# Aura Whisper Killer?! Tectonic Elements TEBM35C10-4



## ErinH (Feb 14, 2007)

These aren't available right now for purchase but I was able to get some samples shipped to me. These drivers are SMALL. I can nearly close my hand with one in my palm. 

While the sensitivity is low, the bandwidth is WIDE and this driver would have no problem covering 400hz+ while having one of the best polar responses for a driver in it's size I've ever seen. 

As an aside, there's a "Contribute" button at the bottom of the page.
If you have a few extra bucks to donate to my test funds, it would be appreciated. To make a long story short, I wound up paying out the wazoo on shipping... overnight from Hong Kong to Alabama... yea... totally my screw up for not catching it before it left but such is life. So, if you can even donate a dollar... if I get enough of them it might help me stay in the clear with my creditors. lol



(ps: yes, I plan to test these in an array... Synergy horn, anyone?...)

Here's the results:
http://medleysmusings.com/tectonic-elements-tebm35c10-4-miniature-bmr-driver/



Hope you guys enjoy!
Erin


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## I800C0LLECT (Jan 26, 2009)

I was looking at these! When I first saw them it reminded me of the 2 pair of whispers you used in the pillars.

Glad to see this up!


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## t3sn4f2 (Jan 3, 2007)

These would be great replacement option for an OE sail panel tweeter in a low powered system.


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## danno14 (Sep 1, 2009)

Patrick Bateman.......


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## naiku (May 28, 2008)

How do these compare size wise (and performance) to something like the Dayton RS75? I am running a pair of the RS75 currently from 1000Hz to about 4500Hz, would love to upgrade to a pair of AudioFrog GB25's but those would blow my budget install right out the window. Just curious how these compare.


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## Babs (Jul 6, 2007)

naiku said:


> How do these compare size wise (and performance) to something like the Dayton RS75? I am running a pair of the RS75 currently from 1000Hz to about 4500Hz, would love to upgrade to a pair of AudioFrog GB25's but those would blow my budget install right out the window. Just curious how these compare.


About 1/2" less diameter and 1/2" less depth which is significantly smaller.

By itself, if I were to guess (Erin do correct me if I'm wrong), I imagine this driver couldn't carry the output of the RS75 in the same bandwidth, but does reasonably well at lower output.

If you're considering the GB25's, from what we heard in Erin's car I imagine you can agree that little driver is serious on top of seriously good. That's one to throw your pocket change in a cookie jar for. You'd be surprised how fast you'll be ordering up a pair.


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## Babs (Jul 6, 2007)

Erin, definitely that was my thought as you mentioned it.. Array potential big time. Steven needs to see 'em if he's not already.


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## Blu (Nov 3, 2008)

Donation made! :thumbsup:


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## naiku (May 28, 2008)

Babs said:


> About 1/2" less diameter and 1/2" less depth which is significantly smaller.
> 
> By itself, if I were to guess (Erin do correct me if I'm wrong), I imagine this driver couldn't carry the output of the RS75 in the same bandwidth, but does reasonably well at lower output.


That is my thinking as well, doubt I would swap the RS75 for them but was curious to know how they compared.



Babs said:


> If you're considering the GB25's, from what we heard in Erin's car I imagine you can agree that little driver is serious on top of seriously good. That's one to throw your pocket change in a cookie jar for. You'd be surprised how fast you'll be ordering up a pair.


Crazy thing is, I never actually listened to his car!! Everything I have read about the GB25's says how great they are though, and for the space I have they are almost identical in size to the RS75.


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## strohw (Jan 27, 2016)

I appreciate your reviews so I donated some money.


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## ErinH (Feb 14, 2007)

I don't know if it helps you or not, but as impressive as these guys are, I have no (immediate) plans to remove my GB25 in lieu of these (at least two would be needed to make up for the low sensitivity). The GB25 is a beast with wide bandwidth itself. 

