frequency range for instrument vs speaker

Other points about low frequency extension are that

1) It's not a brick-wall. Extension to 50Hz generally means that output is at least 3dB down at that point with a noticeable 1dB of drop up much higher like at 80Hz.

2) The effects are worse than the numbers would suggest due to the equal loudness curve spacing at low frequencies. Once you get to 50Hz at moderate listening levels 3dB is like 6dB down at 1KHz which is 1/4 the acoustic power and quite significant (a full 10dB gets you a perceptual halving of volume).

3) The -3dB extension does not imply that the speaker is actually flat to that point. Many small speakers have a bump in frequency response (a few dB) which boosts the harmonics of low frequency instruments and can either give the impression the missing frequencies are still there or make the speaker sound boomy depending on what they're trying to reproduce. This design choice is more likely in speakers with less low frequency extension.

Drew: I understood that speaker frequency response is measured in an anechoic chamber so that consistent comparisons can be made with regard to speaker response performance. In the real world, the speaker sits on a hard or soft floor, close to or far from walls and ceilings. These variables, plus furniture, curtains and rugs create colorations in the music and then we must consider the type of amplifier and cables attached to the speakers and how they respond to the impedence characteristics. So speaker designers can create an instrument that looks perfect on paper when operated in an ideal environment, but how it behaves in our homes can be an entirely different matter, right? For example, just placing speakers near corners in a room can reinforce the base or adding curtains on the wall can dampen down the highs. I also learned in the past that too much dampening in the room kills the music. I have my speakers positioned a good distance from any wall. My speakers sit on spikes on a wood floor but I have a good sized rug placed directly in front of them. I haven't made a detail spectrum measurement but I believe I am close to a flat response curve as I could possibly get. Not saying that it is flat, just that I have acheived a satisfactory balance. I think about all of the parameters that speaker designers must consider both acoustically and electronically and then the nearly infinite variables of peoples' listening enviroment, associated cables and electronic gear and I can see why we have so many types and styles of speakers.

I seem to recall that a typical electric bass guitar drops to mid to high 30's on the open low string. For some reason 38 is sticking out in my mind. lots of fronts will do that but the discussion on spl above my explain why the sub helps out.

06-20-12: Paulsax
I seem to recall that a typical electric bass guitar drops to mid to high 30's on the open low string. For some reason 38 is sticking out in my mind. lots of fronts will do that but the discussion on spl above my explain why the sub helps out.

If you check this chart, you will see that the low E of a 4-string bass is 41.203 Hz. For a 5-string, the low B is 30.868 Hz. Maybe that's what stuck in your mind (with a little modification). Or maybe you were thinking of Eb, which is 38.891 Hz.

Your second part is definitely true. You can't count on many speakers to make meaningful bass below 50 Hz. Many start rolling off around 80-100 Hz. Of course this depends on speaker placement, room-loading, etc. And more expensive speakers definitely go lower.

Still, if Wilson Audio tours the Alexandria XLFs with a pair of Thor subs, I'd say just about *any* loudspeaker would benefit from the right pair of subs properly blended.