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Multi-Way Conventional loudspeakers with crossovers

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Old 24th December 2012, 08:38 PM   #901
Pano is offline Pano  United States
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Pretty close, but you still have to account for boxes, baffles and such.
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Old 25th December 2012, 04:30 AM   #902
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Originally Posted by CopperTop View Post
Just to clarify: you would define 4th order as steep or shallow? What slope do you tend to use in your own speakers?
I would define 4th order as par, not steep, not shallow. 24db/octave still requires keeping better part of two octaves away from strong resonance/break up in avoiding IMD.

As seen in #347:

Click the image to open in full size.

Above crossover at 900Hz is accomplished with 1024 point FIR. This is steep, about 200dB/octave, and typical of what I listen to. With drivers flat for phase and frequency, and about 1/4 wave apart at crossover no ringing is heard anywhere in room. Driver corrections are calculated from measured IR and then convolved with crossover filters to build playback filters.

twest820:

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I agree with the benefits claimed for shallower slopes but the better directivity control and avoidance of driver limitations (such as cone breakup or Bl nonlinearity) of LR4 has consistently been subjectively preferable for me...
This is conflicted. Subjectively claimed benefits? That don't agree with your own subjective preferences? A driver's directivity is physical property of driver, and what it is mounted to.

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Andrew
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Old 25th December 2012, 05:30 AM   #903
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Quote:
Originally Posted by Barleywater View Post
... crossover at 900Hz ... and about 1/4 wave apart at crossover
3 3/4". What drivers again?

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Old 25th December 2012, 07:43 AM   #904
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But then, how do I know that a 'good' setting isn't just a one-off for the particular types of music I've tried it on?
You don't, though experience with live sound and the ability to play an instrument provide a good reference---unplugged can be particularly useful as it eliminates a lot of variables. It's also my experience most characteristics that are supposed to be good for one genre or another aren't actually genre specific. Maybe you notice them more or less with certain mixes but there's not usually a major amount of masking. Harmon-Kardan found about 80% of a speaker's perceived sound quality can be explained by factors other than the actual sound quality but, once those are controlled for, there's a clear, statistically significant, subjective preference for speakers which do well in objective measurements. So you may want to measure some polars.

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Originally Posted by Barleywater View Post
This is conflicted.
The overall optimum in a multidimensional tradeoff is rarely ideal for any particular dimension. I have tried 100-200dB/octave slopes via ReaFIR and, while interesting initially, didn't find them satisfying in the long term and eventually relaxed to around 40dB/octave. Not much difference between that and an LR6. It could be interesting to revisit steeper filters with tools like rePhase and an OpenDRC/miniSHARC but it's not currently a priority for me. I'd also like to try a coaxial magnetostat to minimize motion of the acoustic center over the tweeter to mid XO and see if that produces better results with steeper crosses. But nobody makes one and DIYing one is also low priority for now.
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Old 25th December 2012, 03:40 PM   #905
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Originally Posted by planet10 View Post
3 3/4". What drivers again?

dave
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Linkwitz Pluto type speaker with SEAS Prestige L16RN-SL and Peerless 830970 allows driver centers to be closer together than when on flat baffle.

Top firing woofer only sees reflection from far end of pipe, after sound travels through more than 70" of stuffing. Very little sound re-radiation. No panel resonance.

Forward firing woofer in box tower, distance to back panel is short. Back, sides, and top form incredibly good retroreflector, sending energy back at driver. Little distance for stuffing to absorb back wave unless packed too tight for good low end. This is further aggravated with supper light, acoustically transparent diaphragms found in full range drivers. Box sound.

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Andrew
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Old 25th December 2012, 11:14 PM   #906
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YEs, one way to get the drivers close.

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Originally Posted by Barleywater View Post
Forward firing woofer in box tower, distance to back panel is short.
It is a tradeoff... with the small diameter pipe you have, there are going to be signficant side-wall reflections.

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Old 25th December 2012, 11:34 PM   #907
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Originally Posted by planet10 View Post
YEs, one way to get the drivers close.



It is a tradeoff... with the small diameter pipe you have, there are going to be signficant side-wall reflections.

dave
At what point of pipe are sidewalls reflecting energy back at driver?

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Andrew
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Old 25th December 2012, 11:44 PM   #908
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there are going to be signficant side-wall reflections.
Does not happen in fact (in my experience). Maybe if you tried to run it full-range you'd see something, but I doubt even that, since the back wave is symmetric all around the "enclosure" and any reflections that don't go "down the pipe" tend to cancel. You'll see spider and frame issues before any pipe reflections (but neither, of course, crossed at 1000 Hz.).
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Old 25th December 2012, 11:47 PM   #909
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Does not happen in fact (in my experience).
It certainly does in my experience.

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Old 25th December 2012, 11:51 PM   #910
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It certainly does in my experience.
I'd sure like to see the evidence of that in an end-driven pipe. I don't doubt that it happens if you put the driver on the side of a long thin box and try to run it full-range, though.
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