I'm really curious to see how these drivers behave in an array configuration (using 2+). If the lobing is minimal, which I expect it will be, I'm thinking they'll be a killer option for a cheap 2-speaker array in pillars or dash corners (typical car audio locations). I have a feeling, though, that once you start arraying these you'd want to still use a small tweeter to offset the higher frequency lobing. But, we'll see what the testing shows.

Of course, a single could be used in sail panels pretty easily as well. Just at a loss of sensitivity... however, sail panels are nearly half the distance to a dash install in most cars. So by the "every doubling of distance, you lose 6dB in output" rule, these would actually be a good option since they're closer to you.


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## ErinH (Feb 14, 2007)

Guys, thanks a lot for the donations! It really is appreciated. I woke up at around midnight the other night realizing that these were being overnighted. I then spent 30 minutes on the phone with UPS trying to get the shipment cut down to no avail. So I got stuck paying for overnight international shipping and as you can imagine, it ain't cheap.


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## Babs (Jul 6, 2007)

naiku said:


> That is my thinking as well, doubt I would swap the RS75 for them but was curious to know how they compared.
> 
> 
> 
> ...




If you get a chance to hear his car, you'll be troubled by the dilemma to swap for the frogs. Erin's is phenomenal. But remember a lot of that is some magic placement and an incredible tune. 


Sent from my iPhone using Tapatalk


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## Ericm1205 (May 10, 2016)

donated. keep up the good work


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## Patrick Bateman (Sep 11, 2006)

danno14 said:


> Patrick Bateman.......


Random observations:

1) There's a European loudspeaker that uses these as a full-range, I've heard them and they sound really great. I think it's NAIM?

2) Cambridge Audio uses these too. I've heard it, and it was kinda "meh." It's probably the only speaker I've heard from them that didn't sound good. But most of the stuff that I've heard from them was designed by Henry Kloss, before he died.

3) Flat diaphragms have a really wide beamwidth. I have some of the Tangband honeycomb midranges, and their beamwidth is really wide.

4) I believe you can turn any ol' speaker into a flat cone by simply gluing a disc to the cone. Avantgarde Acoustics does this with their midranges horns. According to Geddes, the ideal wavefront for a horn or waveguide is a flat disc, so that's probably why Avantgarde does this. Danley Sound Labs, BMS, and JBL use ring radiators, likely for the same reason.

5) Parts Express sells a bunch of these BMR drivers

6) If you like the sound of the Focal W-Cone drivers, you might like these too. The W-Cone is simply a sandwich of styrofoam wrapped in fiberglass. I believe the BMR drivers are styrofoam IIRC.


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## Patrick Bateman (Sep 11, 2006)

ErinH said:


> <snip>
> 
> (ps: yes, I plan to test these in an array... Synergy horn, anyone?...)


The cone of a loudspeaker acts like a waveguide. For instance, if a loudspeaker was a perfect piston, the response would start to fall as you go higher in frequency. Because the cone acts like a waveguide, it 'focuses' the output into a narrow beam, and that's how we get flat response on-axis. Basically it's the same amount of energy, but concentrated into a narrower beam.

Due to that, a flat piston isn't ideal for a full-range array. IE, you *want* some beaming with a full-range array; the beaming reduces interference between multiple drivers.

For a midrange array or a synergy horn, the flat cone *could* be an asset. TBH, a lot depends on the price. You can get awesome results from the Pyle sealed back midranges, and those cost something like ten bucks.


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> Random observations:
> 
> 2) Cambridge Audio uses these too. I've heard it, and it was kinda "meh." It's probably the only speaker I've heard from them that didn't sound good. But most of the stuff that I've heard from them was designed by Henry Kloss, before he died.


Do you know which model? I'd be surprised if it using the same 2" driver tested here but maybe...

FWIW, the 3" version is used in the Philharmonic BMR Speaker:
The BMR Philharmonitor

I've read a lot of really positive things from it. 
Speaker review- the Phil-BMR, from Dennis Murphy - AVS Forum | Home Theater Discussions And Reviews
New BMR Philharmonitor from Philharmonic | Audioholics Home Theater Forums

Difference there is (again) that is the 3" and it's also used as just a midrange. 






