20Hz vs 32 Hz bottom end
jim and robin calderwood
solid output all the way down to 20Hz or can I save some amp power and just
go down to 32 Hz and have it not sound that different. Is it a night and
day difference or a pretty subtle difference between the two with hard rock
or techno music?
Thanks, Jim
Tim S Kemp
Hmmmmmmm (or Hum.... )
I had the chance to play a few years back with a Bose installation (802 /
AWC), the AWCs go *reallly* low. Awesome. Whether useful or not I didn't
have time to find out but they were awesome. All those subsonic trips from
bass synths... Awesome....
Denny Strauser
Keep in mind that a 4 string bass goes down to around 40hz & a five
string goes down close to 30hz.
If you use a dbx-120 to it's limits, you'll be lowering some program to
below 30hz.
Also keep in mind that if you're driving sub boxes below their cut-off
(cabinet tuning), you're likely to blow some drivers, if you push it
hard.
Denny Strauser
Rodney Phillips wrote:
>
> "jim and robin calderwood" <ca...@psnw.com> wrote in message
> news:d54a5.12421$L8.4...@east3.usenetserver.com...
> > I'm wondering if it is worth the expense of getting speakers capable of
> > solid output all the way down to 20Hz or can I save some amp power and
> just
> > go down to 32 Hz and have it not sound that different. Is it a night and
> > day difference or a pretty subtle difference between the two with hard
> rock
> > or techno music?
> > Thanks, Jim
> >
>
> IMO any efforts and/or funds expended in the quest of audio reproduction
> below 40Hz in a live rock show is wasted.
>
> Rodney
Denny Strauser
>
> > Keep in mind that a 4 string bass goes down to around 40hz & a five
> > string goes down close to 30hz.
> > If you use a dbx-120 to it's limits, you'll be lowering some program to
> > below 30hz.
>
A dbx 120-XP puts out 25hz - 50hz...
Denny Strauser
Rodney Phillips
Mike Borkhuis
> solid output all the way down to 20Hz or can I save some amp power and just
> go down to 32 Hz and have it not sound that different. Is it a night and
> day difference or a pretty subtle difference between the two with hard rock
> or techno music?
There are several of use here that employ the use of a 'sub-harmonic'
synthesizer. I've got a DBX 120X-DS. It generates tones in the 28-55hz range.
By NOT having a system that's capable of performing in the 25-30hz range, we are
not able to make full use of the sub-harmonic synths....
Course, if you're not using one, you will not need deep bass extension.
Course, you won't have bowl moving bass either... =)
Mike Borkhuis
Worship Technology
Mike Borkhuis
> string goes down close to 30hz.
> If you use a dbx-120 to it's limits, you'll be lowering some program to
> below 30hz.
28Hz per the manual that came with my DBX 120X-DS...
> Also keep in mind that if you're driving sub boxes below their cut-off
> (cabinet tuning), you're likely to blow some drivers, if you push it
> hard.
Assuming you're using a typical ported cabinet. If you're using something a
little more exotic, like EAW 940s (double 12" in a folded horn) or servodrives,
you'll won't have this problems.
Mike Borkhuis
Worchip Technology
David Shorter
> There are several of use here that employ the use of a 'sub-harmonic'
> synthesizer. I've got a DBX 120X-DS. It generates tones in the 28-55hz range.
> By NOT having a system that's capable of performing in the 25-30hz range, we are
> not able to make full use of the sub-harmonic synths....
> Course, if you're not using one, you will not need deep bass extension.
> Course, you won't have bowl moving bass either... =)
Mike,
You really will have to put a dampener on your eagerness when typing replies.
First your sing/sign typo and now you've done it again with bowl/bowel, although
it is possible to construe bowl as a porcelain receptacle that just might be moved
when deep bass extension requires its use. :-)
p.s. Please excuse the descent into scatological humour.
p.p.s. Don't bother checking, I've gone through my spelling with a fine tooth comb. :-)
--
Regards,
David Shorter
DazzReal Sound Labs
Auckland, New Zealand
Any errors in tact, fact or spelling
are entirely due to transmission error.
Keith Broughton
>day difference or a pretty subtle difference between the two with hard rock
>or techno music?
The difference is not night and day and it does take a lot of money to get a
system to do it properly.
Generally, you will find even a system that REALLY goes down to 35 htz flat
at high SPL is a bit unusual in the live PA field.
How much money do you want to spend?...:):):)
Mike Borkhuis
> First your sing/sign typo and now you've done it again with bowl/bowel,
although
> it is possible to construe bowl as a porcelain receptacle that just might be
moved
> when deep bass extension requires its use. :-)
That's what I get for trying to be a wise guy... And replying to messages
while experencing a lack of sleep... :P Not to mention the fact that I'm a
lousy speller....
> p.s. Please excuse the descent into scatological humour.
No problem.....
Mike Borkhuis
Worship Technology
Tim S Kemp
tooth comb. :-)
<pedant>
Fine toothed comb.
</pedant>
;-)
Phildo
Rodney Phillips <wha...@home.com> wrote in message
news:Z6aa5.45092$Yr4.8...@news1.rdc1.tn.home.com...
> IMO any efforts and/or funds expended in the quest of audio reproduction
> below 40Hz in a live rock show is wasted.
>
but still keep the impression of it being really loud and powerful which in
turns saves you7r ears and those of the audience. Try using a dbx120DS
though a real sound system and you'll soon change your mind.
