No. It was just quick listening impression of my prototype. Now I prefer less aggressive sound.
Axial or few off-axis is not enough to calculate Power & DI. Full off-axis response set is recommended. In addition, actual location (X,Y,Z mm) of the drivers is needed to simulate also vertical plane which has significant effect to Power & DI.
--
About Zmin. Should not go below 4. You can optimize total to 4...6 ohms or use parallel coil to attenuate impedance peak at fs.
Thanks
I remodeled using the optimizer to a min of 4R, the optimizer is such a time saver - brilliant!
I'm now looking forward to the toy delivery
I remodeled using the optimizer to a min of 4R, the optimizer is such a time saver - brilliant!
I'm now looking forward to the toy delivery
^Don't buy too much crossover components before measurements. At least it looks that your simulation is based on traced curves only which is usually quite far from truth due to missing baffle loss and diffraction of tweeter and wrong distance acoustic centers. Impedance response of woofer is also different than traced free air Z, but that's not usually problem with 2-way.
My guess it that big coil should be about 1.8 mH (air core 1.4mm wire) and resistors for tweeter 2.2 and 5.6 Ohms.
My guess it that big coil should be about 1.8 mH (air core 1.4mm wire) and resistors for tweeter 2.2 and 5.6 Ohms.
Good point and I also pondered similar re xover components. Many say you MUST measure for good sound, so may be at the weekend I will be able to.
REW recommends impedance is measured vertically in cabinet and using piston weight technique for Thiel, how does one load the piston vertically? Can Thiel from datasheet be used but impedance measured in cab?
Very last question, does one really need to make so many off-axis measurements for xover design?
Cheers
Lea
REW recommends impedance is measured vertically in cabinet and using piston weight technique for Thiel, how does one load the piston vertically? Can Thiel from datasheet be used but impedance measured in cab?
Very last question, does one really need to make so many off-axis measurements for xover design?
Cheers
Lea
I would say don't buy any before measurements. Unless you want to build up a component junk box.
(That can be handy though...)
You're reading about measurement of T/S parameters. That is not needed for crossover design. Just impedance response of drivers in the cabinet, without crossover. That is measured in normal operating position.
This depends on drivers, concept, how immune speaker should be for different locations/acoustics and how sure you want to be (objective view). Mistakes are not so tempting while designing commercial speakers >30 k€/pair. Measurement method and accuracy is decade bigger challenge at home than amount of directions. Setup to get the first measurement right takes 98% of total time.
Last edited:
Just checking, thanks
Valid points indeed. I shall consider the refinement of my year 2000 design more like a novice '10 year makeover', as opposed to production and of the epic £30k touch; however I'm not skimping on the turntable and angle measurement tools you know...
See here:
LOL!
Last edited:
Microphone is minimum-phase device so calibration file should also be minimum phase to get measured phase as correct as possible. Therefore VituixCAD calculates minimum phase response for calibration file without phase column before using it for response compensation. Possible problem in practice is unknown slope after the last frequency point. Program detects the slope by the last 1/2 octaves.
There is no easy way to skip minimum phase calculation at the moment. It is possible by adding phase column to calibration file with non-zero phase value to the first and last (or all) frequency point. For example +0.1 deg to the first point and -0.1 degrees to the last point. I would not do this.
Adding 'Ignore missing phase' checkbox below Calibration text box would be easy solution to allow non-minimum phase result.
Last edited:
Calibration discussion reminded me about one possible problem. Some calibration files start at quite high frequency, typically at 1000 Hz. VituixCAD extrapolates all response files while reading down to internal minimum (5 Hz). This could cause magnitude error at low frequencies if response is not flat at the first 1/3 octaves (1000...1260 Hz). Error has been significant e.g. with Earthworks M23 having truncated calibration file.
Check range of calibration file and clone the first frequency point to 5 Hz if it's higher than 500 Hz.
Check range of calibration file and clone the first frequency point to 5 Hz if it's higher than 500 Hz.
Last edited:
Rev. 2.0.5.4 (2018-10-26)
Impulse response
* Added Tukey 0.25, 0.50 and 0.75 window functions.
* Pre-delay changed to adjustable.
Conversion IR to FR
* Added 'Square root magnitude' checkbox to show IR graph in details.
