Ambience tweeters using small BMR drivers

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Weird psychoacoustic effect noticed - the bass sounds deeper and smoother with the ambience tweeters playing than without. But they don't do anything below about 2kHz. I've heard a subwoofer cause treble to sound better, but not the other way before.

BTW, I didn't play with FIR phase-scrambling the ambient treble, mostly because it would be more work and I want to listen some more. The log-IR plot appears to indicate the the added treble is pretty diffuse anyway (since it comes from multiple drivers playing off ceiling and side walls). Maybe later I'll give the FIR a try.
 
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Weird psychoacoustic effect noticed - the bass sounds deeper and smoother with the ambience tweeters playing than without. But they don't do anything below about 2kHz. I've heard a subwoofer cause treble to sound better, but not the other way before.

BTW, I didn't play with FIR phase-scrambling the ambient treble, mostly because it would be more work and I want to listen some more. The log-IR plot appears to indicate the the added treble is pretty diffuse anyway (since it comes from multiple drivers playing off ceiling and side walls). Maybe later I'll give the FIR a try.

I have experienced the treble to change the sound of my speakers when experimenting with my DML panels especially in the bass/low frequency region...I make my own tweeters using a 13mm exciter and a small super thin piece of 99.9% pure titanium foil.


Although humans cant hear past 20khz, I believe a tweeter designed to reach 20khz-100khz can change the sound of a system due to its ambience.
 
I think maybe it's that the more lively treble gives the bass something to contrast against (in hearing of course). Or maybe the in-the-room illusion just seems to encompass the bass too.

But this isn't an effect I've ever noticed before. Of course most changes of HF I've listened to (that could be checked in a timely with/wtihout manner) in the past was only for crossover or EQ. Maybe different treble radiation patterns or room delayed-energy levels normally affect perception of the rest of the audible range, but it's just not so easily experienced and rechecked.
 
Bill, can you show us room decay measurement with and without the ambience tweeters?

When I added rearside tweeters and finally dipole tweeters to AINOs, decay changed noticably like the sound. But I didn't notice difference in bass range. Harmonics of bass don't reach above 2kHz either, except some transient components of a drum or eg. slapped bass.
 
Bill, as far as audibility is concerned, how do the ambience tweeters stack up against the diffusors you're also using?

a few years back, inspired by Duke's LCS modules, I built up a pair of the DIYSG Volt-10 coaxial speakers in the angled sealed cabinet (f3 circa 70Hz). They were intended to be placed on the floor, aimed up and angled toward the side walls. Unfortunately, too many "moving parts" in my setup has prevented me from integrating them in that role. I did, however, use them briefly as mains and was struck by the coherent quality of the sound, which is what steered me towards your more recent builds.

Your project looks great BTW.
 
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Hi Juahzi,

Next time I get the mic out I'll do some ETC and RT60 plots. But you can get a fair idea of the broadband decay from the Log Impulse Response plots -- the decay rate seems to be about the same with or without, but the density looks higher with the ambients in. I think the bass thing has gotta be some psychoacoustic effect, nothing having to do with the actual bass. It might be accentuated by the fact that the bass in the setup is somewhat limited -- each channel just has two 6" sealed woofers, Linkwitz-Transformed to get down into the 50Hz range. I don't really notice the limitation much when the ambients are playing with.

Hi Brinkman,

The effect of the ambient channels have some similarity with the diffusors, actually, the effect on how large the room sounds mostly. But the ambient channels can be made to be stronger, there's a limit to how much the diffusors can can catch and send back, at least without making all the room surfaces diffusors!

I do wish the ambients were getting more energy to me from the sides/back though. But I don't think it would be so easy to keep ambient speakers near the back of this small room unlocatable. Plus it would be a pain to run wiring to any here. The back walls in this old place are actual plaster instead of drywall.

Bill
 
I was going to ask why you designed these with an emphasis was on the >2kHz region but found my answers earlier in the thread. Still interesting regarding the perceived deepening and smoothing of the bass. Do you think that the boosting of correlated bass overtones in the >2kHz region may be enhancing your perception of the (out-of-band) fundamental?

Hi Brinkman,
The effect of the ambient channels have some similarity with the diffusors, actually, the effect on how large the room sounds mostly. But the ambient channels can be made to be stronger, there's a limit to how much the diffusors can can catch and send back, at least without making all the room surfaces diffusors!