Phildo
Denny Strauser
>
> "Phildo" <LAMS...@pacbell.removethisbit.net> wrote in message
> > Fool. The lower you can go the better. Allows you to bring the volume down
> > but still keep the impression of it being really loud and powerful which
> in
> > turns saves you7r ears and those of the audience. Try using a dbx120DS
> > though a real sound system and you'll soon change your mind.
> > Phildo
> Dickhead. If you wish to trade insults like a child, then just stomp your
> feet, throw your toys and hurl away. If you want to debate an opinion like
> an adult then give that a shot if you can.
Fool....Dickhead.....?
Who is the SSSS-hole here? Take your pick. I really don't care.
> At 20 Hz, A-weighting correction is -50.5 dB
> At 25 Hz it is -44.7 dB
> At 31.5 it's -39.4 dB
> At 40 Hz it is -34.6 dB
I suggest you throw your SPL meter (and your stats) in the trash and
actually listen to the music.
Does that mean that your sound system should disregard the inefficient
area of the sound spectrum?
Maybe we should just try to reproduce the efficient range of 100hz to
8khz.
I think not.
> Conventional 18" front-loaded speakers are already starting to roll-off at
> 40 Hz. If you start wasting your available power into those speakers at 25
> Hz all your doing is wasting power and generating heat. The difference
> between a human's auditory response at 40 Hz as opposed to 25 Hz is 10 dB,
> or what a human will perceive as twice as loud. At 20 Hz it's almost a 20
> dB difference.
Agreed, if your subs roll off at 40hz, you're wasting power (and likely
to blow drivers) if you try to drive lower frequencies.
But that wasn't the initial question.
What if there is a 5 string bass in the band...should the fundamental of
the open "B string" be compromised because the sound system isn't
designed to reproduce 31-32hz?
Not with a PRO sound system.
What if there is a synth that puts out a 25hz fundamental?
Should it just be ignored?
> Try reading the original post for a change. The poster stated "solid output
> down to 20 Hz". Now to me that means just what it says. It would be a
> waste of money to attempt to get a system together that will be reasonably
> "solid" down to 20 Hz. No reason to waste money toward that end.
I guess if you don't care about sound quality as much as
efficiency.....SURE....
> It can be
> better spent somewhere else. If he's got money to blow, then fine. He can
> go and get himself a load of servo-drives and have fun with them, maybe. I
> don't get the impression from most folks that frequent this newsgroup that
> they have money to toss into the wind.
> Rodney
If you buy the cheap Lo-Fi stuff, you're tossing money into the wind.
Buy quality gear and you're making a real investment that will pay off.
Maybe you're just feeling guilty and defensive about owning the cheap
stuff.
Why are you so defensive and offended about an honest response?
Maybe Phildo shouldn't have said "Fool"
Maybe you shouldn't have said "Dickhead"
Maybe you should care more about quality than effiency.
Then again, maybe your clients care more about volume than accuracy.
I, for one, want to hear the fundamentals at least as loud as the
overtones.
Then again, I believe that most people can't tell the difference between
good sound & LOUD sound.
Go ahead and roll your system off at 40hz, but don't try to convince us
that it's the right thing to do.
Denny Strauser
Denny Strauser
>
> "Denny Strauser" <no...@stargate.net> wrote in message
> news:39693A4E...@stargate.net...
> > It depends what you want to do.
> >
> > string goes down close to 30hz.
> > If you use a dbx-120 to it's limits, you'll be lowering some program to
> > below 30hz.
> > (cabinet tuning), you're likely to blow some drivers, if you push it
> > hard.
> >
> -snip-
>
> My point exactly.
I doubt it, I couldn't disagree with you more.
> Why spend money chasing the extremes of the audio
> spectrum.
It sounds like you'd be happy with a bunch of Peavey SP2's and some
Radio Shack mics.
> There is little program material in that range of frequencies.
> IMO the available power is better spent elsewhere. Same goes for the
> high-end. Just because someone can generate frequency content beyond what
> we can hear does it make sense to try and reproduce it?
>
> Rodney
It sounds like you just don't care about quality.
More power to you, but don't try to convince others that efficiency is
more important than quality.
It isn't so.
Denny Strauser
Denny Strauser
> Mike,
> We've gone through this before, quite recently actually.
> Although the "C" curve may seem to be the one to use when the volume is high,
> what you end up doing is effectively robbing yourself of usable bottom end level.
> Most local authority requirements for sound levels refer to the "A" curve and
> that is what the noise police will use if making an objective rather than the usually
> worthless but enforceable subjective assessment they often use.
We HAVE gone through this before.
And I repeat:
The noise code MAY refer to "A" scale (and is very likely to not refer
to any scale), but the local police who enforce the law don't have a
clue.
The "noise police" (who usually don't know the difference between "A" &
"C" scales) tend to use the setting which gives them the highest reading
- "C" scale.
Denny Strauser
Rodney Phillips
>
> Rodney Phillips <wha...@home.com> wrote in message
> news:Z6aa5.45092$Yr4.8...@news1.rdc1.tn.home.com...
> > IMO any efforts and/or funds expended in the quest of audio reproduction
> > below 40Hz in a live rock show is wasted.
> >
> but still keep the impression of it being really loud and powerful which
in
> turns saves you7r ears and those of the audience. Try using a dbx120DS
> though a real sound system and you'll soon change your mind.
>
> Phildo
>
>
Dickhead. If you wish to trade insults like a child, then just stomp your
feet, throw your toys and hurl away. If you want to debate an opinion like
an adult then give that a shot if you can.
