What type of filter is this?

[Doobrey]

My Cambridge Audio amplifier implements a wolfson DAC using a 2 pole Butterworth filter, i have never heard of it before with it not being named like what we see with linear, minimum etc. I have looked around online and I am not really sure what it is exactly. If anyone could help me understand what type it is, impulse etc I’d appreciate it, thanks.

 

[fpitas]

Butterworth filter - Wikipedia

en.wikipedia.org

 

[Doobrey]

Thanks for the link but a lot of this stuff goes over my head, I’m assuming it’s a type of slow linear phase then?

 

[fpitas]

Thanks for the link but a lot of this stuff goes over my head, I’m assuming it’s a type of slow linear phase then?

Not exactly. There are whole series of linear phase filters, like Bessel and Gaussian, and various approximations to linear phase. Butterworth was simply one of the first filters to be mathematically derived, and it features maximally flat response in the passband with no passband ripple. The 2nd order BW has a slight peak in group delay, higher orders start to have significant peaks.

 

[Doobrey]

Thanks for the response, I hear it’s great when used in crossovers but when it comes do DA conversion is it still good enough to do the job or should I look at external converter with a better filter?