Another CSS WR/FR design -- The Bipolar Bipoles - Page 3 - diyAudio
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Old 4th November 2005, 10:28 AM   #21
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Quote:
Originally posted by soongsc
As far as sound goes, bamboo is more springy than wood, so I would suspect baffle vribration coupling into the driver. [
The birch ply (with MDF back) ones have the same problem so it's not the bamboo. The inherent nature of the design doesn't leave a lot of room for the box to move around.

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Old 4th November 2005, 10:30 AM   #22
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Quote:
Originally posted by Scottmoose
what's the wire you're using in the pictures of the bipoles and horns?
unskinned plenum grade Cat 5 -- solids together & stripes together. Those pics are at Chris' place (his front end is better than mine so we do serious compares there -- since he does the build also the 1st place they usually get fired up)

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Old 4th November 2005, 12:18 PM   #23
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by planet10


The birch ply (with MDF back) ones have the same problem so it's not the bamboo. The inherent nature of the design doesn't leave a lot of room for the box to move around.

dave
What does it sound like? Lack of air or mixed up and annoying?
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Old 4th November 2005, 08:16 PM   #24
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[What does it sound like? Lack of air or mixed up and annoying?
for instance, female vocals sound like the singer is at he bottom of a well.... cupped, closed in.

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Old 4th November 2005, 10:09 PM   #25
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by planet10


for instance, female vocals sound like the singer is at he bottom of a well.... cupped, closed in.

dave
Does it measure good but sound like that or just listening first? I guess you don't have BSC of any sort in there, right?
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Old 5th November 2005, 03:56 AM   #26
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Default Measure?

With all due respect - after over 35 years of listening, I don't need to measure when it sounds this coloured.

Regarding BSC, I'm not a fan of passive frequency EQ filters; in fact one of the huge benefits of bipole design is the elimination of the need for it, even with relatively small drivers and narrow baffles.
One of the FR125's strengths is the combination of low frequency extension, excursion and very low distortion, albeit at the price of sensitivity. That, in combination with a very large front baffle and boundary reinforcement from the side exit "horn" of the PAWO provide more than adequate energy at the low end for this listener.

Having built quite a few speaker enclosures over the years from a variety of materials, I'm confident the bamboo is not part of the problem. 19mm (3/4") block core laminated bamboo plywood is pretty damned stiff, and the numerous internal panels of the PAWO provide for a very well braced box.

In fact the esthetics of the results is probably the main reason I haven't moved on entirely to another project. My wife couldn't care less the sound, but is always eager to comment on the look of any new visitor to the livingroom she's letting me "borrow". This is a cute little design, and with 5 coats of nitrocellulose lacquer, they are quite pretty - it'd be more than just a shame to burn them.

Sorry Tom, but after several listening sessions to both the BB plywood and bamboo pair, I'd agree with GM's comments on FR forum regarding the compression chamber. I plan to revisit that during the next week or so, and report my observations.

Regarding the bipoles, we always have way too many designs percolating in our minds than we'll ever have time to get done; it was serendipity that these were the next pair built. As Dave has already provided the Cole's Notes summary of advantages of BP design, I won't repeat; other than to state that properly executed, it can to a very great degree help make the box disappear. This is by far the best combination of performance and WAF of our 5 FR/WR125 designs to date.


While the best speaker enclosure I've ever heard is no enclosure ( open baffle), and I've even built a few of those as well ( but just can't keep them in the house), the designs that are most emotionally satisfying have been bipoles. The soundstage, imaging , depth, and articulate bass, ( even when limited in extension by the driver's parameters ) have become a personal benchmark. In it's current state of development the FR125 in the PAWO is "sorry Charlie....no cigar", but not with out potential - there are many brilliant and just plain stubborn DIY'ers out there
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Old 5th November 2005, 04:38 AM   #27
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While the best speaker enclosure I've ever heard is no enclosure ( open baffle)
I am running my Fr125 on open baffle. Like it very much. It sounds very open, relax, effortless.... The interesting thing is that it sounds louder around the house than at the listening position...
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Old 5th November 2005, 07:58 AM   #28
soongsc is offline soongsc  Taiwan
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I think it's good to gather as much data as you can before coming to a conclusion. Just good engineering practice ans risk reducing efforts.
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Old 5th November 2005, 09:26 PM   #29
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Bipolar should (I'm just getting interested in bipoles afte hearing a few) provide identical benefits to dipolar with the figure 8 radiation pattern, correct? Out of interest, what sort of differences should one expect from bi and dipole speakers (assuming identical drivers used)? I assume the bipoles would probably reach lower, especially if an MLTL or reflex design is used?

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Old 5th November 2005, 10:03 PM   #30
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Quote:
Originally posted by Scottmoose
Bipolar should provide identical benefits to dipolar with the figure 8 radiation pattern, correct?
No, not at all. Bipoles radiate as much (or more?) energy to the sides than a monopole. Dipoles have the figure 8 radiation pattern because the front and back waves are out of phase and they cancel each other at the sides of the speakers.
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