At 20 Hz, A-weighting correction is -50.5 dB
At 25 Hz it is -44.7 dB
At 31.5 it's -39.4 dB
At 40 Hz it is -34.6 dB
Conventional 18" front-loaded speakers are already starting to roll-off at
40 Hz. If you start wasting your available power into those speakers at 25
Hz all your doing is wasting power and generating heat. The difference
between a human's auditory response at 40 Hz as opposed to 25 Hz is 10 dB,
or what a human will perceive as twice as loud. At 20 Hz it's almost a 20
dB difference.
Try reading the original post for a change. The poster stated "solid output
down to 20 Hz". Now to me that means just what it says. It would be a
waste of money to attempt to get a system together that will be reasonably
"solid" down to 20 Hz. No reason to waste money toward that end. It can be
Rodney Phillips
"Denny Strauser" <no...@stargate.net> wrote in message
news:39693A4E...@stargate.net...
> It depends what you want to do.
>
> Keep in mind that a 4 string bass goes down to around 40hz & a five
> string goes down close to 30hz.
> If you use a dbx-120 to it's limits, you'll be lowering some program to
> below 30hz.
> Also keep in mind that if you're driving sub boxes below their cut-off
> (cabinet tuning), you're likely to blow some drivers, if you push it
> hard.
>
> Denny Strauser
-snip-
My point exactly. Why spend money chasing the extremes of the audio
spectrum. There is little program material in that range of frequencies.
Mike Borkhuis
> At 25 Hz it is -44.7 dB
> At 31.5 it's -39.4 dB
> At 40 Hz it is -34.6 dB
Last time I checked, the A weighted scale was for lower volumes... 80dB and
under. For concert type volumes, try the C weighted one.
>Conventional 18" front-loaded speakers are already starting to
> roll-off at 40 Hz. If you start wasting your available power into
> those speakers at 25Hz all your doing is wasting power and
> generating heat.
To some degree yes... On the other hand, you will still get output from the
subs. It's a matter of system design choices. Obviously, if you're not running
material and/or FX that need extended low freqs, then don't build your system to
produce them.
Mike Borkhuis
Worship Technology
David Shorter
> Last time I checked, the A weighted scale was for lower volumes... 80dB and
> under. For concert type volumes, try the C weighted one.
Mike,
We've gone through this before, quite recently actually.
Although the "C" curve may seem to be the one to use when the volume is high,
what you end up doing is effectively robbing yourself of usable bottom end level.
Most local authority requirements for sound levels refer to the "A" curve and
that is what the noise police will use if making an objective rather than the usually
worthless but enforceable subjective assessment they often use.
--
Rodney Phillips
"Mike Borkhuis" <bork...@rochester.rr.com> wrote in message
news:tlva5.1309$PD4....@typhoon.nyroc.rr.com...
> > At 20 Hz, A-weighting correction is -50.5 dB
> > At 25 Hz it is -44.7 dB
> > At 31.5 it's -39.4 dB
> > At 40 Hz it is -34.6 dB
>
80dB and
> under. For concert type volumes, try the C weighted one.
>
>
> Mike Borkhuis
> Worship Technology
>
Let's go to the Equal-Loudness Contours for a pure tone in a free-field. I
am taking these values from contours on a graph, so there may be some room
for interpretation of the graph but I am making a best effort.
For the 70 Phons contour: at 40 Hz, 90 dB; at 20 Hz, 108 dB
For the 80 Phons contour: at 40 Hz, 97 dB; at 20 Hz 114 dB
For the 90 Phons contour: at 40 Hz, 104 dB; at 20 Hz 120 dB
For the 100 Phons contour: at 40 Hz, 113 dB; at 20 Hz, 128 dB
For the 110 Phons contour: at 40 Hz, 122 dB; at 20 Hz, 136 dB
Not too much difference between the levels. Perception does not change that
drastically in this range. It changes some, but not a big amount.
Don't be too impressed with "concert type" SPL amplitudes. You rarely see
an honest depiction of the true time-weighted SPL of a concert. It would be
rare that they would exceed 105 dBL.
Rodney
Rodney Phillips
> Rodney Phillips wrote:
> >
> > "Denny Strauser" <no...@stargate.net> wrote in message
> > news:39693A4E...@stargate.net...
> > > It depends what you want to do.
> > >
> > > Keep in mind that a 4 string bass goes down to around 40hz & a five
> > > string goes down close to 30hz.
> > > If you use a dbx-120 to it's limits, you'll be lowering some program
to
> > > below 30hz.
> > > Also keep in mind that if you're driving sub boxes below their cut-off
> > > (cabinet tuning), you're likely to blow some drivers, if you push it
> > > hard.
> > >
> > > Denny Strauser
> > -snip-
> >
> > My point exactly.
>
>
> > spectrum.
>
> Radio Shack mics.
>
You have no concept of what you are speaking. You haven't a clue as to the
type of equipment that I use or have used. I deal with higher SPL's and
lower frequencies than you will likely ever experience. Don't believe
everything that you see in a brochure. It ain't all true.
Rodney
Rodney Phillips
> Rodney Phillips wrote:
-snip-
>
> If you buy the cheap Lo-Fi stuff, you're tossing money into the wind.
> Buy quality gear and you're making a real investment that will pay off.
This is almost funny.
> Maybe you're just feeling guilty and defensive about owning the cheap
> stuff.
> Why are you so defensive and offended about an honest response?
> Maybe Phildo shouldn't have said "Fool"
> Maybe you shouldn't have said "Dickhead"
> Maybe you should care more about quality than effiency.
> Then again, maybe your clients care more about volume than accuracy.
>
> I, for one, want to hear the fundamentals at least as loud as the
> overtones.
