Note moderators, I am sending this from my AT&T account,
because I could not find the thread on the Google groups
pages, even though I did my initial commentary from that
source. So goes the strangeness of computerland.

Nousaine wrote:

(Howard Ferstler) wrote:

(Nousaine) wrote


Now stop that. My 15-inch subwoofer will produce 120 dB SPL @ 20 Hz @
2-meters
with less than 10% distortion. Just because I need 8 15-inch drivers
with
23mm
Xmax doesn't mean it can't be done

What kind of music or home-theater reproduction requires that kind of
subwoofer output power, Tom?

Eric Bush confirmed several years ago that modern cd recordings can have
significant frequency content as low as 6 Hz. I own such a collection of cds.

I have a couple like that, myself. However, I would say that
few of those discs that exhibit super-low content have much
to offer in the way of meaningful music aesthetics. It may
be fun to experience the low, low rumble or booms of such
discs maybe one or two or three times (the second and third
times being show-off sessions for a guest), but listening to
such material over and over for musical enjoyment is
certainly not something I would care to do - and I doubt
that most music enthusiasts would care to do so, either.

The fact is that most digital recordings (particularly the
dull baroque and classical stuff I listen to for pleasure)
do not have all that much super-low bass, and in many cases
the super-low bass certain discs have are hall-noise
artifacts that are more annoying than musically significant.
Many recording engineers would like to get rid of such
anomalies rather than have them reproduced.

My goal for subwoofers was partially based on Tom Holman's observation that 122
dB SPL at low frequencies may be a useful dynamic headroom limit.

For what? I certainly do not know of any live, acoustic
music situation that would require something like that.
Well, I take that back. I attended a Stan Kenton concert
years ago and even at the back of the hall the high-octane
sound from the trumpets was unsettling. However, no
subwoofer would be required to handle that kind of material.
I have doubts that any midrange and tweeter combination in a
home-audio system could deal with it, either.

This system
will play any recorded program (which includes environmental sounds such as
radial engined aricraft, thunderstorms, trains and artillery) with no dynamic
limits.

Fun for some, but not for me. I guess I am getting old.

As a product reviewer, I have three systems at my place for reference
purposes as well as pleasure. One has a big Velodyne F1800RII for
main-channel work and a Hsu TN1220 for the center. (The Hsu is not
really needed, but I had the sub on hand and so I put it to work.) The
second has a "modified" SVS 16-46PC. The "modified" latter has the
enclosure inverted, with the driver facing up, Hsu style, and with the
grill replaced by another spaced-off wooden disc to reduce
grill-screen noise. In addition, the driver is upgraded to a
considerably heavier-duty, 12-inch TC systems job, and with the amp
power changed from 190 to 320 watts. (An upcoming article by me in The
Sensible Sound will discuss this mod, and a still later article will
involve a comparison between it and the Hsu TN1220 and also between it
and one of the SVS "Ultra" subs.) The third system has a Velodyne
FSR-12 servo that is small but decently potent in the area it
occupies.

The three systems occupy rooms of 3,400, 2,900, and 2,000 cubic feet,
and in each case the subs can generate all the low-bass realism
required with any acoustic music one might want to listen to, and the
two bigger ones can generate all the home-theater, adventure movie
bass the walls can stand. All are capable of going solid to 20 Hz,
with the modified SVS job strong right down to 17 Hz.

Is going beyond that point kind of gilding the lily when it comes to
practical subwoofer performance in typical home-listening rooms? I
mean, if one wants to generate "greater than reality" SPL levels
(sound-effects clashes, or whatever) or frequencies below what one
would hear at any live concert (certainly, any classical-music concert
that did not include a pipe organ) then maybe a wall-cracking
subwoofer is OK.

ANY recording known at reference level. But, again, this is a reference system
used for professional evaluation. I've never claimed that everybody needs one.

Actually, I feel similarly about the systems I mentioned
above. My subs can easily get under the low-end sounds of
the vast bulk of the musical and home-theater material I
have encountered as a reviewer and enthusiast. In my three
rooms, all can easily deliver realistically high levels down
to 20 Hz, and none roll off appreciably down to that
frequency. At the high levels that I occasionally use when
testing subs, I find that my rooms generate so many noise
artifacts of their own (wall-hung pictures, windows, doors,
and shelf-located knick-knacks rattling aplenty) that
worrying about the sound of the sub itself becomes
secondary.
On the other hand, at levels that simulate a live-music
event (note that this does not include rock-concert live
sound, since I never attend such get togethers anyway) the
room noises disappear and my own subs just loaf along. No
need for them to be able to play louder or lower - even for
product- and music-reviewing purposes.

