DIY Flat Panel Speaker Love

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Digging through some BMR specs, it looks like they have impressive off-axis performance at pretty high frequencies for their diameter. Kind of like an RS75 for half the price...though that might also be a brandVSprice thing.
Their high-frequency coverage and LF-output isn't quite enough that I'd want to completely omit a tweeter and woofer, and it looks like some manufacturers agree, so I'm not sure there's much remaining advantage...at least not for hifi.
Obviously there's a nice advantage for affordable lofi singleFRdriver PA though.

Looking at some of the other BMR (advertisement?) videos, it seems many of the other videos are somewhat ironically focusing less on the single-fullrange and wide HF coverage aspects and instead showing examples where large/tall rooms with multiple wall speakers were replaced with line-array type systems to avoid some of the surface bounces.
It's not something exclusive to BMRs nor the TT brand, so it's a little odd that the technology and brand is the focus rather than the better setup.

Maybe there's a cool advantage, directly tied to the BMR technology, that they're forgetting to mention or show in the videos?

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Actually the answer is really simple, so simple in fact you might not believe it. lol I think I did mention it someone here or on another site. I first heard about it from reading Dr.Jose Bertagni's articles and patents. I forget which one and they are so long so dont ask me to find it. LOL Even Tectonic mentions it but uses high tech terminology so its harder to understand. lol

Answer: It has to do with reflections. DML's have a "DIFFUSED" sound. Diffused sound equals less reflections and or WEAKER reflections. Less reflections equals more coherency. In a highly reverberant space there will still be an echo but due to less reflections cancelling each other out the sound will be more intelligible. The only way to significantly cancel out reflections to the point of very little echo is to use room acoustic treatments.

Also its been stated that because these diffused type of reflections dont cancel each other out as much as a conventional cone driver, instead what they do is reinforce and use the reflections to there advantage. Bertagni states in one of his articles or patents that his speaker uses the rear wall reflections to increase performance of his loudspeakers due to its diffused nature.

So one of my advice for DML speakers is " DO NOT USE ACOUSTIC TREATMENT ON THE REAR WALLS" behind the panels like how Tech Ingredients says in his video and or in the comment section.

This is actually the so called "MAGIC" sound of DML's as it sounds like a live show.

A diffused type of sound with weaker reflections will also have way less microphone feed back which is why you can place a DML panel right in back of the mic. as shown in Tectonic video.

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I first heard about it from reading Dr.Jose Bertagni's articles and patents.
Answer: It has to do with reflections. DML's have a "DIFFUSED" sound. Diffused sound equals less reflections and or WEAKER reflections. Less reflections equals more coherency. In a highly reverberant space there will still be an echo but due to less reflections cancelling each other out the sound will be more intelligible.

Also its been stated that because these diffused type of reflections dont cancel each other out as much as a conventional cone driver, instead what they do is reinforce and use the reflections to there advantage. Bertagni states in one of his articles or patents that his speaker uses the rear wall reflections to increase performance of his loudspeakers due to its diffused nature.

A diffused type of sound with weaker reflections will also have way less microphone feed back which is why you can place a DML panel right in back of the mic. as shown in Tectonic video.

A well-diffused sound can easily result more/stronger/worse reflections against lateral surfaces.
Echos cancelling or reinforcing the original source will depend on the location of the surface and source and listener (and the frequency/ies themselves, I think) so depending on this can be finicky for any source...and may still result in slight "ringing" or sloppy sound.

I think the more important aspects for coherency in a gym or auditorium or tunnel will be:
-the echo's volume relative to the source (which is largely controlled by the listeners' distance from source..narrowing dispersion can help avoid the worst reflection locations where possible)
-the echo's pre-delay time (which depends on the distance and angle of source/surface/listener, which can be controlled by careful placement of sources and narrowing/limiting source diffusion)
-the echo's trail length and frequency-response (pretty sure this can only be controlled by room treatment...though careful pattern control can use the audience as "room treatment", lol).

