What are the advantages of very steep electrical filters?

[fjhuerta]

Hi all!

I'm currently designing a speaker based on the Neo3 PDR and the Dayton RS150. So far, the only real problem I've had is measuring the Neo3 (I don't know why, but it has been a bit hard to get a good, smooth measurement with it).

Anyway, I'm now confident that I've good measurements of both drivers, and I'm starting to design a crossover for them. I thought about building a standard 4th order acoustical filter, with a third order electrical on the tweeter and a second order electrical on the woofer.

Then, I found out that a third order electrical plus a conjugate on the tweeter and a second order plus a parallel notch filter and a conjugate on the woofer could get me an 8th order acoustical L-R crossover.

I'm quite curious about it, since I'm always worried that I may be overdriving the tweeter, even with a 4th order. One thing I've noticed is that minimal variations on the components causes a big effect on the overall frequency response.

So, besides rolling off the drivers quicker, are there any advantages of using higher order crossovers? Off axis response seems similar to me... anything else I should know?

[ThomasW]

Scroll down to the section titled 'Crossover Concept'

http://pwp.t-3.cc/ttriff/M8aArticle/RoughDraftText.rtf

[fjhuerta]

Scroll down to the section titled 'Crossover Concept'
http://pwp.t-3.cc/ttriff/M8aArticle/RoughDraftText.rtf

Thanks Thomas, the link was very useful!

I was re-checking my circuit, and I have one sharp impedance peak. I suppose this is part of the problems with steep electrical filters. I'll try to fix this... or find out whether this peak can bring any problems....

[JonP]

Scroll down to the section titled 'Crossover Concept'
http://pwp.t-3.cc/ttriff/M8aArticle/RoughDraftText.rtf

Hi Tom... Have seen that document before.. it's a wealth of information on the early-mid development of the M8a, but it mentions figures and stuff that aren't included. Are any of the pics available, if only to look at on the side?

And, was this ever extended to cover the eventual RS225 version? (or do we just read the thread) ;-)

Thanks...

[ThomasW]

The entire article was published in the Sept/Oct/Nov 2003 issues of AudioXpress. They of course sell back issues, so I don't know if it's kosher for us to post it on the web.

I'll chat with Jon about uploading the graphics to his hosting server...

Jon's never worked with the RS225, the principles talked about in the article apply to all drivers...

Edit: talked with Jon, he'll upload the article over the weekend. It's a 46meg .pdf, so dialup users need not apply

[JonP]

Thanks to both of you... and good thing I have cable! ;-)