DIY Flat Panel Speaker Love

[bradley.s]

Here's the first REW measurement. 20Hz through 20kHz, microphone 36 inches away from speaker on-axis with the mic elevated 28 inches. First image is 1/24 smoothing. Second is no smoothing. But I don't know how to measure speakers so I'll spend the next couple days figuring out how to do it. The CBT array has delays and volume attenuation, however, I have not confirmed the volume attenuation with the mic. I decreased volume with the DSP but haven't confirmed that's what is actually playing through the speaker.

I have no idea if this is functioning like a CBT or a regular array. That's what I hope to find out after I learn how to take measurements.

[bradley.s]

has anyone attempted a small version? Something for desktop use

https://www.parts-express.com/tecton...4-ohm--297-216

[ameuba10]

has anyone attempted a small version? Something for desktop use

[bradley.s]

One amplifier per actuator. They'll be wired in parallel for each segment of the CBT array. Each segment will be delayed, attenuated by DSP. After it is complete I'll need to figure out how to accurately measure it for polar response with REW. If it works like a real CBT I'll need to figure out how to equalize for frequency response. If that works, I'll see if I can reduce the number of actuators.

[bradley.s]

Post purchase rationalization might also be at play. Four years and two thousand dollars is a large investment.

"However, they do not wish to feel they made the wrong decision, and so will attempt to convince themselves, and their peers, that their original choice was the correct one, and the consumer's opinion is better than everyone's opinion, i.e. using sour grapes arguments."

http://www.cognitivebiasparade.com/2...alization.html

If a stated goal is to achieve hi-fi then two grand to arrive at onsies could lead to a lot of post purchase rationalization. For that cash you could build two nice stereo channels, a center, and multiple subs. Floyd Toole said their experiments (double blind) demonstrated a center channel objectively improves the sound. That may be why we've seen the sour grapes arguments and the unsupported superiority.

I don't think there's anything wrong with onsies. No doubt they provide a "best option" under certain conditions. But you'd want to describe those conditions so people knew how to get good value out of them. I also don't think there's anything wrong with making a hobby out of onsies. Experienced speaker designers build two driver bookshelves all the time even though they aren't the best. Part of the reason they do it is aesthetics. Small speakers don't fill up your room and you have some leeway with one or two subwoofer placements. So if you can get good sound out of small speakers that's a win. Similarly, if you get good sound out of onsies -- or MAPs -- and they happen to mount on a wall, that's a win.

OK, now that we've identified the bias at work we can get back to sharing information that helps people build their speakers. Yes, there is a place for onsies. People who have made onsies their hobby have a lot to share in that regard.

[Kornbread]

Confirmation bias, The tendency to process information by looking for, or interpreting, information that is consistent with one’s existing beliefs. This biased approach to decision making is largely unintentional and often results in ignoring inconsistent information. Existing beliefs can include one’s expectations in a given situation and predictions about a particular outcome. People are especially likely to process information to support their own beliefs when the issue is highly important or self-relevant. Information that conflicts with the decision may cause discomfort and is therefore ignored or given little consideration (Casad, n.d.).

To an extent, we all do this. The trick to becoming respected among peers is knowing that we do this and deliberately keeping as much of our biases as possible, out of the equation.

Reference
Casad, B. J. (n.d.). Confirmation bias. Retrieved July 22, 2019, from https://www.britannica.com/science/confirmation-bias

[bradley.s]

I'm starting to suspect your onsies aren't very good after all. I gave you the benefit of the doubt but you haven't shown anything to support your opinions and your criticism of Tectonics' speaker design is based on their business model. At the same time, you criticized researchers with expertise in audio science because their research wasn't commercialized.

Until you demonstrate otherwise, I believe your onsie performance claims are a product of your confirmation bias rather than objective listening or measuring. Show me the money.

[Unbiasedsound]

If you watched the Tectonic videos why are you still building onesies. You've said you're interested in hi-fi. Tectonic's hi-fi panel uses a cluster of four exciters in addition to a ribbon. In my case I'm curious if exciters can work well in a CBT array configuration. But if I was interested in hi-fi I'd build MAPs based on Tectonics clustering.

https://www.tectonicaudiolabs.com/pr...id=product-803

Because a single exciter sounds the most coherent and accurate. Yes my goal for these DML panels is hi fidelity sound quality and everything else is secondary. So what if they use a cluster of four exciters and a ribbon tweeter, have you heard them and what are you comparing them too? Since you are curious go find out and build a pair of hi fi maps based on tectonics clustering. I will be waiting for your results.

