directional speakers

treepmeyer

I apologize, I now realize the importance of the specifics of your post. My responses are related to 2D and Front Imaging: not ‘3D from 2D’ which is Bacch4MAC’s objective.

I just looked it up and realized Bacch4MAC is what my friend wanted me to go to a demo of in Princeton (45 minutes from us). After a glance, I declined, thus I have never heard/experienced their solution in use.

@treepmeyer Directionality is an important concept when it comes to room interaction. The more omnidirectional a speaker is the greater is it's room interaction which always creates problems. Ideally the speaker would project sound only to the listening area and there would be no early reflections in the room. The types of speakers that manage this best are horns and line source dipoles. Dipoles always need the wall behind them covered in sound absorption tile. 

I do not like the term "tight" is regards to imaging. Imaging is either focused or blurred. To hear a system that is perfectly focused or rather focused at the state of the art is an eye opening experience Really well focused imaging will have two distinguishing characteristics, the sweet spot will be extremely obvious and balance will shift between recordings. Gain is never exactly equal between channels of a recording. It is adjusted by ear on systems that can easily be 1 dB in one direction or the other. For most systems balance has to shift over 1 dB to make an obvious difference in perceived balance. With a super focused system 0.2 dB will do it and there will be a tendency to adjust balance with many if not most recordings. Every system that I have ever heard that was this focused was highly directional with one exception and this fellow's listening room was covered in bean bags. I did not count, but there must have been 20 of them. To check balance listen with your eyes closed. Pick an instrument or voice you know is mixed to the center, spin yourself a little back and forth (it helps to have a listening chair that rotates) an stop with that instrument dead ahead. Open your eyes and look where you are facing. If to the left you need to increase gain in the right channel. If to the right increase gain in the left channel. With some recordings especially symphony orchestras you sense more energy coming from one side or the other. You adjust gain so it is equal. 

I prefer the line source dipole. Line sources project acoustic power better than point sources which is why you see them at stadium concerts. They also form a larger, front row image. Line source dipoles project sound in a figure 8 pattern that is exactly as tall as the loudspeaker. There are no reflections from the side walls, middle of the front wall, floor or ceiling. ESLs in particular are extremely directional. Dispersion is controlled by curving the speaker. As an example Sound Labs ESLs come in two curvatures, 45 and 90 degrees. The 90 degree units are for very large rooms. They sell way more 45 degree units. 

If you want a point source system Klipsch Cornwalls are an amazing speaker for the price. If you want to try a line source dipole look at the Magnepan range. If you are a rocker or prefer smaller amps go with the Klipsch's. If you prefer jazz and classical and have plenty of power go with the Maggies. The 3.7i with subwoofers can be the basis for an exceptional system. 

@elliottbnewcombjr Fair question about the theory behind Bacch.   I'll respond as best I can, but the truth is I'm close to being over my head.

In a nutshell, Bacch is a specialized time-domain DSP intended to eliminate crosstalk without coloration.  Theoretica claims that their customized Bacch filters do not have the spectral coloration added by previous attempts at crosstalk elimination.  A Bacch implementation includes calibration using in-ear mics and Webcam head tracking so that the sweetspot follows the listener's head, within reason.

That's about the best I can do.  There is more on Theoretica's website under FAQ, but you may want to look at Edgar Choueiri's book Immersive Sound on Amazon.  Choueiri is quite willing to talk to people about Theoretica's work so I would encourage you to reach out to him, or stop by Princeton if you are close.  If you do have a conversation with him I for one would be very interested to hear your reaction.

Regards, Tom

from their site (emphasis by me):

**BACCH-ORC is the most advanced room correction technology today. Unlike any other commercially available room correction system, BACCH-ORC relies on quick in-ear (binaural) acoustic measurements, millimeter-resolution head tracking, and cutting-edge algorithms derived from years of psychoacoustic research, to produce and apply individualized optimal room correction (ORC) FILTERS: that elevate any stereo loudspeaker playback system to its ultimate level of transparency".

"BACCH-dSP is a 3D audio powerhouse application for mixing and rendering 3D binaural audio over loudspeakers and headphones.

