Crossover Debate: Bessel vs. Butterworth

[MarcMTL]

Guys,

Looking for some advice from past experiences using either passive Bessel or Butterworth nertworks. I'm looking for something to go into a new set of 3-ways, and I've heard many people praise the Bessel. As usual, I get the perfect -3dB cutoff and flat response of a BW when plotting it in WinISD, but by some mysterious force I've heard Bessel is the new name in the game.


Can anyone confirm/advise on this build?

Thanks,
Marc.

[planet10]

What the best XO is depends on everything...

dave

[col]

I was reading about the difference between Butterworth and a Sub-Bessel alignment earlier over at ESP:

http://sound.westhost.com/project81.htm

col.

[Jmmlc]

Hello,

While having excellent time response when only one filter is used, Bessel filters when used in group (by example low-pass + high-pass) don't retain the excellent time response properties of the isolated filters.

You may simulate the result of a complete 3 ways system, even introducing delays between loudspeakers or phase compensation, with my spreadsheet:

http://ndaviden.club.fr/outils/filtre_simul.zip

This spreadsheet gives also the group delay curve of the complete 3 ways system.

With another version of that spreadsheet you can study the square wave response of the complete 3ways system:

http://ndaviden.club.fr/outils/filtre_carre.zip

Best regards from Paris, France

Jean-Michel Le Cléac'h

Originally posted by MarcMTL
Guys,

Looking for some advice from past experiences using either passive Bessel or Butterworth nertworks. I'm looking for something to go into a new set of 3-ways, ...

Thanks,
Marc.

[Syncroniq]

Hey,

The problem is, that you will never get near the target response.
You cant calculate crossovers. Nor the bas or tweeter are imp, frq og fase linear to start with.

You have to get you construction meassured, and then find the right falloff. It might be 16½db/oct for the bas and something different for the tweeter, in order to be in fase and sum the frq.

[Jmmlc]

Hello,

Many people are using my spreadsheet and are reporting excellent sonic results.

Here one example:
http://freerider.dyndns.org/anlage/LeCleach.htm

The goal of such spreadsheet as the one I wrote is to see what are the best results one can obtain if the loudspeakers are ideal.

If in a first time, by this kind of modelisation, you succeed in improving the response (level + group delay) of a 3 ways system based on theorically perfect loudspeakers you should surely improve the results with real loudspeakers.

Also, before to built you have to know what is the attainable ideal. Then it is up to you yo linearize the less than ideal loudspeakers you plan to use.

The initial question was about Bessel / Butterworth. Using that spreadsheet the answer to this question is more obvious than with long sentences.

Best regards from Paris, France

Jean-Michel Le Cléac'h

Originally posted by Syncroniq
Hey,

The problem is, that you will never get near the target response.
You cant calculate crossovers. Nor the bas or tweeter are imp, frq og fase linear to start with.

You have to get you construction meassured, and then find the right falloff. It might be 16½db/oct for the bas and something different for the tweeter, in order to be in fase and sum the frq.

[john k...]

May be of interest.

[Syncroniq]

Hi,

I have Clio 7.3, and have build speakers for a while now. On my website you can see some of my projects, with meassurements.

http://www.speakerbuilder.dk/

Pick a project, and simulate a filter. Then i can show you exactly how it meassures, as i have lspcad and the raw meassuremens of the drivers used.

So, if you give me a crossover layout for this project
http://www.speakerbuilder.dk/content/getPage.asp?id=37

I will show you how it meassures, if build.

[djarchow]

MarcMTL,

I am a bit confused. You mention winISD which is simply for calculating how the woofer performs in it's enclosure, but has nothing to do with the frequency response needed for the crossover. So are you talking about the woofer high pass response in the enclosure or the acoustic slopes for the woofer, mid and tweeter crossovers?

If you are talking about the crossover slopes, then the real question is do you have the ability to measure the frequency response and phase of your drivers in you enclosure? If not then, the rest is academic as without measurements or some pretty heavy simulation using others measurements, you won't know what your final acoustic slopes are and how they will sum anyway and that is what matters.

Kind regards,

Dennis

[Syncroniq]

Just what i have been trying to say...