Patrick Bateman said:


> 3) Flat diaphragms have a really wide beamwidth. I have some of the Tangband honeycomb midranges, and their beamwidth is really wide.


These certainly do. I haven't tested others so I can't really speak to that and dang Tang Band doesn't provide polar response (or any sort of off-axis measurements) for their measurements that I've seen. :/

But these have an interesting design that *may* make them better than the others. The marketing implies that... and the data seems to back it up. More below.





Patrick Bateman said:


> 4) I believe you can turn any ol' speaker into a flat cone by simply gluing a disc to the cone. Avantgarde Acoustics does this with their midranges horns. According to Geddes, the ideal wavefront for a horn or waveguide is a flat disc, so that's probably why Avantgarde does this. Danley Sound Labs, BMS, and JBL use ring radiators, likely for the same reason.


Well, to be fair, I think you're understating the tech here. A piece of cardboard is going to have it's own modal problems (not that I pretend to know what they are and further it would be design dependent). These actually have some science behind them. But Wikipedia be droppin knowledge, yo!


Wiki said:


> _Distributed Mode Loudspeaker (DML) is a flat panel loudspeaker technology, developed by NXT,[citation needed] in which sound is produced by inducing uniformly distributed vibration modes in the panel through a special electro-acoustic exciter.
> ....
> NXT also licenses the Balanced Mode Radiator (BMR), a hybrid technology that blends DML technology with that of traditional pistonic-action loudspeakers.[3] According to NXT, *the resultant speakers feature the low-frequency performance of a traditional loudspeaker, but with a wider directivity and shallower profile, as well as the mid-range and high-frequency performance of a DML. The two types of BMR offered are: the Audio Full Range (AFR)*, a full-range optimized circular speaker; and the High Aspect Ratio Panel (HARP), a long and thin form factor for use in narrower spaces._



(I bolded the more important part to us)





Patrick Bateman said:


> 5) Parts Express sells a bunch of these BMR drivers


I am hoping they'll carry these as well. I'm waiting for the Tectonic Elements to get back to me on this.





Patrick Bateman said:


> 6) I believe the BMR drivers are styrofoam IIRC.


I don't think that's accurate; at least not with this particular brand. Maybe others. 
From my hands I can't tell 100% but they seem paper to me. And the 3" version mentioned above uses paper "cone" according to PE's site:
Tectonic Elements TEBM46C20N-4B BMR 3" Full Range Speaker 4 Ohm


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> The cone of a loudspeaker acts like a waveguide. For instance, if a loudspeaker was a perfect piston, the response would start to fall as you go higher in frequency. Because the cone acts like a waveguide, it 'focuses' the output into a narrow beam, and that's how we get flat response on-axis. Basically it's the same amount of energy, but concentrated into a narrower beam.
> 
> Due to that, a flat piston isn't ideal for a full-range array. IE, you *want* some beaming with a full-range array; the beaming reduces interference between multiple drivers.


I appreciate that input. Though, I think there's an advantage to BMR in an array configuration vs standard cone. In my head I'm thinking two+ drivers which radiate nearly omnidirectionally (like these do) would act like one large piston... at least higher than a conventional dome. 

While these drivers do have some directivity, it's fairly low. Due to this low directivity there's much less lobing taking place between multiples; it would be moved up in the frequency spectrum. So I _think_ you can get away with more - a pair ran full range or 2+ ran with a small tweeter and a higher lowpass filter - than you could conventional cone driver array designs. Again, this is why I want to test these out to see what happens. I have an idea of what to expect but until I measure I won't know for sure if that thought train is headed to the right station or ready to depart the track entirely. 


There are folks using BMRs in arrays, though. 
High Efficiency Speaker Asylum
This curved one is neat:
BMR Curved Line Array - Techtalk Speaker Building, Audio, Video Discussion Forum

*But I am digressing somewhat. I want to be clear, when I say array with these speakers, I'm not really talking about a big line array like the above. A car can't support that. lol

I am talking more in terms of using a pair of these per side potentially with a tweeter depending on how bad the lobing is between a closely spaced pair.
*







Patrick Bateman said:


> For a midrange array or a synergy horn, the flat cone *could* be an asset. TBH, a lot depends on the price. You can get awesome results from the Pyle sealed back midranges, and those cost something like ten bucks.


