I am trying to make sense of the in-box-measurement so I can use it to have a control for my nearfield measurements of a subwoofer.
Here it says "The in-box pressure response peaks close to the box tuning frequency of 37.6 Hz.". So, do I set the f0 to the tuning frequency or do I set it to the peak of the measurement?
Either way, I get a response that does not match the merge of cone+port at all.
Attached are my raw measurements. Port is square 39cm*4cm=156cm², the cone is a 12" so about 525cm². (https://www.thomann.co.uk/the_box_cl_112_sub_mk_ii.htm)
Here it says "The in-box pressure response peaks close to the box tuning frequency of 37.6 Hz.". So, do I set the f0 to the tuning frequency or do I set it to the peak of the measurement?
Either way, I get a response that does not match the merge of cone+port at all.
Attached are my raw measurements. Port is square 39cm*4cm=156cm², the cone is a 12" so about 525cm². (https://www.thomann.co.uk/the_box_cl_112_sub_mk_ii.htm)
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I forgot to close the speaker with the speaker flange. Here is the inbox measurement done correctly. This one correlates to the merged response better, but I'm still unsure what frequency to choose. Unfortunately I don't have the option to measure outdoors.
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Did you make the necessary correction for the microphone-in-box measurement, as shown in figure 6 of the article?
Because the equation does not give absolute values for the sound pressure inside the enclosure.
It just shows that it is analogous to the (f/f0)^2.
It just shows that it is analogous to the (f/f0)^2.
Anyway, this is not very important, since you should merge the Microphone-in-box response to the far field response to get the correct SPL for the loudspeaker.
And the far field response is the reference in this case.
And the far field response is the reference in this case.
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Joined 2003
Using default values of 320Hz, Q=0.707. Comparing to your nearfield measurement, I had to reduce the port output a bit more than expected to get it well aligned. That being said, I would measure complete TSP with extended Z parameters, and run through the enclosure tool and make that comparison, make sure to select "include effect of inductance" in the enclosure tool.
Dashed blue line below is the MIB result.
Dashed blue line below is the MIB result.
Yes, but just about everything in life is "easy once you get the hang of it"😁
Problem is I'm measuring a subwoofer. There is no far field response. But thanks for the hints and help, I think I got it now. 🙂
You could bypass any low pass filter that subwoofer has.
Then you can measure the subwoofer in the farfield at a distance 1 to 1.5 meters.
This will give you a gating window of 4 to 5 msec.
Then you could merge the farfield response (rererence response) to the near field or Microphone-in-box response.
The result will be a full response of the subwoofer.
Then you can measure the subwoofer in the farfield at a distance 1 to 1.5 meters.
This will give you a gating window of 4 to 5 msec.
Then you could merge the farfield response (rererence response) to the near field or Microphone-in-box response.
The result will be a full response of the subwoofer.
I am confused by some library components, related to active xo designs.
There are two versions of LP and HP active blocks, one which has the term "VLC unity gain" and one which doesn't. What are the differences between these two?
And for the amplifier block, I am seeing a +ve and an inverted output, similarly a + and an inverted input. What are these inverted output and input used for?
If the aim is just to represent an amplifier which will deliver gain and time delay, I am unable to understand where I'll need to use the inverting input and output.
There are two versions of LP and HP active blocks, one which has the term "VLC unity gain" and one which doesn't. What are the differences between these two?
And for the amplifier block, I am seeing a +ve and an inverted output, similarly a + and an inverted input. What are these inverted output and input used for?
If the aim is just to represent an amplifier which will deliver gain and time delay, I am unable to understand where I'll need to use the inverting input and output.
See User manual -> How to start ... -> Tip 4
https://kimmosaunisto.net/Software/VituixCAD/VituixCAD_help_20.html#How_to_start_with_VituixCAD
From VituixCAD2 Merger section of manual:
High frequency part
Far field measurements can be added by clicking folder button or dropping files into list. On-axis response
is selected by checking 'On-axis' column in response file list. Default on-axis response is 0 degrees in
horizontal plane. Merged responses (graph below High frequency part) to particular angle can be
previewed by clicking corresponding file from HF response list.
Enter actual measurement distance in mm to Distance text box.
Optional 'Diffraction response X mm' can be selected by clicking folder button or dropping file into text
box. Baffle effect response simulated to actual measurement distance of far field High frequency
responses is selected into this text box. Response type must be 'baffle step' i.e. scaling 0...+6 dB.
The high frequency measurements in Kimmo's merger example above, also included in manual, are located in the "far" directory, presumably measured at 1000m.
Why does the 1000mm diffraction response appear to be applied to the far field measurements when the far field measurements are already 4pi?
There is no sudden transition from "nearfield" to "farfield". A 1000 mm measurement is not yet "real farfield", it just is a good compromise to include the effects of baffle diffraction. Normal listening distance is usually more than 1 m, thus Vituixcad includes the possibility to account for this.
^Correct. 1 m is not full/perfect far field especially with medium and large-sized constructions. Therefore 1 m data is multiplied by diffraction simulation to 5-30 m divided by diffraction simulation to 1m.
Thank you for the replies.
If listening distance, and simulation, is at 2.5m for example, why is a 1m diffraction model being used ?
I was under the impression that the diffraction model provided the effect of 2pi to 4pi at the specified distance. In other words, input is always 2pi. If we want the effect of 4pi at 1m to 4pi at 2.5m, I would expect to be able to input the measurement distance AND the simulation distance?
And if that line of thinking is correct, is it not true that the diffraction model that should be applied is the difference between the 1m diffraction and 2.5m diffraction?
If listening distance, and simulation, is at 2.5m for example, why is a 1m diffraction model being used ?
I was under the impression that the diffraction model provided the effect of 2pi to 4pi at the specified distance. In other words, input is always 2pi. If we want the effect of 4pi at 1m to 4pi at 2.5m, I would expect to be able to input the measurement distance AND the simulation distance?
And if that line of thinking is correct, is it not true that the diffraction model that should be applied is the difference between the 1m diffraction and 2.5m diffraction?
ok, i see it, sorry for the slow understanding.
What threw me off was that the Merger LF and HF windows+descriptions appear similar so I thought 1m diffraction was applied to HF just as 5-30mm is applied to LF. As Kimmo confirmed, Vituix applies the difference (division) between 1m and 5-30m to HF data.
What threw me off was that the Merger LF and HF windows+descriptions appear similar so I thought 1m diffraction was applied to HF just as 5-30mm is applied to LF. As Kimmo confirmed, Vituix applies the difference (division) between 1m and 5-30m to HF data.
Any Mac users here? The keyboard shortcuts don’t work for me. I’ve tried both Parallels and Bootcamp installations. Wondering if anyone has found a workaround, as it’s rather tedious selecting components one-by-one and manually toggling the “Opt” checkbox.
I read the thread, so understand that there will not be any ports and kimmosto’s thinking is “use a real windows machine” 😎 Figured I’d check if others have fixed this, before I go out and buy a machine purely for running VituixCAD.
I read the thread, so understand that there will not be any ports and kimmosto’s thinking is “use a real windows machine” 😎 Figured I’d check if others have fixed this, before I go out and buy a machine purely for running VituixCAD.