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Multi-Way Conventional loudspeakers with crossovers

Line array prototype (with waveguide and CBT shading)
Line array prototype (with waveguide and CBT shading)
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Old 12th June 2018, 08:52 PM   #31
lbstyling is offline lbstyling  United Kingdom
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Quote:
Originally Posted by Patrick Bateman View Post
Interesting stuff. Carver is now using power tapering.

YouTube

discussion begins at the 0:10 second mark
Carver mentions (somewhere in those 5 videos i think?) that the drivers are his design and that he got a company in china to manufacture them on agreement that he has the exclusive rights to them for 2 years, but after this they can sell them under their own name.....

The video is a year and a half old

The bass/mid driver looks very similar to the one you use in your CBT.

Can you put the measurements for your CBT in perspective against other designs? For instance, distortion: lower than a good compression driver? power response?
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Old 13th June 2018, 07:48 AM   #32
TBTL is offline TBTL  Germany
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Do you mean the tweeters? They look like Dayton PT2C-8 (description: 'Perfect for use in line arrays') which already are on the market for quite some time.
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Old 13th June 2018, 10:39 AM   #33
adason is offline adason  United States
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It may be interesting, but i found the image confusing. I spent lots of time listening to his arrays last capital audio fest, changing my seating position...but the image was always somehow phasey. Something iritating was happenig and my brain did not like it.
May be placement of those midranges. Forget the tweeters for a moment and visualize how the mids project sound. Towards each other, and towards the walls. Not ideal.
I think in an effort to make arrays very narrow, he made bad decision on mids.
Just my personal view.
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Old 13th June 2018, 04:14 PM   #34
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by lbstyling View Post
Carver mentions (somewhere in those 5 videos i think?) that the drivers are his design and that he got a company in china to manufacture them on agreement that he has the exclusive rights to them for 2 years, but after this they can sell them under their own name.....

The video is a year and a half old

The bass/mid driver looks very similar to the one you use in your CBT.

Can you put the measurements for your CBT in perspective against other designs? For instance, distortion: lower than a good compression driver? power response?
I've never been a fan of arrays. What Adason describes has been my same reaction. All the line arrays I've heard until 2014, they always made everything sound huge and the image was unfocused.

Y'know how a good set of two way monitors can throw a pinpoint stage? Line arrays are basically the opposite of that.

But the CBT is different; it's not as pinpoint as a minimonitor, but not as diffuse as a line array.

It basically falls in the middle of the two presentations.

The surprising thing to me, is how loud my little CBT+waveguide thing gets. It only has five drivers, and I figured it would distort. But it's really well behaved; it gets as loud as I'll ever need for speakers in my office. I haven't tried it in my living room yet.

It's really difficult to choose between the two options. My unity horn projects have more "sparkle" in the upper treble. It's really really difficult to generate much output above 10khz with a CBT. If you look at the CBT36 user's guide, it's efficiency at 10khz is something like 80dB, and that's with 144 tweeters!

But yowza is the mid-range great on these things. Unities have really nice mid-range too, but I think this CBT + waveguide thing may be a tiny bit better.

I wonder if any of this has to do with HOMs? When gedlee summas were what I listened to, I could listen for hours on end. These speakers are like that too.

Last but not least, CBTs are hard to screw up. My entire crossover is two resistors.
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Old 13th June 2018, 06:26 PM   #35
lbstyling is offline lbstyling  United Kingdom
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Quote:
Originally Posted by Patrick Bateman View Post
I've never been a fan of arrays. What Adason describes has been my same reaction. All the line arrays I've heard until 2014, they always made everything sound huge and the image was unfocused.

Y'know how a good set of two way monitors can throw a pinpoint stage? Line arrays are basically the opposite of that.

But the CBT is different; it's not as pinpoint as a minimonitor, but not as diffuse as a line array.

It basically falls in the middle of the two presentations.

The surprising thing to me, is how loud my little CBT+waveguide thing gets. It only has five drivers, and I figured it would distort. But it's really well behaved; it gets as loud as I'll ever need for speakers in my office. I haven't tried it in my living room yet.

It's really difficult to choose between the two options. My unity horn projects have more "sparkle" in the upper treble. It's really really difficult to generate much output above 10khz with a CBT. If you look at the CBT36 user's guide, it's efficiency at 10khz is something like 80dB, and that's with 144 tweeters!.

