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Help Understanding Tekton Tweeter Array Schematic?
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Old 19th April 2019, 04:08 PM   #21
Juhazi is offline Juhazi  Finland
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Actually I was surprised how well Tekton measured. I would have put the hex tighter. Sad that Stereophile doesn't publish distortion measurements.

Vertical shows extreme angles, up to 15¤ is ok, better than many 2-ways. Anyway perhaps woofers must play too high up.

Click the image to open in full size.
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Old 19th April 2019, 05:42 PM   #22
Juhazi is offline Juhazi  Finland
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Typically Stereophile shows just up to 15¤ measurements, this is Focal Kanta No.2
Click the image to open in full size.
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Old 19th April 2019, 05:43 PM   #23
eriksquires is offline eriksquires  United States
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Allen B : As Juhazi points out, it's' the vertical plot that reminds me of Dr. D'Appolito moving to use higher order filters and the rational behind his choices.



That's pretty awful, but from a practical perspective, owners have been quite happy with it and haven't noticed.
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Old 19th April 2019, 10:12 PM   #24
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by AllenB View Post
I read the comment: ["The closer I sat to the speakers, the less focused the aural images were;"]. This leads me to believe that either the baffle edge contribution, or the vertical polar response (fig.5) is troublesome.

Then I read this: ["Getting the Impact Monitors to focus their best required placing them closer together than I ever could have imagined would work—the centers of their central tweeters were only 5.6' apart"]...

So I was inclined to question the horizontal smoothness. On the polar there is a flawed region between 3k and 6kHz. Could be Patrick is right in suggesting a lobing issue?
The answer to your question is in the CBT curve from Monte Kay that I posted in message #18.

In particular, notice how the top three curves are virtually the same.

This means that if you're within a beamwidth of about sixty degrees (+/- 30 degrees) the sound of the speaker doesn't change.

This can lead to some really peculiar setups. You can put the speakers really close together or really far apart and the sound simply doesn't change a whole lot.

Keele has posted some measurements that show that the SPL level of a CBT barely changes as you move forward or backwards.

It's really eerie, because 99% of us have never heard a speaker that behaves like this.

Here's one way to think about it:

Imagine if you're at a rock concert, and you're two hundred feet from the stage. If you move ten feet, does the sound change very much? No, it doesn't. Because the speakers are 200' away.

A CBT approximates a point source which is much further away.

Click the image to open in full size.

For instance, Jim Griffin's CBT approximates a point source that's about three feet *behind* that back wall. The apparent source of sound is the apex of the arc that forms the CBT. The sound doesn't sound like it's coming from the loudspeaker; it sounds like it's coming from a point somewhere *behind* the speaker, but the source is hazy.

I think that one of the reasons that CBTs sound a bit hazy is because they're illuminating the room with a hundred reflections from dozens of drivers. So our brains don't have a way of processing that. We're accustomed to loudspeakers that sound like they're radiating from a single point in space.

For an audio reviewer, this can be a bizarre experience; it's difficult to 'dial in' a speaker when moving it around the room doesn't change things much.



And, again, people are probably wondering why I'm talking about CBTs in a thread about the Tekton Impact. But the tweeter array is largely a two-dimensional CBT array.

Last edited by Patrick Bateman; 19th April 2019 at 10:15 PM.
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Old 21st April 2019, 05:19 PM   #25
eriksquires is offline eriksquires  United States
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Hi Patrick,

Forgive my ignorance, but you posted a great deal which I feel like playing devil's advocate to. Please illuminate the areas where I lack enough understanding.

Quote:
For instance, Jim Griffin's CBT approximates a point source that's about three feet *behind* that back wall.
Not sure how this is different than my current two way, except for the lack of haze. I mean, ideally, I want the speakers to disappear and transmit the recording, not the speaker and it's location. I don't hear the acoustic center of my speakers. I hear a deep soundstage.

Quote:
illuminating the room with a hundred reflections from dozens of drivers.
That's called dispersion! But it also sounds like you are saying : "The drivers don't integrate well enough to become a single planar wavefront."

Quote:
moving it around the room doesn't change things much.
So it is independent of room boundaries? Sounds great to me!

Best,

Erik
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Old 21st April 2019, 10:56 PM   #26
wesayso is offline wesayso  Netherlands
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Quote:
Originally Posted by Patrick Bateman View Post
I think that one of the reasons that CBTs sound a bit hazy is because they're illuminating the room with a hundred reflections from dozens of drivers. So our brains don't have a way of processing that. We're accustomed to loudspeakers that sound like they're radiating from a single point in space.
I don't believe in this analysis... think again, each driver has it's reflections at slightly different positions than the next. That's why it is less placement dependent, as long as it has a little room to breathe.

