Holographic imaging

Mapman, The pure Omni's are designed to propagate a signal in a 360 degree circle so when you are listening to them you are hearing a small direct signal (think of a 'point source type speaker' listened to in the near field which excludes most of the reverberant sounds from room surfaces). In addition, you are hearing all of the reverberant sounds arriving at different times depending on the distance they will travel. Great atmospherical potential hear. And one of the reasons that some of the manufacturers claim that they are great with large orchestral music, but few claim that they are great for solo vocals. Actually the direct sound with an Omni is a minor component of the sound field.

Omni'his, well executed, will give a great 'sound stage' effect. It will fill your room and you'll be happy to some degree anywhere in the room. But in the final anyalysis all of the reverberant energy will blur the direct signal and obscure any real holographic imaging.

Think of my analogy to a live person 50 ft away clearly recognized as such compared to a life sized and colored paper cut out. And then in a fog you can't tell one from the other.

To a lesser degree than Omni's, you have the same issues with panels and electrostats. Some of the electrostats and panels (I have both types in the closet) have developed a manner of shaping to signal to enhance the sense of focused imaging, which make the principle sounds real life size (like vocalists in particular) and maintaining a big sound field.

But, as you have probably guessed, the better the sense of focused imaging the more they lose the sense of a huge airy sound stage. I believe, like my panels and electrostats, Ohm's latter designs (after the F models) went from 360 degrees to a speaker which reduced its off axis energy to reduce the amplitude of reberberated energy and enhance the on axis signals. I could be wrong.

That is one of the reasons some folks want speakers which can produce sharp pin point imaging and take great care in setting them up to minimize reverberant energy - then you hear what is in the pits and grooves with out added room effects, at least to the extent that you can, or wish to exclude them. Some folks like near field listening which takes out most reverberant energy, especially when you deaden the 1st reflection points on the sides, the ceiling, the floors, and the wall behind the speakers. Needless to say, but I will, a lot of folks don't like this sound. But it is exactly the circumstances that allow the creation of sonic holography.

I hope this makes a bit of sense to you. But the bottom line is you really have to hear what I'm talking about. It is hard to describe. But, what the hell - here goes.

About 20 years ago I went into a retail shop near Berkley, Ca. They had a small listening room which contained Theil 4a's, powered by Threshold SA2's, driven by a CJ5 pre amp, an Oracle TT and I forget the cartridge. They played Opus 3's "Depth of Image". One cut has a group of guys playing pan flutes and drums (the flutes are a toughy). Anyway in the middle of the cut they flubbed up the flutes and broke into a brief conversation. I kid you not, the talking was so realistic that I felt you could easily walk into the middle of the group and join them. Replicating this experience has occupied me ever sense. I think I'm as close as I can get in my present environment with my current stuff, but I ain't there. Yet! :-)

The thing that makes this subject difficult for many, I think, is that most folks have not heard a really holographic imaging system with appropriate recordings (often very minimally miked recordings) and confuse great soundstaging from holographic imaging. I know I didn't until I heard one.

BTW, if you have any doubt in your mind about what your system is capable of, get a recording from Opus 3. They did a series of 'test' disc's one of which was called "Depth of Image" and another was "Timbre". They were originally on LP's but are now available in a compilation of CD over the internet.

These recordings are compilations of several recordings put out by Opus 3, from solo vocalist, solo instrumental, small bands, small jazz groups, large jazz orchestra, etc. Forgive the fact that they are all Swed's. Each cut will have a description of what you should hear. If you don't hear what the cut sez, you have work to do. It is all there. Some of the cuts are excelent for resolving (or at least identifying problems in your system. For example, a recorder playing in its high registers. You get that right and you have a fine HFR - get it wrong and your ears will bleed. I highly recommend these recordings for set up and equipment evaluation as well.

Hope that helps a bit.

Well, I've got a different take on what 'holographic' imaging is, as opposed to 'soundstage'.

Soundstage, for me anyway, is represented by highth, width, plane of front of the image, and a feeling of some depth behind the plane of the speakers. The size of the soundstage can be maximized to where it appears outside of the speakers and up into the corners of the room. This can be caused by out of phase information inherent in the recording, the sound reflecting off room surfaces, and the type of speakers (bipole, dipole, omni's, etc all of which have different radiation patterns). But none of this is necessarily representative of 'holographic' imaging.

My definition of 'holographic' imaging means the reproduction of a sound (it has to have its origin in the source) which is not only located appropriately in space, it is well defined, and takes on the appearance of a full dimensional tone. The visual parallel would be a cardboard image of a person 50 ft away and a live person 50 feet away. You can tell the difference, unless you have a heavy morning fog, or rain, etc, to obscure the difference.

I think any well put together and set up 2 channel system can do excellent soundstaging which will have good front to back spacing, BUT to make it really 'holographic' you need a system which is highly resolving.

Its the tiny detail lost in most system's that rely on room reinforcement that make a difference. Some speaker types can never get you to 'holographic' (omni's would be a gross example of great soundstagers which are incapable of truly 'holographic' imaging) and some speakers (such as direct cone or horn speakers) which are blessed with high resolution can easily represent the full image. It is the reproduction of the very subtle signal that takes you all the way to holographic imaging.

I think its far less an issue of electronics, given a reasonble level of quality, albeit tubes or ss, than it is in the transparency/resolution qualities of the speaker.

But, FWIW, to my ears, you can't beat highly resolving speakers with cone drivers and tubes if 3D imaging is your goal. There is a lot of things they might not do for you, but holographic imaging won't be one of them.