Sure, there may be an occasional boomer recording (CD or
DVD) that should tax a typical super sub (as opposed to a
home-built super-duper sub played at levels one would never
encounter at either a live, acoustic-instrument concert or
in a killer-grade movie theater), but I do not think that
kind of recording is something most people would miss if
they never heard it. And while you note that your system is
used for professional evaluation, you also note that not
everybody needs one for that kind of performance. The reason
most do not need it is that most do not listen to material
of a kind that would require a sub of that kind to be
installed in their homes. Hence, having a system that can
deal with that kind of material at those frequencies and at
those levels is not based upon a need to "reference"
material that anyone would normally purchase. All one needs
for reference work is a system that would equal, or maybe
slightly surpass, what a serious, realism-oriented music or
home-theater enthusiast would want.

However, I find that kind of excess to be just that: excess when it
comes to practical home-music or home-theater listening requirements.
Supporting this kind of mega-subwoofer overkill probably misleads a
lot of audio enthusiasts who are mainly in it for the musical or
home-theater satisfaction, as opposed to owning what is essentially a
sound-effects-recording "rumbler" for the living room.

You may also be excluding the crop of car-audio enthusiasts who are used to
getting 120 dB SPL in their cars. Shouldn't they be allowed to experience this
level of performance at home too?

Well, adult people should be allowed to do what they want,
including wrecking their hearing. (OK, loud bass will not
normally do that, but if we are talking about flat output
then we are going to have to admit that frequencies above
the bass range will be equally loud, and those can harm
one's hearing.) Actually, I find car "hi-fi" to be an
oxymoron, because there is just no way to get "realistic"
musical sound from a motor vehicle that is generating road
and motor noise. Again, I say this as a baroque and
classical freak who likes quiet backgrounds underneath his
music.

OK, I am a fuddy duddy, but I must say that it mystifies me
that anyone would want 120-dB sounds in their cars or in
their home systems. However, I suppose that if someone wants
to have 120-dB bass at 15 Hz in their car or living room
they should go ahead and have it. Not my bag, but to be
truthful a lot of things that people do are not my bag.

Rather than
invest in a overkill subwoofer (as opposed to one that is just strong
and solid right down to 20 Hz or a tad below), perhaps the individual
should back off a bit and put their surplus cash into additional
recordings, a superior surround processor, or better satellite
speakers.

Fully agreed.

And I have to agree with you when it comes to individuals
who want to really pull out all the subwoofer stops.
However, I do not think that super-duper subwoofer
performance is particularly important when it comes to most
musical or home-theater situations. Actually, it almost
looks like an automotive horsepower race, rather than
something that relates to the accurate reproduction of
live-music-style sound.

Subwoofers are fine, and I would not do without one for a minute.
However, one can go a bit over the top, I think.

IMO there is no such thing as over-the-top for dynamic capability. If I have a
system that would produce 120 dB SPL+ (using 2 meters distance) over the
complete human sensory range in a very quiet room than you can play anything
from a soft breeze to a black powder cannon at reference level.

No doubt. However, the vast bulk of all recordings are not
in this category. I suppose for me the question involves
whether we are talking about an audio system as a musical
(or home-theater) reproducer or whether we are talking about
a device that is basically a sound-effects machine that
makes use of exotic recordings as source material.

OTOH if you are a person who has no recordings that ever approach dynamics
limits of the media than you only need the dynamic capability required of the
source material. But, I know of only a handful of DIY systems that have
anything that comes near to reproducing the true low frequency dynamics of
known commercially avaliable cds.

Again, there are commercially available CDs that are maybe
as you say, but I would guess that they are musical dead
ends - at least by my rarefied standards.

I mean, I have a copy of one or two Bass Mekanic discs that
certainly go low enough. (I got these to help me evaluate
subs and not to listen to for fun. Indeed, I would go out of
my mind if I had to listen to them for musical pleasure.)
Ironically, I had a buddy from out of town drop in some time
back and I put one of the discs on for him and he flipped
out. He went out and bought a copy (and probably purchased
other Mekanik discs, too, for all I know), and now he
listens to them for pleasure! He has a pair of Velodyne
HGS-15 subs, and I suppose they do the trick pretty good,
even if they will not go all the way to the bottom.

Takes all kinds.

Howard Ferstler