DIY Flat Panel Speaker Love

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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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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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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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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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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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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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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 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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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.

[Unbiasedsound]

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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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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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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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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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)?