You have understood the first part - that having a flat frequency response and adequate bandwidth are basic necessities to reproducing the combined pressure waveforms created when sounds from multiple instruments combine. All the information is in the pressure waveform, as our own ears tell us. This is still a bit simplified, because the rule is true only for minimum-phase technical devices: microphones, loudspeaker transducers, and amplifiers. Phase shift can distort the waveforms, but it turns out that humans don't hear it, especially when listening in normal rooms. We don't hear "accurate" waveforms in reflective spaces - like normal listening rooms or concert halls.
I’m curious about what, if anything at all, frequency response leaves out in telling us how loudspeaker will sound.
As I understand you’ve written that most things that matter will show up in the frequency response - including driver or cabinet colorations due to resonances (please correct me if I’m wrong).
I know there’s of course off axis measurements, and similarly neutral speakers can have different dispersion patterns which can cause them to sound different depending on the room and set up. But that’s still essentially about frequency response.
So my question is, what of importance does frequency response leave out, if anything?
So two scenarios:
1. If you were comparing (blind) loudspeaker A and B, and loudspeaker A seems to be revealing slightly more Sonic detail, for instance very subtle recorded room acoustics or very subtle artificial reverb is revealed on speaker A, would the explanation of that difference likely be spotted in the frequency response of each speaker? Or is it possible for two speakers to measure essentially neutral, but one has a slightly livelier cabinet, or the other design has gone to heroic measures to make a completely inert cabinet. Is it possible that Sonic advantages from a more inert cabinet might reveal the type of subtle details I’m talking about, and this factor would not show up in or be obvious from evaluating just the frequency response of the two speakers? Or will any such audible difference at all in the designs be captured in the frequency response?
I guess another way of putting it: as long as you have a flat frequency response, will that assure the speaker is producing all the recorded detail un-obscured, and no other parameter of the design would affect this?
2. There’s been occasional discussions about the perceptual effects of larger speakers and larger drivers versus smaller speakers and smaller drivers. The idea of being that there is something about a truly big speaker that can give a sense of larger scale versus a smaller speaker, even if they both have the same frequency response specifications.
So as a thought experiment: let’s say we had A super Duper Speaker comparator system for blind testing they could accommodate any size speaker. And let’s say we have some “ pick your neutral” stand mounted monitor (say a good Genelec monitor) combined with a subwoofer or two, and we’ve got those measuring with flat frequency response from 20 Hz to 20 K.
On the other hand, we have a huge PA system, of the type you might find in a very large club, and this system has also been made flat from 20 Hz to 20 K.
So in terms of strict frequency response, they are essentially the same. And we play them back at the same sound levels.
And yet, at least intuitively, I think we’d expect that even playing at something like an 85 DB level, the systems would sound different, the scale of the PA system sounding significantly more grand. And probably more convincing in various ways for instance recreating an orchestra, etc.
Is there anything wrong with these intuitions?
And if not, what would count for the Sonic differences between these two systems that have the same frequency response played at the same volume levels? Is it something to do with the sheer amount of air being moved by the larger system? Or is that not even a factor if we’re talking about the same levels and the same frequency response?
(Thanks to anybody else who wants to chime in on this).