TOPIC:

I am experimenting with linear-phase crossovers and as a first step, I wanted to create an all-pass filter network.

When importing a simple 2nd order maximum phase FIR filter exported from FIR Designer M by Eclipse Audio, I get frequency filtering in the miniDSP software.

What am I doing wrong?

I followed this guide.

For any helpful replies, thank you in advance.

Quick update, I found out that there's a longer delay needed as the all-pass filter is at such a low-frequency.

Now I ran into another problem, I get an error saying that I use invalid coefficients, after clicking the ok button many times, the values change to undefined.

Can someone please help me out here? I am still using the guide linked above.

Thank you in advance

I'm not familiar with FIR Designer, but why not post in the FIR Designer section of the forum here so Michael will notice your query and answer it.
www.minidsp.com/forum/fir-designer-by-eclipseaudio

I don't know why you desire to create an all-pass filter with a FIR scheme. All-pass filters are easily created with the IIR method via the advanced portion of the basic PEQ function in the miniDSP products.
As an example, a simple 2nd-order all-pass at 38Hz can be created with these coefficients.

a0 1
a1 1.990076284018420
a2 -0.990100904053144

b0 0.990100904053144
b1 -1.990076284018420
b2 1.000000000000000


Dave.

thanks for your reply dreite!

I just posted it

My goal is experimenting with linearising phase problems, and in the case of the speaker I am using, a normal IIR 2nd-order makes it worse, while a Maximum Phase FIR filter enables me to linearise it.

I attached some pics for clarification.

Yes, an all-pass filter creates further phase shift.

You're desiring to create a correction filter to unwrap the phase shift of your normal roll-off and/or crossover filters?
So, yes, a utility like FIR Designer will do that. You just need to compute the correct coefficients in the correct miniDSP format and it will work. I suggest to query Michael and he can identify your problem.

Dave.

Yes, the end result will hopefully be a crossover design that incorporates a mixed filter design to get a linear phase system

He always delivers great answers so I am hopeful

Thanks for your help as well Dave!