The extremely diffused sound can be great help for a situation where there will be several quieter sources spread around near listeners to maximize direct-source volume over reflection volume, but any decent 2way/3way or appropriately small single FullRange conventional driver can be designed to do this as well.


I don't believe a BMR with wider diffusion compared to a conventional cone array at the same listening-distance SPL and same frequency-response will result in less microphone feedback.
But you can minimize feedback with either speaker type by being aware of the microphone and speaker diffusion/pickup pattern and by using the mixing board's equalizer to tame problematic frequencies...so the video might've simply been making good use of conventional means.

A wide-diffusion onstage PA without additional audience-only/primary reinforcement PA will mostly result in the stage/players getting blasted by more SPL than the middle and back rows of the audience. A bad situation, even with BMRs.
A wide-diffusion stage-monitor PLUS additional audience-facing PA will have the monitors facing the stage toward the mic dead-zone, and audience PA would be forward or high, also in the mic deadzone...so neither is causing microphone feedback because of their location/facing/controlled-diffusion-pattern. Easily accomplished with either technology.
A controlled-diffusion array can probably be tuned to do a decent job at both stage and audience coverage from onstage while avoiding feedback...but this can be accomplished with either technology.

I'm likely missing some important benefits somewhere, however.
I'm sure the BMRs can do some really cool things, and I'd love to hear some pros/cons from anyone experienced with large, indoor live-sound (preferably an objective 3rdParty instead of a salesman/installer/customer, if possible).

[Unbiasedsound]

https://www.youtube.com/watch?v=_KI5NJCqnPc

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https://www.youtube.com/watch?v=_KI5NJCqnPc.

If that's the only speaker delivering to the audience, the back row is going to get a much weaker level compared to the poor, abused top-of-singer's-head.
It's hard to draw any conclusions when there's no A/B comparison (or comparison of any kind) to draw any conclusions from. The SPL from that speaker isn't mentioned. The rest of the speakers being used (if any) aren't mentioned. I don't think they even said whether or not the speaker in-frame was the one being used at the time. :(

A conventional driver monitor with decent EQ from the desk to avoid problem frequencies and a sensible SPL (both to avoid feedback and to avoid deafening the singer) should also be able to accomplish this.
A conventional array might have better luck by narrowing the vertical dispersion to avoid blasting the singer and the ceiling...focusing more audio onto the audience, further avoiding feedback, and lessening the amount of floor/ceiling-echo.

I don't know if that particular TT speaker being shown is a focused array type (I suspect it is) or a wide-dispersion type. I'll try to take a look at their website in hopes of finding some information on the different models and their patterns.

Some of the TT BMRs (maybe all?) have really lumpy mid/high response that looks like comb-filtering. This levels out under 1/3oct smoothing which they use in many of their graphs, but it might help against feedback if the mic/speaker are positioned where there's a null in the worst problem frequency/ies for the mic. This would kind of be a specialized advantage of the BMR that would take a pretty niche design to attempt using conventional drivers...though it's also pretty finicky either way and would require a very careful mic-handler. A neat trick, if possible, but not practical.
I'm not sure what other things the BMR driver itself could do that would give it any advantage against mic feedback in that position. I'm going to try and look into this a little more.

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The Tectonic folks said that speaker (or at least all the similar ones I could find so far) has 165degree dispersion, so not a controlled-dispersion array.
However they also said it doesn't reflect off walls or any hard surfaces despite their own examples clearly showing it does...so I'm feeling pretty suspicious of their claims, and don't know which (if any) can be believed. Maybe it was just a particular person or persons who got a little drunk on their own hyperbole, but a lot of the same people are in many of the videos...and seeing one of their representatives either make a gross error in wording or seemingly lie through their teeth...that erodes trust pretty fast.

Can anyone tell me why the corners of a DML panel need to be rounded?

