3D imaging

What makes speakers produce a 3D image is being symmetrically equidistant and pointed towards the listener. Period.

All the other stuff contributes, of course. But you asked specifically about speakers. 

But hey, don't take my word for it. Prove it to yourself. Point one speaker off to one side instead of at you. Move one a foot closer or further away. Notice nothing else changed- same recording, same room, same components.

Speakers are like real estate: location, location, location.

If you want to do some research, look into Head Related Transfer Functions.

For most speakers, having good room acoustics is key.

Thanks for the input millercarbon. I rotate 3 sets of speakers in my system,(Hornshoppe Great Horned Heils,Nola Boxer 2's,and Graham Chartwell LS3/5's). They all throw a great 3D image,so I guess I'm doing something right. I was just curious if the speaker design was responsible. 

 I've read posts on other forums where posters think that attaining 3D imaging is just chasing unicorns. Obviously they are doing something wrong. 
   
  As a side note,I've been at this hobby for a bit,and I'm no spring chicken. I just don't have a ton of technical knowledge. This is one reason I frequent this site. There are a large number of members here that DO have a vast knowledge of things audio. I find that exposing myself more to the technical aspect of this hobby will help me understand what I am hearing to a greater degree. 
    Again,thanks for your response,
           Ray

Thanks for that info erik,I will be doing some reading!

What makes speakers produce a 3D image is being symmetrically equidistant and pointed towards the listener. Period.

While precisely balanced speakers are important, not all speakers sound at their best this way. 

Quite frankly, some speakers sound better off-axis. A lot of high quality tweeters have resonances which you can tame by toeing the speakers out.  Further, if you have a very small room, sometimes crossing the speakers in front of your head reduces side reflections significantly and improves imaging.

Lastly, as some speaker developers have discovered, despite our best intentions, sometimes listening below the tweeter axis is also beneficial.

The final judge is your ears and your circumstances.


Best,
E

This is all fascinating stuff. Of course some of what I'm reading about HRTF is way above my head,pun intended. I had absolutely no idea that the size,and shape of your head,and torso play a role in what we hear. That explains a lot about what sounds pleasing to me,may sound like nails against a chalkboard to you. The plot thickens............

Thanks for the input millercarbon. I rotate 3 sets of speakers in my system,(Hornshoppe Great Horned Heils,Nola Boxer 2's,and Graham Chartwell LS3/5's). They all throw a great 3D image,so I guess I'm doing something right. I was just curious if the speaker design was responsible.

 I've read posts on other forums where posters think that attaining 3D imaging is just chasing unicorns. Obviously they are doing something wrong.
   
  As a side note,I've been at this hobby for a bit,and I'm no spring chicken. I just don't have a ton of technical knowledge. This is one reason I frequent this site. There are a large number of members here that DO have a vast knowledge of things audio. I find that exposing myself more to the technical aspect of this hobby will help me understand what I am hearing to a greater degree.
    Again,thanks for your response,
           Ray

Okay. Thanks. Got it. First stab answered your literal question. Now with more info I can give a much better answer.

Almost all our sense of location comes from the midrange on up, and is based primarily on arrival times. That's why location is so important, and makes a difference to the point even as little as 1/8" can be noticeable.

 I was just curious if the speaker design was responsible.

It is. Sound waves coming off a driver radiate out in an arc. Because of the way waves travel they reflect (bounce) or diffract (scatter) or refract (bend) off anything they hit. 

Now this is a Big Deal for speaker designers, because it turns out sounds that arrive within a window of about 3 to 5 milliseconds of each other tend to be perceived as coming from the same source. 

So let's say you have a midrange driver mounted in a great big speaker with an edge around the speaker like for a dust cover. Sound coming off the driver radiates out and all along the way is reflecting off the baffle, and then reflects and refracts again at the edge. 

Physics: sound travels roughly 1 foot per millisecond. So all the reflections and refractions are well within this critical window.

Now you know why so many drivers are mounted flush, in super smooth baffles, with nothing sticking out, and often with felt or other material to absorb these reflections, and all in a cabinet no bigger than it absolutely has to be. 

There's also the speaker cabinet itself. Its hard to notice because so much of the sound comes from the drivers, but play something loud and feel the sides of the cabinet, especially the front. If that is moving at all then its radiating sound. So now you know why so many really good speakers are massive and have super strong cabinets. If the cab vibrates at all it is in effect another speaker blurring arrival times and ruining imaging. This is really, really hard to do, especially as you get bigger and bigger, and goes a long way to explaining why so many small speakers are sound staging champs.

