No x-over speakers

[gonglee]

I want to build a 2 way without x-over like Axiom m3ti, and was wondering if I need to use a capacitor on the tweeter like Bose 301.

Will it sound harmonically richer?
What are the pros and cons, besides from leaving the woofers unprotected from surges.

[BAM]

Use a very high quality capacitor on the tweeter and you will be very close to your goal. The other trick is finding a woofer that rolls itself off in the uper ranges, instead of breaking up and distorting. Take a look at the Reference 3A MM De Capo. (http://www.reference3a.com) It uses no lowpass on the woofer and a single capacitor on its tweeter. Its woofer is designed to smoothly roll off in the upper ranges. Unfortunately, I don't know enough about available midbass drivers to recommend you one (The Reference 3A driver is proprietary), but those are the two big considerations.

[borges]

This is interesting stuff. I have never built a speaker myself but my interest is gaining. Actually, I thought it would be fun to use my Xilinx and DAC board to implement digital x-over.

So I wonder, what do woofers and tweeters really do? If put AC into a woofer and increase the frequency, does it roll off like a 1st order filter? (I can kind of imagine damping and a 90deg phase lag.) Or does it degrade into all kinds of weird behaveor?

And then there are tweeters, what limits their lower operating frequencies? Are there other reasons than preventing the tweeter from tearing apart to keep low frequencies away from it? Do tweeters roll off gently too?

I guess what I need is speakers-for-filter-designers-101. Any links?


Greetings,
Børge

[Mark25]

You do need to use a capacitor for the tweeter to protect it from low frequencies, thumps, etc. Unless you use a piezo type tweeter. Bass units can handle thumps, etc. TheBM220.8 bass unit made by Volt rolls off better than most at the top end, (no real nasties) but it rolls off quite high, 3500Hz and is a big mid driver, so may be suffering from unwanted lobbing effects at the top end of it's F range.

Sounds very good though, even with a X-over, not cheap!
Mark

p.s. there's an article comparing reference 3a's de capo with the upgraded version, the royal Virtuoso, in Issue 28 of hi-fi+ magazine.

pps. somewhere on the ESP site, by Rod Elliot, there's some theory about why it is not ideal to go X-overless, sorry i can't be more specific than that though.

[gary f]

There is also the vifa P13WH that can be used with no Xover. There is projects in the archives about P13 with a tweeter with one cap only.

F