Depth Imaging

My KEF 104/2s are 92" apart and flank a Sony 36 XBR. The fronts of the KEFs are 38" from the wall, 35" from the side walls. Frequencies below 80 Hz are shunted to a Velodyne HGS-15. I improved depth imaging for stereo by removing two equipment cabinets that sat on each side of the XBR and between the KEFs, and removing the cabinet around the XBR. Horizontal and vertical imaging are excellent.

I want a larger video image to better match the large sound stage. Front projection is an obvious answer that would improve audio depth imaging further, but I'd need a flat panal display behind a pull down screen so we don't have to sit in a dark room for regular TV viewing. An alternate is a flatter monitor that sits between the KEFs, e.g. a plasma or the new 60" Sony XBR Qualia spin-off rear projection.

This raises the essential question of this post: Is it the mass or the relective surface area between the speakers that interferes with good depth imaging? That is, would a 60" plasma monitor interfere any less with depth imaging than a 60" rear projection monitor? My knowledge of acoustic propagation and its effect on depth imaging is not up to the task, so I'm seeking help.


Unfortunately, anything you put in between the speakers is likely to have an adverse impact on the soundstaging that the speakers can deliver. Large flat reflective surfaces are the most difficult to deal with. Once you decide something must be in between your speakers, it's all compromise from that point forward. Moving from a 36" screen to a 60" screen is just going to make the soundstaging that much more challenging. Our nemesis for many years in a former home was a large upright piano between the speakers. For us, the solution for listening was some heavy damping/absorbtive material placed over the piano and the speakers pulled forward further into the room, but we could never achieve satisfactory recreation of depth in the recordings. Today, in a different house and room, we have nothing in between the speakers, the speakers about 1/3 of the way into the room, and the soundstaging, including depth reproduction, is excellent.
Hi, Rushton is correct, for best soundstaging you need to move tv away from speakers. It is the reflective surface of the tV that is messing with your soundstage and depth imaging
Excellent call there Rushton, I had a similar problem and then cure by moving an old teak Hifi component cabinet that we were unwilling to part with out from between the speakers and the result has been most satisfying soundstage wise. It is a beautiful piece of Scandinavian modern furniture but it just confused the imaging. I ran 6m cables from the front-end gear and cabinet on an adjacent wall to the mono blocks and speakers and now all is well. It cleared so many things up that were not quite right about the sound. Donbellphd, is it an option to sink your TV into the wall with acoustic treatment flanking it? Then as Rushton suggests dampening the screen when critically listening. Good luck in your endeavor.
Donbellphd, I suspect the plasma will intefere less than a rear projection set. That is just a suspicion. It may turn out that the deeper rear projection might just break things up a bit. There are now screens from Sony and DNP that enable front projection with some ambient light. These screens are more expensive than typical ones. I suspect that a good projector and one of these screens would be less expensive than a 60" plasma. I suspect that such a projector set up would off the best sound, especially if you could draw drapes over the screen.
RF Sayles et al.

It is an external wall, so it would not be possible to sink the TV. I think the message is what I imagined it might be, i.e. front projection is the way to go if you want to maximize depth imaging in a system used as your home concert hall as well as your home theater.

The KEF 104/2s are about a foot wide and front ported. I don't have a good understanding of the dispersion of acoustic energy around the speaker, except that they generate a large lateral and vertical soundstage and image well within it. For example, the London CD of Solti and the Chicago Symphony performing Mahler's Second Symphony place the soloists firmly in front of the orchestra and the choir behind and above the orchestra; instruments within the orchestra are well arrayed with seemingly accurate timbre. The soundstage seems to extend well beyond the speakers; the horns that are usually staged in balconies appear to come from the upper corners of the room. The harpsichord is quite believably sitting between the KEFs in the Archiv CD of Pinnock performing Bach's Goldberg Variations as is the piano in the Philips CD of Brendel performing Beethoven's Eroica Variations.

Donbellphd, My point was to illustrate that reflection is an obvious detriment as was fore mentioned, but mass and volume of a given object, even hard wood as compared to the flimsy plastic of TVs is also a detriment. Plasma may even be an issue in volume. I apologize for not addressing you query to the point, "Is it the mass or the reflective surface area between the speakers that interferes with good depth imaging?" The answer is both and it is more complicated than just "depth" in what you will lose when putting most anything in between your speakers. Try it out with a surrogate. We have a Hifi shop in town that ran into this very issue and was capable of eliminating a "mass and volume" issue by sinking the plasma TV into a wall. I'm sorry that is not a viable solution for you. What appears obvious is that you have an excellent execution of your system so far. Enjoy!

Please just refer to me as db.

I visualize acoustic waves emanating from the front of the enclosures, some of which leak around the sides of the narrow baffle -- I assume imaging is the driving force behind the trend to narrow enclosures. This must be true, otherwise moving the speaker enclosure away from the wall wouldn't have the efficacy it so obviously does. I further suppose a reflective surface between the speakers interferes with backward propagation, and that it's backward propagation that results in the perception of depth of stage. If that's so, then even a razor thin large reflective surface, e.g. a large ultra thin plasma, between the speakers will interfere with depth imaging, so it doesn't matter how deep the monitor (my proximation to mass) if the waveforms can't get back to reflect off the wall. Just trying to understand this stuff so I can put it to use.

My reference for depth imaging may be unrealistic. It was a zillion dollar system with, I believe, a pair of humongus Montana speakers located about 2/3 of the depth of a commercial building with high ceilings in Studio City. The depth imaging of the Harmonia Mundi LP of McGegan conducting a set of Corelli Concerti Grossi was extraordinary. All the instruments on my CD of this recording are well portrayed, but the depth of stage is not realized.

I think your posts have moved my thinking back to a front projection solution for home theater, because stereo music is at least equally important to me as HDTV and DVDs.



Your experience with depth imaging on that super expensive system can be replicated with much more modest systems, so don't give up on your pursuit of this aspect of music reproduction if it's important to you! My first experience with excellent depth reproduction was in a 12x16' room with moderately priced conrad-johnson tube electronics and Celestion SL-6 speakers. This was in the early- mid-80's. As we listened to the Tallis Scholars performance of the Allegri Miserere on a Classics for Pleasure (CFP) LP, the soundstage seemed to extend back into the next room past the wall behind the speakers! It's all about having speakers with great imaging capability and electronics that are not messing up the timing of the music.

Good luck continuing your search.