.  Whatever you do, please share photos.

 

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Plywood is my first choice for material, second one is glass fiber lamination impregnated with polyester resin. My idea is to use two layers of 3mm (~3/32 inch) glued together on mold. I think wood is better material. What will be best way to impregnate horn inside surface, some sort of varnish?

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Welcome Dubravko!

 

Polyurethane varnish will make an excellent, durable finish for wood.  Paint is normally used on fiberglass. 

 

The midrange (squawker) driver used by Klipsch was an Atlas PD-5VH, not the PD-4.  You might find a PD-4 will not go high enough to reach the lower limit of a T-35. 

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Actualy I have problem with mid speakers, last owner told me that this speakers are PD-4 but unfortunately on metal case do not exist any nameplate. I will not be sure until I test speakers with white noise and spectrum analyser.

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So...this is not same thing, bad luck. I will test my speakers to resolve mistery. But, based on pictures, my units are bigger and perhaps lower in frequency response. If they are not suitable for operation I will replace units with some modern before building of plywood horns.

 

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May I suggest you look at B&C drivers?  They are made in Italy and should be easier for you to get.  Especially look at the DE500 and DE550.   In the U.S. they cost about the same as a PD-5VH does here and the curves look to be easy to mate with other drivers/speakers. 

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