Then there is the fact that just as much sound radiates off the back of the driver and into the cab as out into the room. Very big problem. Unless its highly damped this sound will reflect off the back of the speaker and come right back out through the driver. Only delayed. Another hit to imaging. So even internal construction and damping matters.

Now if you caught the 3-5 ms rule then you also learned why it helps imaging to have speakers placed 3-5 feet away from walls. 

You ask for vast knowledge of things audio, you get vast knowledge of things audio. What else you wanna know?

Excellent explanation. That explains why my choices in speakers seem to work so well in my small listening room.(9x13x8) This room has only one purpose,so I have no restraints as far as set up goes. Obviously with a small room,I have to make certain compromises,but I think I have done a pretty reasonable job of speaker choice and placement. My biggest compromise is distance from side walls, not much I can do about that,however I do have treatments at the first reflection points,which helps. I guess my next question will be a little more involved. How do downstream electronics help or hinder 3D imaging?

Rocray -

Of course, to preserve the location data you need good room acoustics. I strongly recommend GIK accoustics. Great advice and very cost effective products.

I do have rudimentary treatments,however a room treatment overhaul is just over the horizon. Thanks for the recommendation E. I have heard nothing but great things about GIK.

My biggest compromise is distance from side walls, not much I can do about that,however I do have treatments at the first reflection points,which helps. I guess my next question will be a little more involved. How do downstream electronics help or hinder 3D imaging?

Distance from side walls is but one room factor, only mentioned because you were asking about speakers. The answer to how electronics help or hinder imaging is short and sweet and controversial as hell: no one knows.

Oh, there are theories galore, just none that hold water. 

But to segue back to the room segue, damping first reflections with what is basically a few bucks worth of OC703 is an old school Stone Age imaging tweak. Next generation room and speaker treatments like Synergistic Research High Frequency Transducers are far more sophisticated and effective.

HFTs work on the principle of dither. Professionally used in video for years now, dither is a very particular sort of noise that when added to a signal actually improves the perception of clarity and resolution. Each HFT is only about 1/4" in diameter, and shaped like a tiny little speaker horn. Exactly how the darn things work is a Ted Denney trade secret, but they do indeed work. The improvement in sound stage width, depth, layering, focus, and palpable presence is remarkable. 

I've got a lot of experience with room treatments. You simply cannot do with conventional absorber/diffusor panels and tubes anything even remotely on the level of HFT. They help, but not like this. Do a set for each speaker, plus a couple more for the walls and ceiling, realize you only thought your speakers disappeared. With HFT they are GONE! Heck, your room is gone! 

Actually crossovers do matter, steep slopes screw up phase and that means poor impulse response all inside the 3-5 ms “ rule “
actually electronics do matter, negative feedback also screws up time and phase and can lead to TIM, wonder what the T stands for ?
time alignment of the drivers matter
pistonic drivers matter, an out of phase cone is destroying the image information as well as screwing up frequency response
low reflection cabinets, treatment inside the cabinet AND a low reflection driver magnet are available in certain products
managing the grill edge can reduce the baffle step effect and so can managing driver directivity- not all drivers radiate off axis at same level, so reflections can be down in amplitude reducing reflections
cabinets matter
:-)
oh and how a driver stores and releases energy can be seen in the impulse and waterfall plots, pay particular attention to those mid ranges wired out of phase, panels with edge clamp issues, speakers that start negative, waterfalls that never end....
vast is a relative thing, I am just a student...

And unless you are listening in the near field, the room matters a lot.... a mix of absorption and diffraction are key ....

I just put the Chartwells back in the system. They are 6'9" apart. My seating position puts me 7' from each speaker.(triangle) I guess that puts me in the near field camp? I'm ok with taking some of the room out of the equation.

millercarbon and tomic601, Thanks for taking the time in answering theses questions and help me get a better grasp on what my ears(brain) hear. Am I far off the track in stating that audio or should I say"better" audio is partly based on manipulating the brain? 

With respect to the Chartwells my guess is that you will get a better soundstage by moving the speakers closer together, making them 5 feet apart, even less perhaps, with no toe-in. Most speakers are set too far apart. 

I do have these with no toe in,so let's give it a whirl moving them closer together. I'll report back with my results.

