What makes instrument immediacy, -separation & -bo

StonedTemplePilot,

There's a trade-off relationship between immediacy and richness. The more dominant the first-arrival sound, the more immediate (front-of-the-hall) the presentation. The more dominant the reverberant energy, the more rich and ambient (rear-of-the-hall) the presentation. Room acoustics, speaker positioning, and speaker radiation characteristics come into play here.

In my opinion, the characteristics that would give what you're looking for in a loudspeaker are a slightly downward-sloping on-axis response and smooth power response along with a somewhat narrower-than-normal radiation pattern. You also want a speaker with good dynamic contrast (minimal thermal compression), as this correlates well with liveliness at low volume levels.

If you listen from more than 5 feet away from the speakers, most of the sound energy that reaches your ears is reverberant sound. A key difference between live (unplugged) and reproduced music is this: Live instruments produce natural-sounding reverberant fields, but most home sound systems don't. For example, listen to a piano from the next room, through an open doorway with no line-of-sight to the instrument. All you can hear is the reverberant energy, but it sounds totally natural and convincing. On the other hand, very few sound systems will sound real when listened to from the next room, and this is because they do not generate a spectrally (and dynamically) correct reverberant field.

Now the idea is not to have a system that you can listen to from the next room - the idea is to have a system that replicates as close as possible the sound field of a live performance. And in my opinion this cannot be done without getting the reverberant field right.

In your listening room, you want a strong, diffuse reverberant field that ideally begins to arrive as long after the first-arrival sound as possible. You do not want an overdamped room, and most home listening rooms are overdamped (carpeted, with overstuffed fabric furniture). Large plants and lots of wooden furniture are good for diffusion, or you can get dedicated diffusors. Since most of the sound energy that reaches your ears is reverberant sound (assuming you sit more than 5 feet away from the speakers), in my opinion it makes sense to start with speakers and proceed to room treatments that give you a natural-sounding reverberant field.

Regarding amplification, SET and OTL amps along with low feedback Class A solid state amps have distortion characteristics that are in harmony with how the ears work. The commonly used total harmonic distortion specification has no useful correlation to how we perceive sound - the amplifier industry has been measuring the wrong thing for years.

Duke
dealer/manufacturer

Shadorne, I'm not convinced that recording in an actual performance hall is necessary to create a sensation of live performance in playback.

In any case, there are certainly many recordings that are made live-in-the-studio & combine a sense of room acoustics with correct placement of instruments & good separation. All the CIMP direct to two-track jazz disks are recorded with musicians in one room & no close miking or compression. Or a Ry Cooder ensemble outing like "Buena Vista Social Club." The excitement of Derek & the Dominoes "Layla" is partly due to the (mostly) live-in-the-studio recording with leaks across multiple microphones. Though the sound of this session is sometimes maligned, the original LP is actually a pretty good test LP. On a good system you can hear both good instrumental separation and fidelity, as well as a very active room that communicates the energy & dynamics of a live performance in spades. In a larger setting, MTV Unplugged gigs like Alice in Chains, Nirvana, and Pearl Jam at Benaroya Hall manage to be remarkably good at separation, fidelity, and you-are-there in a real performance space.

But even many recordings that don't have technically "correct" instrument separation and obvious room effects (such as ECM or Chesky jazz CDs with the drum kit spread all over the soundstage from left to right and other instruments layered on top or behind), the sound can be uncannily real in terms of fidelity, separation, & sense of real life.

But a bad playback system deadens that sense of living, breathing performance in every case.

A key difference between live (unplugged) and reproduced music is this: Live instruments produce natural-sounding reverberant fields, but most home sound systems don't. For example, listen to a piano from the next room, through an open doorway with no line-of-sight to the instrument. All you can hear is the reverberant energy, but it sounds totally natural and convincing. On the other hand, very few sound systems will sound real when listened to from the next room, and this is because they do not generate a spectrally (and dynamically) correct reverberant field.

Excellent point. This is one of the easy tests that I have been using with speakers for years; does it sound realistic from outside the room?

Funny thing is that most people think I am absolutely crazy when I say this is a good test of the speaker quality! I have had salesman grab me and insist I sit in the exact sweetspot where the floor has been marked with masking tape....whilst I prefer to walk around... as a speaker that sounds right throughout the room is what I usually prefer. If I have to sit in a spot marked X for it to sound right then I don't need to waste my time on an audition

Interesting points about reverberant fields in the original performance, the relative contribution of first arrival vs. reflected sound, and hearing realistic piano sounds in the next room. However, after fixing the variables of room treatment & speaker position, I've observed huge improvements in realism & spacial representation after modifying the circuits of high-quality commerical separates. Even quite expensive stock electronics are compromised & fail to communicate the low-level information necessary for realism & spacial cues. Room variables can only contribute modestly toward remedying such inherent shortcomings. The good news is that the gap between built-to-cost and near SOTA-equipment can often be closed in the aftermarket with light modifications.

I would add that the same improvements to circuits that reveal low-level information required for spacial cues, also reveal textural details & corrected pitch & timbre in voices & instruments. So it's not just about uncovering deep background. This is why that piano sounds so natural when heard from the adjacent room. This type of improvement has nothing to do with room treatments or reflected sound.

However, such improvements in electronics (at least when driving my Merlin or Wilson speakers) do nothing to enlarge the sweet spot. If anything, the effect is lens-like in the sense that movements in and out of the sweet spot are more easily detected & create dramatic shifts in L/R imaging.