Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

[fjhuerta]

Hi all!

I'm almost finished with my open baffle build, but there's a thing that has still me confused.

I do not know how to implement an active filter on LSPCad.

I built a very simple schematic with a DCX2496 component and an output buffer, and apparently I can model filters now.

The thing is, I know the DCX2496 and the MiniDSP implement several functions differently. Notches, specifically.

I just wanted to double check - if I use L-R filters and low and high shelf filters (not notches) can I take the LSPCad values and plug them into the MiniDSP? Will they work properly?

Thanks!

[winslow]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

Should.

[charlielaub]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

The thing is, I know the DCX2496 and the MiniDSP implement several functions differently. Notches, specifically.

Bingo.

The real problem that I have found with the DCX2496 is that the filters/EQ that they use are not the same as textbook functions of the same filter type. This has been documented elsewhere on the web. It's one reason why I prefer the MiniDSP units with ALL filters and EQ implemented using the advanced biquads. In fact I felt so strongly about this I created the Active Crossover Designer tools so that the MiniDSP could be programmed with the EXACT filters that are represented internally within ACD. It can be very disappointing when you develop a great crossover only to have something else happen when you implement it with your DSP unit...

-Charlie

[johnk...]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

I don't recall the form of the notch/peak filters in the DCX, but the shelves are set by gain and the pole closest to the zero gain side of the filter, if you follow me. Recall that the gain is F1/F2 and the center frequency is sqrt (F1xF2) where F1 and F2 are the poles. For miniDSP the Q = .5

[fjhuerta]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

I don't recall the form of the notch/peak filters in the DCX, but the shelves are set by gain and the pole closest to the zero gain side of the filter, if you follow me. Recall that the gain is F1/F2 and the center frequency is sqrt (F1xF2) where F1 and F2 are the poles. For miniDSP the Q = .5

I see... so, shelves and filters *should* be identical, while notches aren't (I think I'm understanding correctly)...

Charlie, can I download your ACD from somewhere?

Thanks again!

Javier.

[charlielaub]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

I see... so, shelves and filters *should* be identical, while notches aren't (I think I'm understanding correctly)...

Charlie, can I download your ACD from somewhere?

Thanks again!

Javier.

You sure can. Here's the link:
the Active Crossover Designer web page

-Charlie

[fjhuerta]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

That's some amazing work Charlie! I've been using the ACD tools and, while I had some issues at first, I managed to get some good results with them!

Here are a couple of comments I have regarding your tools.

1) They don't work with Excel 2003. I tried them with Excel 2003 (in english) and Excel didn't recognize some of the functions used.
2) They don't work with Excel 2007 in other languages than english.
3) I had no issues with OpenCalc.
4) If people from outside the US have problems with Windows, there's a change that needs to be done. In the Control Panel, the regional settings must be changed to "US / English". Otherwise, the spreadsheet calculations fail. This happened with both OpenCalc and Excel.
5) For best results, one needs to export the driver+filter FRD sheet to a TXT file and optimize manually the filters with something like LSPCad.
6) I got the 2 way X-Over plug-in, but one needs to get the 2 way Advanced X-Over plug-in. The standard plug-in cannot use biquad filters.

As I said.. amazing work. I could have never built the filters without your tools. THANK YOU!

[charlielaub]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

That's some amazing work Charlie! I've been using the ACD tools and, while I had some issues at first, I managed to get some good results with them!

Here are a couple of comments I have regarding your tools.

1) They don't work with Excel 2003. I tried them with Excel 2003 (in english) and Excel didn't recognize some of the functions used.
2) They don't work with Excel 2007 in other languages than english.
3) I had no issues with OpenCalc.
4) If people from outside the US have problems with Windows, there's a change that needs to be done. In the Control Panel, the regional settings must be changed to "US / English". Otherwise, the spreadsheet calculations fail. This happened with both OpenCalc and Excel.
5) For best results, one needs to export the driver+filter FRD sheet to a TXT file and optimize manually the filters with something like LSPCad.
6) I got the 2 way X-Over plug-in, but one needs to get the 2 way Advanced X-Over plug-in. The standard plug-in cannot use biquad filters.

As I said.. amazing work. I could have never built the filters without your tools. THANK YOU!

Thanks for posting this. Since my local language is English I never tried to use the ACD tools with any other language setting... I wonder what is different? Maybe some worksheet functions are not recognized because they are given a different name in other languages?

I actually have Excel 2003 (Professional) and that is what I used to build the tools so I am surprised that you are not able to get them working in 2003. What seems to be the problem there, specifically?

I wonder how much interest there would be in a "filter optimization" extension? This could be implemented using Excel's solver. In OpenOffice Calc you need to use some macro programming because there is no appropriate non-linear solver available.

Again, thanks for your comments and the feedback. I really appreciate users posting their experiences so that I can make the tools better for everyone.

-Charlie

[fjhuerta]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

Charlie, I found the functions that don't seem to be working on Excel 2003 (I'm also using Professional). I'll send them to you. It could possibly be because I'm using a Spanish version of Windows and an English version of Office. Strange thing is, the error (#NAME) seemed to happen because Excel wasn't recognizing the function itself.

Regarding the regional localization, it seems that at certain points numbers are interpreted as text. I assume this is because of decimal points and commas used to separate thousands, millions, etc. That's the only change that could be affecting calculations. Those errors appeared as #VALUE in both OpenCalc and Excel 2003 / 2007.

[charlielaub]

Re: Is it possible to use the DCX 2496 filters on LSPCad and apply them to a MiniDSP?

Charlie, I found the functions that don't seem to be working on Excel 2003 (I'm also using Professional). I'll send them to you. It could possibly be because I'm using a Spanish version of Windows and an English version of Office. Strange thing is, the error (#NAME) seemed to happen because Excel wasn't recognizing the function itself.

Regarding the regional localization, it seems that at certain points numbers are interpreted as text. I assume this is because of decimal points and commas used to separate thousands, millions, etc. That's the only change that could be affecting calculations. Those errors appeared as #VALUE in both OpenCalc and Excel 2003 / 2007.

Yes, it's likely that Excel or the OS is changing the names of some or all functions into the local language and the English function names are not recognized.

All numbers should be formatted using the dot or "period" to indicate the decimal point.

-Charlie