where did I goof on this hornresp model?

[freddi]

its a simple speaker ;layout - like the Cubo Infra with some front chamber

my attempt at an entry comes up with very low particle velocity with a LAB12 at 40v input.

 

[freddi]

S5=550.00
Con=1.80
F45=0.00
Sd=506.70
Bl=15.25
Cms=3.42E-04
Rms=1.59
Mmd=146.45
Le=1.48
Re=4.29
TH=1
Vrc=0.00
Lrc=0.00
Ap=0.00
Lpt=0.00
Vtc=1200.00
Atc=500.00
Pmax=100
Xmax=5.0
Path=0.0
Mass=0.00
Re'=0.00
Leb=0.00
Le=0.00
Ke=0.00
Rss=0.00
Rms=0.00
Ams=0.00
Fr1=298.00
Fr2=0.00
Fr3=0.00
Fr4=0.00
Tal1=100
Tal2=100
Tal3=100
Tal4=100
Comment=NEW RECORD - TAPPED HORN SIM FOR CUBO INFRA TYPE

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FILTER
      0   0.01    0.0     -1      0   0.01    0.0     -1      0   0.01    0.0     -1
      0   0.01    0.0     -1      0   0.01    0.0     -1      0   0.01    0.0     -1
  100   25    0    0
  4  30.50.5
  10.50.50.5
SSSS
0111
1011
0022
0111
111 
000
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 

[GM]

Please use the Export option to attach the file.

 

[freddi]

here 'tis

 

[GM]

Thanks! OK, at a glance it's long since running out of Xmax @ > ~50 W, i.e. apparently you either typed in the wrong Xmax or didn't update the existing 100 W/5 mm from a prior sim.

At its published 500 W/14 mm, peak SPL jumps ~ +9 dB, but still shows nearly the same peak velocities, so no clue unless maybe its long connecting tube acts as a well tuned acoustic absorber.

 

[Rademakers]

I thought that my latest post in this thread explained it rather well: https://www.diyaudio.com/community/threads/cubo-infra.382710/page-2

If you make a sudden large jump in surface area, in a short section of path length to become the tapped horn mouth, it shows the particle velocity at that large surface area (which is naturally low). However if 10 cm before that the port is breathing like a mad bull, because in your case it's way to small, that's what you're really interested in.

 

[weltersys]

Thanks! OK, at a glance it's long since running out of Xmax @ > ~50 W, i.e. apparently you either typed in the wrong Xmax or didn't update the existing 100 W/5 mm from a prior sim.

At its published 500 W/14 mm, peak SPL jumps ~ +9 dB, but still shows nearly the same peak velocities, so no clue unless maybe its long connecting tube acts as a well tuned acoustic absorber.

The LAB12 Xmax is 13mm, Xlim 22mm, power is 400 watts.

The 20Hz Fb of Freddi's tapped horn model is probably not indicative of the Cubo Infra's Fb.
As Cubo (Rademakers) just explained, the Hornresp diaphragm and horn mouth peak particle velocity don't reflect the particle velocity at the cylindrical port constriction.

Art

 

[GM]

Oops! Managed to copy the 12C's specs. 🙁

 

[weltersys]

The LAB12C does have a 500w power rating, but the same Xmax and Xlim as the LAB12. All the other LAB12C TS specs are slightly different.

 

[GM]

OK, thanks! For whatever reason my HR driver database is wrong. 🙁

 

[GM]

If you make a sudden large jump in surface area, in a short section of path length to become the tapped horn mouth, it shows the particle velocity at that large surface area (which is naturally low). However if 10 cm before that the port is breathing like a mad bull, because in your case it's way to small, that's what you're really interested in.

Indeed! Not knowing the Cubo's design, a quick glance of his HR schematic just looked like a 'fast' pipe end correction to me.