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Hi All;

One thing that I just learned (by screwing up and then fixing it) was that when you implement a baffle step correction filter you should use a high shelf with negative gain rather than a low shelf with positive gain.

I needed a baffle step correction at 400Hz. I had originally used 5-6dB with a turnover at 400Hz with a Q of 0.5 (that value was estimated). This means that at low frequencies there is 6dB of gain applied; at 400Hz there'd be 3dB and by the time you get to 1kHz there's be less than 1dB and eventually 0dB for the rest of the spectrum.

I did this and the bass improved as expected. Measurements were flatter and I was happy with the result. On some recording however (Pat Metheny  One Quiet Night or Strawbs Hero and Heroine) there was significant distortion in the low frequency range. It was not present on all recordings but these two were awful.

Did a lot of thinking and on a hunch changed the filter from this FR_Before to FR_After; executing the two files side by side and and compensating for the gain (adjusting the volume control) and the distortion was gone.

So at least in this application attenuation seems to be better than gain.

I hope that this helps some people.

I have attached the Audio Weaver file.

Cheers
Matt





3way_800_2k5_vc_2021_10_18_canned3.awd

Hello;

One useful feature that I'd like to see is to display the script that is being executed. It could be a temporary display at boot up/startup or it could be a line on the main screen under the volume/input setting.

Hi David;

Are there any details about the implementation of DSD over USB? A standard or anything or is this all contained in the Amanero interface?

Thanks
Matt

Thanks David;

It's not that; although I do admit that putting it there might be incorrect. I cannot get second order filters to work no matter what. I was also having the same issue with biquads too but I got that sorted.

It turns out I was making an error in specifying the file type in the server when loading on to the target; I wasn't selecting "compiled script" which is what now makes the biquads work and all frequency responses are as predicted even with 192kHz sample rates. I am not doing any really low frequency operations; a shelf at 400Hz for baffle step is about the lowest so no decimation.

I also have to (thanks to your post on the AW forum) invert the signs of a1 and a2 and make sure that I use CSV or text files to set the coefficients in order to get sufficient precision. I view that as a complete miss on the part of DSP Concepts that they cannot simply be typed in to 8-10 decimal places but it's a small issue.

The file type change did not resolve the SOF issue. I had even resorted to using AW 8.XX to create a design but 6.18.02 Server to upload in case there was a bug in the AW models (probably not).

As for the above issue with file type; I don't recall consciously doing that when loading a canned 3-way crossover design based on the canned AW Butterworth/Linkwitz-Riley crossover macro model. All of those variations in crossovers worked right off the bat. So did the millisecond delays.

Anyways; as long as I have my Excel spreadsheet for computing the biquad coefficients all seems well. I can even load up multiple files and via the AW Server Flash Memory Manager switch between several different designs with a mouse click for measurement and listening comparison; there's a beep when you switch live but nothing too awful.

It's a lot of fun to experiment with different crossovers so quickly. This is a absolutely fantastic product.

Thanks and stay safe.

Matt

Hi David;

I have had very good results with the canned crossover in Audio Weaver but was wanting to experiment with the SOF component. I'd like to give the Harsch crossover a try. BW4 lowpass with a BES2 high pass plus a half cycle of delay at the crossover frequency for the highpass.

I cannot for the life of me get a SOF to work in any kind of state; frequency response in Audio Weaver looks fine but I do not see any change in the response of the woofer. I typically am trying to use the variable Q LPF; cascade or even two singles; with Q's of .5412 and 1.3065 to make a 4th order BW. The filter has no effect on the measured FR (ARTA). Is there  box I have to check or some kind of gotcha?  I have attached the file. Maybe it will be obvious.

I know that I can use the canned BW filter (it works no problem) but at some point I have to make Bessel high pass filters and the SOF would allow that. Otherwise it's biquads and I have had some success with them but still ironing out some issues.


That’s the left woofer channel that is connected.

Thanks
Really enjoying the preamp.
Matt

another_try.awd