frequency range for instrument vs speaker

My Vandersteen 5A's have a bunch of pots in the back that adjusts frequencys from the very low bass to the midbass. Richard himself helped me with my setup and told me that the goal was NOT to get a flat frequency response...just s pleasing one. Flat frequency response is a-musical.

06-23-12: Tonywinsc
Johnnyb, you explained it well. It takes a lot of effort and work to get it balanced across the broad spectrum. ... Like you said, you have to work very hard to balance all of that out and get it to work. You are taking great pains to get the reflections and the sources to all come together at the listening position. I still doubt you can achieve a balanced 20-20k in a small room.

Sorry; I have a nasty virus right now that's got me grumpy. You've been gracious and make good points. An advantage of the stand mount/subwoofer approach is that if you have to put your system in a smaller room you can dial back the subwoofer(s). Even a JL Gotham G213 can be turned down to reasonable levels in a small room, but you can't do that with a pair of Wilson Alexandrias (or other passive large full-range speakers) which will inevitably overload a small room.

You are right. Full spectrum audio is achievable but takes a lot of patience and money. More than I have of either one. I certainly don't want to discourage the enthusiasts that are working to achieve that, but it is also good to share our failures and successes so others learn something from it. I'm pretty happy where I am with my system today. I think my large size and volume listening room combined with the wood floors made a tremendous improvement in the sound of the lower registers. I had the Thiel CS3.6 pair when I moved into this house and they just didn't seem to be enough for this large room. When I got the CS6 pair the sound filled in nicely. I'm not trying to play at loud volumes, just that the larger speakers seem to fill the range better in a larger room. The converse is true too- smaller speakers work better in a smaller room.
Everyone has a different path to take in this hobby. Many are happy to have the mid-range magic of Quads, which I also used to enjoy immensely at a friend's house years ago with female vocals, and others want the full range to go with their broad stage orchestral music and others the hard kick and punch of rock and roll.

One of the things that bothered me most about early digital recordings (actually, until very recently) was not the harshness, brightness or grain, it was the very obvious (to me) sense that there was a frequency extension ceiling above the music; that the upper harmonic extension simply came to a screeching halt; technically speaking, around 21KHz. Some would argue that we can't hear above that range. Well we can argue that one forever, but wether it is the absence of harmonics above that range, or the effect that this absence has on lower audible frequencies doesn't matter, it is audible either way. I hear a similar effect at the bottom end of the spectrum. Wether it is the ambience cues that we hear/sense, or undertones, or whatever, when the speaker is incapable of reaching into the lowest octave there is an audible low frequency ceiling (floor?), where just as with the high frequency ceiling, things come to a halt and one hears/senses the absence of limitless extension even if there is no musical content in that frequency range. All this compared to the sound of live music, of course; not just in a hall, but also what one hears in a studio.

06-22-12: Onhwy61
>I think Frogman is correct, but it should be put into perspective. Suppose you were an audiophile with limited funds. Would you be better off pursuing bass response down to 20Hz, or compromise at 50Hz (with room reinforcement) and put more money into going for a better quality midrange and treble? Unless you're an absolute bass fanatic the answer is self-evident.

The answer is counter-intuitive and not at all self-evident without a far better understanding of acoustics and psychoacoustics than the average audiophile's. The combination of physics and consumer market expectations make getting quality midrange without last octave extension unlikely so seeking good high frequency performance means looking for the same things that give you lower bass.

Beyond a room's Schroeder frequency (100 - 200 Hz in typical domestic rooms) and assuming the speaker is correctly voiced for your chosen placement with respect to room boundaries how natural a speaker sounds comes almost entirely from

1. Its polar response with the ideal being flat on-axis with directivity increasing monotonically with frequency. Our brain determines timbre from the spectra of what it believes to be a direct sound and its delayed reflections. An increase in reflected high frequency energy isn't consistent with natural sources (directivity increases with frequency) and environments (natural materials like foliage absorb and diffuse more at high frequencies where they're becoming acoustically large) and doesn't sound right.

This comes predominantly from the driver/baffle sizes/shapes you use including options to increase directivity from an acoustically small driver with a wave guide or cancellation from acoustic dipoles and cardioids.

Untamed driver and cabinet resonances can also play a negative role, showing up as amplitude peaks at all angles.

2. The distortions which go with approaching and exceeding a driver's linear limits. Harmonic distortions change the timbre and IM distortion adds non-musical sounds that weren't in the recording and damage the midrange.

Unfortunately you can't build a flat baffle 2-way with conventional cone and dome drivers which does well in both areas. When you compromise with a smaller mid-range to get better polar response you lack the displacement needed for clean reproduction of lower frequencies (250Hz is probably a nice lower limit for a 4" driver, 150 Hz 5", 120Hz 6-7", 80Hz 8.5", 40Hz 10"). When you compromise with a larger midrange to get clean output at acceptable listening levels you end up with a noticeable harshness resulting from the significantly broader dispersion crossing to the tweeter at 2-4KHz or beyond. People work around that with some success using a drop in output in the range (the BBC dip) although the resulting speaker is more sensitive to the room (you'll notice the lack of energy in a large/absorbing room because there's less compensation for the on-axis dip) than a speaker built with more uniform directivity.

Sticking to flat-baffled vaguely box-shaped speakers that most consumers shop for the solution is at least a 3-way, whether in one cabinet or separate boxes. 120Hz and beyond can work well crossing to stereo "sub-woofers" which are better described as woofers, although if terms like "pole", "zero", and "biquad" aren't in your vocabulary that probably won't end well as a DIY exercise.

Once you do that the extra extension has negligible additional parts cost, although it costs you 9dB of efficiency for the same cabinet size or a box 8X as big at the same efficiency. Most consumer speaker company marketing departments compromise with lower bass to satisfy more listeners, smaller cabinets for spouses, and less efficiency.

The intuitive but incorrect counter-argument is that you're better off with fewer more expensive drivers. It fails because a pair of drivers in a conventional configuration have audible and measurable problems from their inherent physics that more appropriate sized less expensive drivers with lower total cost (and better sound) do not.

Whether you're spending $200, $2000, or $40,000 on drivers flatter on-axis and more monotonic polar response sound more similar than different. Deviating from that design goal is not good although the specific failings vary. It's like Tolstoy's comment "Happy families are all alike; every unhappy family is unhappy in its own way."