3-Dimensional Soundstage

The problems created by small rooms are many:

1) small room nearby first reflection points will cancel direct on axis information by arriving late, therefore creating large dips in response you cannot fix with EQ or any kind of DSP.

2) In a small room, a speaker with poor off axis reponse will make imaging almost impossible as the frequency response of the reflection and the frequency response of the direct sound are different, causing dips/cancellations in in multiple places when direct and reflected sound are added together at your ear. The sum of the sound is what the the mic/measurement system looks at. So the room correction DSP corrects the direct sound coming out of the source (which was likely not that wrong to start with) based on what the refelctions are doing. The problem is the direct sound was fine, it was the refelcted sound that was messed up. SO via room correction, you are fixing/repairing/EQing only the direct sound NOT the reflected sound which is the real problem. The reflected sound is still just as different from direct sound as before due to physical room problems (like glass or highly reflective walls or poor speaker off axis). The reflected sound only gets better by boosting or altering the direct sound so the sum comes out better. And this new sum only works for one tiny location- 1 foot that way the reflected sound is different and the "solution" or fix (room correction) would be different. This is why we say you cannot fix room problems with electrical soliutions because the room problem never goes away.

2) small rooms cannot support bass. The lowest note a room can support depends on its dimension: a 32Hz note requires a 35 foot room dimension to exist, a 50 hz note requires a 22 foot long room dimension, a 85Hz note requires a 13 foot dimension! Complaining about bass in a 10x12 room is like arguing that wavelengths dont exist. Expecting much below 100Hz in a 10x10 room will just frustrate you. If you are stuck with a 10x10 room, you are better off letting the dream of great bass go and focusing on great midrange and top end. Headphones can be a workaround. Multiple (4, one on each wall) small subs turned low can also help.

3) highly reflective surfaces such as glass or hard painted walls or ceilings are destructive to mid and top end by reflecting sound in a particular bandwidth. Using absorption to stop the reflection all togther is one countermove; diffusion can change the angle of reflection and randomize it by creating actually more reflections (so none dominate), as major reflections often get stuck between parallel surfaces and keep ringing for a long time. Clap your hands in a room and you’ll likely hear this slap echo and the frequency it emphasizes.

Brad

The last two posts were both very good and packed full of info that I agree with. It seems to me that very few people realize how critical specific tonality (represented by a detailed freq response curve) is to soundstage characteristics. It's absolutely primary and critical, and acoustics (timing at listening position), clarity, and dynamics are also factors, but don't matter without the right freq response.

@lonemountain - I agree 100% which is why I went with stats in my 12 X 16 (small) room.  No first order reflections.  Also, as for room size and bass, problem, in my opinion, can only be solved by applying real eq (parametric, not graphic) at, probably 200hz or 250 hz and below.  Bass in a small room will always smudge the lower midrange at any reasonable listening level.  

I have appreciated a quite nice separation of instruments in my system’s soundstage. I have read many times about people experiencing depth in their music and have never appreciated this.

Category 1: Least expensive

If you are happy/satisfied with a flat 2D sound that becomes a face smacking wall of sound when you crank up the volume, that’s all there is to it. That’s the old school "hifi" that many dudes have been happy with for decades. Don’t worry about depth or 3D if you fall in that category.

Category 2: Very expensive

No matter the recording, some level of partial 3D and pertinent depthwise spatial nuance is created primarily in the digital domain with FPGA dacs, processors like BACCH, etc (still inside the domain of channel based stereo)... There are also elements of speaker design, analog circuits design and setup - speaker positioning/listener positioning/room, etc that play into its conduciveness.

Category 3: Can be as expensive, more expensive or less expensive than category 2

True immersive 3D envelopment/immersion/detail/full on spatial nuances/etc, which is more representative of live unplugged events in great acoustic spaces can be accomplished with object based audio, i.e. more than 2 speakers and pertinent object based audio processors.

Note: "All knowing seers" in the 3 above mentioned categories will claim that they achieved audio nirvana in said category (to each his own/who cares).

I am of the mind that "time alignment" is very important for the best 3D image.

I had been working on a replacement pair of speakers for my JBL L200/300s that would do justice to the female voice and developed the "Mermans" that use JBL 2241H (18"), JBL 2251J (9.5") and the ESS Great Heil. The crossovers use Audyn Q4 caps, heavy gauge air core chokes, and high wattage, Dale 1% resistors.

At first it was a matter of getting everything to play nice together. Then it was a matter of getting a smooth flat frequency response in the room, and I wasn’t getting it from the Heil.

So I made modifications to the Heil, and Carlos Santana’s amplifier jumped out into the room infront of the other instruments. It just happened! The RTA shows that the modification filled in a dip in the 3-8kHz range vasting increasing the "order of the crossover" and this is where the detail lies! Further modifications, and the soundstage and imaging are like anything I’ve ever heard at any price. And I have one-off, Altec Big Red Supers (triamped), LS3/5As, JBL L200/300s, and L112s), as well as have been to shows and showrooms (Magico, Focal, etc.) so I’ve heard some decent stuff. My source is an Oppo95 through a Yamaha RX-Z9 RECEIVER in "Pure Direct" mode. I use no eq or room correction, electronic or physical and the room is ~5,000 cubic feet. I can play clean to concert levels and believe that you need a certain amount of volume (i.e., loudness) to envelope you for proper imaging.

And, the other day one of the gents from AudioKarma came by for a listen. He has Altec 604 Hollywoods, ADS, and ???). On the first track (equipment not even warm), he said this was nothing like he’s experienced and he just heard a $100,000+ system with $40K monoblocks. He said he was going to have to re-assess everything.

BTW, I am in Orange County, CA, and anyone is welcome to come by and experience this for themself.