I wonder if any of this has to do with HOMs? When gedlee summas were what I listened to, I could listen for hours on end. These speakers are like that too.

Last but not least, CBTs are hard to screw up. My entire crossover is two resistors.
With the treble output, I have really changed my tune in the last couple of years. I just dont think that 14kHz + matters much to the sound/dopamine calculation at all. My current jbl2452H titanium diaphrams break up at around 15kHz, and although I can hear it, it really makes shockingly little impact on the sound quality, but the graph looks truely awful!

Being in my 30's I can still hear out to 17kHz, but I have even tried to eq the breakup up by 10db, (just to see) and it really wasn't *that* bad. It just sounded like the old focal/JM Labs toxoid tweeter... Some sibilance, but otherwise most would call the sound *exciting*.
When in doubt, its good to remember that records don't play that high, and I don't hear many complaining about that.

Quote:
But yowza is the mid-range great on these things. Unities have really nice mid-range too, but I think this CBT + waveguide thing may be a tiny bit better
Coming from someone who has made as many projects as yourself, thats quite a statement!

I think the biggest advantage is that the CBT speaker could be considered high on the WAF scale (when done right) especially compaired to the other options I would consider to be modern attempts at Hi Fidelity.

I anecdotally imagined that CBTs may have the kind of advantage that the AMT tweeter has of not having to work hard.

With pattern control I think this is the next frontier. Not gaining it, but deciding what the ideal amount of direct vs reflected sound is. Or, making speakers that give you control over the proportions. I notice that Linkwitz keeps his eye on the competition fairly sharp with this page:

Constant directivity loudspeaker designs

He has high praise for the Beolab 90!

On the HOM front- I can't remember where we got with this one. Audiable or not? Controversial if I remember right.
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Old 13th June 2018, 06:40 PM   #36
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by lbstyling View Post
With the treble output, I have really changed my tune in the last couple of years. I just dont think that 14kHz + matters much to the sound/dopamine calculation at all. My current jbl2452H titanium diaphrams break up at around 15kHz, and although I can hear it, it really makes shockingly little impact on the sound quality, but the graph looks truely awful!
The Achilles Heel of arrays is that the maximum output at high frequency is that maximum output of a single unit. So you can use 144 tweeters like the CBT36 does, and the maximum output above 10khz is still something like 85-90dB. It's really low.

I still need to tinker with them so more, but I think that's why my CBT-ish thing lacks "sparkle", it just can't generate much output above 5-10khz.

Click the image to open in full size.

My local Best Buy has the big expensive CBTs set up for it's sound system, and the lack of output above 5-10khz is unmistakable.

I have some ideas on how to fix this; I think that a long line of small tweeters may not be the ideal solution. (stay tuned.)

Quote:
Originally Posted by lbstyling View Post

Being in my 30's I can still hear out to 17kHz, but I have even tried to eq the breakup up by 10db, (just to see) and it really wasn't *that* bad. It just sounded like the old focal/JM Labs toxoid tweeter... Some sibilance, but otherwise most would call the sound *exciting*.
When in doubt, its good to remember that records don't play that high, and I don't hear many complaining about that.



Coming from someone who has made as many projects as yourself, thats quite a statement!
They really are special. I can see why Keele has practically abandoned all other technologies.

One of the really interesting possibilities I think, is to use one technology on one axis and another technology on the other. For instance, this thread is about a speaker that's a CBT on the Y axis and a waveguide on the X axis.

Ulrich Horbach, who worked with Keele on the Horbach Keele filters, has designed a speaker that's a WMTMW on the X axis and a shaded array on the Y axis.

I honestly think these type of combos are likely the future. If you do a CBT on both the X and the Y axis, the size just gets insane fast.

Quote:
Originally Posted by lbstyling View Post

I think the biggest advantage is that the CBT speaker could be considered high on the WAF scale (when done right) especially compaired to the other options I would consider to be modern attempts at Hi Fidelity.

I anecdotally imagined that CBTs may have the kind of advantage that the AMT tweeter has of not having to work hard.

With pattern control I think this is the next frontier. Not gaining it, but deciding what the ideal amount of direct vs reflected sound is. Or, making speakers that give you control over the proportions. I notice that Linkwitz keeps his eye on the competition fairly sharp with this page:

Constant directivity loudspeaker designs

He has high praise for the Beolab 90!

