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Old 20th March 2017, 05:49 PM   #1
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Default New CBT Woofers

When I heard the new CBTs at CES, I'd assumed that they were using the Dayton ND65 woofers. But they said they weren't, and that it used a new driver with improvements requested by Don Keele.

I believe the original CBTs did something similar; the Dayton ND91 has more BL and a shorting ring iirc. (It's based on the Dayton ND90.)

So...

Let's see what's going on with the new Dayton ND64, versus the old Dayton ND65.

Click the image to open in full size.

Click the image to open in full size.

From a quick look at the spec sheet, it looks like:

1) the new ND64 is cheaper
2) the new ND64 has half the xmax

I'd speculate that what they were trying to do is lower the moving mass. The MMS of the ND64 is 16% less than the ND65. This may contribute to it's high frequency extension.

Click the image to open in full size.
It's a bit odd that Dayton overlooked a couple of other drivers in their stable. For instance, the Tectonic Elements TEBM35 has lower mms, flatter response, and lower cost than both the ND64 and the ND65.
(http://medleysmusings.com/tectonic-e...re-bmr-driver/)
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Old 20th March 2017, 08:10 PM   #2
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Patrick - Dayton doesn't make or own Tectonic Elements does it?
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Old 20th March 2017, 08:18 PM   #3
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I can't make heads or tails of the situation with Parts Express, Dayton Audio, and Aura Sound.

I bought some "Aura Sound" drivers last year, and their performance was quite a bit different than the published specs.
And AuraSound drivers were unavailable for about six years or so, from 2006-2012.
And Dayton ND90s look virtually identical to AuraSound NS3s.

Putting all of that together, I wouldn't be surprised if some factory in China simply started stamping out replicas of the old AuraSound drivers. Or perhaps they even bought the tooling?

Tang Band speaker was founded twenty years ago, but all of those old AuraSound spec sheets are signed by "Ben Tang." Coincidence?
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Old 20th March 2017, 08:47 PM   #4
jrh0516 is offline jrh0516  United States
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The baskets on the NS3s and ND90s are were different on my 2015 models

I assume you saw this thread Nice, ND64's for us! - Techtalk Speaker Building, Audio, Video Discussion Forum
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Old 23rd March 2017, 12:32 AM   #5
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Quote:
Originally Posted by Patrick Bateman View Post
When I heard the new CBTs at CES, I'd assumed that they were using the Dayton ND65 woofers. But they said they weren't, and that it used a new driver with improvements requested by Don Keele.

I believe the original CBTs did something similar; the Dayton ND91 has more BL and a shorting ring iirc. (It's based on the Dayton ND90.)

So...

Let's see what's going on with the new Dayton ND64, versus the old Dayton ND65.

Click the image to open in full size.

Click the image to open in full size.

From a quick look at the spec sheet, it looks like:

1) the new ND64 is cheaper
2) the new ND64 has half the xmax

I'd speculate that what they were trying to do is lower the moving mass. The MMS of the ND64 is 16% less than the ND65. This may contribute to it's high frequency extension.

Click the image to open in full size.
It's a bit odd that Dayton overlooked a couple of other drivers in their stable. For instance, the Tectonic Elements TEBM35 has lower mms, flatter response, and lower cost than both the ND64 and the ND65.
(http://medleysmusings.com/tectonic-e...re-bmr-driver/)
Don's partner was involved in the driver design so that's why the Tectonic drivers weren't used. The goal was to have a driver with a rising response to counter the CBT's downward sloping transfer function.
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Old 23rd March 2017, 07:21 AM   #6
Omholt is offline Omholt  Norway
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For a passive CBT you have to use a driver with a rising response like Craig says. So that limits the options.

Besides, Dayton is PartsExpress own brand, and obviously they would prefer using their own.
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Old 23rd March 2017, 05:02 PM   #7
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Hi,

Quote:
Originally Posted by Omholt View Post
For a passive CBT you have to use a driver with a rising response like Craig says. So that limits the options.
Why not use a standard tone control, possibly supported by a tailored passive shelving filter with a few dB lo-frequency attentuation? 3 dB per octave as in CBTs is a common recording margin anyway, some recordings are brighter, some duller, some nuttier, some french-beddier.

Uli
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Old 23rd March 2017, 06:28 PM   #8
Omholt is offline Omholt  Norway
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Quote:
Originally Posted by Grasso789 View Post
Hi,
Why not use a standard tone control, possibly supported by a tailored passive shelving filter with a few dB lo-frequency attentuation? 3 dB per octave as in CBTs is a common recording margin anyway, some recordings are brighter, some duller, some nuttier, some french-beddier.

Uli
That's possible. From a commercial standpoint though and when offering a passive speaker, it may not be the best move.
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Old 24th March 2017, 12:18 AM   #9
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I mixed up octave and decade: A driver model with flat response causes a CBT made of such drivers to fall by 3 dB per octave, but recording margins are usually within 3 dB per decade. If Don had used a flat-response driver model for his new home CBT, the treble control would have to be turned up all the way.
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Old 24th March 2017, 02:15 AM   #10
jrh0516 is offline jrh0516  United States
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The CBT demo'ed at MWAF in 2016 used a DSP. It would be interesting to know if there are any passive components in the CBT 24 as it's preassembled.
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