> Then again, I believe that most people can't tell the difference between
> good sound & LOUD sound.
That's the one statement that I agree with.
> Go ahead and roll your system off at 40hz, but don't try to convince us
> that it's the right thing to do.
>
> Denny Strauser
I don't remember trying to convince you of anything. I was replying to a
poster who sought advise. If you disagree, that's fine. It's obvious that
we will not agree on this subject so no use wasting more bandwidth.
Rodney
David Shorter
> We HAVE gone through this before.
> And I repeat:
> The noise code MAY refer to "A" scale (and is very likely to not refer
> to any scale), but the local police who enforce the law don't have a
> clue.
> The "noise police" (who usually don't know the difference between "A" &
> "C" scales) tend to use the setting which gives them the highest reading
> - "C" scale.
>
> Denny Strauser
That's your noise police, not my noise police.
Key Audio (Kenneth Kareta)
I think You've made the best point here ...
If You're building a system for voice only reproduction,
a flat response down to 20 Hz is a serious waste of wattage.
However,
If You're building a system for the next "Lil' Kim" or electronica tour,
then, a flat response down to 20 Hz, might be a consideration.
If Your running an all purpose local system, it would be in Your wallets best
interest,
to build to a happy medium, that may not be *flat* down to 20 Hz,
but can push enough air to shake your average clients room.
--
Ken Kareta, Owns,.
Key Audio Services
Rodney Phillips
> David Shorter wrote:
> We HAVE gone through this before.
> And I repeat:
> The noise code MAY refer to "A" scale (and is very likely to not refer
> to any scale), but the local police who enforce the law don't have a
> clue.
> The "noise police" (who usually don't know the difference between "A" &
> "C" scales) tend to use the setting which gives them the highest reading
> - "C" scale.
>
> Denny Strauser
Refer to my post about the equal-loudness contours.
Rodney
Matt Stoody
A-weighting because they don't know any better.
MFS
David Shorter wrote:
>
\> Most local authority requirements for sound levels refer to the "A"
curve and
> that is what the noise police will use if making an objective rather than the usually
> worthless but enforceable subjective assessment they often use.
>
Phildo
> Dickhead. If you wish to trade insults like a child, then just stomp your
> feet, throw your toys and hurl away. If you want to debate an opinion
like
> an adult then give that a shot if you can.
>
capable of producing a powerful low end down to the lowest frequency that is
being fed through it. My dbx120 and the bass players low B string certainly
need that power in the low end.
One of my pet hates is seeing a house graphic with all the low end cut. I
prefer to give the audience an impression of power and volume by making them
feel the music instead of blasting their hearing away by just increasing the
rest of the frequency spectrum and not using the system to its full
potential. IMHO it's worth going down to 20Hz because any increase in the
low end gives you more to work with. It's difficult to explain but since I
started using the dbx120 I've been able to get more out of systems and make
them come to life simply by adding that low end. It allows the subs to work
more efficiently since they don't have to produce so much 80-125Hz wooliness
which normally passes for low end making for a cleaner, more powerful sound
which keeps the audiences hearing intact (pity you can't say the same for
their bowels). Until you've had experience with the 120DS and a system with
decent subs it sounds crazy but trust me, once you do you'll understand why
I got so riled when you replied to the post and called you a fool. You can
never have too much low end at your disposal and the lower you can go the
better.
Phildo
Rodney Phillips
>
> Rodney Phillips <wha...@home.com> wrote in message
> news:lXua5.46685$Yr4.8...@news1.rdc1.tn.home.com...
> > Dickhead. If you wish to trade insults like a child, then just stomp
your
> > feet, throw your toys and hurl away. If you want to debate an opinion
> like
> > an adult then give that a shot if you can.
> >
> OK I apologise for the "fool" part but I still say a system should be
> capable of producing a powerful low end down to the lowest frequency that
is
> being fed through it. My dbx120 and the bass players low B string
certainly
> need that power in the low end.
>
Let me clarify one thing. I don't propose filtering the signal at 40 Hz
unless it's causing me a problem with the subs. I would just prefer to let
the system take care of that itself as most systems that I have used were
running double 18's for the subs. They will take care of the roll-off
nicely. Setting a high-pass filter at 40 Hz would be a mistake. I might
roll it at 31.5, but it would depend on how the system was responding. One
must remember that the 40 Hz would be the -3dB point, not where the roll
starts. My point is, most (not all) audio reproduction gear sucks below 40
Hz, at least it has little power capability down there. There is also
little program material down there, so I would not suggest to anyone that
they spend a lot of cash to try and attain a "solid" response down to 20 Hz
because it will require quite a bit of effort. I would rather concentrate
on the frequencies that the speakers can produce well. There is also an
issue with the auditory perception of sounds at 20 Hz as opposed to 40 Hz
and higher, which is why I posted the equal-loudness data. It will take a
lot of power at 20 Hz to get any benefit.
Rodney
John Halliburton
> IMO any efforts and/or funds expended in the quest of audio reproduction
> below 40Hz in a live rock show is wasted.
>
Hmmmm, so let's say any one using five string bass', synths, organs, etc. in a live
rockshow don't matter? Having just seen Tony Levin and band(including Larry Fast,
Jerry
Marotta, and Jesse Gresse) I would have to disagree-again. The dynamics of a full
range sound system capable of reproducing clean bass below 30hz are so much more
satisfying and to me, realistic, that I really find this "nothing below Xhz is
necessary"
argument short sighted. One of the main reasons this arguement started years ago
was that
nobody had product that could go below 50hz in a PA setting.
