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Old 3rd September 2009, 10:09 AM   #11
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Default Resonance Notch and time alignment

You guys are 100% correct and I started the excercise with healthy amount of scepticism. I just have a brief listen now with proper xo point, notch etc, even time alignment. The 8" definitely beams at the frequency and they are running right at their upper limit.

However it's quite surprising the similiarity of sonic signature and soundstage that is projected by these speakers compared with S9. Yet one is poly cone, one is metal. I'm not sure whether it's that P13 is so great, or the Seas which are not good ???? ... or at a certain point they all sound the same???

Still I think I would pass a blind test. If I could recall the P13 was more "muddy" in the lower freq., if that's the appropriate word or valid observation at all. The Seas have a hint of shrill but this could be my mind just playing out or that it's the tweeters being strained. I really like the 300-800hz region of the Seas. I * do not* hear more details compared to P13, just cleaner somewhat.

More investigation and understanding is needed.

As Cuibono pointed out, it's impossible to remove the resonance peak completely as harmonics from lower frequency would show up. I was able to reduce about 10db worth but that's it. Further notch depth strangely did not affect the acoustic transfer function:

Click the image to open in full size.


The system is properly time-aligned, and I had to delay the tweeter much more which seems to point out that the acoustic center of the Seas is much further to the back proportionally compared to P13WH (and physically too of course).
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Old 3rd September 2009, 06:29 PM   #12
cuibono is offline cuibono  United States
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Originally Posted by Rudolf View Post

What I can't see: Where are you going to get a tweeter that is capable of 1.5 kHz and still small enough to allow for a decent dipole radiation at something like 5 kHz? The dipole separation distance of the 27TBFC/G - mounted back to back (and without any further baffle) - would be 13 cm minimum. This is corresponding to a first dipole peak at 1.3 kHz. Beyond 1.3 kHz you would loose the CD effect of the dipole radiation pattern.
The Neo3 will do this well, it seems. Not too expensive either!

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... or at a certain point they all sound the same???
That would be my guess. Good luck with your design!
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Old 3rd September 2009, 11:32 PM   #13
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That would be my guess. Good luck with your design!
I had a bit longer listening session last night and more convinced that S9 and S10 sounds similar, albeit the difference in xo point, baffle width, and cone/driver material. I will do proper measurements outside this weekend to confirm and remove subjectivity.

If that observation is correct then this is both good and bad news. The good news is that the similarity may reflect the accuracy of reproduction. If speakers are correct, shouldn't they all sound the same? In that case one could listen to S9, S10, Orion, or NaO and they all *should* sound the same?

The bad news is then there is little room for improvements? And what's left is about getting value for money? And that means using L21 is not the way to go because P13 (and other smaller mids) are cheaper, not to mention the added complexity of notch filter, larger baffle (looks), more expensive tweeter requirements etc. of the larger L21.
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Old 4th September 2009, 02:35 AM   #14
CLS is offline CLS  Taiwan
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Hmmmm .....

What are the mid and high level settings in yor xover? Is the midrange attenuated (related to tweeter)?
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Old 4th September 2009, 03:14 AM   #15
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No. Actually I needed to attenuate the tweeters due to higher sensitivity (93db).
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Old 4th September 2009, 04:50 AM   #16
CLS is offline CLS  Taiwan
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Ah! then it's the midrange is still too small!
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Old 4th September 2009, 08:41 AM   #17
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Originally Posted by gainphile View Post
I had a bit longer listening session last night and more convinced that S9 and S10 sounds similar, albeit the difference in xo point, baffle width, and cone/driver material. I will do proper measurements outside this weekend to confirm and remove subjectivity.

If that observation is correct then this is both good and bad news. The good news is that the similarity may reflect the accuracy of reproduction. If speakers are correct, shouldn't they all sound the same? In that case one could listen to S9, S10, Orion, or NaO and they all *should* sound the same?
My opinion is no, S9 S10 Orion NaO with the same electronics (amplifier, crossover etc.) cannot sound the same because the drivers are not the same and they don't have the same performance. They sound similar at small levels for example.

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The bad news is then there is little room for improvements? And what's left is about getting value for money? And that means using L21 is not the way to go because P13 (and other smaller mids) are cheaper, not to mention the added complexity of notch filter, larger baffle (looks), more expensive tweeter requirements etc. of the larger L21.
It is not the same setup, with a L21 you go down to 100Hz but with a P13, you cannot.
What I can say, you never have the perfect solution. I test severals configurations and i prefer the solution Woofer : (20-500Hz) + 5" (500-3kHz) + tweeter (>3kHz).
Perhaps the configuration SUB (20-150) + low mid 8" (150-600) + high mid 5" (600-3kHz) + tweeter (>3kHz) should be a great solution for you ?
The room should be a little larger now ?
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Old 4th September 2009, 09:46 AM   #18
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My opinion is no, S9 S10 Orion NaO with the same electronics (amplifier, crossover etc.) cannot sound the same because the drivers are not the same and they don't have the same performance. They sound similar at small levels for example.

My S9 and S10 don't use the same electronics. The xo points are different and so is the dipole notch. But acoustically (or psychoustically?) they may be similiar. My brief observation seems to point that at certain point the smaller details such as cone material don't really matter. And perhaps changing drivers etc. is a futile exercise. I agree with your comment on SPL limit, fortunately I don't listen at live level.

Perhaps more energy should be allocated to, for example, investigate tweeter's directivity. It seems to be the achiless heel of typical dipole setup.
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Old 4th September 2009, 11:14 AM   #19
ttan98 is offline ttan98  Australia
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M
Perhaps more energy should be allocated to, for example, investigate tweeter's directivity. It seems to be the achiless heel of typical dipole setup.
Put it(tweeter) in a shallow/std. waveguide/horn improves directivity, eg Bassline from Dan
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Old 4th September 2009, 12:05 PM   #20
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Perhaps more energy should be allocated to, for example, investigate tweeter's directivity. It seems to be the achiless heel of typical dipole setup.
Yes it is ! To find a true dipole tweeter at a good price. The geometry of the panel is critical :smaller is better ?
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