Absolutely. The big feature here to me was the size, though. These particular drivers are itty bitty! 
I imagine a sealed back midrange is going to be a bit larger at least in terms of depth.


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## ErinH (Feb 14, 2007)

Randomness from myself as well... 


A fellow on TT asked what I thought about using these as a midrange from 250-4khz (like the 3" is in the above application). I think that would be a bad idea. There are certainly better suited midranges for that application. The aura for example would be better suited. This gives up too much sensitivity to mitigate it's advantages by using it as a small midrange only. The exception would be a small array+tweeter like I discussed above (which I can't guarantee would be great but I have a feeling it would be pretty awesome)


FWIW, Tectonic actually bought out the company who originated this BMR design which was HiWave. If you type in "Hi-Wave.com" you'll get redirected to Tectonic Elements | Revolutionary Speaker Components. 


Also, here's a pretty basic info page on what BMR is (also mentions Cambridge Audio using these as Patrick mentioned above):
Balanced Mode Radiator speaker tech explained: What is it and does it make a difference? - Pocket-lint

And here's some other companies using them:
Tectonic Elements Powers New Advanced Designs From Music Fidelity and Parrot


Also, here's a good thread over on diyaudio regarding the 3" fullrange version (note: content starts on this page but tons of info on BMR designs before this page).
Near full range BMR (Balanced Mode Radiator) - Page 21 - diyAudio
In the same vein as the 3” fullrange, I ound this guy’s review on the TEBM36S (which I assume is discontinued)
https://passion4audio.wordpress.com/driver-testing/


I think with designs like this companies' products can be compared within the same set. So the positive reviews for the 3” and the above data for the assumed discontinued driver combined with the engineers getting a bit smarter about things certainly gives credence to the notion that the 2" driver I tested will be well received by the DIY crowd.


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## Patrick Bateman (Sep 11, 2006)

ErinH said:


> I appreciate that input. Though, I think there's an advantage to BMR in an array configuration vs standard cone. In my head I'm thinking two+ drivers which radiate nearly omnidirectionally (like these do) would act like one large piston... at least higher than a conventional dome.


There's a few different ways to do arrays. Here's a couple ideas.









In an array like this, we have two things going on. First, the line is going to act like one large narrow driver below 4500hz. This is because the wavelengths are long enough that the wavefronts merge together perfectly. (4500hz is 3" long.)

Above 4500hz, things get trickier. At this point, *the wavelengths are shorter than the center to center distance. For instance, at 9000hz, the wave radiated from one driver in the array is 180 degrees out of phase with the driver below it (and above it.)

That's how arrays create these horrendous lobing problems, which are REALLY audible at any concert venue, particular at high frequencies.

For a deeper dive with some illustrations, check this out: http://www.danleysoundlabs.com/danley/wp-content/uploads/2012/01/line-array-paper.pdf

The paper above pushes Synergy Horns, and obviously I think those are a great solution 

But if you want to stick with arrays, there's a couple things that can help:









First, you can curve the array.

And second, you can use drivers that beam; IE, conventional domes and cones.



At this point, it will probably sound like I'm trashing the BMRs.

I'm not - I've heard them in the Cambridge speakers and in NAIM, and the NAIM sounded fantastic.

If I were going to use them in an array, I'd probably curve the array electronically. You can experiment with this in the wavefront simulator in Hornresp. Basically you'd get the wide beamwidth and low diffraction of a flat cone, but with the advantages you get from curving the array. (Less interference between the drivers.)



I really wish there were some affordable tools to simulate this. 

*


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## glockcoma (Dec 22, 2015)

Donation made, these look really interesting. I've had great result the the 3 1/2" BMR
in boom box builds. 


