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Old 4th November 2005, 05:33 PM   #1
BHD is offline BHD  United States
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Default Phy Km30

I've been thinking about purchasing this driver, anyone here have much experience with it? The limited reviews by users seem to be pretty positive, but any input would be helpful...

I've also modeled it using Thorsten's (or is it planet 10's?) open baffle calculator, but it doesn't take into account that the recommended baffle is a folding type. What sort of effect does folding an open baffle have on the in room frequency response? More bass? Less bass? No effect at all?

Any help would be appreciated.

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Old 4th November 2005, 06:39 PM   #2
ScottG is offline ScottG  United States
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Default Re: Phy Km30

Quote:
Originally posted by BHD
I've been thinking about purchasing this driver, anyone here have much experience with it? The limited reviews by users seem to be pretty positive, but any input would be helpful...

I've also modeled it using Thorsten's (or is it planet 10's?) open baffle calculator, but it doesn't take into account that the recommended baffle is a folding type. What sort of effect does folding an open baffle have on the in room frequency response? More bass? Less bass? No effect at all?

Any help would be appreciated.

Depending on the nature of the baffle you could experience a resonance generated by "baffle".

http://www.musicanddesign.com/u_frame.html

Try the ZIP file here:

http://www.musicanddesign.com/measure_dipole.html
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Old 4th November 2005, 09:16 PM   #3
BHD is offline BHD  United States
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Thanks for the info, ScottG.

Looking at the site, it seems as though the PHY baffle would be a bit better than the U baffle, since the wings would be at roughly 45 degree angles instead of 90. I wonder if the different widths of the left and right wings makes a difference, possibly breaking up resonance modes.

When I plot out the performance of the KM30 on Thorsten's spreadsheet with the baffle listed on the PHY site, it seems to have dropping bass response. Which is odd, since many people mention the excellent bass they're getting with this speaker in an open baffle. My goal is to get good flat response down to 40Hz in my (relatively) small room. Can anyone tell me if that's a reasonable expectation with these drivers?
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Old 5th November 2005, 07:28 AM   #4
ScottG is offline ScottG  United States
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Quote:
Originally posted by BHD
Thanks for the info, ScottG.

Looking at the site, it seems as though the PHY baffle would be a bit better than the U baffle, since the wings would be at roughly 45 degree angles instead of 90. I wonder if the different widths of the left and right wings makes a difference, possibly breaking up resonance modes.

When I plot out the performance of the KM30 on Thorsten's spreadsheet with the baffle listed on the PHY site, it seems to have dropping bass response. Which is odd, since many people mention the excellent bass they're getting with this speaker in an open baffle. My goal is to get good flat response down to 40Hz in my (relatively) small room. Can anyone tell me if that's a reasonable expectation with these drivers?
Remember that a lot of people that use this driver also use amps with high output impedances (like SET's).. i.e. the higher amp impedance the more it will re-act to the rising driver impedance near fs - the result is that there is plenty of bass. (in fact its the upper bass lower midrange (70-100 Hz) that usually has the depression.)
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Old 5th November 2005, 03:17 PM   #5
BHD is offline BHD  United States
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Hmmm... one of the things that interests me about open baffle loudspeakers is the quality of the bass. Depending on the inability of a tube amp to control the bass to give me more bass doesn't sound all that great to me.

So, no one has any experience with this driver?

Has anyone tried using an EV 12TRXB in an open baffle? When I plug in the T-S parameters into the open baffle calculator, it models almost exactly the same as the KM30.

http://www.geocities.com/tadgesualdo...arameters.html

Anyone tried it?
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Old 5th November 2005, 04:35 PM   #6
ScottG is offline ScottG  United States
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Quote:
Originally posted by BHD
Hmmm... one of the things that interests me about open baffle loudspeakers is the quality of the bass. Depending on the inability of a tube amp to control the bass to give me more bass doesn't sound all that great to me.

So, no one has any experience with this driver?

Has anyone tried using an EV 12TRXB in an open baffle? When I plug in the T-S parameters into the open baffle calculator, it models almost exactly the same as the KM30.

http://www.geocities.com/tadgesualdo...arameters.html

Anyone tried it?
I think you'll have a difficult time finding anyone that's used it because its so expensive.

as to the more bass vs. control issue, that has a good deal more to due with the driver and the ability of the amp to "dump" current. Note the impressions of reviewers on Nelson Pass's f1 (which is a solid state amp with a high output impeadance):

http://www.6moons.com/audioreviews/f...irstwatt3.html

http://www.enjoythemusic.com/magazin...irstwattf1.htm

While they are solid state amps.. you can achieve similar results (in the bass region) with better tube amps.
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