directional speakers

I think Narrow Dispersion is the wrong way to go.

Imaging, wide and precise starts with the engineering, then IF vinyl, the cartridge's wide channel separation and tight center balance make a big difference for imaging: both before you send the signal to the speakers. Digital (CD, Streaming -not me) already produces separate L/R, again, the engineering making the difference. The recorded signal is producing better or worse imaging prior to the pre/amp/speakers.

Tweeters are the narrowest dispersion, thus they need to be directed at the listening position, both horizontally and vertically to seated ear height, (slanted front face or leaning the speaker back solves this) and has the advantage of altering the initial reflections off the floor and ceiling and eventual reflections off the rear surfaces.

Horns, for tweeters and midrange typically, are designed for controlled directivity, oriented correctly, go for wide horizontal dispersion, combined with limited vertical dispersion. (as well as horns increase in a driver's output (thus high sensitivity) Check the Polar Graphs to see both horizontal and vertical dispersion.

Toe-In, and Angle of the drivers are important. As noted, tweeters need to be aimed directly at the listener. Wide dispersion will maintain better frequency balance better than narrow directivity.

Alternate Toe-In (forget spikes). For two listeners, I aim the left speaker directly at the right listener; right speaker directly at the left listener. This uses the DBX Imaging Concept: you are nearer one speaker for volume and you get more direct dispertion/volume from the other side.

Rear Wall/Corner/Ports. I am no fan of ports, if so, front. Distance from corners can be messed with, and measured via sound pressure meter and cd test tracks (not LP)

It looks like there is a divergence of opinion about how wide the speaker’s radiation pattern should be.

Given that the BACCH-SP system is using the spatial information already on the recording to present an exceptionally wide soundstage, rather than relying on strong early same-side-wall reflections to do so, I agree with Theoretica’s recommendation of speakers that are "more rather than less directional".

I pursue spatial realism in my speaker designs by a different route than what Theoretica is using, and in the course of product development I conducted quite a few controlled blind listening tests. I find a trade-off relationship between soundstage width enhancement due to strong early same-side-wall reflections on the one hand, and image precision, soundstage depth, and clarity on the other. I prefer the latter package of attributes, hence my preference for relatively narrow-pattern speakers, BUT my approach DOES give up some soundstage width relative to wide-pattern speakers.

The BACCH-SP arguably offers "you can have it all, and better than before", and in the context of what their processing does, strong early same-side-wall reflections are counter-productive.

Duke

@audiokinesis The tradeoff you describe is very interesting.  I,too, would choose imaging precision, soundstage depth and clarity over soundstage width.  We'll see if Bacch allows me to have my cake and eat it too.

Thanks

@treepmeyer, in my experience interaural crosstalk cancellation works; it significantly expands the soundstage in width and depth, and enhances the sense of being within the acoustic space on the recording.

I owned an electronic interaural crosstalk cancellator in the early 80’s and it worked but colored the sound, and Theoretica has addressed the coloration issue.

In the mid-80’s I made a passive interaural crosstalk cancellator using large foam wedges which worked but was impractical. Theoretica has addressed the practicality issue.

Polk Audio made, and I believe still makes, speakers that use a secondary array of drivers to provide interaural crosstalk cancellation. Ime their approach works too.

But Theoretica’s processing goes beyond interaural crosstalk cancellation; it also uses de-correlation, which ime further improves perception of the acoustic space already on the recording. And since the BACCH processing is extracting information from the recording itself, the sense of spaciousness won’t have the "sameness" from one recording to the next that can arise with synthesized spaciousness contributed by upmixing to delayed rear channels.

To the best of my knowledge, techniques for interaural crosstalk cancellation only work within a fairly small listening area, typically one person wide and maybe two people deep. So there is that limitation. My understanding is that some versions of the BACCH system do head-tracking and therefore work from a wide range of listening locations, but still only for one (or two) people at a time.

(I have no affiliation with Theoretica.)

Duke

@audiokinesis Everything you say is consistent with my understanding.  I'll report back in a month or so when I get the Bacch system up and running.