Linear Phase Passive Crossover

[jayam000]

I visted 2-Way Crossover Designer / Calculator website.
There is one filter called Linear Phase. how it differes from Buterworth & linkwitz? i am interested in 4th order.

 

[63781]

Linear Phase is not possible in the analog domain.

That calculator will anyway give very wrong results with real-life drivers, since it is assumed that both impedance and frequency response of the drivers is flat.

 

[jayam000]

Linear Phase is not possible in the analog domain.

That calculator will anyway give very wrong results with real-life drivers, since it is assumed that both impedance and frequency response of the drivers is flat.

you are right.
But i want to just know how it differs from normal butterworth & Linkwitz filter design.

 

[Jmmlc]

Hello,

You may read that message:

http://www.diyaudio.com/forums/multi-way/161300-crossover-phase-behaviour.html#post2081002

Best regards from Paris, France

Jean-Michel Le Cléac'h

 

[phatChance]

Linear Phase is not possible in the analog domain.

That calculator will anyway give very wrong results with real-life drivers, since it is assumed that both impedance and frequency response of the drivers is flat.

While there is some truth to that, analog can be approximately linear. For example, all solid state amplifiers used transistors which are non-linear components however most amplifiers are designed to operate within the linear region.

A linear phase filter is a filter thats delay is constant regardless of frequency. To achieve the same desired order as a non-linear filter, linear filters tend to be far more complex.

For things such as image processing linear phase filters have a big payoff but for audio you can usually get away with using non-linear filters unless you are striving for perfection, which I'm guessing you might be.

 

[speaker dave]

I believe they are using a Bessel filter shape. A Bessel filter has linear phase or flat group delay in its passband via a softer corner shape. This, of course, does not mean that a combined system will be linear phase.

David S

 

[tvrgeek]

Yes, through the passband is what is important. Of course, you can toss that out the window as soon as you have two drivers. Errr, that's why we have a crossover, so that means we are in a jam. Then we have to deal with the driver itself. This is where the advanced measuring and modeling from a tool like SE comes in. With enough years of practice, you can get things to behave quite well. Look at the ZAPH designs for inspiration. No web fill-in-the-blanks crossover designer is going to get you any where near correct as they assume a resistive load and nothing on the mechanics and acoustics. Log off and measure.