Mike Borkhuis wrote:Mike makes a very good point regarding the sub harmonic synths,
which I have experimentedaround with and think they have a valid use-if you don't
have speakers capable of using the extra
low freq. generated by the synth, you are wasting the potential.
Now, about that bowl rattling bass, you meant bowel, right?
Best Regards,
John Halliburton
Servodrive, Inc.
www.servodrive.com
John Halliburton
Keith Broughton wrote:
> The difference is not night and day and it does take a lot of money to get a
> system to do it properly.
>
> Generally, you will find even a system that REALLY goes down to 35 htz flat
> at high SPL is a bit unusual in the live PA field.
Well, anyone with Servodrive subwoofers can do 28hz with no problem.
> How much money do you want to spend?...:):):)
Another point, having really good low frequency response in a system can
actually "sound" louder(fuller, more dynamic sound) than without.
John Halliburton
>
> My point exactly. Why spend money chasing the extremes of the audio
> spectrum. There is little program material in that range of frequencies.
> IMO the available power is better spent elsewhere. Same goes for the
> high-end. Just because someone can generate frequency content beyond what
> we can hear does it make sense to try and reproduce it?
Well, Dolby for one had a paper a number of years ago regarding sound quality
with
greater bass extension in the sound system, concluding that it was very
beneficial.
We have always found that sound systems with our product sound much better,
and as
Phildo points out too, it doesn't have to be driven as loud to sound that way.
BTW, the A weighting corrections you present should be a clear sign that
having good subs
in a sound system makes all the difference. Since they follow the human ear's
loss of sensitivety
to lower frequencies, having more reproducers to make up for it only makes
sense.
Denny Strauser
It does cost considerably more to provide good quality sound down to
20hz.
On the other hand, many bands these days have 5 string basses that go
down to 31-32hz.
It is probably expecting too much to ask for a system that puts out
20hz; but 30hz seems to be a realistic goal, these days.
At the same time, unless a bass player has an SWR rig or a Bag End rig
w/ ELF processor, he probably doesn't even know what the open B string
fundamental on a 5 string bass should sound like.
I've found this to be the case, more often than not.
If you have had the pleasure of hearing the Ultra Sound/Meyers/Grateful
Dead sound system, you know how much difference that "extra mile" can
make.
That system went down to 5hz, and could put out 120db of 20hz at 100
feet. Serious bass.
If you read the Aug '93 (?) article in "Pro Sound News" or the "Absolute
Sound" article on Dan Healy & Grateful Dead sound (somewhere between '90
& '92 ?) you'll recall that they said something to the effect that it
was the best sound system that ever was - and maybe that ever will be.
I've seen about 25 GD shows, and the sound never ceased to AMAZE me;
even when the band sucked.
At stadium shows, they stacked the 2x18" Meyers subs 1-wide & 14-high -
and even tilted the stack back at some shows to direct the sound to the
upper levels.
That's an array of about 22" (W) by 50' (H).
That would give you horizontal dispersion control down to frequencies
that most sound systems only dream of.
They also eliminated all capacitors in the signal path to preserve phase
coherence (and HARD WIRED all mics).
If you put a DC into a channel strip, the only thing protecting the
speakers was the processor that "knew" the long term & short term heat
dissipation of the speakers, and the maximum excursion of the drivers -
and would attenuate the amp inputs until the drivers were not asked to
do what they were not capable of doing.
Maybe that was a little (to say the least) overkill for most situations,
but if you ever heard this system, you know the difference between
outstanding and excellent.
I'm not going to try and tell anyone what is "right", but that "extra
mile" clearly separates the great from the best.
It's up to each of us to decide what is "worth it".
Denny Strauser
John Halliburton wrote:
>
> Keith Broughton wrote:
>
> > The difference is not night and day and it does take a lot of money to get a
> > system to do it properly.
> >
> > Generally, you will find even a system that REALLY goes down to 35 htz flat
> > at high SPL is a bit unusual in the live PA field.
>
> Well, anyone with Servodrive subwoofers can do 28hz with no problem.
>
> > How much money do you want to spend?...:):):)
>
> Another point, having really good low frequency response in a system can
> actually "sound" louder(fuller, more dynamic sound) than without.
>
Rodney Phillips
"John Halliburton" <byk...@interaccess.com> wrote in message
news:396E78D0...@interaccess.com...
>
>
> Keith Broughton wrote:
>
> > The difference is not night and day and it does take a lot of money to
get a
> > system to do it properly.
> >
> > Generally, you will find even a system that REALLY goes down to 35 htz
flat
> > at high SPL is a bit unusual in the live PA field.
>
> Well, anyone with Servodrive subwoofers can do 28hz with no problem.
I don't want to put your product down, but in all the years I worked with
audio systems I encountered 1 system that was using the product.
Rodney
Rodney Phillips
> >
> >
> > My point exactly. Why spend money chasing the extremes of the audio
> > spectrum. There is little program material in that range of
frequencies.
> > IMO the available power is better spent elsewhere. Same goes for the
> > high-end. Just because someone can generate frequency content beyond
what
> > we can hear does it make sense to try and reproduce it?
>
>
>
> Well, Dolby for one had a paper a number of years ago regarding sound
quality
> with
> greater bass extension in the sound system, concluding that it was very
> beneficial.
> We have always found that sound systems with our product sound much
better,
> and as
> Phildo points out too, it doesn't have to be driven as loud to sound that
way.
I'm very surprised that you feel a system with your speakers sounds better.