* Added 'Minimum phase' checkbox to switch minimum phase extraction on/off for calibration file. Warning in red if phase response is flat while magnitude is not. Earlier minimum phase extraction was done by default if phase column was missing in cal/mic file.
Code maintenance
* Main part of response calculation with complex numbers changed from custom class to more accelerated System.Numerics.
* Removed compatibility functions related to directory separator.
Impulse response
* Added Tukey 0.25, 0.50 and 0.75 window functions.
* Pre-delay changed to adjustable.
Conversion IR to FR
* Added 'Square root magnitude' checkbox to show IR graph in details.
* Added 'Minimum phase' checkbox to switch minimum phase extraction on/off for calibration file. Warning in red if phase response is flat while magnitude is not. Earlier minimum phase extraction was done by default if phase column was missing in cal/mic file.
Code maintenance
* Main part of response calculation with complex numbers changed from custom class to more accelerated System.Numerics.
* Removed compatibility functions related to directory separator.
Quick update as goodies have arrived....
Surprised with with current setup, not as horrendous as predicted! I didn't realise my ears weren't so bad.
This is at 1m, right channel only and in room.
https://1drv.ms/u/s!AgmKo7c0CB2xjEE4Q6A0-wfCc-w0
Surprised with with current setup, not as horrendous as predicted! I didn't realise my ears weren't so bad.
This is at 1m, right channel only and in room.
https://1drv.ms/u/s!AgmKo7c0CB2xjEE4Q6A0-wfCc-w0
Last edited:
Yikes! I hadn't released that the microphone compensation profile in ARTA did not adjust the phase response if no phase data was in the mic profile.
That might explain why the phase at high frequencies in some of my measurements isn't quite what I'd expect.
However for the purposes of designing a crossover and getting correct phase tracking between drivers, provided all drivers measurements are using the same microphone profile with "uncorrected" phase, the relative phase between drivers should still be correct, and ultimately it wouldn't matter from a phase tracking/alignment perspective ?
I hadn't released that the microphone compensation profile in ARTA did not adjust the phase response if no phase data was in the mic profile.
I suppose that is quite common/standard in measurement programs. Also CLIO (10-11) does not modify phase by magnitude of cal file i.e. measured phase is not exactly correct with non-flat mic. Maybe the reason is that in the old days frequency response was measured without phase, with pink and spectrum analyzer or recording magnitude with sweep. Microphone manufacturers continue this tradition, and software manufacturers don't want to guess and calculate minimum phase, though it is better approach in theory.
I will use min phase calculation for cal files and that is also recommended in user manual.
Tip for users that concern and miss phase data in their microphones calibration file, first step is into free Rephase open microphone file and reverse curve then EQ it flat as a pancake using IIR filters and export that IR, second step is import IR and export as frd or txt file with whatever program for example REW can do that and calibration file now includes minimum phase numbers. For IR settings into Rephase suggest set it to use same samplerate as actual measurement chain because phase do change at HF area for the various rates especially if we also try set some extended tails onto original phase-less correction file.
kimmosto thanks sharing your work also therefor few minuttes ago made a small donation and myself soon should give it a try, it is advertised "Conversion IR to FR" can i ask will it do the other way around too for example one present program a frd file and want it converted to IR which is a feature i miss to save on used work time with prediction models etc.
kimmosto thanks sharing your work also therefor few minuttes ago made a small donation and myself soon should give it a try, it is advertised "Conversion IR to FR" can i ask will it do the other way around too for example one present program a frd file and want it converted to IR which is a feature i miss to save on used work time with prediction models etc.
Last edited:
VituixCAD is able to do all that (in addition to internal minimum phase extraction in Calculator). Calculator tool for mirroring, Main program for EQ, Impulse response for IFFT and Convert IR to FR for FFT. Though IFFT+FFT is not mandatory.
IFFT with file exports is in View->Impulse response window. Source response could be either total SPL, driver's SPL or driver's filter transfer function.
So VituixCAD does basically same things as rePhase but I haven't done so much details into IFFT tool because target of VituixCAD package is to handle "everything important" for multi-way design. Not enough lifetime to look all details with a microscope
...Not enough lifetime to look all details with a microscope
That is a very understandable and good argument
Thank you for hints myself then need to look up manual and get program installed to get feet wet.