@tomic601 : Transient Intermodulation Distortion - applies only to amplifier distortion!

Ok geoffkait, I moved them a foot closer,and to my ears the soundstage became pinched and limited to only between the speakers. I then moved them back out in 1" incriminates. They are now about 6" closer,and the soundstage has opened back up.

millercarbon,do you use HFT's with traditional acoustic treatments,or are these applied alone?

Please try the exact opposite: move them further apart and toe them in, so they cross before your head. This was a recommendation of Living Voice for their loudspeakers and it works nicely for mine. You avoid a lot of wall reflections this way and have a wider sweet spot. You have to move around a little to find the best setting.

Good luck!

Actually when you move them farther apart the center image goes missing in action. As Bob Dylan sez at the end of all his albums, good luck! As I’ve oft mentioned on these fora the only real scientific way to find the absolute best locations for ANY speaker in ANY room is the speaker set up track on XLO Test CD and other similar test CDs. All other methods are only approximate. It’s like trying to solve x simultaneous equations in x + n unknowns. Some rooms there’s nothing you can do.

I've had the Chartwells for a couple of months now. I started placement farther out and toed in. About the same place that I have the Nola's set up. Sounded good,but the 3D imaging wasn't what I was looking for. I then started moving them a little closer,and bingo,we're getting there. Eliminated toe in,Shazam! Spooky 3D imaging! Today,I moved them about 6" closer,and my heart is going pitter patter. They say football is a game of inches,add the audio game to that.

🤗 🤗 🤗 🤗

Stereo is an illusion for sure and  audio is certainly not only science but also physchoacoustics, brain/ear are as yet inseparable... well for most...

there is that pesky brain/ear/ego bit as well

Many of us think high TIM amps don’t image well, 

for more insight on your LS 3/5a and why they are so good, check out all the work the BBC went to in creating them, lots of science in that one and some ear brain also

while not strictly an 3/5a, I have a set of modified KEF101 that are image champs...

how fun enjoy your music

also get Jim Smiths book on getting better sound

IF you want to experiment with a very affordable low TIM SS amp with gorgeous sound, try an Audionics CC2, circa 1978...

there are others, if the science of that interests you check out Dr Matti Otola papers on subject

I have read a bunch of articles online about the LS3/5's/5a's. Very fascinating stuff!  I feel like I am listening to an important part of audio history. I am definitely experiencing pride of ownership with the Graham Chartwells. 

Do a master set,

I just read a bit about Master Set a couple of weeks ago. Have you tried it,and if so,what were your impressions?

Not many people realize that there can be a tradeoff relationship between soundstage width and imaging precision.

Strong early sidewall reflections expand the apparent width of the soundstage but they do so at the expense of imaging precision, and this can include soundstage depth. Many people prefer this expanded soundstage width, but for the most 3D imaging from a given pair of speakers, strong early sidewall reflections should be avoided.

Note also that the ear is getting conflicting messages about the soundspace you are in: It is getting the spatial cues on the recording about the actual (and/or engineered) soundscape; and it is getting cues about the playback room. We want to encourage the former but suppress the latter. The early reflections are telling us that we are in a small room, so again we want to minimize them. In particular the early reflection off the wall behind the speakers tends to impose its signature on our impression of soundstage depth. Likewise a strong early-onset reflection from the wall behind us is conveying small-room signature.  Imo set-up geometry, reflection management, and diffusion are generally preferable to absorption for suppressing early reflections because absorption removes energy that would have been beneficial as later reflections, and absorption is most effective at high frequencies therefore it correspondingly alters the spectral balance of the reverberant sound (which is usually undesirable).

There is of course a lot more to 3D imaging than this.

Duke

I believe this is the first time I've heard anyone mention diffusion vs absorption at early reflection points. However,thinking about what you said about removing energy,it makes sense. Thanks for your post.

Diff + absorb + random = good, lots of variation in surfaces, textures, a loved in room is often FAR superior to the audio ph dedicated room with rack between speakers and a forest of amplifiers on the floor....

Lived in room, but loved in is better!!!! Spellcheck...,

Two huge advantages to headphones 🎧 are you don’t need room treatments and you don’t have to drive yourself crazy with speaker placement. What a relief! 😂

I'm not a fan of headphones. I haven't used mine in a couple of years. For me,speakers are my drink of choice. I actually find it fun in a way, to mark where speakers are placed,listen for a couple days,then move them to see where I'm at.

