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Old 8th December 2012, 03:34 PM   #21
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Originally Posted by dewardh View Post
Typically what one "gives up" is "quality" in the range from 10 to 20 kHz. . . . but that has to be the most overpriced and under-delivering frequency band in all of audio . . .
Especially if you're over 65!
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Old 8th December 2012, 03:49 PM   #22
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Originally Posted by john k... View Post
Especially if you're over 65!
Too true . . . . . . but when I think back to peaky (and awfull) phono cartridges, and the nasty HF resonance of some (very popular) condenser microphones, I remember wishing I couldn't hear it back when . . .

The great contribution of the "Baxandall" tone control was chopping the high frequencies first . . . everyone who could hear used to set them a click or two down from "flat" . . . (if you didn't do it yourself it was how you knew the wife had been listening to the Hi-Fi).

Last edited by dewardh; 8th December 2012 at 03:52 PM.
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Old 8th December 2012, 03:51 PM   #23
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What Dave quoted is correct, I have seen a couple tweeters that could be used in a consumer type speaker in my time that could be crossed at 500 hz or below... a couple and Dave mentioned lobing, this normally happens in an MTM in mid frequencies,(I normally use 3rd or 4th order crossed at 2k or below) so to use a first order network, you would indeed need a low cross over point..... I wasn't trying to open a can of worms, I was just saying that the op, clearly stated "using a 1 inch dome".... you won't find a 1 inch dome that can cross below 500 hz.
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Old 8th December 2012, 04:45 PM   #24
dewardh is offline dewardh  United States
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Originally Posted by timlub View Post
you won't find a 1 inch dome that can cross below 500 hz.
You won't find a 1 inch dome that's usable below 1500 . . . and the only reason to go that low is that the (big) cone below it will sound worse pushed higher.

Which is the "why?" of 3-ways . . .
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Old 8th December 2012, 04:46 PM   #25
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Originally Posted by head_unit View Post
Yes. Because what you are talking about is just the magnitude in decibels of the sound. You are completely missing the TIME response.

Example: speaker A has an on-axis dip -3dB at 2 kHz, but off-axis output is very high. Measures 0 dB at the listening position.

Example: speaker B is flat on-axis at 2 kHz, but off-axis output is none.

The two speakers measure the same at the listening position, but the ratio of direct to reflected sound will be quite different as will the time arrival and smearing of said sound.
Great point!

When I measure the 2 way I've described (1" tw + 6.5"wf) in a quasi-anechoic environment, the on-axis frequency response is fairly flat. The measurement can be considered anechoic because I adjust the time domain window to ensure I'm not including any reflections in the data.The XO frequency is 1.9KHz. The in-room listening position measurement (on-axis) frequency response slopes down but doesn't have a dip around the crossover frequency.

If the 3 way anechoic on-axis measurement is also flat, than in the same room as above, I'd likely have a bump around the crossover frequency.

If that train of thought is correct, it seems as though the 2 way off axis dip caused by mismatched directivities is far enough off axis that it doesn't significantly effect the on-axis in-room frequency response.

Doesn't that mean the 2way will be less sensitive to reflections yielding minimal room to room frequency response deviations compared to the 3way? And therefore there will be less smearing of the sound with the 2way?

Let's assume optimal execution of both designs without taking into account THD.
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Old 8th December 2012, 05:02 PM   #26
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it seems as though the 2 way off axis dip caused by mismatched directivities is far enough off axis that it doesn't significantly effect the on-axis in-room frequency response
you have to consider phasing more on a 2 way (getting the drivers to work in unison), so it depends on the crossover point and sloped selected. With a 3 way it is much easier to avoid phasing problems.
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Old 8th December 2012, 05:10 PM   #27
dewardh is offline dewardh  United States
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Originally Posted by leadcoma View Post
Doesn't that mean the 2way will be less sensitive to reflections yielding minimal room to room frequency response deviations compared to the 3way?
No, it just means that it's harder (essentially impossible) to get flat (in room) power response with a 2-way (while maintaining flat on-axis response).
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Old 8th December 2012, 06:46 PM   #28
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my 2c worth:
crossovers are tricky, and there is twice as many in a 3way than a 2way. An active set up makes it very eay to play around to find a good setup.
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Old 8th December 2012, 08:26 PM   #29
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Originally Posted by Barleywater View Post
Crossover point selection based on human vocal range rather than driver performance is recurring theme, and is poor design compromise.
Driver performance can be choosen to XO whereever one would like.

Crossovers are a compromise, each and every on of them replete with evil. Personally i find an XO right where it is most easily detectable a compromise that i choose not to make.

Quote:
Tweeter claiming performance down to <300Hz is classifiable as full range
Count the octaves. The same criteria would make the midwoofer in any 2-way with an XO > 1000 Hz a full-range as well.

Quote:
and will be replete with IMD and break up issues
You are sure? Every driver has some break up issues. There may be more IMD up high, but less than a midbass in a cone + dome in the critical band. And is that measured IMD important? Certainly some other measured distortions in the few studies extant have been shown to be irrelevant (most notably THD). None that i know if that coorelate IMD to sonics. And what do we gain by making the "supposed" compromise to cross this low? No lobing and phase coherence.

With all the compromises necessary to design a speaker, the poor performance of even the best speakers compared to the ultimate potential (i estimate that the best are noymuch over 10% of the way), it is entirely possible to design 2 completely valid speakers that are very different.

Measurements are a tool to help design a speaker. But there is very little understanding of how they those measures correlate to what the ear/brain percieves. In the end what is important is how well the speaker (with all the other kit in the system, they cannot be ignored) commuicates the emotion of the music to the listener.

And the speaker pictured does a very good job of that and at a surprisingly low cost. A clear success. Nitpick it all you want, it does the job.

dave
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Old 8th December 2012, 08:31 PM   #30
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Originally Posted by timlub View Post
I was just saying that the op, clearly stated "using a 1 inch dome".... you won't find a 1 inch dome that can cross below 500 hz.
He did, my intention was to open things up a bit.

I have heard a couple systems that have 1" domes that XO nicely as 1.2 KHz in a 2-way and even that lower XO makes a difference in those qualities i hold dear. The one that you can actually buy wouldn't be suitable for an MTM thou.

dave
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