DIY Flat Panel Speaker Love

[bradley.s]

Wait, those first images were measuring the back of the speaker. That's probably why it dipped to negative 100 first. These photos are measured from the front of the speaker.

[bradley.s]

This is what I get when I select the Step Response checkbox. First photo with red line is zoomed in to show -500u to 10.0m. Second photo with green is zoomed out to show the whole line.

[Kornbread]

Make it look like this.

[bradley.s]

Here's the graph under the impulse tab. I don't know what I'm looking at or if I measured this correctly. I placed the mic one meter from the speaker at 28 inches in elevation.

[bradley.s]

A paper somewhat related: Implementation of a Dipole Constant Directivity Circular-Arc Array. Array is physically curved but it's dipole. In contrast, the MAP array I'm trying to learn how to measure is a physically straight delay-curved attempt at a CBT. I assume a physically curved array is better. On the other hand, a physically straight array might gain from near wall placement by angling the axis toward or away from the wall. With a curved array either the bottom or top would need to be moved away from the wall. I don't know, I'm tired and burned out for the day.

http://faculty.tru.ca/rtaylor/public...ementation.pdf

[bradley.s]

I don't know how to test impulse response. I'll have to learn how to do it.

[Kornbread]

Curious to see what the impulse response looks like. Post that unaltered please.

[bradley.s]

Second photo, no smoothing.

[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.