Bringing back the focus shouldn't be too hard. Making it sound just like a point source, but better behaved inside the room. Check out some in room measurements of a CBT, I believe Omholt has shown us a few.
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Old 22nd April 2019, 02:22 PM   #27
Jim Griffin is offline Jim Griffin  United States
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Hate to post on a thread on the Tekton tweeter array but I want to relate my thoughts on how my Modified CBT24 sound in my listening room. I describe my speakers in my thread at:

My New Line Array--It's a Modified CBT24

I disagree with Patrick that a CBT sounds 'hazy' or at least my speakers don't exhibit such sound. In my room vocals and instruments sound clear and are correctly placed across the soundstage. My CBT functions on a ground plane so any floor reflections are mirrored so they are correctly placed in time by the floor which doubles the inherent size of the array. The shading of the array as it extends upward diminishes any sound which might reflect from the room ceiling. Furthermore, in my room the speakers are spaced so that side walls are 10-12 feet away from them. Thus any side reflections would have to travel at least double those distances to impact a listener. Thus the distances involved to the ceiling and sides reduce extraneous sounds and thus mitigate any reflected sounds heard by a listener within the room.

Again this confirms Don Keele's comments about the coverage of a CBT. He states that CBTs exhibit constant beamwidth, constant directivity, constant coverage, and near constant radiated power within the room. I'm hearing the same sound in my listening room with my CBTs. A CBT creates a 'sweet room' effect versus just a 'sweet spot'.

CBTs also do not suffer from combing effects. You can move your ears up and down a line of speakers and hear consistent sound no matter your distance to the array.

Last edited by Jim Griffin; 22nd April 2019 at 02:33 PM.
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Old 23rd April 2019, 01:21 AM   #28
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by eriksquires View Post
Hi Patrick,

Forgive my ignorance, but you posted a great deal which I feel like playing devil's advocate to. Please illuminate the areas where I lack enough understanding.



Not sure how this is different than my current two way, except for the lack of haze. I mean, ideally, I want the speakers to disappear and transmit the recording, not the speaker and it's location. I don't hear the acoustic center of my speakers. I hear a deep soundstage.



That's called dispersion! But it also sounds like you are saying : "The drivers don't integrate well enough to become a single planar wavefront."



So it is independent of room boundaries? Sounds great to me!

Best,

Erik
Let me clarify some of my comments on CBTs sounding "hazy."

Click the image to open in full size.

Conventional loudspeakers look like this. The left speaker, right speaker and the listener form a triangle. The loudspeakers are equidistant to the listener.

Because the loudspeakers are equidistant, the depth of the soundstage is generally defined by the distance to the loudspeaker.

Click the image to open in full size.

In a CBT, the pathlength to the drivers varies quite a bit. I've heard the CBT24 and the CBT36, and the depth of the soundstage was nebulous.

The top of the CBT24 is nearly two feet deeper than the BOTTOM of the CBT24. I believe that this variance in depth is audible; when listening to the CBT, the depth of the stage isn't apparent.

Click the image to open in full size.

Three years ago I rented some SH50s and listened to them in my tiny condo in San Diego. They exhibit the same behavior; basically it's really difficult to tell where the sound is coming from.

I've told this story a million times, but here goes again:

While renting the SH50, our thirteen year old daughter literally asked me which speaker was playing. And this was while she was sitting one foot away from the SH50s. I think that's wild; she was literally getting blasted by a SH50 playing 100dB+, and she couldn't even tell if it was on. Try doing THAT with a conventional speaker.

Again, I think the key to this is that the DEPTH of the drivers is varied. (In the CBT 24, the top of the loudspeaker is nearly two feet further back than the bottom. In the SH50, the woofers are about one foot closer than the tweeter.)

It's a neat trick I think. It's eerie. When listening to music, it was bizarre how the HORIZONTAL positions were pinpoint, but the DEPTH of the soundstage was nebulous.

If things were reversed, it would be VERY BAD. For instance, imagine a loudspeaker where the HORIZONTAL locations are nebulous, and the DEPTH of the soundstage is pinpoint? You wouldn't want that, it would sound terrible.
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Old 23rd April 2019, 02:14 AM   #29
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by Patrick Bateman View Post
The top of the CBT24 is nearly two feet deeper than the BOTTOM of the CBT24. I believe that this variance in depth is audible;
Wouldn't an equivalent waveguide (at the same apparent apex) do the same? One of the functions of the shading is to manage diffraction. In the case of this wavefront the sound traveling over your head will continue that way with diffraction normal to it.
Quote:
she was literally getting blasted by a SH50 playing 100dB+, and she couldn't even tell if it was on. Try doing THAT with a conventional speaker.
I find that a single driver waveguide will do this.
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Old 23rd April 2019, 02:25 AM   #30
eriksquires is offline eriksquires  United States
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What I'm not getting is the very large discrepancy between the CBT design goals and Patrick's position.

The goal of the CBT is a single unified wavefront, but Patrick seems to feel this does not happen, and there is instead many little ones.

An impulse response would be really interesting at this point.
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