On the HOM front- I can't remember where we got with this one. Audiable or not? Controversial if I remember right.
Beolab 90 is the best speaker I've ever heard. They (finally) opened up a B&O store in Orange County, I need to get out there and hear the Beolab 50. I tried to hear the Beolab 5 in their LA showroom but the speakers weren't working. It's funny that I've cloned it's lenses in 20 different permutations but I haven't heard the Beolab 5 in over ten years, way back when B&O had a store in Portland, which has since closed.

As for WAF, I think the exciting thing about the CBT is that you can basically 'dial in' how 'pinpoint' the image is. From what I can see with my experiments, the more you shade the array, the more 'pinpoint' it gets.
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Old 13th June 2018, 09:52 PM   #37
Omholt is offline Omholt  Norway
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Line array prototype (with waveguide and CBT shading)
Quote:
Originally Posted by Patrick Bateman View Post
The Achilles Heel of arrays is that the maximum output at high frequency is that maximum output of a single unit.
That's incorrect. Your wrongly mixing phase issues and output. Whereas the shading removes a good amount of the added dB in the highs you normally get with multiple drivers, there's still an increase in output. The sensitivity of the tweeter in CBT36 is extremely low, in the area of 70-73 dB (can't remember exactly). So there is actually an increase of 6-9 dB in the highest frequencies.
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Old 13th June 2018, 10:05 PM   #38
Patrick Bateman is offline Patrick Bateman  United States
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Originally Posted by Omholt View Post
That's incorrect. Your wrongly mixing phase issues and output. Whereas the shading removes a good amount of the added dB in the highs you normally get with multiple drivers, there's still an increase in output. The sensitivity of the tweeter in CBT36 is extremely low, in the area of 70-73 dB (can't remember exactly). So there is actually an increase of 6-9 dB in the highest frequencies.
According to the manual, the efficiency at 8khz is 79dB. That's consistent with what I am arguing here:

The sensitivity of a line array is no greater than a single element when the wavelengths are shorter than the elements.

Dayton is kinda hiding that fact by not quoting a sensitivity figure above 8khz. Basically 8khz is right in the range where this phenomenon is occurring, it's the frequency where the comb filtering is beginning for the tweeters in the CBT 36. They're 12.5mm in diameter; that's 27.2khz. We'd expect to see comb filtering begin right around a third of that number, or 9khz, which is exactly why Dayton is quoting a sensitivity rating at EIGHT khz.

http://www.daytonaudio.com/media/res...bly-manual.pdf


"14.1.12.4. Sensitivity (2.83 Vrms/1m):
Note: the raw sensitivity (no crossover or EQ) of the CBT36 is frequency dependent. It is roughly flat from 80 to 300
Hz and then rolls off at 3 dB/octave (10 dB/decade) up to 20 kHz. See later section “CBT36 Power Rolloff” in
Appendix 2 for further explanation of this rolloff. For more details see Fig. 26 in this section. Here are some
approximate sensitivity numbers at different frequencies:
80 to 300 Hz: 94 dB
800 Hz: 89 dB
8 kHz: 79 dB"

Last edited by Patrick Bateman; 13th June 2018 at 10:08 PM.
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Old 13th June 2018, 10:36 PM   #39
Omholt is offline Omholt  Norway
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Line array prototype (with waveguide and CBT shading)
Quote:
Originally Posted by Patrick Bateman View Post
According to the manual, the efficiency at 8khz is 79dB. That's consistent with what I am arguing here:

The sensitivity of a line array is no greater than a single element when the wavelengths are shorter than the elements.
Nope. The sensitivity of the driver is lower than 79dB. It' closer to 70 dB, thus there's is an increase compared to using a single driver. The tweeter in CBT36 is both very small and a full range driver, hence the extremely low sensitivity. With appropriate drivers one can achieve very high sensitivity in a CBT speaker.

You're mixing phase issues (lobing and combing) with output. Two different things. Both lobing and output is increased with multiple drivers. It's the shading in the CBT that minimizes the output.
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Old 13th June 2018, 11:12 PM   #40
wesayso is offline wesayso  Netherlands
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@Patrick Bateman, did you follow the Infinite Line Source Theory thread?

It will show the 3 dB/octave drop in SPL output, even for a theoretical ideal model.
Infinite Line Source: analysis

This has nothing to do with the suspected starting point of combing, which you simply cant predict as being a third of the size of the tweeters.
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