Is soundstage DEPTH a myth?

It is no myth, and you don’t need to spend a ton of money.

But you do need to get things right.

The speaker spacing, both to each other as well as the back and side walls, is very important. You also want "time alignment" between the drivers.  And you want symmetry in the room. Soundstage/imaging/depth are all dependant on constructive as well as destructive interference and phasing and for these to occur properly, both speakers essentially need to be the same and "see" similar environments so they are the same in the seating area.

And..., if you want to feel "encompassed," you’ve got to bring the volume up to realistic listening levels!

I know it sounds cliche, but I’ve spent years putting together and perfecting a pair of speakers that image like no others I’ve heard. And I have JBL L200/300, JBL L112s, Altec, Big Red Supers (triamped), and Chartwell LS3/5As, and have heard Magico and Focal at demos, as well as lots of other varieties at listening parties.

If you get down to the Orange County, CA area, you are welcome to come by and hear what it is all about. Meanwhile, I leave you with this YouTube video. This is just the two inner speakers playing with no sub attached, no eq, and no room correction, either physical or electronic. The room is large (27’ x 16.5’ x 7-1/2->15’ ceiling, and open to the entrance hall and dining room.

This is an SACD played on an Oppo95 ($300 used) through a Yamaha RX-Z9 RECEIVER ($4,050 new at 10% off in 2002) in "Pure Direct" mode. The speakers use a JBL 18" 2241H, JBL 2251J, and ESS Great Heil that I’ve modified ($1,500 total investment with used drivers but new crossover components from ebay).

This shows the spectrum in the seating area without the 18" connected to alleviate the "noise" associated with floor and room bounce. I know it look a bit "bright" but that is a personal preference and I think it makes music more lively and brings out the microdetail. As shown, the crossovers are all the way up and there is even a "flat switch" that removes the upward tilt, engaged for overly bright or noisy cuts.

All caps are Audyn Q4s, all resistors are Dale 1%, all inductors are heavy-gauge air core.

So what do they sound like? Well if you believe in YouTube (many don’t) put on some really good headphones and take a listen. And while you’ll hear a nice smooth response, and lots of detail, you loose the imaging, but are welcome to come by for a demo any time. This was recorded on a Nikon D750 DSLR.

https://youtu.be/oLgQCHmXSUU

Our ears have no direct depth perception mechanism like our stereoscopic eyes do. Our brain can simply measure the convergence angle of our eyes for things up close. Once the convergence angle gets close enough to zero everything is just far away. That’s why the moon looks like it’s the same size and distance as the sun. Or maybe you can see that the sun is over 200 times the diameter of the moon just by looking. I can’t tell.

But there are definitely indirect ways for our ears to perceive depth, and the most obvious methods are reverberance and tone. There’s also another potential way of perceiving depth with sound and that is lateral shift as you move slightly. As with visual perception, things close will seem to move quickly relative to your motion, while things that are far away will seem to follow you along. A strange effect of the phantom center image when using just two speakers is that sounds that are panned hard to each speaker will tend to stay put, so as you move your head left or right you will get proportionally closer or further to the apparent sound from each speaker. On the other hand, center panned images  tend to follow your movement. If you move left, the center panned vocalist seems to follow you in that direction. This could conceivably create a sense of depth for some people, and may explain why they don’t like a center speaker for music. The center speaker will pin the vocalist to one specific location and that could make them seem closer. That’s a complaint I’ve heard and taken interest in because I am an oddball who absolutely LOVES a center speaker for 2 channel playback of music, but I try to commiserate with those who disagree with me. I really don’t care much about soundstage depth but I continue to perceive it on 2 channel recordings whether I’m just using 2 speakers or deriving a center channel.

@toddalin  

 How did you get stereo in the recording? The mic. in the picture looks mono. It’s interesting to hear the original track over headphones and then compare it to you recording, which sounds more reverberant and brighter.

The Behringer mic used to display the spectrum is mono. You cannot "analyze" mono pink noise through both speakers simultaneously because of constructive and destructive interference in the room. I've shown only the left speaker, but the right is similar.  The audio recording was made with a Nikon D750 DSLR camera.

Yes the recording is more reverbrant because it picks up the untreated, big, room acoustics. The brightness is my preference (but also the room) and could be turned down at the L-pads or flattened to a more conventional curve with the switch on the crossover.

Thanks for clarifying the use of the Nikon camera’s microphone. You had mentioned that but I didn’t make the connection to it also being the audio source. Is it the camera’s built-in mic. or a separate mic. you attached? I can hear the stereo separation.

I own that same Behringer DEQ2496 and it's calibrated microphone. It's been a useful tool over the last 15 years or so that I've owned it. Yes, you can't calibrate the tweeters at the same time unless you can somehow get the distance to each tweeter exact within about 1/8". That should get you up to about 10,000 Hz. Of course our ears are separated on our head so our ears really don't like two tweeters playing into both of them at the same time either. At least my ears don't care for it.