In a nut shell, point source speakers are replicating what is on the recording, including, if the resolution of your speakers and electronics are up to it, all of the spatial information created by the environment in which the recording was made. It is this subtle spatial information that can create a holographic experience. And that is exactly why I feel that resolution is the key to obtaining holography. And I'm not talking about equipment with an uptilted FR which will appear, initially at least, to the inexperienced, as having a high degree of resolution.

Omni's, electrostats and panels, as well as dynamic speakers with rear firing drivers, are creating their own environmental sounds by bouncing signals off a bunch of surfaces, and all of these reverberant signals are laid over all of the reverberant signals on the recordings. So if you happen to have a recording which was made in a good acoustic and a simple mik'ing system was used, and it had the potential to creat a holographic image, you would never hear that potential realized with Omni's as its own reverberant field would obsure the subtle acoustic information in the recording.

You might ask "If the recording was a 'studio' recording, multi miked, and made in a dead acoustic, wouldn't it sound better with my Omni's? And I would respond "Yes, I believe it would". But you are just putting lipstick on a pig. Sorry, I couldn't resist using that very popular expression. :-)

In fact, probably the majority of recordings are made in studios with dead acoustics, multi-miked, dynamically compressed to be heard over boom boxes, and these are exactly the type of recordings will sound best over Omni's, etc.

You may love your Omni's but IMHO they can't do everything. And holographic imaging is one of the things they don't do. But, until you have actually heard really holographic imaging you won't appreciate the difference.

But then that is just my POV reflective of my personal experience. I'm sure many others will agree with your POV.

BTW, I had one of those Carver's when it first came out. Very interesting affect. The first thing I noticed playing an LP of a live performance with audience applause, was that it made you feel that you were sitting amoungst the customers who were clapping. Very interesting devise, that thin little box, but ultimately more distracting and unpredictible than sonically enhancing. Maybe I didn't have many suitible recordings, I don't really know. The holography demo I referred to, took place only a few years later, and that was both impressive and not distracting. Go figure.FWIW

Mapman, For the fun of it I just visited the site you refererenced. JC! This guy made and sold omni speakers! If he is your bible on the subject .......oh well. As I said, we all go our own way gladly ignorant of anything that doesn't fit our preconcieved notions. Myself included.

"There are many ways that lead to Rome....."

And some of them pass right by Sofia's house, and you pause to think of her as you once did in the past. :-)

Lets face it, very few recordings were made in a fashion that I believe is required to set up the possibility that an audio system might produce a sonic hologram, as I would hear it.

As a pratical matter most everything we hear is the result of multi-miking, mixing down, compression, often by a low-end recording engineer in an anechoic studio or an unoccupied symphony hall (an echo chamber perhaps?). So if we are happy with our systems when it can reproduce this music well and even remotely remind us of a live event we should be content.

Mapman, You've got the right idea. You know what you hear, you know what you believe, and you're undetered by anything which might threaten your sonic/intellectual illusions. We should all be so fortunate, but we chase dreams anchored in the opinions of others.

Detlof, Yes, perhaps, but to much truth isn't always a good thing! In this day & age, I'd much rather see her at a distance with her clothes on! When in Spain I keep looking for the street where Penelope Cruz lives. Now there is 'real' wisdom. :-)

Rebbi, Regarding your comments about the frontal plane of the sound v the frontal plane of the speakers, and Tvad re your view supporting Rebbi's definition of 'holography', in my limited experience I have found that putting sound out in front of the plane of the speakers is more related to speaker design (I have only experienced this phenom with a horn/cone hybrid and it a general soundfield attached to most recordings. But it was facinating especially with that old Carver 9 holograpy machine in the loop).

But I have only heard 'holography' (my version) with cones and a few recordings, but I haven't heard horns in many years - certainly not since I developed a lot more sophistication about this process. Wish I had those old horns back so I could listen to see if they would sound better than cone drivers in this respect.

Oh well, too much too doo about seeing rare birds. :-)

Musicnoise, I didn't choose to list stuff I can't endorse beyond its application to my system and my sensitivities/sensibilities. So I took a pass on all wires and tweaks. Far too subjective for me. :-)

For my listed stuff I can give you a reasonable description of how it sounds to me heard with associated components, including tubes, with multiple speakers and electronics, and most certainly over my Bolero's the only thing I really prize. But wires and tweaks is just too too much. Hint - George designed most, but not all, of it.

Oh, BTW, I can indorse for the atheist heavy guage Belden PC's and Canare 4s11 speaker cable. Nothing esoteric, SOTA, or expensive there. Just great benchmark stuff for modest systems. Oh, one more thing, I use Trolls for cable risers. Keeps them out of mischief. :-)

This is fun, I agree with both Shadrone and Tvad.

In this forum the 'emporer's new clothes' is inappropriate, I think. It's more the the 'emporer's old clothes'. If you've been here for any time you've seen it before, ad infinitum, ad nauseam. It's just that some claims are so far fetched that they become self defeating. Personally I enjoy threads on reasonance control with components and room acoustics. Some solid concerns taken to an absurd level just to sell products to the eager audiophile with a real or percieved problem. Generic observations and advise given to cure a very specific problem which require equally specific solutions. Almost as much as the Sunday funnies.

But that is probably half the fun of the hobby. Playing with tweaks and ancillary equipment. If folks want to believe these claims and recieve benefits from these beliefs, good on them. Let them go in peace. They could actually be right! :-)

But when a manufacturer/designer comes forward to explain or defend his product he does so at his own peril. Roger Paul is not the first one, nor will he be the last. At least when designers of 'mystical' equipment do come forward and fail to provide an intelligent explaination of their product's function, they do much to remove all doubt from inquiring minds about the likelihood that the product is going to be found to be metorious. And if the designer can't adequately explain his design and it's the audience's dullness that is responsible, well - what did he expect to find here anyways, a bunch of astrophysicists (rocket scientists)? :-)