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1st order crossover?

The speakers I have, have a 2 inch dome driver that has crover points at 1,000 and 2,000. In the owners material and set up a lot of attention is given to phase and time. Each driver is in it's own cabinent and a measuring device is used to align each cabinent after measuring the seating position from top of sub and floor to ear distance. Can the crossover points for that 2 inch dome be 1st order "6db per octave" when it is not even covering an octave. It has been said that drivers for 1st order crossovers have to cover such a wide frequency range. That is not the case here. Hope to learn a few more things on 1st order crossovers. Thanks
saygrr
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jeffreybehr's avatar
jeffreybehr
805 posts
 
Hi-pass and lo-pass filter points of 1000 and 2000Hz, respectively, make NO sense for a midrange dome. Maybe they're 100 and 2000?
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saygrr OP
72 posts
 
I will list all of the crossover points. 120,1,000,2,000,and 6,500. I like the speakers a lot. I am just curious about the 1,000 and 2,000 points. If there are knowledgable folks out there that can shed some light on this matter I would appreciate it.
Thanks Jeff
jdombrow
371 posts
 
What speakers are they? Have you tried asking the manufacturer or the dealer?
honest1
586 posts
 
The crossover point is not the frequency that the driver suddenly stops making sound, but the point where it is 3 dB down. It takes at least 10 dB for one sound to drown out another, so the useful range of that driver at 6 dB per octave is at least 500 to 4000 Hz. It is an unusually small range, but maybe the mid woofer and lower tweeter just didn't have enough musical overlap to work, so this dome is just bridging the gap. This is a range where many systems sound harsh, maybe because the drivers are working at the limits. By putting a dome here, maybe it allows the other drivers to work more comfortably. Are they Thiels?
saygrr OP
72 posts
 
They are Essence 10As. Yes I have asked but Dale keeps the specifics of his designs to himself. The owners material does say the crossover is 1st order and "This is the only filter that is both phase and amplitude coherent." Have owned the speakers for 12 years. Had them updated once. Have always been wondering about that 1,000 to 2,000 part of the crossover. These are my favorite speakers. I also like Vandersteen and Green Mountain. I know that just because the crossover points are far apart does not mean that it is 1st order but when it is this close can it be 1st order?
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drubin
3,274 posts
 
I don't see why not. 1st order just means the slope of rolloff is at 6db/octave, so the dirver is in fact operating over a greater range than 1000 -2000. That's the tough thing about 1st order crossover designs-- the drivers have to perform well over a much larger frequency range than they do in higher-order designs.

This is a 5-way design? I suppose that is one way to work around the demands of gradual slopes. Is this the same Dale who now makes the Intuitive Design products?
onhwy61's avatar
onhwy61
5,229 posts
 
I know nothing about your particular speakers, but there's no reason it couldn't be a first order crossover with a very narrow range. I speculate, but the tweeter couldn't operate effectively below 1kHz (an octave below the midrange crossover point and only -6dB down in level using a first order design) and the lower midrange driver couldn't go as 4kHz, so the designer added a separate driver to span this frequency region. It could work, but it looks like you have three drivers with significant output in the critical midrange. Again, I know nothing about your speaker and I'm just speculating on an hypothesis.
saygrr OP
72 posts
 
Yes it is the same Dale. He makes great products. Have not heard any of his Intuitive Design products, but really liked the Essence stuff he made. Thanks for your input guys.
saygrr OP
72 posts
 
Hi Honest1. It sure is an unusally small range. What ever it is he did he did well. They are Essence 10As.
Thanks Jeff
suits_me
121 posts
 
As others have said the first order aspect of the crossovers has nothing intrinsically to do with the narrow range of the one driver, except that the designer evidently like first order crossovers and thought this implementation worked best with his drivers.

It would be just as unusual an implementation for Joseph Audio, with their steep slopes, to have a single driver with crossovers at 1k and 2k.
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