To me it's a supply and demand issue. In all the years that I have been
around any audio shows, both as a paying customer and worker I have not once
heard anyone say "Man, that would have sounded so much better if the
low-frequency extended down to 20 Hz instead of 40 Hz." Matter of fact, I
never once thought that myself.
>
> BTW, the A weighting corrections you present should be a clear sign that
> having good subs
> in a sound system makes all the difference. Since they follow the human
ear's
> loss of sensitivety
> to lower frequencies, having more reproducers to make up for it only makes
> sense.
My point was and is that is requires much more equipment to accommodate a
frequency range down to 20 Hz, which is directly proportional to the drain
on a contractor's finances. Most audio contractors that I have seen doing
the regional type shows could spend $40,000 much better than chasing a 20 Hz
lower end. Let's face it, I don't see a lot of posts here from DB, Clair or
Showco. I don't get the idea that most folks here have money to burn.
Rodney
Rodney Phillips
> Rodney said:
>
> > IMO any efforts and/or funds expended in the quest of audio reproduction
> > below 40Hz in a live rock show is wasted.
> >
> Hmmmm, so let's say any one using five string bass', synths, organs, etc.
in a live
> rockshow don't matter? Having just seen Tony Levin and band(including
Larry Fast,
> Jerry
> Marotta, and Jesse Gresse) I would have to disagree-again.
So, if Larry or Jerry or whoever decides to bring a Wavetek to the venue and
start pumping out 12 Hz sinewaves then what does someone do? Call Wyle Labs
and order up a WAS-3000 and a compressor? Now, that would indeed rattle
some bowels.
>The dynamics of a full
> range sound system capable of reproducing clean bass below 30hz are so
much more
> satisfying and to me, realistic, that I really find this "nothing below
Xhz is
> necessary"
> argument short sighted.
To each his own. I just don't see it as a demand of the fan base or
promoters. If it was, I suspect that more systems would accommodate it.
Rodney
Dave Nicholas
that!!!!
As for the low B on a bass it is 38Hz... That is damn low.
Dave
Rodney Phillips
> I can see both sides of the argument.
> It does cost considerably more to provide good quality sound down to
> 20hz.
> On the other hand, many bands these days have 5 string basses that go
> down to 31-32hz.
> It is probably expecting too much to ask for a system that puts out
> 20hz; but 30hz seems to be a realistic goal, these days.
> At the same time, unless a bass player has an SWR rig or a Bag End rig
> w/ ELF processor, he probably doesn't even know what the open B string
> fundamental on a 5 string bass should sound like.
> I've found this to be the case, more often than not.
I can also, although it may not seem so. John mentioned some paper that
stated that a system with the extra response was more satisfying to listen
to. I would imagime that most of us could listen to two systems
side-by-side and would probably prefer the system with the little bit of
low-frequency extension provided that right pieces of music were played.
But, is it worth the extra money to the contractor and does it provide any
return on his investment?
-snip-
> I'm not going to try and tell anyone what is "right", but that "extra
> mile" clearly separates the great from the best.
> It's up to each of us to decide what is "worth it".
>
> Denny Strauser
>
Clearly, this is true. It's up to each individual to weigh his investment
versus the return he may realize.
Rodney
George Gleason
> Dave& denny, As a veteran of 130 some GD showsI can say the was amazing
(esp the low end) it was weird when they would start vibrating to building
its self and phil/dan/mickey(not sure where it came from) would find a
sympathetic vibration and the entire structure would throb.
That aside I would not hold the GD and esp Dan up to any other sound
yardstick dan had a uneven mix harsh some nights flat others muddy lots
of the time. He was always adding his own "personality" to the mix and in
the early 90s got his ass fired. it often took him 45 minutes or more to
tune in the system.
If you want to talk QUALITY you need go no further than Pink Floyds
Division Bell tour.
I was so dissapointed when It was announced they were to play the
Carrier Dome(site of the worst sound I have ever heard time and time again)
I thought that It was "the dome" and nothing could be done to get good
sound. After all if the Dead couldn't get a good sound in there who could?
Well It was amazing every seat crystal clear tight punchy bass
absoutly the best sound I had ever heard ANYWHERE for a major rock show.
After that show I felt cheated when I bought a ticket and what ever
sound company couldn't deliver that"sound". I always felt the(a) the room
was able to prevent great sound,but after Pink Floyd I knew that ANY room
can sound like studio headphones if the sound company has the right tools
and cares about what it does.
So when we as PROs cry about tough rooms.There are few tougher then
Syracuse own Carrier Dome and Turbosound flashlight in the hands of (Brit
row I think) proved that the room can be turd but it can be polished if you
got the right stuff.
George
Phildo
Dave Nicholas <dn...@home.com> wrote in message
news:IIxb5.11249$8u4.1...@news1.rdc1.bc.home.com...
> My God 5hz!!!!! holy shit!! at that freq, you don't hear that you feel
> that!!!!
>
OK, I'm the sort of engineer that likes to make the front row require
nappies (diapers for you Americans) but a system like that frightens me [1}
Phildo
[1] yet somehow turns me on - god I need help!!! :>)
Mike Borkhuis
> frequency range down to 20 Hz, which is directly proportional to the drain
> on a contractor's finances.
Hmmm... Let's think about that for a sec....
The Servodrive subs (horn loaded double 15"s) are more efficient than a
normal double 18". Using less power to produce more output over a larger
frequency range. Per their info on their site, you'll run 4 of their boxes
(with less power) compared to 9 double 18"s. That's less equipment (speakers
and amps) to provide the same volume with extended bass responce.
Now, take Shaun's beloved KF940s. Again, an efficient speaker (horn loaded
double 12"s) that offers extended bass responce using less power. I've
seen/heard 12 of these (6 per side) provide enough bass to fill a stadium.
