Mid-bass horn (easy to build)

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I've designed a great sounding mid-bass horn that's super easy to fabricate. I'm using a JBL 2240 18" driver, but have simulated (Hornresp) inexpensive B&C 18PS76 18" woofers that perform almost as well and cost under $200.00 apiece at Parts Express. I've posted info on my web page: inlowsound.com
Check out the Diy 80 hz mid-bass horn page.
 

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Very cool! I am in the design stages for building a ~65hz midbass horn. I like seeing what others have done.

My ony concern is that the horn is a bit small (theoretically) for 80hz loading. Have you measured the impedance sweep?

From your plans, I gather your horn is roughly 32" long and has a circumference of nearly 96". Typical horn math philosophy suggests that the mouth circumference be one wavelength and the depth is > 1/4 wavelength. The wl of 80hz is 168". 96"/168" = .57 wavelength and the depth is ~1/5 wl.

I don't know how critical this is, just raising the standard questions.
 
There will be no problem with this 80(75Hz) horn. If you look at Edgars 80Hz it is only ca 60cm long and Am ca 3000cm2 and that one works OK.

Here we have over 80cm length and almost 5000cm2 Am. The only concern could be the rather high Mms. But the sims says something else.

Carpenter,

If you sim the horn like an Exp(no big difference) you will be able to leave the less relevant "constant directivity" and instead use directivity, on- or off-axis at choosen angle. I normally use 20 degrees for lower placed midhorns.

Your horns will fall just a little bit more than the Exp.
 
Thanks for the input, guys.

This horn hits the drum passages with power to spare and sounds excellent while performing its job. I hear very little distortion compared to the exponential horns I used to build. Hornresp has been such a blessing -- what an amazing age we live in.

I've been asked to supply more information on my Diy 80hz horn page and will do so in the near future.
 
FWIW, I am not critizing the choices made. These are certainly more reasonably sized then full mouth horns. My question/concern only has to do with what effects do the compromises have. I simply have no experience here and would like to ponder the issue.
 
FWIW, I am not critizing the choices made. These are certainly more reasonably sized then full mouth horns. My question/concern only has to do with what effects do the compromises have. I simply have no experience here and would like to ponder the issue.

If you have an excellent subwoofer section, then you will find this mid bass horn is just the right size. In fact, I designed it to tamp down the sub bass -- it always felt like a tank down low in that my system had gobs of power, but felt clunky. This horn gives plenty of snap and punch and takes my system from very good to excellent in the performance dept. It's no longer a Cadillac, but more of a Formula 1.

Edit: the horn is allowed a smaller mouth because of the plane it was designed to perform in. It gets the back wall and the floor, and perhaps even a bit of the side wall for the very bottom end of its spectrum. Believe me, there's more bass there than I expected, and because of the light cone/powerful motor in this 18" driver, the power is out of this world.
 
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very cool, had a good read of your site. Particularly liked the fabrication instructions for that huge paper horn, what kind of efficiency do you get from it?

I'm pleased that you found my web site interesting. It's a pet project of mine.

The paper horns are extremely efficient. The JBL 2446 compression drivers are rated at 110db 1w1m and the horns are operated well above their cutoff, so I'm sure the initial rating holds. With these horns, a three watt amplifier is plenty strong enough to keep up with the rest of my system.
 
Nice work with the horns John and with the website. I saw it yesterday and had a glance through the whole thing. Always good to see some diy projects put up to inspire others.

Thanks for the kind words, Paul. How are your horn projects coming along? It's been awhile since I last looked at your bass horn project (years actually). Did you ever get that huge bass horn built?
 
Good memory! The day I walked into the room in question the idea evaporated. I realised I had to do some work on the room, which I've since done. I also realised it would just take up too much room. I now have a more sane plan for tapped horns under the floor, much more practical. I also have subs which sound much better before horn loading. I'm in the early stages of a Synergy horn, getting my head around Akabak!
 
Good memory! The day I walked into the room in question the idea evaporated. I realised I had to do some work on the room, which I've since done. I also realised it would just take up too much room. I now have a more sane plan for tapped horns under the floor, much more practical. I also have subs which sound much better before horn loading. I'm in the early stages of a Synergy horn, getting my head around Akabak!

The bass horn on my home page works like a charm, is small for all the bass it produces, and will eventually be tested in my great room (for now, my brother is using the first prototype in his band). It was your profound interest in bass horns that spurred my desire to design a compact, efficient bass horn. I can't wait until the day comes that I have about 4 of these little monsters in my great room.

I've been thinking about housing the body of the bass horns outside the house with a little shed roof over them and placing siding around them so they look like the house. That way, the mouth is truly in the corner of the room and there's more visual space to enjoy. My large media room is on the second floor, so I'd have to place the horns on a deck/porch -- talk about getting spousal approval :eek:
 
On your web page it looks like you have built the Jensen imperial from the plans from decware. How do you compare to your other bass units you have built?

If you happen to have read my home page (down near the bottom) you'll notice that I made mention of my neighbor (who owns the shop where I build my speakers) and the conversation we had regarding my folded bass horn vs. the Imperial horn I fabricated for him.

The Imperial is a large, decent sounding horn, but doesn't have anywhere near the efficiency of my folded horn, not to mention, my folded horn uses 2 Lab 12 drivers which at $300.00 a pair don't cost an arm and a leg, unlike the B&C 21" subwoofer in the Imperial (I fabricated) which cost $650 or more.

The large tapped horn I fabricated is a blast, but doesn't sound very linear. It does make gobs of bass and if used below 40 or 60hz is a monster.

Overall, the folded horn has the least amount of resonance, the greatest efficiency, cost less than the other sub-bass horns, and is smaller.

Can you guess which one is my favorite? ;)
 
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Sorry to harp on that same topic, but do you happen to have an impedance sweep of that horn. That horn looks really interesting and I am just trying to determine how much truncation below 1/4 wl affects the horn loading.

See for instance the last chart in this link:
Lenard Audio - Education - Horns and Large Systems and Line Arrays.

Thanks a bunch for that link, Josh. I can post the radiation resistance modeled by Hornresp if that helps your thirst for knowledge.
 
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