Also something to ponder on. I have always wondered why NXT and Tectonics only market there products for PRO PA and Live Band reinforcement instead of marketing there products to the audiophile community. Plus I have never seen any of there products in any local hi fi audio and video stores that I use to frequent.

[bradley.s]

If you watched the Tectonic videos why are you still building onesies. You've said you're interested in hi-fi. Tectonic's hi-fi panel uses a cluster of four exciters in addition to a ribbon. In my case I'm curious if exciters can work well in a CBT array configuration. But if I was interested in hi-fi I'd build MAPs based on Tectonics clustering.

https://www.tectonicaudiolabs.com/pr...id=product-803

[Unbiasedsound]

Your explanation was good enough for building single exciter stereo DIY speakers. But the Tectonics guy is building speakers used in professional installations so he needs to be accurate. You should probably watch his videos so you can get ideas on how to improve your speakers.

SIGH!!!!!!!! I have watched ALL those tectonic videos before multiple times awhile back. Since you are building a design using multiple exciters you should watch those videos to improve on your design.

[bradley.s]

Your explanation was good enough for building single exciter stereo DIY speakers. But the Tectonics guy is building speakers used in professional installations so he needs to be accurate. You should probably watch his videos so you can get ideas on how to improve your speakers.

[Unbiasedsound]

No. This is how it works.

https://www.youtube.com/watch?v=tWZdPkH9IgA

That video technically supports what I said SMDH....DML's have a very diffused sound the echo reflections are less prominent then with conventional cone speakers therefore the reflections are less directional.

This is one of the reasons DML's have very little to no microphone feedback.

[bradley.s]

DML's from what Ive read already have less room reflections then conventional cone speakers.

No. This is how it works.

https://www.youtube.com/watch?v=tWZdPkH9IgA

[Unbiasedsound]

Nice find geosand and bonus points for ease of comprehension.

This one sentence tells me what I need to know about multiple exciters vs one exciter per panel as NXT is probably the best known contributor to distributed mode loudspeaker technology. They had big plans for its implementation. "This technology, developed by now dissolved company NXT, involved placing surface exciters in positions along a panel that correspond with that panels resonant frequency" (Zielinski, Obiora, & Sansoucy, 2018).

Ok, these guys read my experiment with the panels. The wood frame holding the panel in with the aid of window seal foam ... where's my name in the reference section?


Reference

Zielinski, D., Obiora, O., & Sansoucy, D. (2018, April 25). Development of a Resonant Panel Speaker[PDF]. Worcester Polytechnic Institute.

These sentences tells me what I need to know about that articles main goals. Which is more about Aesthetics and not hi fidelity sound quality.

This report covers the development of a walled mounted, low-profile speaker system. A format that
could be hung from a wall in a way similar to a painting, and the capability to hit low notes. While a small number of speaker manufacturers have created dimensionally impressive
models, they are almost all very expensive or have limited frequency ranges, leaving a gap in the
sector for more affordable speakers that can achieve an ideal range.

You really believe the works he CITED are the only places his knowledge came from?.....I wouldnt doubt for a second that he read this thread or any other thread on any other forum pertaining to DML technology...most wont cite a forum because its not a scientifically based study but credit should be given where its due. If 5 years from now another scientific study on DML's comes out and they mention the Karsonator technique you will all know he got that technique from me. LMAO


Now like I always ask of those articles is where are there DML panels? Who has heard them? Who has built them? What have they been compared to?

[Unbiasedsound]

Not sure if this has been posted before.
An attempt to create a bass DML, 40hz. They are seemingly successful to some degree and it seems to use techniques that have been discussed here before: https://web.wpi.edu/Pubs/E-project/A...er_Stabile.pdf and its relatively easy to read and understand...

I skimmed through that article and if I am not mistaken they don't use a Spline/brace to hold and stabilize the exciter in place which is a very important factor especially in the lower frequencies at higher excursions where the movement becomes more pistonic then modal it will need something to push off of like a spline or brace.