Again, that's less equipment (speakers and amps) to provide the same sound with
extended bass responce.
Now it would seem that both of these setups would provide a system designer
with a setup that provides deep bottom octave responce while using less gear
(costing less) than a 'normal' setup using the 'mandatory' stacks of double
18"s....
- Disclaimer: I'm not a very experenced person with all this... I've only
been doing sound for about 2 years... SO, my info might not be accurate, feel
free to correct it (and me) accordingly.
Mike Borkhuis
Worship Technology
Mike Borkhuis
> sub harmonic synths, which I have experimentedaround with and
> think they have a valid use-if you don't have speakers capable of
> using the extra low freq. generated by the synth, you are wasting
> the potential.
>
> Now, about that bowl rattling bass, you meant bowel, right?
Yup... That should have been bowel... Me and my lousy spelling... :P
Course, if you can move a bowel, you should be able to move a bowl too... ;)
Mike Borkhuis
Worship Technology
Phildo
> I'm very surprised that you feel a system with your speakers sounds
better.
> To me it's a supply and demand issue. In all the years that I have been
> around any audio shows, both as a paying customer and worker I have not
once
> heard anyone say "Man, that would have sounded so much better if the
> low-frequency extended down to 20 Hz instead of 40 Hz." Matter of fact, I
> never once thought that myself.
That's because they or you have mever experienced a system that will go that
low. Once you've experienced one that is set up and run properly you'll
understand.
> My point was and is that is requires much more equipment to accommodate a
> frequency range down to 20 Hz, which is directly proportional to the drain
> on a contractor's finances. Most audio contractors that I have seen doing
> the regional type shows could spend $40,000 much better than chasing a 20
Hz
> lower end. Let's face it, I don't see a lot of posts here from DB, Clair
or
> Showco. I don't get the idea that most folks here have money to burn.
Yes it can cost more but if you can afford it then it's well worth it. It
does need more power but you don't have to put out so much in the low mids
to give the impression of bass when you have the real thing available. As
I've said if you've never had it you won't miss it.
Phildo
Mike Borkhuis
> Syracuse own Carrier Dome and Turbosound flashlight in the hands of (Brit
> row I think) proved that the room can be turd but it can be polished if you
> got the right stuff.
That's one thing I actually like about having a church background... Church
sanctuaries (most of them anyways) were not designed for PAs... The usually have
a sound/effect like the carrier dome's. The advantage comes in the fact that
most rooms I go into now are easier than what I usually do.
Most guys come at it from the opposite side.... Doing either outdoor or
theater/auditorium type stuff. It's much easier to go from tough rooms to easy
Vs easy to tough.
Mike Borkhuis
Worship Technology
Phildo
George Gleason <g.p.g...@worldnet.att.net> wrote in message
news:2DCb5.3553$tI4.2...@bgtnsc05-news.ops.worldnet.att.net...
> If you want to talk QUALITY you need go no further than Pink Floyds
> Division Bell tour.
> I was so dissapointed when It was announced they were to play the
> Carrier Dome(site of the worst sound I have ever heard time and time
again)
> I thought that It was "the dome" and nothing could be done to get good
> sound. After all if the Dead couldn't get a good sound in there who could?
> Well It was amazing every seat crystal clear tight punchy bass
> absoutly the best sound I had ever heard ANYWHERE for a major rock show.
That's a properly set up flashlight system for you. having it in quad just
made it better. It's one of the best I ever heard with only a VDOSC powered
show for competition.
>There are few tougher then
> Syracuse own Carrier Dome and Turbosound flashlight in the hands of (Brit
> row I think)
Yep - Brit Row it was. Andy Jackson at FOH (which caused a few
misunderstandings since BRP had a trainee in the warehouse with the same
name), can't remember the monitor guy, 5 desks on the tour (2 FOH, 2 Mons
and the quad), lost an XL3 to 20 gallons of water at Modena (Italy), the
first gig at Earl's Court in London a load of bleachers collapsed during the
intro (which lead to "pulse" having the alternative title of "A momentary
collapse of seating") - hell, I could go on for ages about that tour. Brit
Row flew loads of people to Paris for the 25th anniversary show and the last
night at Earl's Court with the ensuing party would be a night you'd never
forget except I got so drunk I can't remember much :>(
Phildo
Rodney Phillips
> > My point was and is that is requires much more equipment to accommodate
a
> > frequency range down to 20 Hz, which is directly proportional to the
drain
> > on a contractor's finances.
>
> The Servodrive subs (horn loaded double 15"s) are more efficient than
a
> normal double 18". Using less power to produce more output over a larger
> frequency range. Per their info on their site, you'll run 4 of their
boxes
> (with less power) compared to 9 double 18"s. That's less equipment
(speakers
> and amps) to provide the same volume with extended bass responce.
I have never seen the servos as replacements for 18's or 15's but as
compliments to them. It would depend on your system configuration, but I
can't see them in a role serving the entire low-frequency end. Maybe it's
because I have never seen it done. Might work, but I would have to see and
hear it.
> Now, take Shaun's beloved KF940s. Again, an efficient speaker (horn
loaded
> double 12"s) that offers extended bass responce using less power. I've
> seen/heard 12 of these (6 per side) provide enough bass to fill a stadium.
> Again, that's less equipment (speakers and amps) to provide the same sound
with
> extended bass responce.
I have not heard the KF940's. I assume that these are the boxes that
require a 25 Hz high-pass filter be used with. According to their
literature the response of an array of four will be down 10 dB at 21 Hz.
