8,8 meter basshorn "6090 Monster"

[Landoctor]

Bringing back from the lost depths...

Skramstad,
Did you ever build another of these? Any new projects you have worked on that bested this one?
Thanks,
Donovan

[AndrewT]

Originally posted by Skramstad
..........The good part is that the extra 20cm also works as bracing. However the force working on the hornwalls of such a horn is enormous all the way down to the throat, so even more bracing is needed.

what is the thickness of the panelling?
are those 4x2 (100x50) timber braces around the horn?

How big do you think any panel can become before lack of rigidity becomes an issue?

If doing it again what changes would you make to the structure?

[Skramstad]

Hi,
I never had the opportunity, time or space to build another, but I have plans to use the horn in a permanently sound system outside my house. It is possible I have to change some of the modules to wrap the horn 90degrees around the corner beneath the porch, but I'm not going to do that before next summer

About rigid panels:
at the mouth I would not recommend any unbraced area more than 50x50 cm (maybe even smaller).
At the throat there is so much vibration that I would recommend that all large format horns should come with two drivers in this configuration: (driver]throat[driver), then they will counteract the unwanted vibrations in the throat.

Changes that I would like to do:
Before the permanent installation of the horn I would change the 2"x2" bracing with at least 2"x4" bracing and add more bracing. Inside the horn fiberglass or polyester could be used to make it more airtight than with plywood alone.
At the mouth I guess that a 3"x9" frame should be nice if the horn cannot be installed in a large wall.

Story from the field of another project which has been going on since 2004:
At the Mølla festival scene in Gjerstad Norway, I have designed a large format horn system with two 7meter long horns for low frequencies. The guys who have built them have done a wonderful job with curved walls and extensive bracing, more than 100meter 2"x4" for each horn. For 20Hz performance this is more than good enough I guess. The weight of each horn is approximatly 1500kg, so they do not move around
The black metal band Mahem had an awesome performance this year. The details, sound level and attack of the large horns were quite impressive when Hellhammer and Nekrobutcher got it going with double bassdrums and bassguitar
By the way, Mayhem have one of the greatest sound engineers I have ever heard. When it comes to mixing black metal, Spencer is the man!

Attached you will find a picture from the Mølla scene 2007.

[alibaba]

I want it!
Planning to build the largest horns in Africa, would appreciate any help regarding calculations/plans. they should fit below a concrete stage 9m x 6m x 1m, available speakers Eminence Omega 18". Any advice?

[simon5]

Happy to see you again, Skramstad.

May I suggest new drivers for your basshorn ?

Last time we talked together, you wanted higher efficiency, lower Xmax, lower Qts, and higher BL.

What do you think of this :
http://www.hempacoustics.com/Tsuzure...heet_ready.pdf

Efficiency : 96 dB/W/m
Xmax : 14 mm
Qts : 0.36
BL : ~35 (if I calculated correctly)

I hope to see your feedback soon about my crazy ideas...

[alibaba]

Would appreciate any help, advice or suggestion on a pair of basshorns which i intend to build in Kaduna, Nigeria. available space is 9m x 6m x 1.2 m, it is actually a 1200 m2 club with a concrete stage and the horns should be built in under it. Room dimensions are 51 x 24 m. Should be the biggest horns on the continent, all the credits go to the designer.
email to belabecker@hotmail.com, i'm a new user, can't send mails from within the forum

thanks in advance

[el`Ol]

Do you mean something like that?
http://www.royaldevice.com

[Skramstad]

Alibaba:
It would be nice if some of the audiofellas on this forum will help you with the design of your new subs. But we would need some more info:
*What is the positon of the stage (such large horns are highly directive, so we should get the dispersion characteristics correct, the system as a whole should have quite similar dispersion characteristics in all passbands to ensure a natural sound).
*What kind of materials do you have access to and what is the thickness of the wall (need that to make a CAD drawing)?
*How many Omega 18 drivers do you have?
*Is the depth of the stage 9 or 6meter?

Just did a quick simulation with two Omega 18 drivers and got a quite impressive result on a 9m long straight horn which could be placed beneath one half of the scene. At 22Hz the drivers simulated a large displacement, so you will need a notch there or a dynamic EQ to prevent too large excursions. If you do not have such prosessing power available, the maximum effect would be about 400Watts for two drivers (still out of Xmax values, but not Xmech, so that should sound just fine at 22Hz, that is my experience at least The sound pressure at 1000Watts had an average of about 135dB half space from 18-100Hz which also should be a perfect passband for the horn.

Simon:
Love your crazy ideas, but I did not find all the parameters I needed to simulate the 25" driver in a modified 6090 horn. Do you have access to more parameters?
A nice thought: with an fs of 18Hz it would go all the way down to about 9Hz in the 6090 horn (one octave below fs is the maximum low frequency extension that is possible without exceeding Xmax values concerning all drivers I have tested in large horns (no driver has gone any lower than that.....yet).

el'Ol:
Just love the concept of the Royal device, every house should have such a device instead of a basement.
I do not think alibaba meant beneath the floor, but beneath a stage standing on the floor. If that is the case, a Hornresp simulation is easily transformed to an assymetric easy to build largeformat basshorn

[simon5]

Hi again Skramstad !

The specs were lying a bit. They call it a 25" woofer but that's external diameter, not the usual middle surround measurement, effective diameter is more like 19"... so my BL estimation was very wrong, effective BL is 21. Sorry for that! Is that BL high enough? They even cheated on the efficiency, they state 96 dB/W/m but with those specs it's a 93 dB/W/m or a 96 dB/2.83V/m...

It looks less interesting for your project... sorry again!

Here's more specs :

Qes = 0.39
Qms = 2.5
Qts = 0.337
Fs = 18 Hz
Vas = 788 liters

Mms = 425 grams
Cms = 0.184 mm/N
Rms = 19.22655 N*s/m
Re = 3.6 ohms

BL = 21.06394 N/A
Dd = 47 cm
Le = ???
Sd = 1737.8 cm^3

Xmax = 14 mm
Pe = 1000W RMS and 3000W Program
Vd = 2.43 liters

SPL 2.83V/m = 96 dB
SPL 1W/m = 93 dB

Tell me if you need more...

[AndrewT]

Hi,
with a strong motor and that enormous 19inch diameter cone, will the cone buckle under the high pressure load that the horn imposes?