It looks like Tectonic might disagree in some situations, at least with their larger DML10/DML500 models.
Why do you think they need to be rounded, and can you think of any pros/cons that might explain why TT decided to use sharp corners in these designs?
Are there some advantages to keeping corners, and are the cons potentially situational where they might sometimes be worth the tradeoff?

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Not sure its worth responding since you are going to doubt everything I've said or posted including actual videos in which you make outlandish assumptions like was the speaker in the frame the one being used at the time. REALLY??? It seems you just want to argue instead of trying to understand how DML's BMR's work.

This is why I dont like to give out the answers directly....Instead I will just ask the questions to make people think for themselves and maybe give a few hints along the way. LOL

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I think I realized some of my mistakes (because I'm socially inept) in my responses above.
While I was talking about different ways to deal with echos and feedback, you took the time to find a video specifically showing a pretty worst-case scenerio for feedback with a BMR speaker performing well.
Instead of acknowledging the work and attention to detail you paid to find that example, I focused on explaining and complaining.
This was likely pretty offensive, and I didn't mean to offend you, so I apologize.

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I can tell you are a technical type of person who likes everything explained to you in technical detail and terminology. When I post a vid that shows almost no explanation you seem to make assumptions because not enough info. was given like the train station vid.

When I posted the Tectonic vid of the microphone feed back which is basically self explanitory you started to doubt everything about it. Your first sentence was IF that is the only speaker playing, A/B comparisons, SPL, etc. Unless you've never experienced microphone feed back from a conventional cone speaker then I could understand why that vid is hard to understand. I like to sing karaoke and have a karoke system in my home and when I found out about DML's have very little to no microphone feed back I switched my karaoke speakers to DML and WALA it worked no microphone feed back.

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Not sure its worth responding since you are going to doubt everything I've said or posted including actual videos in which you make outlandish assumptions like was the speaker in the frame the one being used at the time. REALLY??? It seems you just want to argue instead of trying to understand how DML's BMR's work.

This is why I dont like to give out the answers directly....Instead I will just ask the questions to make people think for themselves and maybe give a few hints along the way. LOL

I'm not doubting YOU and I'm not doubting BMRs, I'm just doubting some of the marketing that comes from TT promotional videos....and complaining about a lack of important information in them.
I've seen other major companies use some sneaky methods to exaggerate what their product can do, even when their product is genuinely great and should be able to stand well on its own merits.

I'd love to know what advantages and disadvantages BMRs can have, and why.
Like I said, I'd particularly love information from any unbiased 3rd Party who has experience with these that they can share.
That means YOU and others like you who can talk candidly (frankly?) about stuff like this.
What have YOU experienced, and what have YOU learned when comparing your BMRs/DMLs beside conventional drivers?

Why do you think Tectonic decided to use panels with corners for some of their designs (like the speaker in the latest link you shared)?

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Also most of the explanations I give do not come from me, its what I've learned from other pioneers in DML technology, mainly Bertagni and a few others. No DML company is perfect as they all have flaws in there designs. One needs to be able to distinguish the truth from the flaws.

One of the flaws of Tectonic is they didnt round the corners but it could also be because they didnt need to as there DML gear is designed and used for Pro audio use in live performances rather then in home for the audio enthusiast/audiophile. There BMR drivers on the other hand is used in home for the audio enthusiast which is why they are sold here on P.E.

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I think the DML/BMR pattern-based-radiation allows them to achieve an interesting work-around for the usual limits of diameter VS high-frequency-dispersion that conventional pistonic drivers have.

There are caveats where the BMR's mids/highs produced this way exhibit what appears to be something like comb-filtering, but this is generally not enough to show after 1/3octave smoothing which I think means the response should sound smooth to most listeners.

