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How to build large round front horns?
How to build large round front horns?
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Old 4th November 2009, 02:44 PM   #1
Studio Au is offline Studio Au  United Kingdom
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Default How to build large round front horns?

I plan to build a second more 'analogue' system. Room is 5m x 4m

Turntable, valve phono stage and valve amplifier, partnered with some high efficiency front horn 3 way speakers.

I live in the UK, and hope to complete the project for a small amount of cash as possible.

Current idea is to create an Avant Garde Uno Nano imitation.
Avantgarde Acoustic Hornlautsprecher

A high frequency driver and Dayton 8" waveguide to handle top end.
Parts-Express.com:*Dayton H08RW 8" Round Waveguide 1" Threaded | horn lens horn tweeter horn bell horn compression driver DaytonAudioWaveguides070109

Large sealed 10" or 12" subwoofer cabinet, perhaps two in isobaric.

And most importantly a front horn. Currently ideas have lead to an 18" tractrix 250Hz round horn for 1" compression driver.

I have the means to make the a positive plaster mould, and wish to be able to create multiple horns from this.

Any bright ideas for materials and an easy way to create the horn form, and the best way to include screw or bolt mountings?

Paper mache, mulch, fibre glass, carbon fibre, plaster of paris, bandages etc.....
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Old 5th November 2009, 01:44 AM   #2
CLS is offline CLS  Taiwan
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The Paper Horn - Home

Fiber glass:
Azurahorn -Le Cleac'h Acoustic Horns - DIY Manafacture

About the Dayton wave guide for HF, I got 8", 10", 12", and I prefer the largest one. Even if I don't need its lower cutoff. Those wave guides in different mouth sizes come with very similar depths (lengths), so flare rate of the larger one is obvious faster (wider). I found this good for home use where 'short throw' and wider dispersion would be mostly preferred. Comparing side by side, the sound of 8" is somewhat congested, while the 12" is much more open.

BTW, all these Dayton wave guides I have simply suck in the throat size - they are all obviously larger than 1", I remember 29mm or so. Some mods are needed according to your driver's exit to make the transition smooth - and this is critical to the sound quality.
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Old 5th November 2009, 12:20 PM   #3
Studio Au is offline Studio Au  United Kingdom
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Thanks CLS, i was hoping you may contribute.

I have seen lots of sites and pictures, your setup the one you have posted on here and on your profile is my aim.

Ill do a sketchup drawing of the horns with 12" Daytons and a 15" sub

The Azurahorns look very nice, and seem to perform very well, I have heard people say the fibre glass isn't the best, I am swaying towards the paper mache option for ease, cost and room for error correction not to mention that it is non resonant and pretty inert. Was thinking of casting a solid plaster tube 2-3" on the outside to add mass, dampening and the option to drill mounting holes.

I was planning on creating something very similar to Stereo-Labs 250Hz horn
1.0" Stereo Lab cf250 Hz Tractrix Kugelwellenhorn - Stereo Lab

These are on offer until tomorrow, so perhaps i will buy one before spending weeks creating mine.

These however run from 1-2" compression drivers. Can any cheap CD's frequency be extended down to lower end of 250Hz? Have been looking at the mid priced B&C's under 100gbp.

Next step is to create some very large 'Oris 150' types with some Lowther full range drivers, but for now I am happy to experiment with 18" and a compression driver.
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Old 5th November 2009, 12:26 PM   #4
Studio Au is offline Studio Au  United Kingdom
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Also, I have a Behringer DCX 2496 and currently using a pair of eBay Zero Class T 2020 to drive my current diy speakers, so altering the crossover point should be fine.

Anyone tried powering twin 15" Isobaric sub with the cheap 2020's on eBay?
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Old 5th November 2009, 04:58 PM   #5
Studio Au is offline Studio Au  United Kingdom
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Click the image to open in full size.

Ideas for sealed enclosure

a) 18" mid horn, 12" High horn & 2x 10", possible 8"s isobaric, active.

b) 18" mid horn, 12" High horn & one 12" active. Faceted front and curved rear (think B&W 802D) on granite slab.
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Old 6th November 2009, 02:23 AM   #6
CLS is offline CLS  Taiwan
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Hi, Thanks for the kind words. But in fact, the current status of my system is sort of a patchwork I like most of its performance and can live with it happlily, but I know it's not perfect...

My Oris 150 horns were bought many years ago (I guess mine is the first batch of the product). I couldn't afford a pair of Lowthers at that time, so I kept using the existed Focal midrange drivers I had (and I'm still using them). Unlike Lowthes, the Focal mid can not reach the very top of HF, so I need tweeters. This, started the whole messy story afterwards.

Using big midrange horn is full of dilemmas. The big size inevitably makes very far center to center distance to any other HF sources. At the lower end it's probably OK, but not at the higher end. The mid-high integration inevitably runs into many problems.

