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Trials with the little Tectonic BMR 2"
Trials with the little Tectonic BMR 2"
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Old 7th August 2018, 12:48 PM   #31
wesayso is offline wesayso  Netherlands
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Hope to read about your experiments soon, bwaslo.
I have virtual sources behind the listening position, reflecting of close by side objects.
This makes them arrive laterally at the sweet spot.
They are lowpassed at ~3500 Hz though, else I could hear them separately.

I've always wanted to try running up to higher frequencies coming from the front. Never got around to it, partly because I wouldn't know where to hide them from the wife if I liked it too much.
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Old 9th August 2018, 08:11 PM   #32
bwaslo is offline bwaslo  United States
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Trials with the little Tectonic BMR 2"
Getting there. The BMR drivers came in and I 3D printed a few little enclosures for them to try out, maybe later today. A printed box is about the only practical way to mount these little suckers if you plan to use the tiny mounting holes, the cutout is pretty complex and not much room for error. Of course, if you plan to use wood and construct by hand, you could just cut a 46.5mm dia hole and use silicone glue to mount the driver, but the mounting holes wouldn't be usable since the holes are on a diameter of only about 47.5mm! The screw sizes, btw, would be either M2 or #2 self-tapping type. About the same size as the screws that hold remote control units together. I got some on order from ebay.

These things are TINY, here is one in my not-particularly-large hand:
Trials with the little Tectonic BMR 2"-size-jpg

These are two enclosures I made to test it out. The black one was supposed to be a revised version (different side mounting slots), but I managed to choose the older file instead when I went to print last night
Trials with the little Tectonic BMR 2"-photo-1st-2-jpg

The plan (if this works out) is to have 4 of these per side mounted to the back of each speaker, firing upward and toward the sides. With one each, I don't expect to get much volume from them -- not sure I'll get enough with 4 each for that matter! Hoping that running them with a highpass will let me drive them a little harder.

This is what the 'revised' version looks like. Mostly just moved the mountings more toward the fronts and changed some angles/slopes to make things easier for the 3D printer.
Trials with the little Tectonic BMR 2"-screenshot-png
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File Type: jpg photo of 1st 2.jpg (61.4 KB, 884 views)
File Type: png screenshot.png (25.5 KB, 733 views)
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Old 9th August 2018, 08:25 PM   #33
Patrick Bateman is offline Patrick Bateman  United States
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I've screwed around with Ambiophonics. The fundamental problem that I ran into was that the processing nukes the bass and the dynamics. This is because the processing adds an inverted signal to cancel crosstalk, and while the inverted signal widens the stage dramatically, it also kills bass and dynamics.

One day, on a lark, I had an idea:

What if you put the crosstalk cancellation speakers NEAR THE LISTENER?

So the speakers are on the other side of the room, and the crosstalk cancellation speakers are near the listening chair.

Trials with the little Tectonic BMR 2"

Imagine a Polk SDA where you took the 'cancellation' speakers, removed them from the box, put them near the listener, then time aligned the signals to compensate for the pathlength difference.

Obviously, this only works for a single seat. But it worked astonishingly well for me, way better than any of my ambio experiments.

I wound up abandoning the project, because I'm totally ADHD, but it definitely worked.

It wasn't 100% great; for instance I found that on a lot of recordings the effect was TOO dramatic. It's jarring to have a soundstage that seems to encompass the entire room. Fun in small doses, a bit exhausting after a while. But that's easily addressed with a simple volume knob on the 'crosstalk cancellation speakers'.

I wrote it up here:

Crazy Wide Soundstage - Car Audio | DiyMobileAudio.com | Car Stereo Forum
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Old 9th August 2018, 08:36 PM   #34
bwaslo is offline bwaslo  United States
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Trials with the little Tectonic BMR 2"
I don't think that would work for me (even if I had a place near the seat for yet more speakers!). I'm really bugged if when I move around (or go into/out of a room) and the sound image swoops around dramatically. That was the main failing for me when I used synthesized back channels with an old dolby setup. Even if it worked when I was seated, the experience of having strongly localized speakers heard with normal living movement was still enough to continually emphasize the fake-ness of it all.
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Old 9th August 2018, 11:21 PM   #35
bwaslo is offline bwaslo  United States
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Trials with the little Tectonic BMR 2"
Well, so far so good. I should probably start a separate thread about this, over at multiway.... When I get further along.

