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My New Line Array--It's a Modified CBT24
My New Line Array--It's a Modified CBT24
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Old 9th April 2018, 06:07 PM   #51
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by Jim Griffin View Post
Hank, If you can afford the SBs, I would certainly go that way and cut to the chase. But I will review your spreadsheet for any gem we haven't seen. xrk971 had some positive comments on the SB65s and others have praised them. My main complaint about the SB65s are the plastic frame requires care but most small drivers like these suffer similar concerns.
It's enraging. It's probably the best full range driver under $50, but I'm reluctant to buy another one because I've destroyed half of mine. Some of my frames cracked, and I found out the hard way that if you solder the connections the heat melts the frame instantly.

Peerless sells a really nice aluminum full range driver, and I have sixteen of those, and every last one has fallen apart. Most of them died because the surround dried up and cracked.

It's gotten to the point where I've just switched back to paper cone midranges because most of the aluminum ones seem to commit Hari Kari.

For some reason, the AuraSound titanium drivers don't exhibit any of these issues. I have fifteen year old AuraSound Whispers that look nearly as good as the ones I've bought this year.
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Old 9th April 2018, 06:31 PM   #52
Patrick Bateman is offline Patrick Bateman  United States
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Originally Posted by xrk971 View Post
The SB65 is an excellent driver that probably has the highest smooth (no breakup) reach of any full range driver. It resembles a 1in aluminum dome tweeter in some ways. My main complaint is lack of sensitivity but when in an array that’s not an issue. The Faital Pro 3FE25 in 16ohms might be worth looking at as well. Super sensitive and quite smooth.

If you want the close CTC distance the Fountek FR55EX is also worth a closer look. Also Nd magnet and aluminum cone.
I've probably evaluated about twenty different midranges for various Unity Horn projects. Here are some favs:

- The SB Acoustics 2.5" is just about unbeatable at the price. As noted in another post, I stopped buying them because they keep breaking.
- If cost is no object, AudioFrog sells a midrange similar to the SB but the AF is much more sturdy. It's an aluminum frame iirc.
- The AuraSound whisper is a killer driver, but it's ridiculously large voice coil rolls off the highs. (2" voice coil on a 2" driver!)
- Peerless sells a bunch of 2" drivers. Many are very similar. For instance, they have two models that look virtually identical, but one has lower inductance and more extended highs. So read the spec sheet carefully. Tectonic Elements TEBM35C10-4 Miniature BMR(R) Driver | Medley's Musings

This driver needs to get more love. It has nearly as much displacement as the AuraSound, but more extended highs because the voice coil is smaller. Best of all, the neo motor allows for some insanely compact CTC spacing. And it's really cheap.


If I were going to build a CBT I'd probably go for the Peerless 2" with the rising response (It's a paper cone model and I'm too lazy to look up the part number) or I'd use the Tectonics. The AuraSound is nice but it's difficult to pack them tightly in a curve array because they're so bulky. And the AuraSound treble isn't as good as the Tectonics.
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Old 10th April 2018, 01:28 AM   #53
Jim Griffin is offline Jim Griffin  United States
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Yes, the SB Acoustics SB65 can be a pesky little critter if you don't treat them right while making all of those connections.

While you can solder the various connections between connecting wires and driver terminals, I chose to use crimp connections for the drivers (Parts Express # 095-286 and 095-287) to the wiring harnesses. I assembled the wiring harnesses before feeding it though the enclosures. The polarized crimps also help maintain the polarity of each connection between the wiring harness and the drivers.

These crimp connections must be used with care as too much pressure can easily smash one of the SB65 drivers. I used my needle nose pliers to hold the speaker's terminal landing area while carefully inserting the female crimps over the spade connections. On some of the female crimps, I enlarged their opening a bit to enable smoother connection. I did crush two drivers before I got the hang of it so 48 out of 50 units were successful.

Bottom line is to use care and you will be successful. Any of the drivers you mention are tiny units so much care is needed in the assembly process.

