Forum Replies Created
1 November 2022 at 7:08 pm #581
Regarding the -108.1 dB gain, with “Normalise magnitude to max” checked, the Import tab looks for the peak in the measurement and shifts the response so that the peak is at 0 dB. The FIR Creator workflow needs the response to be around 0 dB. (Maybe your measurement magnitude response has units of dB SPL and your mic was close to the loudspeaker.)
Regarding your FIR filter, provide a screenshot of the Export tab and a link to you project *.fdp file.
EA Support20 October 2022 at 2:48 pm #576
Crown itechHD’s require a specific number of coefficients. The last we checked, it was 897, but it might have changed. You may need to try different files with different numbers of coefficients until it works.If you still can’t get it to work, I suggest contacting Crown. They may have a problem with the FIR loading.
Regarding precision, your 2nd screenshot shows that the coefficients do match. It’s just that the iTech display is rounding/truncating at 6 decimal places, which equates to approximate -120 dB relative to full scale; so I think you’ll find the trunction doesn’t matter.
EA Support19 October 2022 at 6:36 pm #574
The region around 150 Hz has fairly high phase slope at import and it looks like the tabs, prior to the Phase Adjust tab, have added additional phase slope; which looks to be from HP filtering. The result is a phase slope high enough that it’s marginal*, in the plotting, between showing a step between plot points (as in your screenshot) and wrap. Given that this freq region way out of band – it looks to be at approximately -60 dB relative to the passband – it’s safe to ignore.
* The plotting groups/averages the >16000 raw FFT data points into a smaller log frequency spaced set at approx. 1/96th oct spacing. Sometimes in this averaging, very high phase slope regions can go either way.
EA Support16 October 2022 at 10:07 am #571
The Target response import loads almost all of our supported formats, including CSV. See Text and CSV on:
If your CSV is a magnitude curve, ensure your CSV file has 3 columns; frequency (Hz), mag (dB) and phase (degrees). The phase can be set to 0.0.
EA Support13 September 2022 at 6:25 pm #565
We’ll take a look but can’t promise any changes to address this. Odd handling of “.” in filenames is a problem shared by many apps; not just ours. All I can suggest for now is to not use “.” and instead use something else like the underscore. For example “filter_xyz_V0_2”. I do this myself in other apps.
EA Support8 September 2022 at 11:18 am #563
>> Do you have a proper workflow how to achieve a 2- or 3-way System with a linear phase from about 100 Hz to 15 kHz?
The 2-way tutorial on the website shows how to use the FIR filtering, in particular the Auto Mag and Auto Phase, to force each loudspeaker driver toward a target response; which in your case would be linear-phase high-pass and low-pass responses.
>> Is there a possibility to show the step response of the hole speaker system?
Not in FIR Designer M at the moment. However the Wavelet display (in Second View) shows the response of the whole system and you can use this to confirm that the system is tending towards a symmetric, vertical line (which flares both sides at lower frequencies), indicating a pure impulse which, by definition, gives the step response you are looking for.
EA Support7 September 2022 at 6:46 am #557
What you’re expecting is what happens when the LF rolloff is minimum phase. What is shown is what happens when the LF rolloff is linear-phase.
To investigate the effect more, run FIR Designer without any loudspeaker measurement on the Import tab, then put a HPF filter either on the IIR filters tab or the Mag Adjust tab. If using the Mag Adjust tab, try minimum and linear phase and watch the effect on the step response. Examples below.
BTW In your screenshots, check “Show FIR Filtered loudspeaker” to see all filtering applied to the measurement. This is what is used to create the step response.
6 September 2022 at 6:51 am #553
- This reply was modified 4 months, 3 weeks ago by EA Support.
>> Unfortunately we experience Audio architect to not read the FIR (csv) file.
>> Audio Architect gives the error message “An Incorrect Number of coefficients were entered.”
>> Find attached csv file exported according to your instruction (897 samples) + the message from Audi architect.
>> Can you test my attached file?
It’s possible Crown have changed something and require a different number of coefficients. Either export the file again with fewer taps or edit the CSV file in a text editor to remove some lines. Repeat until the error message goes away. Note the last coefficients in the file are 0.0 anyway.
From your screenshot, Audio Architect is reading the coefficients and displaying them. It’s just the Apply button that triggers the error message.
(Your file loads correctly for us into “I-Tech HD series” and doesn’t give the error.)
>> Some questions.
>> In FIRd I have the sample rate set to 48kHz. Will this influence the exported coefficients?
>> Maybe the DSP in Crown HD amp need to have the same?
Changing the sample rate in FIR Designer will affect the values of the coefficients, but not the number of coefficients or taps.
As so what sample rate to use, that’s a question for Crown. It’s most likely 48 kHz.
EA Support6 September 2022 at 6:43 am #552
Thanks for the screenshots. That’s exactly as expected and it’s caused by the linear phase LF rolloff in the filtered loudspeaker response. The only way to have a step response that steps up and stays up is to have a loudspeaker that has a flat response to DC.
To investigate the effect more, load FIR Designer without any loudspeaker measurement on the Import tab, then put a HPF filter either on the IIR filters tab or the Mag Adjust tab. If using the Mag Adjust tab, try minimum and linear phase and watch the effect on the step response.
EA Support5 September 2022 at 7:29 am #546
Put your images on a file sharing tool like Dropbox or an image hosting website, then put the link in a post here using the “IMG” option. (A web search should show a few sites.) If you use Dropbox, copy the share link then change the URL ending to have raw=1. For example
EA Support4 September 2022 at 7:20 am #544
>> there does not seem to be a way to copy and paste the filter prototypes used to design a
>> target curve from the Mag sub-tab of the Target tab in workflow mode, to the Magnitude
>> Design tab of the Direct Design mode
That’s correct. The more common use case is the other way around; that is, design a target in direct design mode, save as a FDT file and import this on the main workflow Target tab.
>> It would be nice if we can have the FIR Designer target file export in addition to the
>> Export SMAART target file feature or an ability to copy filter prototypes between the two modes/tabs.
EA Support1 September 2022 at 7:46 pm #541
Long ramps in the filtered loudspeaker’s step response are usually from the LF rolloff. (Linearising the phase at very low frequencies requires a very long FIR filter.) Maybe post some screenshots of the step response and the filtered speaker’s mag/phase response.
EA Support22 August 2022 at 5:41 pm #539
>> Biamp Tesira FIR Block doesn’t allow values +/- 1,
>> Is there a way to remove them during export?
On the FIR Designer export tab, there’s an “Output Gain (dB)” parameter. Use this to reduce the bulk level of the FIR filter by entering a negative dB value until the +/-1 warning goes away, then export.
Then elsewhere in the Biamp Tesira system, add a gain block to boost to recover the lost level (if you need to).