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Ambience tweeters using small BMR drivers
Ambience tweeters using small BMR drivers
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Old 22nd August 2018, 06:19 PM   #41
bwaslo is offline bwaslo  United States
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Ambience tweeters using small BMR drivers
wesayso has done a LOT more on this than I have, I hadn't read about his experiences till now. My experiments have been very limited here and were only recently done, so count me as a rank beginner on ambience add-ons. I should try different bandwidths and spectral balances (though the little drivers I have aren't able do well very low.

My thinking on 2k-20k was that (at about 5db down) was what was needed to better balance out the in-room power response to the on-axis response. I'm still not sure that that makes physical/psychoacoustic sense -- does a significantly delayed (15msec) contribution to power response work similarly to one that isn't so delayed? Since you mostly hear the power response energy as delayed reflection or ambience, it would seem ok that way, but having only part of the spectrum so delayed seems maybe harder to justify.... And, as seems obvious to me at least, the direction that sound comes from is at least as significant as its spectral balance.

I also should set up some mixing so I can do L-R and R-L stuff to try, for now I just send Left to Left and Right to Right, though both are radiating in all directions across the front wall and ceiling. I have FIR in the DSP box, but haven't done any reverb stuff with it yet either. The question come up about what time-diffusion would be right to use, right now it still sounds like the same room, only deeper and livelier, but I don't what everything to sound like its in the same concert hall.

From my listening so far, I'm still very positive on the effects, particularly for this difficult little listening room. My friend (also named Bill) who came over yesterday also liked the sound in here better with the ambience speakers playing, though overall he preferred the downstairs system (with the larger 3D-printed synergy horns and diffusers). He said he'd like to hear the basement system with ambience tweeters added also (he liked the treble upstairs better, but the more full midrange downstairs better).

In the interest of keeping the footprint of the upstairs system minimal, I put together a little ICEpower stereo amplifier for the ambience speakers, small enough to hide behind the small 32inch flat TV in there. I'll post some pics on that (a 3D-printed case for it of course!) over on the Solid State forum. Funny, I have a stupid number of power amps here, just none that could be discretely hidden in here! Some wire dress still needed, but the overall visual impact of the ambient-enhanced system remains nice and understated --

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Last edited by bwaslo; 22nd August 2018 at 06:23 PM.
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Old 23rd August 2018, 12:36 AM   #42
wesayso is offline wesayso  Netherlands
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I'm a bit surprised about the levels you use. If I recall correctly I'm down 10 to 12 dB from the mains. I've tried them a little louder but it gave me a 'wet' sound, of course my bandpass is completely different. As is the direction it comes from.
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Old 23rd August 2018, 12:46 AM   #43
bwaslo is offline bwaslo  United States
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Ambience tweeters using small BMR drivers
The level was first chosen because it was what was need to about square up the power response (which I'm still not sure makes sense). I think I like it that high, but it might seem a little wet (in this room, that seems like a good thing).

The level, btw, has to be measured with NO windowing since the ambient HF contribution comes well after the direct response and consists of a lot of energy in the room later than that. It's closer to about 10dB down (see Ambience tweeters using small BMR drivers) if measured only for the first 25msec....
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Old 23rd August 2018, 01:03 AM   #44
mlee is offline mlee  Canada
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Some of my quick impressions. I messed with this a bit and the late ceiling splash (LCS) like speaker outlined by Audio Kinesis. My impressions were:

Found the LCS sounded more like open baffle but with too much information and felt it was illuminating the back wall too much. I did not play with it for long as I felt it was too finicky to get correct. Gave a meatier midbass/midrange.

Next was just a rear ambient mid/tweeter. Equalized the reflected wave it to mimic the frequency response of the front speakers (up to 10khz) but down about 10-12dB and delayed a bit. As I recall around 5-10mS. What was neat is I felt you could shape the sound a by crossing over at different frequencies. Tried everything from 100hz HPF to 10khz. It seemed like you could highlight different parts of the spectrum to taste. In the end I felt it did not add enough to justify the system complexity and eventually used the extra channels for subs. I felt it did add a small amount of clarity to most recordings with a bit more spaciousness.
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Old 2nd October 2018, 03:54 AM   #45
bwaslo is offline bwaslo  United States
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Ambience tweeters using small BMR drivers
Well, after almost two months of using these, I'm sure now I wouldn't want to do without them -- at least not in this room. I'm sure I could mess with the filter setting forever but last moved the cut-in point to 1500Hz, delay of 15msec, and that has sounded good to me since. At least enough to keep me from messing further with the DSP settings.

I printed up a set of enclosures for 8 BMR drivers to try downstairs but haven't gotten around to installing them yet. Maybe a project for this week (I'm a temporary bachelor while the wife is out of town visiting family and friends).
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Old 2nd October 2018, 11:45 PM   #46
Pano is offline Pano  United States
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Ambience tweeters using small BMR drivers
It is interesting how much reflections, even synthesized ones can open up the music, rather than muddy it. Wesayso has found that with his kickers.

I often listen on quadraphonic headphones in which the rear (surround) channels are simply derived from the stereo pair. Throw in a little room reverb and not only is the sound much more spacious than with normal headphones, it's much easier to hear into the music and follow different lines or instruments. Just adding that delayed sound seems to make it easier to hear more detail, real detail. Funny how our. hearing works.
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Old 8th November 2018, 09:15 AM   #47
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I wouldn't call this the dark side, many statement loudspeakers have these ambience enhancers like Sonus Faber Aida or SE17 which have all sorts of elements in the back for "soundscape control".
Using a small sealed tweeter, like the scan speak automotive range with wide dispersion would make this addition quite unnoticeable. The differences (if reasonable) in front/back sensitivity apparently not matter that much because the ambient sound is quieter.
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Old 19th December 2018, 01:23 AM   #48
bwaslo is offline bwaslo  United States
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Ambience tweeters using small BMR drivers
I finally got around to phase-scrambling the signal drive to the ambience tweeters. Basically just took RePhase and devised a phase target that erratically changed up and down from 1kHz to 20kHz and let it optimize 48 taps of an FIR filter to that. The fit wasn't terribly good (needed more taps), but I had already used 2k taps each to linearize the phase of the main speakers.

Still, it did make a difference. The sound is perceptibly a little less bright and maybe the center image is better defined (but not sure of that one, might be just what I'm expecting -- hard to do a quick A/B). Very natural sound, yet nicely live like headphones can't do.

I might at some point put all the FIR taps toward phase scrambling the ambience channels as it hasn't in the past seemed that linearizing the phase of the mains made all that much difference.
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Old 19th December 2018, 06:26 PM   #49
Brinkman is offline Brinkman  United States
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Ambience tweeters using small BMR drivers
Interesting, Bill. If you donít mind me asking, what was the thinking that prompted you to make the phase erratic?

Also, I sent you an email about a week ago but it may have ended up in your junk or spam filter.
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Old 19th December 2018, 07:25 PM   #50
bwaslo is offline bwaslo  United States
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Ambience tweeters using small BMR drivers
Just looking to make any reflections non-coherent, like they'd tend toward in a big room. I'm trying to get the best of both worlds, controlled directivity for solid image and least changes with listening position, and delayed (and non-coherent) ambience for live sound and depth illusion. I think it works out pretty well.
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