BMRs have been said to suffer less from destructive frequency cancellation from reflective surfaces compared to conventional pistonic drivers. I'm guessing this may be a result of their comb-filter-resembling mid/high response, potentially making it less likely for coinciding frequencies to phase-cancel with their own reflections..?
HOWEVER, frequency response changes from room modes and reflections/cancellations are only one aspect of dealing with reflected sound.
Reflected sound with longer distance differences between the driver and surface still produces an audible delay between source and reflection arriving at the listener. This delayed sound can be very distracting, and it's not something that BMRs are said to handle any differently than conventional pistonic drivers (at least as far as I've read at this point).

I think it's important that these two aspects of room reflections aren't confused with eachother.



The unique advantage I've seen for the BMR is its impressively wide mid/high-frequency dispersion at larger sizes.
I think this BMR advantage should allow a larger-than-typical midwoofer (and the higher SPL ceiling that presumably grants) to more easily reach appropriate frequencies to join a similarly highSPL tweeter or maybe even cover both mid+tweeter duty itself if the high-frequency response is good enough for the application.
Cool stuff!

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This comb filtering effect is what makes DML's/BMR's have a "DIFFUSED", type of sound that conventional cone speakers do not have making it less likely for frequencies to phase cancel there own reflections. This is what I've been trying to explain to you as my grammar is far from good. LOL

Also DML's radiate sound from the front and back and even sides while BMR's are not as they are designed to be put in a enclosure.

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Looking at the large Tectonic DML measured specs, it looks like it can reach peaks up to ~120db with a +/-5db response from 100hz to 2-3khz according to their heat chart.
The response above 2-3khz for these larger DMLs gets...weird. But the power-response (and I think the listening-window response) might still be fine, so I'm not sure how audible those quirks really are for most listeners.
Still, 2-3Khz is a lot easier to reach with a compression driver at full power compared to trying to crossover at 1-1.5khz to a pistonic midwoofer large enough to reach ~120db (I think 8"-10"diameter).

I also enjoyed this largely positive video review of a 3way using a BMR midwoofer:

https://www.youtube.com/watch?v=7JZjb293HVo

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This comb filtering effect is what makes DML's/BMR's have a "DIFFUSED", type of sound that conventional cone speakers do not have making it less likely for frequencies to phase cancel there own reflections. This is what I've been trying to explain to you as my grammar is far from good. LOL

Please don't get mad or frustrated. I'm not trying to argue, but more pointing out something that might be important:

It's typically bass frequencies where phase-cancellation/room-modes/nulls/etc. are a problem. Long waves and all that.
But I'm also pretty sure the BMRs behave like a regular pistonic driver for their bass frequencies.


I wonder if their lack of phase-canceling mid/high-frequencies works with eachothers' signals when multiple drivers are used to play the same signal. Normally you don't see multiple tweeters used for a speaker (aside from line-arrays) because the phase-combing gets very difficult to avoid.
The same thing can happen with multiple midwoofers playing the same frequencies if their center2center spacing isn't close enough and their LowPass/XO isn't low enough.
I think I remember seeing an MTM build using the Tectonic BMRs, but I don't know if it was a 2way or 2.5way design.

Anyway, if that works well, that'd probably be a nice alternative to coaxial drivers for center-channel speakers in height-restricted setups (small 5.1's and soundbars, etc).

EDIT:
Just realized if multiple BMRs signals don't combine for phase-canceling, then they probably also don't combine for additive benefits either. I'm pretty sure it's both sides of the same coin and you can't have one without the other or viceversa.

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I dont get mad or frustrated if you ask me sincere legit questions.

I agree BMR's behave like a regular pistonic driver in the bass frequencies. DML's also are pistonic but need way more power then a BMR to drive them to pistonic mode due to being inefficient in bass frequencies. This is why I recommend using a DML subwoofer which is just using a sub amp with low pass to drive the exciter into pistonic motion or even better a bass shaker because it can reach lower fr. response.

There is still comb filtering effect when using multiple BMRs or exciters but its effect is not as apparent then conventional cone drivers. Easiest way to fix it is to use crossovers in a 2 way or spacing them close together.

https://www.youtube.com/watch?v=2DlseXMEcDA

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OOoh. I think I might've figured out the microphone feedback thing.

