VituixCAD

kimmosto

Member
2005-10-06 10:37 am
A short remark on correctness of simulation of Infinite Baffle in VituixCAD.
Calculating everything with Mms (published on datasheet) without splitting into Mmd and two possible/probably different air loads is quite common though clear simplification causing some errors and limits what can be simulated. VituixCAD plays with this simplification familiar also with some other tools such as WinISD and UniBox. IB simulation gives the same result as closed box with infinite volume.
Especially horns and transmission lines require different approach. In addition, air load is frequency dependent so Mms = Mmd + Mm1 x some constant value is not fact with wide range of radiating areas and compliances.

Anyway, "Acoustics: Sound Fields and Transducers" by Beranek & Mellow says:
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Especially horns and transmission lines require different approach. In addition, air load is frequency dependent so Mms = Mmd + Mm1 x some constant value is not fact with wide range of radiating areas and compliances.
Generally speaking, the added mass is a slightly different representation of the radiation reactance. We recently discussed this briefly in the ath4 thread. Anyway, VituixCAD is great software, thanx for it !
 
^This would be very interesting, possibly inspect the design in an simulated environment with sound samples and all (EASE, catt, Odeon stuff). Although software is very expensive and not perhaps for hobbyists to enjoy.

ps. ABEC VACS has balloon export but seems not working on my version at least (grayed out). Could one export from Vituix, import to VACS, export to balloon?:)
 

dave123

Member
2004-06-01 6:58 pm
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^This would be very interesting, possibly inspect the design in an simulated environment with sound samples and all (EASE, catt, Odeon stuff). Although software is very expensive and not perhaps for hobbyists to enjoy.

ps. ABEC VACS has balloon export but seems not working on my version at least (grayed out). Could one export from Vituix, import to VACS, export to balloon?:)

Yes that would be very interesting. I have Odeon 16.08 combined and can import 3D CLF Balloon into the simulation but have to tool to measure the speaker 3D Balloon, but I have a turntable that I can use to measure the speakers automatically using Clio. I was wondering if VituixCAD is able to combine all these measurements as 3D Balloon.
 
Hi Kimmo,


I've found a very insignificant but for the sake of it here it is:


In Auxiliary tool, box volume, internal width (see picture). Calculation of net volume is ok.



And I have a request if possible, we can export listening window (for example) It would be nice to be able to export impulse response of listening windows (for example) in a format that would be compatible with Hypex HFD software import.


Jean Claude
Are the other measurements also not correct? side panels are 18mm only front panel is 36mm
 

kimmosto

Member
2005-10-06 10:37 am
Impossible say without measurements of few transfer functions or screenshots from their design software. Following responses are needed:
1) Parametric equalizer 1000 Hz, +12 dB, Q=2.0
2) Parametric equalizer 1000 Hz, +6 dB, Q=2.0
3) 2nd order shelving low pass filter 1000 Hz, +12 dB, Q=1.0
4) 2nd order shelving low pass filter 1000 Hz, +12 dB, Q=0.5
5) Bessel low pass filter 24 dB/oct, 1000 Hz.

What is sampling rate? Probably 96 kHz because promised band is up to 40 kHz.
Note1: More responses are needed if DSP has BW or Slope parameter instead of Q.
Note2: Cannot promise support if Monacor has proprietary biquad calculation (such as Lake or Hypex). Brands using other that RBJ compatible equations will be ignored.
 
Please check the following information:

Request 1 - Parametric equalizer 1000 Hz, +12 dB, Q=2.0
iDMlm66.png


Request 2 - Parametric equalizer 1000 Hz, +6 dB, Q=2.0
xKeSQn3.png


Request 3 - 2nd order shelving low pass filter 1000 Hz, +12 dB, Q=1.0
Note: I couldn't found a way to select the Order and the Gain of the low pass filter, the option for Low Pass filter only allow Frequency and Q.
SxEMxeB.png


Request 4 - 2nd order shelving low pass filter 1000 Hz, +12 dB, Q=0.5
Note: Same as above
tIf31kB.png


Request 5 - Bessel low pass filter 24 dB/oct, 1000 Hz
1RKioN2.png



Notes:

  • Sampling rate: 96kHz
  • The Monacor is built using the AllDSP platform, so it should share the same DSP equations.

Please inform me if this enough, if not, please specify whatever information you need, i'll do my best to get it.
 

kimmosto

Member
2005-10-06 10:37 am
Yes, Low Shelf was needed.
BUT there's severe problem with parametric EQ. Shape is not analog equivalent or RBJ compatible digital or dbx compatible familiar with some graphic equalizers. It's something else which cannot be supported at the moment.
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Green trace is Monacor, and magenta is closest available with Q=2. So Monacor is out of the game without document how biquad coefficients are calculated.
 

kimmosto

Member
2005-10-06 10:37 am
Equations for peaking filter by RBJ. This is compatible with most of the DSP devices and apps:
Fs (the sampling frequency)
f0 (center Frequency)
A = 10^(dBgain/40)
w0 = 2*pi*f0/Fs
alpha = sin(w0)/(2*Q)

H(s) = (s^2 + s*(A/Q) + 1) / (s^2 + s/(A*Q) + 1)
b0 = 1 + alpha*A
b1 = -2*cos(w0)
b2 = 1 - alpha*A
a0 = 1 + alpha/A
a1 = -2*cos(w0)
a2 = 1 - alpha/A
Equations to calculate b0...a2 for Bell filter in Monacor DSP is needed.