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Old 31st August 2011, 05:02 PM   #11
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I guess there's nothing stopping you from trying your idea, however popular opinion says that in a generic woofer crossed low to the 85wk or a generic tweeter crossed high to the 225wk would be more appropriate solution. But there's no saying for sure. No matter what, I don't think it could hurt to buy two pairs of very good drivers and experiment a bit!

I've always been tempted to try the fullrange/generic woofer solution ala the FAST speakers. But I have one holdup: everyone here talks about how bad multi-way systems are because they cross in the sensitive midband region. But judging by the fact that many more instruments and voices cross the 3-400hz region than, say, the 2 khz region, is this really better than making a typical 2-way? I don't know, to be honest.
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Old 31st August 2011, 05:06 PM   #12
chrisb is offline chrisb  Canada
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Originally Posted by talaerts View Post
Yes, meanwhile I already thought that if I cross low, then I can take a more generic woofer. Still, my original idea was to run the FF225WK full range (with BSC), and add the 85WK in from say 8khz. Decisions, decisions...
No matter what mid/bass driver is used, I'd opine that it'd be a terrible waste of the BW over which the 85WK works so well to cross it over that high.


Chaz: that's why we started playing with our XO for FAST /etc in the 250/ 350Hz range - sure you'll restrict the ultimate attainable SPL, but as I consider sane listening at under 80dB average, that's generally not an issue for me.
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Last edited by chrisb; 31st August 2011 at 05:09 PM.
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Old 1st September 2011, 08:28 AM   #13
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Thanks all for the good feedback. I begin to realise that it will make more sense to use the FF225WK with a generic matched tweeter, or the FF85WK with a generic matched woofer.
Of the two options, crossing high to a tweeter seems the cheapest option. Isn't it correct that it's not evident to cross with good audio quality at say 200 hz with passive components?
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Old 1st September 2011, 08:36 AM   #14
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I consider 200 Hz to be the transition point (ie less than 200 Hz should be active). To cross that low you would need to have a cabinet on the order of 60 cm wide to incorporate baffle step into the woofer/mid-tweeter transition.

dave
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Old 1st September 2011, 03:36 PM   #15
chrisb is offline chrisb  Canada
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I consider 200 Hz to be the transition point (ie less than 200 Hz should be active). To cross that low you would need to have a cabinet on the order of 60 cm wide to incorporate baffle step into the woofer/mid-tweeter transition.

dave

not to forget the cost and size of quality passive components required to achieve even a simple 1st order XO at that low a frequency (assuming 8 ohms each, that'd be approx 100mf for the HP and 6mH for the LP)
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Old 1st September 2011, 09:08 PM   #16
Greg B is offline Greg B  United States
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My unfashionable suggestion is that they be crossed over at approximately 1000-1200Hz. This way, there is enough bandwidth available from both drivers that a true first order crossover could be utilized, and the freq is low enough (within ~ 1wl) that good integration should be attainable.

Also, the little FF85 will have some hope of keeping up dynamically with the 8" driver.

Separate BSC will need to be employed on the FF225, but the loss in efficiency is approximately equal to the SPL difference between it and the FF85, so it all works out.

A simple cap and coil is not going to cut it, but it could still be done with a fairly simple crossover. Consider putting the FF85 in a stuffed tube or aperiodic to flatten the Z curve.

If going the full range + supertweeter route and crossing at 8k or whatever, I think a horn supertweeter will sound better, or perhaps a ribbon or even mini K-tube (as suggested previously).
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Old 1st September 2011, 09:35 PM   #17
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My MTM, FF85K + 2 MArk Audio No6 woofer is 1st order series at ~350 Hz (baffle step) has no problem with bass or dynamics. In my room we had to turn it down to talk at points.

Click the image to open in full size.

As Chris has indicated a number of times, there is considerable merit in letting the FF85 carry most of range (5-6 octaves in my MTM and in Tysen)

dave
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Old 1st September 2011, 09:36 PM   #18
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Originally Posted by Greg B View Post
My unfashionable suggestion is that they be crossed over at approximately 1000-1200Hz. This way, there is enough bandwidth available from both drivers that a true first order crossover could be utilized, and the freq is low enough (within ~ 1wl) that good integration should be attainable.

Also, the little FF85 will have some hope of keeping up dynamically with the 8" driver.
there is some precedence for this approach in the old SDX7/alpair5 combo. Crossover points anywhere from 500hz to 1.5khz were suggested, and I remember at least one person saying that the higher crossover point worked out much better. While that was just one opinion, and of course a very different speaker, it's at least one example of a full range drive being used successfully as a tweeter.
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Old 1st September 2011, 09:38 PM   #19
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As Chris has indicated a number of times, there is considerable merit in letting the FF85 carry most of range (5-6 octaves in my MTM and in Tysen)

dave
Yeah, I'm getting more and more into the idea of a silver flute W20 + FF58WK
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Old 1st September 2011, 09:42 PM   #20
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The silver flute is one of the ones on our short-list when we run out of SDX7. I have 6 of the W14s too (a pair will be tried in FH3)

dave
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