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## Patrick Bateman (Sep 11, 2006)

Here's a thought:

The cast magnesium basket on that driver is utterly silly and unnecessary on a speaker that's only going to play down to 200hz. Tymphany uses a flimsy plastic basket on the well-regarded TC9, and it works great.

The reason that line arrays don't play to 20khz is because of the pathlength differences from one driver to the other. *Ideally, each driver would be less than an inch in diameter, even smaller would be better.*

As noted above, curving the array helps.










What if we put both of these ideas together?

Get yourself about eight of the Parts Express exciters (same idea as the BMR), and bond those exciters to ONE piece of mylar.

So you'd have one long continuous diaphragm, eliminating the interference between the individual drivers.

It would work a lot like a BG ribbon, but it would be driven from the back of the diaphragm, instead of the edges.










Curving the array yields a lot of benefits, but it may have been too expensive for BG to implement it. Or maybe line array theory hadn't evolved enough for them to know it. (Software has come a long way in the last ten years.)


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## Patrick Bateman (Sep 11, 2006)

Here's some diagrams and cutaways of the NAIM BMR.

One of the 'neat' things about this technology is that it seems fairly straightforward to make your own drivers.

For instance, imagine if you could turn the entire dash of the car into a loudspeaker? That might sound silly, but it should be fairly straightforward. The output of a loudspeaker is dictated by bore and stroke, the same as the motor in your car. Here's some math:

An Aurasound Whisper has a bore of 20mm and a stroke of 3mm.
A BMR would have vanishingly low stroke, perhaps as little as 1mm. *So the key is to use a large bore.* If you used a bore of 60mm, the BMR would have the same displacement as the AuraSound. You can scale this up in a hurry if you have the entire dash to play with (or the whole wall of your house.)

It should be fairly easy to hit high SPL with a big surface and an array of these BMRs.

The big problem is going to be interference.

The solution to interference is curvature.









You can curve the array horizontally, like Martin Logan does here. That curvature gives you a beamwidth of about 45 degrees, fairly similar to what you'd get with a horn loudspeaker. Note that Martin Logan DIDN'T curve it vertically. And I'd argue that curving it vertically is a fine idea, but it's probably too expensive to do that. (If you curved it both horizontally and vertically, you'd get a diaphragm that looks like a giant contact lens, and if you look at the JBL CBT white papers, that's exactly what the ideal shape looks like.)









If you curved it electronically, you'd get something that looks like the QUAD ESLs. And I can't easily name a speaker that's more renowned than the QUADs. It blows my mind to hear these at audio shows, and realize that this is a forty year old design which has managed to stay competitive against decades of progress in loudspeaker design.

QUAD curves the array with a passive xover, but in 2016, MiniDSP would be the obvious solution.


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## Patrick Bateman (Sep 11, 2006)

I'm having one of those moments where I'm resisting the urge to throw my stereo in the trash and give this a try


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> I'm having one of those moments where I'm resisting the urge to throw my stereo in the trash and give this a try


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## ErinH (Feb 14, 2007)

I just wanted to thank those of you who kicked over a few bucks in donation again. With all the help, I've nearly managed to clear the cost of shipment. So, thanks again, all. I really appreciate it. I learned a lesson from this when dealing with manufacturers who are separated from the guys in their shipping department. 

Thanks a ton, folks!


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## ErinH (Feb 14, 2007)

Got a reply back from the mfg rep today.

Here's some info:


> Thank you for your review and your comments. For my part, I would like to add that the (TEBM35C10-4) driver is fully available and in mass production: we will advise regarding US distribution as soon as possible. I can also confirm that this is our smallest driver and as such, it is priced accordingly. We envisage the price to be in the region of $4 to $5 for 10k volumes.


I don't know the likelihood of PE carrying 10k+ of this and I don't know for sure if the $4-5 he quoted me was expected MSRP or dealer price. But, if nothing else, it's a good indication of pricing in line with their other drivers sold here in the States which is about $15-20 each. So I'd expect them to be no more than that to the end user.


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## Patrick Bateman (Sep 11, 2006)

GROUP BUY!!

