I'm a tuba player, and regularly play notes down into the 30's and 40's Hz. While the overtones define the characteristic timbre, there is still plenty of fundamental in those sounds. Of course, I can't compare the recorded tuba sound with my own playing--playing the instrument leads to all sorts of cranial vibration that affects perceived hearing. But I've had all manner of other tuba players in my house trying out instruments and comparing notes (so to speak), and do not find that my Revel speakers are incapable of producing the full sound of the instrument. A good player can probably achieve a higher level than those speakers, though that's not a test many will tolerate. But the timbre is correct.
I suspect a lot of what's down below 40 Hz is modal reverberation in the recording space more than music, but if it's a good recording space I probably want to hear that. When I installed a (necessary) sub to bolster the low-end response of my Canton GL260 speakers at my electronics bench, I found that it was very easily overdone, calling unrealistic attention to itself. I'm sure it was ringing that space, which has a linear dimension of 60 feet at its longest and can resonate pretty low standing waves. I had to back it waaaaay down to keep the system from sounding like I was hearing it through closed windows. Those speakers roll off about 70 or 80 Hz, and that's where I started with the crossover, but when I put it there, the hole in the lower mid bass was annoyingly obvious. I didn't achieve a seamless sound, where the sub's presence was undetectable, until I raised the crossover to as high as it would go (160 Hz, I believe). It's not localizable because it's on a shelf below the top of my workbench, which prevents on-axis sound. I didn't measure anything and did it all by ear in about ten minutes, but when I thought it sounded like real music, I wasn't even sure I had it turned up enough to be audible until I turned it off and suddenly it again sounded like a transistor radio. Yes, it helped immensely. But those speakers only have single 5" woofers and their porting increases low-frequency Q, and this thread is about full-range towers in comparison.
My Revels, on the other hand, have a pair of 8" woofers in each cabinet
plus a mid-range (NOT a mid-woofer like later versions), with the same radiating area as an 11" driver. It would take a fairly large sub to deepen that usefully, it seems to me. I'm sure there's music that would benefit from it, but I'm equally sure I have very little of that music in my library. Higher-end Revels have an additional woofer or two.
As to Fletcher-Munson, we must acknowledge that our reduced ability to hear low frequencies affects our perception of live music, not just recorded music. A tuba playing a 39 Hz Eb1 at 70 dB SPL (unweighted) (and there are several of those in Shostakovich's 5th, for example) may sound about as loud the clarinet's 990 Hz B5 played at 40 dB, but
that's the way the musicians will play it if that is their objective
. That's one reason my tuba has a bell diameter of 20" and the clarinet a 20th of that. The playback system does not have to provide that additional bass amplification--it's already there in the recorded levels if that is the musical intent (and if the recording engineer didn't screw it up). The playback system can produce that if it can produce pink noise flatly. The amp may run out of power on the low note before the high note, or the speakers may bottom out or compress on those frequencies at the desired overall listening level, but Revels driven by a 350wpc amp don't seem to.
Rick "easy to see the house's air handling system in that graphic" Denney