At the heart of BACCH-dSP is BACCH® 3D Sound, a proprietary technology developed at Princeton University that allows the listener to experience stunning virtual reality 3D imaging using only two loudspeakers."

the in-ear microphones are : "used to generate personalized digital filters for BACCH® 3D Sound". (from those speakers, in that space, at the in-ear microphone's specific location.

.......................................................

Without reading about Theoretica, I presume, by OP's statement, that NARROW DISPERTION speakers are recommended i.e. narrow is best for the in-ear microphones reception NEEDED to produce the filters to create Individualized optimized room correction.

Playback via those filters want to be reproduced by the same narrow dispertion speakers.

This is definitely designed for 1 person, centered, keeping their head/ears where they were when the in-ear microphones received the in-room signal to create the filter for that specific room.

Audio Presentation: 2D Stereo; 5.1 Directional; 3D Enveloping

Live sound is generally ‘front stage based’ (except ‘surround theater’ like Cats), presenting 2D directionality (varying greatly with seat location). Conveying the sense of a particular space, but almost never experienced as surround sound.

I listen to ‘Front Stage Based’ 2D (live and recorded/reproduced). Quality equipment and speakers for fidelity. Two Speakers to provide Stereo Imaging. (great Mono fidelity already existed). The Stereo Imaging is greatly affected by the Space the Speakers are in.

Bacch4MAC (3D from 2D). Nyet, a blunt no from me. I lived thru the era of unsuccessful ’enveloping sound’ attempts, Quad etc.

I have never liked or wanted ’stereo everywhere from 2 speakers’, like Bose and others attempt, and not a big fan of attempts of 3D from 2D, like Bacch4MAC is.

It should be noted: 3D Immersion from 2D is different than Dolby 5.1 ‘directional sound’ (developed for Video).

Video’s Sound: I used to grab the speaker wires out of old CRTs, hook up better speakers, realizing the audio signal was far better than what we heard from the dinky speakers within. I was thinking about improved fidelity, not directionality

Dolby 5.1 is ‘improved front imaging’ via center speaker along with better front speakers spaced widely apart: combined with directional effects of specific sounds, placed here or there by programming, to be produced by separate additional directional speakers, for often unseen sources i.e. helicopter from rear left …. The ‘.1’ adding a sub-woofer for a Dinosaur Stomp. Dolby is enhanced directionality, not 3D immersion. (excepting battle scenes, earthquakes, ... still created by specific programming for INDIVIDUAL directional speakers, not 2. Individual Room Correction is adjusted by specific locations of 5 speakers and 1 sub, volume matched by ear or automatically volume matched by ’In-AVR’ signals and microphone provided. Those adjustments are based on and re-produced from/to the center listening position: 1 person, dead center.

‘Sound Bars’ attempt, like Dolby 5.1 to produce improved directionality (not 3D immersion) via ‘processing tricks combined with special drivers within.’

Note: omitting a center channel speaker while listening to 5.1 totally eliminates the sounds specifically programmed for the center speaker, i.e. most dialog compromised). No Center Channel Speaker: 5.1 content: Changing the AVR to 2 Channel Stereo very often improves the primary sound as center programmed sounds are added equally to both FL and FR

Now, I watch a lot of Video on my small Dolby 5.1 Home Theater.

VIDEO: I concentrate on Improved Front Imaging: 2 or 3 persons sitting on a couch: (3 persons: the Majority or 2 persons the Entire audience off-center.

Or, 1 person, i.e. proximity to an end table). the entire audience off-center, Important for both front 2D Imaging (stereo: no center or rear speaker/content) and the improved front 2D of Dolby 5.1. 2.1 simply adds a subwoofer to 2D Stereo. .

My Vintage DBX 100 speakers, are designed specifically to create a wide front stereo image. (I call the DBX 100 solution ‘cross toe-in’). Aim the Left Speaker toward the right side/Aim the right speaker to the left side. Stereo Imaging is widened based on: relatively equal volume l/c/r via opposite side increased directionality combined with volume from near side proximity. DBX 100’s have 3 tweeters (front/side/rear) to solve highs that have too narrow dispersion to work via ‘cross toe-in’.

Pseudo 5.1 (created from recordings that were not specifically made for 5.1) very often sounds better when the AVR is changed to 2 Channel Stereo. Often selecting ‘direct’ changes Pseudo 5.1 to 2 channel. I find much content is Pseudo Surround.