I wasn't giving it much thought until YOU mentioned that your DMLs do indeed work great at avoiding feedback compared to your previous drivers.
I'm betting (assuming? hoping?) mic feedback depends on sustained feeding/cycling of the signal...long enough to really get the mic's diaphram resonating.
If the DML/BMR combing, combined with the natural human unsteadiness, is enough to interrupt the cycle so it can't sustain enough to resonate..viola!
Granted, I'm pretty sure a mic on a stand could still feedback under that hypothesis....and I'm also pretty sure a loud enough signal (one that gets resonances moving in less time) could still feedback under that hypothesis.

Maybe something to test..while wearing earplugs.

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My theory is similar to yours as I believe its due to the "diffused" sound aka combing. The unsteadiness part did not work when using a conventional cone driver as soon as the mic is in align with the speaker even for a split second it will start to hum but with the DML even when barley moving there is no feed back.

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Also why would you believe me and not that video on DML mic feed back? I never knew about DML's ability to avoid feed back until I watched that video. Anyone with a exciter and a mic can easily confirm it for themselves.

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Also why would you believe me and not that video on DML mic feed back? I never knew about DML's ability to avoid feed back until I watched that video. Anyone with a exciter and a mic can easily confirm it for themselves.

Like I said earlier;
"I'm not doubting YOU and I'm not doubting BMRs, I'm just doubting some of the marketing that comes from TT promotional videos....and complaining about a lack of important information in them.
I've seen other major companies use some sneaky methods to exaggerate what their product can do, even when their product is genuinely great and should be able to stand well on its own merits."

Tectonic lied in one (or more) of their videos. That makes it extra difficult to know which parts can be trusted.

You aren't selling anything, and you don't have a good reason to make something up.
You might be mistaken about something (just like any of us) but I'll happily give you the benefit of doubt.

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I also pointed out that TT do have flaws in their design so its obvious that they could be "MISTAKEN" on certain aspects of DML tech. or they are wording it wrong or a misunderstanding. I highly doubt TT. are trying to mislead us on purpose as I dont believe that is there true intentions.

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fantastic dml speakers part 4 - YouTube Check this vid out of someones canvas DML panels. They sound "HORRIBLE" to me but according to him they sound really well. lol

Now before anyone says well you cant tell how a speaker actually sounds like over a recording on youtube unless you hear it in person is true to a degree.

The reason I know for a fact that they dont sound good is because I built some myself awhile back. Even Bertagnis speakers sound better then those.

I can see why he likes them as he is not a audio enthusiast aka audiophile and just your average joe because his speakers sound similar to Bose as it has no highs or lows. LOL
'

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On the DIY forum this is the direction some of them are following which is a disaster. LOL

(1) Panel speaker in progress - YouTube

This is what NOT to do when building DML's. LMAO

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Yes that is the best subwoofer placement on the left high up half in the shelf. LOL

P.S. Yes I know he said he put it there because of the clutter but thats just funny to see at least for me. LOL

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For shits and giggles I wanted to see what would happen if I took the Audyn True Copper Cap off of my Flag ship DML speakers and put them on my little satellite DML speakers and OMG. My friend came over and he said are those the same DML sat speakers he heard last time and I said yes but I upgraded the capacitor and he was like wow they sound so good. He said last time you said you would sell these to me for $60.00 and I said yeah but without those Copper caps lol and then he asked me how much more are those caps and I said they cost more then what it cost me to build that DML sat speakers. lol Although he said the cost is not worth it he also stated that it does sound better then before. We played a Diana Krall track and her voice is so silky smooth with that Audyn True Copper cap which does make a significant difference when compared to the Audyn Q4. I just wish the Audyn True copper caps werent that expensive.

Meanwhile back at the DIY Forum they are still trying to figure out the basics of DML's LMAO