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Multi-Way Conventional loudspeakers with crossovers

Horn questions
Horn questions
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Old 7th June 2018, 07:19 PM   #1
damkel is offline damkel  Denmark
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Join Date: Jun 2014
Default Horn questions

Hi For my next project I would like to build a high efficient horn speaker system. It is going to be active using a minidsp. I need some inspiration regarding choice of drivers and horn. Maybe some guidelines about making the horns myself. I have seen some midrange horn made from plywood that looks awesome but what about dimensions etc...? I guess it should be three way? I am worried about bass. I would like to avoid something enormous so how deep can I go and at the same time have the high efficiency? Would a compromise be to add a dedicated subwoofer? Sorry for all the noobish questions but that is what I am :-)
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Old 7th June 2018, 08:43 PM   #2
hweb is offline hweb
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Don't worry about being a noob. Everyone was one once...


My advice is to keep it simple for your first project. Of course, everyone will have a different opinion of what simple is for a horn project, but here is mine:
1) Make it a 2 way. A 3 way is MUCH harder to get right.
2) Use a JBL2226 midbass driver. It is a very good performer. One of the best, really, for this kind of application. They are commonly available on the used market in good shape for under $150. If you ever tire of it, you will easily sell it for almost all of what you have paid for it. Not so for most other drivers.
3) Put it in a sealed enclosure of about 70 liters. You can vary this by as much as +/- 20 Liters and still get good performance with a sealed enclosure. Much harder to mess up than any other type (bass reflex, for example). Don't worry about not having enough bass. If you are indoors room gain will take care of that for you. EQ can also be your friend.
4) Use a well regarded horn. The Parts Express part number 299-2303 is very hard to beat and it mates well with a 15" driver (like the JBL 2226) as the horn starts to "unload" around the same frequency as the 15" driver starts to beam (around 1.1kHz) - a perfect match! Plus it's super cheap.
5) Use a decent compression driver. If cost is a big factor, the Selenium D220Ti is acceptable and currently on sale very cheap. If you can swing a few more $, the Peerless DFM-2535 is a good choice as is the Dayton Audio D250P. If you can stretch to $100 a pop, the B&C DE250 is (almost) universally liked.
6) Use an active crossover. A Mini-DSP is a good bet, but others are fine as well. Active will allow you to get into the ball park of a decent sounding speaker pretty quickly (much faster than a passive crossover, IMHO). Plus you have the possibility of EQ and delay which makes it a lot easier to dial in the sound just right. You can also opt for a separate subwoofer if you ever feel the need (you won't need it for music unless you idea of music is pipe organ - maybe for movies...)
7) Get some measuring equipment and play around. This is the part that takes the longest to master as there is a lot of confounding measurements that are due to the fact that you will usually be doing them indoors and the room has a huge influence. At least with an active system it's pretty easy to get kind-of in the right ball park by ear, so you'll have something reasonable to listen to while you are learning.
Finally, if you don't like my advice, google up "econowave" and just build an established design. You won't learn as much, but it's easier.
Don't forget to have fun!!!
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Old 11th March 2019, 07:33 PM   #3
damkel is offline damkel  Denmark
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Join Date: Jun 2014
Before I get to my question I would like to give a late thank you to hweb for a fantastic and very detailed reply. I actually found two 2226h on the second hand marked and bought both the horns you recommended and the B&C DC250 new. I have now two test speakers playing in my living room and I must say the sound great. I have some noise problems from the minidsp which seems not to be uncommon with high efficient speakers, so I am considering trying a couple of Hypex FA122 plate amps which have DSP and takes care of my power amp problems.

But to get to the question… Now this is DIY and I have seen some horns made in playwood that looks really nice. So how do I get the measurements for making a horn? After "talking" with my old friend Google I have found out that maybe I should make a Tractrix horn. I found a spreadsheet here: Tools – Volvotreter Homepage My problem is that I don't know what to do with all these numbers. I can se that there is some numbers to use with AutoCAD, but I don't have AutoCAD so that is not of much help.

Can anybody help and explain how to use the spreadsheet to make a horn? Maybe there is a better tool?
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Old 11th March 2019, 10:31 PM   #4
AllenB is offline AllenB  Australia
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Join Date: Oct 2008
You need to know each distance measurement has a cross sectional area. This defines a three dimensional horn.

With higher frequency horns calculate each step back to a simple cross sectional shape, like circular (diameter), or maybe square.

For lower frequency horns you may combine a few marks to make the whole horn from a bunch of conical sections. You might decide to include folds or non symmetrical section shape.
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Old 12th March 2019, 01:15 AM   #5
hottattoo is offline hottattoo  United States
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damkel,

Check out Bert Dopenberg's site, he has lots of experience with horn speakers and not far from you. Good luck
BD-Design, only the best!
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Old 12th March 2019, 02:27 AM   #6
cspieker is offline cspieker  United States
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Join Date: Jul 2018
Location: South Dakota
I remember going through the same process many years ago when I built mine. I imported the spreadsheet into Autocad and it drew the curve. I then added the conical throat section at the proper angle. I then took the file to the metal shop to have the shape cut out of steel so I could follow the shape with a duplicator on a wood lathe.

Unfortunately it's been too long for me to remember much detail. I did have to learn a little autocad. Don't remember that being a huge deal. There is also a method where you can use card stock paper and cut and glue many stacked rings to make a mold for fiberglass etc. I tried that first and found it to lack enough precision to be useful. Sorry I can't remember more, but if I eventually figured it out it can't be rocket science. Good luck! Craig
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Old 12th March 2019, 08:16 AM   #7
Rob Dingen is offline Rob Dingen  Netherlands
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Location: Netherlands'
Hi, You can look at the site of Yuichi. Theres a lot of information how to build your own horn. Yuichi's Audio Lab. If you want to build a round horn look at the Tractrix horn there ar a lot of excel sheet that can do the calculation. And download the Hornresp program, there you can design a tractrix and many more and export the horn contour.

Rob
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Old 12th March 2019, 08:08 PM   #8
cspieker is offline cspieker  United States
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Location: South Dakota
A couple of thoughts about your upgraded horn system.

1. I was able to get better sound out of a Tractrix horn than the other profiles.

2. Crossing over low (500-600hz) dramatically improved midrange quality. I use radian 475 in a 375hz Tractrix.

3. I had better luck with a low efficiency subwoofer driver for the woofer. Sure you can't use tubes for sub 500hz, but you get real bass and strangely enough, with the woofer I used, it just sounded more "right" meshing with the horn. I used Dayton 12" HF.

Just my experience, your mileage may vary.

My system if you are interested :


the "SPIEKER" my almost 20 year prototype finally done
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Old 13th March 2019, 06:24 PM   #9
hottattoo is offline hottattoo  United States
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Here is another diy horn system using oblate spheroid profile.

DIY Axially symmetric oblate spheroid CD waveguides, in solid Oak
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Old 14th March 2019, 08:39 AM   #10
frangus is offline frangus  Australia
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Oh man, I wish people would stop recommending the Selenium and DE250 compression drivers, can we move on from 15year old technology?. The peerless one trounces them for. Fraction of the cost of the DE250. Also as suggested try a tractrix horn alongside the conical flare horns that everyone here loves as most people I have collaborated with prefer the tractrix profile over the conical and they load far better than the conical / oblate spheroid ones.

if you can stretch your budget, the radians are the smoothest compression drivers O have used
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