I'm in for two


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## geshat00 (Jun 1, 2016)

What I am wondering is how many other drivers in this size might perform the same or Better. I know partsexpress carries the Peerless/Tymphany in this size. They also carry the Peerless 2" with the huge magnet that they recommend rear mounting.

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## Orion525iT (Mar 6, 2011)

Interesting little things, but with low power handling and low sensitivity, maybe only useful in multiples. But they might work great tucked deep at the windshield and dash junction. 

Incidentally, I recently bought 25 of the little 2" square NXT/HiWave square jobbies from PE to use for midbass bandpass. Only needed 20, but at the price break, 25 was the same cost.


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## schmiddr2 (Aug 10, 2009)

Orion525iT said:


> Interesting little things, but with low power handling and low sensitivity, maybe only useful in multiples. But they might work great tucked deep at the windshield and dash junction.


Yeah, I'm guessing 89db is about it's max at 1m. With a L and R it may be 92db.

I'm using the TB W2-800SL in an on-axis dash mount application; even crossed at 300Hz they are loud enough for general or even spirited listening, they will get louder but with added distortion and potential for damage. They are about the only "mid" that would fit in my (strange shaped) dash and will do what I want.

Still interested in the Tectonics, but I would have to mount them in horizontal pairs L and R if I wanted to use doubles and I'm not sure that's recommended.


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## bigbubba (Mar 23, 2011)

I might be interested in trying a set of these in my truck. After this weekend I just found out one of my 2 5/8" Pioneer mids may be blown and I will need something about that same size or I will have to rebuild my pillars....again.


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## 1fishman (Dec 22, 2012)

Patrick Bateman said:


> If you curved it electronically, you'd get something that looks like the QUAD ESLs. And I can't easily name a speaker that's more renowned than the QUADs. It blows my mind to hear these at audio shows, and realize that this is a forty year old design which has managed to stay competitive against decades of progress in loudspeaker design.
> 
> QUAD curves the array with a passive xover, but in 2016, MiniDSP would be the obvious solution.
> 
> [/font]


IIRC mine were made in 1966 making them 50 years old. I really miss the sound but they sure were bulky as heck in a small room.

Subed for more info on these little drivers


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## geshat00 (Jun 1, 2016)

I know Erin is busy, but what if we could get him to test more of them?

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## bnae38 (Oct 3, 2015)

Any word on these little guys, very interested in GB


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## Jscoyne2 (Oct 29, 2014)

whats so special about the aura? i dont remember hearing many good things about it.


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## bnae38 (Oct 3, 2015)

Not the aura.

http://www.tectonicelements.com/wp-content/uploads/2016/02/TEL-DS-TEBM35C10-4.pdf


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## Jscoyne2 (Oct 29, 2014)

bnae38 said:


> Not the aura.
> 
> http://www.tectonicelements.com/wp-content/uploads/2016/02/TEL-DS-TEBM35C10-4.pdf


:aura wisper killer: as in the wisper was good but heres something better?


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## bnae38 (Oct 3, 2015)

Oh gotcha.

Dunno, would be fun to play with at the cost they're probably going to be, that's all.


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## Bayboy (Dec 29, 2010)

Jscoyne2 said:


> whats so special about the aura? i dont remember hearing many good things about it.



The Aurasound Whisper (NSW2-326-8A) is an exceptional driver for it's size and that I can attest to. Very low distortion, high excursion capability, & response characteristics that's near the top in it's size class. They've been out for a while so the hype on them has waned a bit. Plus when most are able to fit something larger, then why not? The only immediate fault I could find with them is the mid mounting point makes it somewhat of a pain unless rear mounting. Still, they're impressive so anything of similar size being able to compete or beat is saying a lot.


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## bnae38 (Oct 3, 2015)

Available at Pe now https://www.parts-express.com/tectonic-elements-tebm35c10-4-bmr-2-full-range-speaker-4-ohm--297-216

Would be fun to play with a couple, but i just got the illusions in..

Interesting looking driver.


