directional speakers

treepmeyer

"I just bought a Bacch4Mac bundle and am thinking of upgrading speakers.  Theoretica recommends speakers that are more rather than less directional.".

Perhaps you could summarize the beneficial theory you are pursuing.

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.