Some Midrange Horns

[jpbturbo]

Hi all,

My first post here.

Just thought I'd share a couple of pics of some new midrange horns I've been building.





The curves for the horn are based on the tractrix expansion and the spreadsheet on Erik Forkers website.
Inspiration was drawn from an old article by Dr. Bruce Edgar on using cone drivers in tractrix horns for midrange use.
They are made out of 1/2 inch oak plywood.
The sides being kerfed and formed to the top and bottom pieces which were cut out with a jig saw.

Currently the driver I'm going to use for these is some Galaxy audio,
http://www.parts-express.com/pe/show...number=290-015

Probably not the best driver to use but I had them laying around.
The throat size of the horn is a little on the large side but I'm making the back panel removable so I will be able to try out a slightly larger driver further down the road.

The mouth is sized for about a 325Hz cutoff with a 2:1 aspect ratio.

For now I will try them as the midrange in my Klipsch Heresy speakers.
The stock midrange exponential horn(klipsch K-700) sounds somewhat constricted.
I'm hoping for a more open sound with the tractrix based horn.

The crossover in the Heresy uses an autoformer with multiple taps to provide varying degrees of attenuation so I hope to be able to balance the output reasonably well.

Peace,
Josh

[Pano]

Those are cool! Nice work. Should be fun to test.
I've have not heard good things about that driver, but it may work fine with a horn load. Who knows? You will.

Please post more pix as you get further along.

Oh - and welcome to the forum!

[CLS]

Nice build! Congratulations.

Some years ago, after I read the Tractrix midhorn article by Mr. Bruce Edgar, I also attempted to build a pair. I ordered some MDF, cut them into shape, and then the curvy sides hauled me down It's so hard to get right by hand tools (which were all I had). Keeping vertical along a curve which is tilted, it's beyond my skill And I lost patience and energy on those stripes, too. So eventually that project failed.

It's good to see some one else did it. More or less compensates my own failure.

Oh, I'm wondering if it's possible to add round-off extensions to the horizontal edges? It should help on the mouth diffraction issues.

And I'd also love to see a dipole horn! If it's possible.

Originally Posted by panomaniac

...

I've have not heard good things about that driver...

Wow! That's horrible! But it got several 5-star reviews. Does that also mean the reviews are not a good reference?

[Inductor]

Good job Josh and welcome aboard.
If the freq. measurements are close or similar to the Neodymium one, it will work better with a horn.
Galaxy Audio S5N-8 5" Neodymium Full Range Driver 8 Ohm
http://www.parts-express.com/pe/psho...20&ctab=3#Tabs

[jpbturbo]

Thanks for the kind words guys.

I have also read some less than stellar(get it? stellar, galaxy) info about the galaxy 5" drivers.
But one day a few weeks ago I was on the phone with my dad talking about the Edgar midrange horn article and he said, "Hey, I'm gonna send you one of these hotspots I've got sitting around and you can try it with the galaxy drivers if you'd like."
Sounds good to me.
I'm not one to turn down free drivers and I didn't have any other cone drivers available.

Anyways,
Laid out the curve in Adobe Illustrator as such,


Then I transferred the curve to the plywood and cut out the curved shape with my trusty bosch jigsaw.
Actually I just got the jigsaw so I have no idea how it will do in the long run but so far it seems great!

I made a jig to hold the top and bottom pieces of the horn,


I held the top and bottom onto the jig with some bungee cords and clamps.

For the curved sides I was going to use some thin sheets of Masonite and glue them together to make a curved laminate but my local Lowes only had 4x8 sheets and they wouldn't fit in my car (my pickup is awaiting funds to straighten the frame after the wife drove it into a ditch).
So instead I took some of the oak plywood I used for the top and bottoms and ran it over my table saw a million times to cut kerfs in it to make it flexible.

Then there was much clamping and gluing and some small nails.

I made up the back pieces last night, the holes for the drivers aren't as round as I would like so I'll probably do some more work on them before I stain and paint.

Here's what it looks like in the corner of the living room.


Up close,

The tweeter is an Eminence APT-50 with a lens designed by Bob Crites to be a drop in replacement from the Klipsch K-77(which is basically an EV T-35).
http://www.critesspeakers.com/

Here it is from the side.
It looks a little rough without paint,


And from the back,


I didn't really have a driver in mind when I started these so the throat is larger than it should be.

However,

It sounds WONDERFUL.
Upper midrange is very detailed compared to the stock horn and compression driver.
I put on a CD by Bela Fleck and the Flecktones and my wife almost immediately said "I've never heard THAT before!".

I listened to some celtic music with tinwhistle and pipes and the breath sounds and overtones were RIGHT THERE.

I'm pretty happy with the sound for now.

But,
I'll probably try adding some roundover edges or whatever they are called.
These are most likely going on the front of some vertical Klipsch MWM style bass horns I'm planning on building.

[CLS]

The throat of the horn is bigger than the driver. How did you determine that size? Any particular reasons?

As to the roundover edges, before you actually make them, you may try towels (or other sound absorbing materials) on the top/bottom horizontal edges. Then you may judge if you like it or not. Roundover or sound absorbing materials on edges make the sound wave see a gradual change towards the outside of the horn, instead of the abrupt sharp edges which produce severe diffractions.

[jpbturbo]

there was no real reason other than I started building these horns planning on using a larger driver but then my dad sent me a pair of the galaxy drivers so I figured i'd try them anyways. i'm getting ready to cut some new parts out with a more suitable sized throat. what percentage of the driver should I have showing through the throat?

[CLS]

No answer to the throat size.

Recommended reading:
http://www.centauriaudio.com.au/diy/mh28450.html

[jpbturbo]

Thanks for the link.
It looks like a larger throat helps with the high frequencies.
Bruce Edgar mentions a similar bump in the lower midrange(around 500Hz) that you can flatten out by having a gap between the driver and the horn filled with open cell foam or something similar.
Even though mine are fastened directly with no gap I'm not hearing this probably because my crossover point is around 700Hz.

Looks like we are going to try a smaller throat/longer horn in the next iteration which will be tried out on some Klipsch LaScala speakers with a crossover point of 400Hz so we will probably try the foam gap on those.

I did notice that I'm not alone in having the throat size larger than the driver though.
http://www.diyaudio.com/forums/full-range/87174-full-range-pics-post1795786.html
Post #556
Not that I can think of any real advantage to having it that way...

Peace,
Josh

P.S. Sorry about the formatting of my last post, my phone doesn't play nicely with the forum software.