Re-reading the thread just now, I forgot that the diffusors are in your basement setup and the ambient channels are for the upstairs. Please let us know your impressions of the diffusors and ambient channels in tandem if you decide to bring your new toys downstairs. It would interesting to know if they play well together or if it is more of an either/or proposition.
 
Do you think that the boosting of correlated bass overtones in the >2kHz region may be enhancing your perception of the (out-of-band) fundamental?
Could be, I guess. I wouldn't think there'd be too many bass overtones up at 2kHz, though? But I have read that bass is perceived much by spacing between overtones rather than just fundamental energy. If there are enough overtones up at 2kHz, I guess the spacing of them at their fundamental would still apply.

It would interesting to know if they play well together or if it is more of an either/or proposition.

I'm guessing that these particularly ones might be more either/or. The diffusors have the directional waveguides fired largely right at them, so they get a lot of energy to work with. The array of the small BMRs fire off omni in every direction above and to their sides, not as much would get to the diffusors. Though I am considering making another array (or maybe using the 3" BMR version) and ceiling mounting them downstairs closer and directed into the diffusors to ping them harder!

Odd stuff, mixing point source directional waveguides and wide coverage (but delayed) ambient channels, but it does seem to work. I'm hardly the first to have done this, but hadn't experienced it myself before. The diffusors are kinda the same thing, though, and those really do it for me. Relearning what others already knew, I guess.
 
I was reading along from my vacation address in the sun :).

This thread does give me new ideas to try though. While I have ambience coming from behind, they do not have the localisation problems Bill mentioned. For that they needed to be cut off at ~3500 Hz. Anything higher and they were distracting.
This makes me curious about having ambient tweeters up front for that top part of the frequency spectrum.

I'm hoping Bill will be willing to try a little mid/side EQ along with this ambience project one day. A couple of line array users have tried it and stated it worked for them. I'm curious if it would also work with the synergy approach.
 
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Hi Brandon,

I'm running then 2kHz to 20kHz. I tried running them lower for a short time into the midrange, but it seemed to make the midrange thicker -- not sure it was worse, but I had gotten used to it at 2kHz&up, didn't want to change that. I might go back and try that again, though after a while.

I don't think these are an atmos alternative, they are meant to 'move the front wall further back'. They do that particularly well. Going to have a friend over later today to hear it. See if he feels the same feeling of loss when the ambience is turned off!
 
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This intrigues me. I've given up trying to put surround in at home for movies as just no where sensible for the rear channels within my construction abilities and WAF. But ambience I can do. I'd always been put off by the number of people who have tried it and then gone 'meh' and taken it out. But this makes me want to try....
 
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Perhaps it depends on implementation. I tried rear firing tweeters and thought "meh". Bill is covering more bandwidth than I did, and he's using delay. That's gotta make an audible difference. Better dispersion , too, seems like.

Using Yamaha derived ambient channels did work for me, but the level needs to be low.
 
My ambient channels were one of the most rewarding projects I have done.
I started with L-R and R-L signals, delayed, attenuated and band passed (150 to 3500 Hz) and reflected/diffracted off of walls and other nearby stuff. It arrives from a lateral angle at the listeners seat and it's content is balanced to mimic the front FR...
I have played with timing, they are set about 17 ms behind the fronts. Shorter timing like ~9ms works excellent on orchestral stuff, not that well on studio material.
Later on I did mix back some L+R into the mix, though at a lower level than the L-R and R-L base.
Extending the L-R and R-L channels higher in frequency made them obvious. Though I can run the (L+R) content that's mixed in a bit higher without detrimental effects. In fact I prefer it that way.

After initial success with this mix I later added reverberation to these ambient channels. I prefer to have them on at all times.

I'd have to be very close to the ambient speaker itself to notice it is playing, though turning them off while listening makes a clear difference in imaging and feel of envelopment. I've done a lot of experiments with these ambient channels and my general goal is for them to hide the real properties of my room, without them being noticed.

Before I added reverberation I've tried using impulses of real spaces (measured ambience in a real space) as the back drop. This added noticeable coloration and put the same stamp on every song. The reverb changes with content and is different on each song played. It doesn't have a signature of its own, it adds to the feel of being in a larger space than my room is. It makes the listening area wide open, as it seems to get rid of the real boundaries, especially when listening with eyes closed.

The work of David Griesinger has been a huge inspiration, but it all started for me on the DIYMobileAudio forums where member Werewolf/Lycan (also a member here, follow the link) made an excellent case on how to make a car cabin sound bigger than it is.
 
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