Reverse engeneering with VituixCAD?

[Azrael]

I am planning to use a ribbon tweeter. I need to measure this with a pre-capacitor in order not to endanger my measurement amplifier.

It doesn't seem to be provided in VituixCAD, but is it possible to add it as a feature, that in such a case a back calculation is offered, how frequency and impedance response would look like without this protection capacitor?

I think such a feature could be useful in many other ways as well..... 😎

Best regards,
Michael



Translated with DeepL

 

[AllenB]

You could determine the difference a capacitor makes when applied on this impedance and add it back on. It's a little fiddly to do but it should be possible.

Or, you could keep the capacitor connected all the time and simply work with it. This is a valid alternative.

 

[DcibeL]

Measure with 2 channel system as described in the measurement guide(s) with the capacitor within the feedback loop, and the removal of the capacitor can be inherent to the measurement itself, requiring no additional work to compensate for it.

The capacitor can be "removed" from measurement data regardless, it's not a missing feature. First, load in your driver impedance, then place the capacitor in series with the diver in the crossover. Export the filter response of the driver. Load this filter response and your measurement into the calculator tool, use division to apply compensation.

 

[kimmosto]

Calculator has function:

Protection Capacitor A z B
Compensates effect of protection capacitor in series with driver while frequency response measurements with semi- or full dual channel mode i.e. reference channel is connected to output of sound card or power amplifier. Not between protection capacitor and driver!

Load frequency responses (txt/frd) to A and impedance response (txt/zma) to B. Verify that Linear input mag A and Linear result mag are unchecked, and Linear input mag B is checked. Enter series capacitance to C/uF text box.

Default result filename extension is uncap.txt.

In addition REW has possibility to start sweep at safe frequency. Minimum phase function in Calculator tool includes extending frequency response slopes at LF with maintained excess delay.

So there are at least four official, supported and documented methods to measure and/or process frequency response of fragile driver.

 

[Azrael]

Many thanks for the hints, especially for this one:

Calculator has function:

Protection Capacitor A z B
Compensates effect of protection capacitor in series with driver while frequency response measurements with semi- or full dual channel mode i.e. reference channel is connected to output of sound card or power amplifier. Not between protection capacitor and driver!

Load frequency responses (txt/frd) to A and impedance response (txt/zma) to B. Verify that Linear input mag A and Linear result mag are unchecked, and Linear input mag B is checked. Enter series capacitance to C/uF text box.

Default result filename extension is uncap.txt.

I tried the handling of this function right away: it works even if several frequency responses are imported into "A responses", e.g. if numerous measurements at different angles have to be processed simultaneously. Very nice! 😎👍

Many greetings,
Michael