The single driver actually seems to do pretty well. Seems to work best so far crossed in about 1700Hz, playing about 4 or 5 dB below the mains. I don't have the FIR phase scrambling in, yet, that will take some more work. I also haven't measured anything yet. Delay sounds best around 15msec (WAY more depth to the sound field, but the ms value doesn't seem touchy). Over 25msec starts to sound too thick, under 5msec affects the tonality more (at least when the BMR is crossed in lower in frequency).

Oddly, it makes it easier to differentiate instruments and voices. Maybe that's just from more treble info in the room. Hard to say. I have to say it does sound much better to my ears so far. Turning off the ambience field brings on actual disappointment, don't want to leave it off. So I'm going to go forward and print out 8 of the enclosures.

Patrick's mention of crossing the channels gave me something that was easily tried, and it does seem to make the room fill more. Having the BMRs at back of the SmallSyns does well at preventing any speaker localization. If I had a way to wire them and make them look good, I'd consider putting some 'wall sconce' sets up in the far edges of the room, though that might still cause the sound field to shift too noticably when moving in the room.
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Old 9th August 2018, 11:35 PM   #36
Patrick Bateman is offline Patrick Bateman  United States
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That's so cool!

Linkwitz Orions beaten by Behringer.... what!!?

About a decade ago, there was a thread about the Linkwitz Orions being beaten by a cheap Behringer speaker. But the curious part, which no one seemed to notice, is that they were BOTH beaten by a speaker inspired by the Bose 901.

That got me tinkering with speakers that are intentionally designed to create reflections. And one of the curious results was that it DID seem to do things that were counterintuitive. For instance, you would expect that intelligibility would be terrible. But instead, it was improved.

My 'hunch' on why this happens is The Precedence Effect. Basically a conventional loudspeaker has a handful of strong reflections. (Ceiling, floor, side walls.) But a speaker with numerous arrivals, will have a confusing series of audible cues.

My 'hunch' is that our brains isolate the first arrival and discard the plethora of late arrivals, similar to how we can understand a conversation in a 'live' room, but a recording of a 'live' room is unintelligible.

With a small series of strong reflections, the brain is confused, trying to determine which signal is the most important.

Or at least that's my theory.
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Old 9th August 2018, 11:58 PM   #37
bwaslo is offline bwaslo  United States
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Trials with the little Tectonic BMR 2"
I think that's on the right track. My guess is that two speakers cause relatively few reflections, all of which make the positions easy to locate, and make clues about how far away the speakers are, hurting the depth illusion. Controlled directivity cuts some early reflections and making more long-path delayed reflections. So more relections of various (and longer) delays helps disguise the fact that there are only two spot channels producinf it all.

I'm also of the opinion that the directions of sounds matters a lot, even more than frequency response. Natural sound doesn't come from just two spots in front of you, if the instruments are spread out in a room you are also in. Even contrived sounds from other directions (but delayed enough to not mess up the precedence effect or get into the tonality integration time) are still more "accurate" than sounds that come only from two spots. Particularly if those spors are different for different frequency ranges.

Of course that's just my theory at the moment, likely to be modified or even change entirely in the future!
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Old 10th August 2018, 03:08 AM   #38
perceval is offline perceval  Taiwan
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Quote:
Originally Posted by bwaslo View Post
Natural sound doesn't come from just two spots in front of you, ...!
That’s why I love my OB setup so much.

When dealing with most speakers, the music seems “projected” to my head, but with my OBs, it radiates to me, which I find more pleasing.

I know it’s not for everyone, but it works for me.
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Old 10th August 2018, 10:10 AM   #39
Juhazi is offline Juhazi  Finland
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I agree with perceval
Sort of tour de force to use highly directive synergys as mains and then do dsp tricks/spatial enhancement with additional ambience speakers! But still, this is a very interesting topic and bwaslo can write excellent reports of his experiments.

My living room system has a AV receiver as preamp and I can listen to 2.0 stereo or 5.0 Dolby ProLogicII processed sound too. Now with dipoles I don't use processing any more for music, but do listen DD multichannel for movies and TV.
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Old 12th August 2018, 02:47 AM   #40
bwaslo is offline bwaslo  United States
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Trials with the little Tectonic BMR 2"
To end this threadjack, my yammerings (a lot copied from here) are moved to
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