If I were you, started from scrath, I'd tend to build the following configurations, both are actually 3-way but with different approaches:

1) 2-way + super tweeter
2) 2-way + subwoofer

In 1), the mid (horn) needs to stretch out on both ends, say, 300-10kHz or so. I guess Azura AH-340 may be a good choice. Then you may use big woofers (18" or even bigger) to do the bass job all the way down without additional subs. The super tweeter above 8-10kHz yields much less problem than crossed around 2-4Hz. Such system tends to be very big in size, ultra high efficiency, very very dynamic, and a bigger "WOW" factor in the looks. The down side is not so optimized directivity and thus not so good imaging.

In 2), the horn (or WG) covers from 1kHz or so to the very top. Ok, maybe with bigger better driver and bigger WG, from 600-800Hz. Below this, I'd choose direct radiator instead of horn. 15" midbass would be optimal. Then the subs could be anything you like. Such system is still big, but can be tidier than the above. With proper WG, you'll get very good directivity control and also top performance in other aspects.

As to the big throat/big mouth horns like Oris 150, I think it'd better be used as what they're designed for -- with fullrange drivers. Still compromised in directivity, though. Sigh~ dilemmas everywhere.

About the mid bass or even subwoofer section with direct radiators, I'd like to urge you to try OB. It's so easy to build, even baffle-less dipole works excellent. Just hook up some standing or suspended 'naked' woofers and you're good to go. No excuse not to try it.

On the other extreme, a full size, no cheating bass horn is also excellent, but very few can afford (the space). I myself love bass horn so much, but just can not use it in my own place.

Good luck, and update us your progress.

Last edited by CLS; 6th November 2009 at 02:28 AM.
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Old 6th November 2009, 03:02 AM   #7
Studio Au is offline Studio Au  United Kingdom
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Great info, I personally would sway toward 2way + super tweeter, for easy integration using the Behringer DCX, as separate subs could easily be added and tweaked with plate amp if needed considering three way requires 3 power amps or a 6 channel amp.

But most importantly, what about 1" compression drivers into he Stereo-Lab 250hz horn, is this enough to cover majority of the mid section +/- 400-3khz.

eBay offer has expired but website still lists them at 20% off. It seems a far smaller outlay than the other horns I have seen. And low cost is essential for this big plan, low budget build.
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Old 6th November 2009, 04:32 AM   #8
CLS is offline CLS  Taiwan
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TBH, I have no idea about that Stereo-lab horn. And I also have no idea which 1" compression driver can do 400Hz.

By the picture on the link, the horn looks very long (deep). By inuition, it might tend to beam, or simply no good for HF. This will make it difficult to work with super tweeter.

I suggest you dig deeper into the following 2 threads before action:

Geddes on Waveguides
Jean Michel on LeCleac'h horns

There's so much valuable information in them. I haven't figured them all out myself, so can not provide further advice.


If I'm going to build anything new for 'myself', I'd like to 'simplify' the system to 2-way:

1.4" compression driver for 300 or 400Hz and up (I'm hoping 20kHz top end)
15" naked woofer array for below

Simply put, it'll be similar to a "modern version" of Siemens Eurodyn or WE theater system
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Old 6th November 2009, 07:48 AM   #9
ScottG is offline ScottG  United States
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Do some modeling in axidriver with appropriate compression driver exit diameter and exit angle:

(..of course selecting the compression driver you find most promising for the application. I'll note that *value*-wise for one inch exit drivers the Celestion CDX1-1425 seems pretty tough to beat (..though it may not be suitable for your particular application):
Celestion CDX1-1425 (drivervault)


Use a CAD program to model the physical shape. Don't forget to model-in the coupling plate for the particular driver to the horn (..without altering the horn's profile in relation to the driver).

Use/convert the model to a Machine Shop vendor's needs. Perhaps:
CNC Machine Shop | Custom Waterjet, Plasma, Laser Cutting | eMachineShop.com
or a company that performs precision lathing.

Note that the *amount* of material is a factor, as is the *type* of material. (..generally look to ABS plastic.)

Once you have your profile you can then use a specialized cement/concrete casting compound to create a mold (..that doesn't require a releasing agent), and then with a bit of ingenuity you can cast to your heart's content (..or until the mold degrades). Alternatively you can skip the whole casting process and just use the horns from the machine shop. Note that IF you go the "casting" route that you'll almost certainly be looking at a 2 piece horn, 1 for the horn and the other for the coupling plate.

Of course once you have priced everything out, you may find it's cheaper to purchase a horn from a vendor depending on what you require and various added costs. BUT it's unlikely you'll get exactly what you are looking for.
perspective is everything

Last edited by ScottG; 6th November 2009 at 07:52 AM.
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Old 6th November 2009, 03:27 PM   #10
Pano is offline Pano  United States
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How to build large round front horns?
Originally Posted by CLS View Post
1.4" compression driver for 300 or 400Hz and up (I'm hoping 20kHz top end) 15" naked woofer array for below
Yeah, I like that idea. I've piled up some stuff to do that. If you think your system is cobbled together, have a look at my pile of junk!

Getting a horn and compression driver to really work down to 300Hz is not easy. 500Hz is more easily achievable. If you go open baffle on the low end, you'll want a separate amp for that. To get real low end out of the OB it takes a fair amount of power.

Have fun with it! It won't be easy, but the results will be well worth it.
Take the Speaker Voltage Test!
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