Acoustic Horn Design - The Practical Way

[VoxCelestial]

Truly impressive.

 

[tmuikku]

Yeah nice work, cardioid midwoofers as well.

 

[kipman725]

very impressive

 

[CristopherPwandek]

Thanks.
However, the current developments in the Ath thread show that the effort to integrate a midrange driver is basically no longer necessary. Either I or my printer are too slow to keep up.

 

[Bobbit]

Hi all,

Amazing to see all the great projects people are sharing. Besides just getting inspiration from all people contributing to this forum, here's our two cents from Addit Audio.
This is our take on a high output monitor speaker. We call her “The Monihorn”. The speaker features a 440mm ATH horn as basis with midrange ports for 3 4" mids. A 12" driver with a passive radiator takes care of the lowend. It's a 3 way design with DSP and amplification onboard.
The cabinet itself has been 3D printed in one piece with a large scale industrial printer. Print time around 10 hours. Material used was PETG (post industrial recycled PET with 30% glassfiber) . The woofer and amp holes were cnc milled after the printing. Horn and woofer mounts are all 3D printed with a MJF printer. Foam was used to fill the hollow print for added stiffness and dampening. Essentially creating a composite sandwich.

Here are some measurements and photos from the process!

 

[454Casull]

Fantastic! Wish I could listen to that beauty. And the name, very inspired.

 

[bmc0]

Very cool design! I see you used my python script for the directivity plots .

 

[Wright]

Gorgeous!

 

[HammerSandwich]

The speaker's a creative design, and the measurements look great.

But never mind the speaker. That is one hell of a CNC!

 

[Bobbit]

Thanks for the kind words!
Thanks for sharing that Python script with the world bmc0! It came in handy

 

[Boden]

What make and type is the woofer of the Monihorn?

 

[TNT]

One looks like B&C 12BG100 (front?)

//

 

[Bobbit]

Well spotted TNT

 

[TNT]

and the bottom one - the same?

//

 

[Bobbit]

Bottom one is passive

 

[TNT]

Aha! Now as you share the design in the "Make" thread, would you care to present also the other driver make and type?

//

 

[maiky76]

and tell us about the Horn MEH simulation/ ATH script?

 

[Bobbit]

Drivers:
CD - B&C DE250
Mid - B&C 4NDF34
Low active - B&C 12BG100
Low passive - Dayton Audio RSS315

MEH simulation and ATH params I need to dig up somewhere

 

[QuantumMottle]

Beautiful

 

[speetpeet]

and tell us about the Horn MEH simulation/ ATH script?

The design goals were (pretty standard):

• consistent DI (throat adapter to prevent beaming)
• wide coverage
• directivity control at least down to ~1000hz

Here's the ATH script for this version:

; ATH 4.9 20230530
; MoniHorn v2
; -------------------------------------------------------
; CircSym mode
; Throat adapter
Throat.Ext.Angle = 5
Throat.Ext.Length = 22.5

R-OSSE = {
    R = 197.15
    a = 39
    r0 = 9.5
    a0 = 23

    m = 0.76
    r = 0.30
    q = 3.65
    k = 18.6
    b = 0.0
    arcterm = 160
}

Rot = 0

; -------------------------------------------------------

Mesh.AngularSegments = 64
Mesh.LengthSegments = 40
Mesh.SubdomainSlices=

Mesh.RearShape = 1
Mesh.WallThickness = 5.0; [mm]

; -------------------------------------------------------

ABEC.SimProfile = 0
ABEC.SimType = 2
ABEC.f1 = 250 ; [Hz]
ABEC.f2 = 20000 ; [Hz]
ABEC.NumFrequencies = 100
ABEC.MeshFrequency = 40000 ; [Hz]

ABEC.Polars:SPL = {
  MapAngleRange = 0,180,37
  NormAngle = 20    ; [deg]
  Distance = 3      ; [m]
}

; -------------------------------------------------------

Output.SubDir = "monihorn"
Output.STL = 0
Output.ABECProject = 1

Report = {
    Title = "MoniHorn throatring v2"
    NormAngle = 15 ;
    Width = 1400
    Height = 900
    SPL_Range = 50
    MaxRadius = 90
    PolarData = "SPL"
    OffsetFR = 0 ; [dB]
    GnuplotCode = 2x2n+w.gpl
}