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## ErinH (Feb 14, 2007)

Yep. I meant to post this a few days ago. My contact at TE emailed me to let me know they were available. Thanks for the reminder... I need to update a couple threads.


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## Patrick Bateman (Sep 11, 2006)

Hmmm, so ten of these per side would raise the efficiency to a semi-acceptable level (90dB). And an array of ten can handle 100 watts RMS.

So $80 for an array that should be able to do 200hz to 20,000hz with no crossover.

Hmmmm....


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## evan_perez (Mar 2, 2015)

Just curious, how do you think these would perform for rear fill (added ambiance)? I've seen several people using the Aura whisper for rear fill, but this seems like an interesting option. Any thoughts?


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## Babs (Jul 6, 2007)

Patrick Bateman said:


> Hmmm, so ten of these per side would raise the efficiency to a semi-acceptable level (90dB). And an array of ten can handle 100 watts RMS.
> 
> So $80 for an array that should be able to do 200hz to 20,000hz with no crossover.
> 
> Hmmmm....


 Do it!


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## Patrick Bateman (Sep 11, 2006)

Things are super slow this time of year and I've been tempted to buy the Epique CBTs since I heard them at CES.

But they're sold out.

The Tectonic driver illustrates a problem with arrays that I don't see discussed a lot:

*The absolute maximum SPL at high frequency is the same as a single driver.* This seems counterintuitive, that you could have 36 drivers in an array and it will be no louder than a single driver at high frequency. Here's how this works:

Basically when you have two drivers and they're within about 1/3rd of a wavelength, they'll sum constructively. They'll basically behave as if they're a single unit.

For instance, if you have two 12" subs in your trunk, and they're playing 375 Hz * or less,* they'll sound like a single unit. This is because 1125Hz is twelve inches long, and 375Hz is one third of that. (One third wavelength.)

But when you apply this to high frequencies it gets ugly fast. The tightest that you can pack the TEBM35Cs together is a center-to-center spacing of 2". (Because they're 2" in diameter.) So that means that they'll sum constructively below 2,250Hz.

Due to that, you can see a couple things:

1) Due to the destructive interference above 2250Hz, it's not going to sound like a good clean dome tweeter. Whether that's a deal break is the question though. I've heard the Epique CBTs, they sound great. Do they sound like a good dome tweeter? No. But they do a lot of other things really well. It will depend on what your priorities are.

2) It really makes a case for figuring out how to combine some type of waveguide or dome with an array.









On a side note, I wonder if the very clean treble that ribbons offer is partly due to their very high efficiency? For instance, this is a run-of-the-mill Fountek ribbon, and it can do close to 100dB with one watt at 20khz.

To put that in perspective, I can't find ANYTHING besides a ribbon that can play that loudly above 10khz. Even compression drivers can't do it. True, they can hit close to 110 dB in the lower treble, but at very high frequencies, they're starting to roll off, because of their "mass rolloff."



TLDR: The TEBM35C10-4 looks really compelling for an array. Thing are tricky though, because the maximum output above about 5-10khz is no better than a single unit.


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## Patrick Bateman (Sep 11, 2006)

The new Apple speaker has been well reviewed. It uses an array of seven BMRs. I wonder if it's the same driver reviewed in this thread?

https://www.reddit.com/r/audiophile/comments/7wwtqy/apple_homepod_the_audiophile_perspective/


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## Patrick Bateman (Sep 11, 2006)

I horn loaded this BMR and posted the results here:

John Sheerin got Apple to use horns! - Page 2 - diyAudio

Apple is using horn loaded BMRs in their new speaker that came out this week.


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## Elgrosso (Jun 15, 2013)

Patrick Bateman said:


> The new Apple speaker has been well reviewed. It uses an array of seven BMRs. I wonder if it's the same driver reviewed in this thread?
> 
> https://www.reddit.com/r/audiopHa j...tqy/apple_homepod_the_audiophile_perspective/


Ha just found out the same thing!
I was almost about to buy one to try, but no aux in... this means it can't work really well with all streaming stuff.


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