It’s OK to like speakers. There’s room for everybody in this hobby. 🤗

Thanks! I was afraid I wasn't going to be allowed in the club!

So I built my system on research by Prof. Edgar Choueiri made during his work at Princeton in his 3D Sound Lab I experienced over 20 years ago: 

The moment for me was playing on humble Sansui speakers in my home under construction listening to a recording processed through the BACCH filters, my mind was officially blown. 
BACCH 3D sound works best with very directional speakers that limit reflections. I have optimized my room from the listening position on my current system with time alignment, phase, and room interaction on 12 biquad filters operating at 96/24 on each of my 8 channels of my fully active set up. 
The image is stable and amazing on my system and it feels like being there, friends and neighbor’s jaws drop, but it actually gets better, and I’ve heard it. . . the last piece is BACCH. Take a look at the technology:
https://www.theoretica.us/bacch4mac/
Hoping to add it this Spring! 

millercarbon,do you use HFT's with traditional acoustic treatments,or are these applied alone?

Sorry for the late reply. So many threads ruined so often and so fast by the same few people I tend to say what I think needs to be said and then that's that. But anyway...

Here's a photo of my room. Its old, 2004, but its good because it shows some of what I went through. http://theanalogdept.com/c_miller.htm
The yellow panels are Owens Corning acoustic panels, the same as used inside 90% of expensive professional room treatment. There's people like Duke (Audiokinesis) you can trust to post gold. Then there's guys like me who have to work at it more. This photo is working at it. 

Just like Duke said above, its real easy to over-do it, acoustic panels predominately affect the top end, and so can really alter the rooms acoustic. So this was moving them around learning first hand just what that means. The room now has none on the walls. Only the corner tunes remain. Very effective, with hardly any downside in terms of being overly damped.

My tests were made moving whole panels around. First reflections requires only about a one foot square. It could be that if I went back and tried just a small one like that, might like it. Heck now to think of it got some in the shop might just do that. Just because it sounds great doesn't mean it can't sound even greater. 

HFT are a completely different technology, much more sophisticated, work regardless of the room, and so are used together with the same traditional acoustic panels. 

They don't have to be. Look around YouTube, there's a demo in a very ordinary room, pretty crappy room actually, way too lively, way to sparsely furnished, no acoustic treatment at all. Ted adds HFC and even on laptop YouTube you can hear the improvement. Pretty remarkable stuff. 

millercarbon,beautiful system! I understand completely about people chiming in and kind of being the poop in the punch bowl. One thing I have learned in this hobby is to not discredit something that might be different or off the beaten path. Especially for things I have no experience with. When starting out trying to achieve better sound,I truely believed there was no way a cable could make any difference. As my equipment got better,well,I'll leave it at that. Hopefully this spring I'll begin the room treatment overhaul. Like you said,just because it sounds great,doesn't mean it can't sound greater.
    The journey continues.

rocray OP
What makes speakers produce a 3D image? I figured the first thing is the recording itself. I’m guessing mic placement has a lot to do with this. Next I would imagine is room,and speaker placement.

The last one is the biggie, you should have nothing between the speakers, and as far back as you can get, this will be the best way of getting the most imagining and depth properties to be had.
Forget placing your "glitzy equipment" in between your speakers (so you can gaze at it in wonderment while listening) this is a killer for image and depth, it should all be at the side, well back
Cheers George

To my ears,I seem to be getting very pleasing(again to my ears) imaging. However,I do plan on heeding your advice in moving my equipment next to and slightly behind my seating position. I’m expecting even better imaging with that change. This will also coincide with treating my room better. Fortunately as this is a dedicated listening room,I am able to pull the speakers out well in front of my rack. This being a temporary solution until I can free up space to move my lp collection out of my small (9x13x8) room.

I have always preferred having the speaker facing straight forward. I do take careful measurements that they are the same distance from the back wall and that I sit in exactly the midpoint between the two speakers.  Yes, this makes for a VERY small sweet spot.  But I am the only person who listens who even cares about imaging and the sweet spot so, I suit myself.  

 I have tried numerous times to toe in speakers in varying degrees, including directly at my sitting position. It makes for a larger sweet spot. However having them pointed straight forward allows for the image to go beyond the outside edge of each speaker.  I much WIDER soundstage is achieved for me this way. 

Look into MA Gold 100 5g. Better image than Focal Sopra 1 and Diablo monitors. Truly sleeper speakers.