Last edited by Jim Griffin; 10th April 2018 at 01:35 AM.
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Old 10th April 2018, 06:58 PM   #54
HankF is offline HankF  United States
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This Tectonic 65mm square frame driver looks interesting:
http://www.tectonicelements.com/wp-c...BM36S12-4A.pdf
FR drops off at the very top end, but good X mech max and low end.
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Old 10th April 2018, 09:51 PM   #55
Jim Griffin is offline Jim Griffin  United States
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Hank,

On the Tectonic 65mm unit the best part is that it fits the size so that the 2.625 inches c-t-c distance is OK. Beyond that the frequency response is a mess above about 3.5 kHz. The 7-8 dB dip at 4.7 kHz is hard to deal with and would be hard to mitigate. Finally the more than 10 dB dip between 15-20 kHz will hurt. The balanced mode drivers have inherent dips in their response so I figure that the 4.7 kHz dip is the result of that effect while the larger dip near 20 kHz is just its roll-off as frequency increases.

I don't know what the Tectonic driver cost but given the relative cost of their 75 mm driver, it likely would be $10 or slightly under.

In my mind the SB65 is still the driver to use for this application. The beauty of the SB65 is that its frequency is relative flat across the band with a rising high end which counteracts the normal frequency roll off when drivers are arrayed.

Last edited by Jim Griffin; 10th April 2018 at 09:53 PM.
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Old 10th April 2018, 10:05 PM   #56
Patrick Bateman is offline Patrick Bateman  United States
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FR-without-legend.png

I don't disagree with your assessment; I'd go a step further and say the SB65 is arguably superior to what's in the PE CBT Epique.

But the lil' BMR is an interesting candidate. It's a feb dB hotter in the top octave.

TEBM35C10-4-PR-Sm-624x686.jpg

It is ridiculously small. The diameter is about the same as a 2" driver, but the depth and the shape of the motor make it friendly to mounting in a curved array.

But SB65 is almost unbeatable in it's class.
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Old 11th April 2018, 12:58 AM   #57
Jim Griffin is offline Jim Griffin  United States
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Thanks Patrick for the input.

Yes, the Parts Express ND64-16 (PE #295-519) is the driver you get with the Epique CBT24. It has a rough frequency response in the upper two octaves and its sensitivity is 80.2 dB @2.83 V/1m. The SB65 beats it in most everything you can imagine which is why I chose it for my Modified CBT24 project.

I Googled the photo you posted and it came up with the Tectonic Elements TEBM35C10-4 which is Parts Express #297-216. It has a very smooth response albeit with a gentle falling slope across the band. Its polar plots are to die for. I could fuss over a few more specs such as its 10 watts power handling or its 80 dB @1W, 1m sensitivity. But it would be the perfect 2 inch class driver for a MiniMe CBT or other small speaker. I did notice that several P-E buyers expressed issues that made them swap for different drivers but having the right driver for their application is sometimes critical.

I'm sticking with the SB65 for my Modified CBT24 plus I like how it sounds in my listening room.

Last edited by Jim Griffin; 11th April 2018 at 01:20 AM.
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Old 11th April 2018, 02:15 AM   #58
perceval is offline perceval  Taiwan
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I bought 4 of those little tectonic round 2" drivers.

Indeed, they are light and tiny! I'm having difficulties sourcing screws that are small enough to fit the holes!

I initially tried one in a tiny OB. Didn't work too well. Then, I put one in a sealed bottom, with the mini OB on top, and again, not too great. Maybe it's their wide dispersion pattern that interferes with OB.

Finally, I used all four in a mini sealed array and finally, they sounded great!
Sweet sound, nicely balanced. They are not loud, but offer a nice presentation.

As others mentioned, distortion comes up quickly lower than 300Hz, but it might be able to go lower when used in a full on array of 25 (or 36!) which would reduce distortion, and help with the sound pressure they might reach.

The only sad part is they cost $14 each over here.
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Old 13th June 2018, 05:53 AM   #59
Patrick Bateman is offline Patrick Bateman  United States
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Here's Jim's pics, from the 2nd page:

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