That 20 Hz is hard to come by.
> Now it would seem that both of these setups would provide a system
designer
> with a setup that provides deep bottom octave responce while using less
gear
> (costing less) than a 'normal' setup using the 'mandatory' stacks of
double
> 18"s....
>
Would be nice if it would work out that way. Maybe with some combination of
boxes and subs it will.
Rodney
John Halliburton
> frequency range down to 20 Hz, which is directly proportional to the drain
> the regional type shows could spend $40,000 much better than chasing a 20 Hz
> lower end. Let's face it, I don't see a lot of posts here from DB, Clair or
> Showco. I don't get the idea that most folks here have money to burn.
>
> our products too. Chasing a 20hz Holy Grail isn't what I am recommending,
> budget always
gets in the way, but I have seen a lot of people who don't spend the money to
buy the best
loudspeakers they can afford(old rule of thumb, put the lion's share of your
budget in transducers,
they do the hardest jobs) and it shows. It doesn't have to be our product
necessarily either(just
my biased preference), just that when someone has put together a system with
enough clean
low frequency output, it almost always sounds better.
Best Regards,
John
John Halliburton
>
> I can also, although it may not seem so. John mentioned some paper that
> stated that a system with the extra response was more satisfying to listen
> to. I would imagime that most of us could listen to two systems
> side-by-side and would probably prefer the system with the little bit of
> low-frequency extension provided that right pieces of music were played.
> But, is it worth the extra money to the contractor and does it provide any
> return on his investment?
I understand your point, but I don't think we were debating the business
aspects as much
as performance issues. Personally, I think it is worth it if the use of the
particular system
involvers full range reproduction of sound. Seems to me that it could be an
extra profit center
to the installer if they can demonstrate the improved sound quality offered by
having good subs
installed with the rest of the system.
Best Regards,
John
www.servodrive.com
John Halliburton
Phildo wrote:
> > My God 5hz!!!!! holy shit!! at that freq, you don't hear that you feel
> > that!!!!
> >
> Where can I get one of these !?!?!?!?!?!?!? :>)
I'll check and see if we can still put together a sonic boom simulator system
similar
to the one done for Georgia Tech a few years ago. Repsonse to 3hz. Threshold
level at 3hz for humans
is about 120db. The 3hz sub boxes had 5hp blowers to move enough air. S/N
ratio
wasn't great for audio work though, but when you have a system that uses
Basstech 7
subs as "Mid bass" cabinets...
Then of course there was the other end of the spectrum, using ultrasonic energy
to levitate
materials for containerless processing in space. Enough spl at 21khz to ignite
a cigarette from
the air friction.
Best Regards,
John Halliburton
www.servodrive.com
>
David Shorter
> Yep - Brit Row it was. Andy Jackson at FOH (which caused a few
> misunderstandings since BRP had a trainee in the warehouse with the same
> name), can't remember the monitor guy, 5 desks on the tour (2 FOH, 2 Mons
> and the quad), lost an XL3 to 20 gallons of water at Modena (Italy), the
> first gig at Earl's Court in London a load of bleachers collapsed during the
> intro (which lead to "pulse" having the alternative title of "A momentary
> collapse of seating") - hell, I could go on for ages about that tour. Brit
> Row flew loads of people to Paris for the 25th anniversary show and the last
> night at Earl's Court with the ensuing party would be a night you'd never
> forget except I got so drunk I can't remember much :>(
Phil,
Do you know Sarne Thorogood, he was one of the audio engineers on the Division Bell
tour? Last time I saw him he was with the Chemical Brothers.
Phildo
David Shorter <dazz...@ihug.co.nz> wrote in message
news:396FF108...@ihug.co.nz...
> Do you know Sarne Thorogood, he was one of the audio engineers on the
Division Bell
> tour? Last time I saw him he was with the Chemical Brothers.
>
Phildo
Rodney Phillips
Now, that I can agree with. I agree with buying good transducers because
they have the toughest job in the system. I hate cheap speakers almost as
much as cheap wine. I would also make sure that I put an appropriate amount
into the FOH desk for the shows that I was going after. Some items are just
purely expenses and some are investments. Make the investments good ones.
Rodney
Rodney Phillips
>
> I understand your point, but I don't think we were debating the business
> aspects as much
> as performance issues.
My point is more from the business end of the spectrum and the return on
what you invest. If someone has the funds to spend and it doesn't hurt his
bottom line, then sure why not. If the contractor is making an informed
purchase and is willing to spend the money to chase that last octave then
I'll be glad to listen to the result. But, I would make sure that all of my
other bases were covered like microphone selection, FOH mixer, necessary
effects, great monitors, etc.
>Personally, I think it is worth it if the use of the
> particular system
> involvers full range reproduction of sound. Seems to me that it could be
an
> extra profit center
> to the installer if they can demonstrate the improved sound quality
offered by
> having good subs
> installed with the rest of the system.
>
> Best Regards,
> John
> www.servodrive.com
>
If they can support themselves fiscally, even at a break-even, then that's
great and at that point it becomes worth the expense. From what my exposure
has been, the promoters are most interested in cost/deliverable when hiring
a contractor. What the promoter hears from the customers is very important.
What the engineers, band and fans tell him and show him is what counts.
Would someone like Phil be thrilled to mix a system that went from DC to
daylight. Sure he would. Would he be just as thrilled to mix the band
through that system on a Mackie desk? I doubt it. If you can make a case
to the promoter , or whoever is doing the hiring, that your system is better
than others based on the little bit of extended response, then that will
indeed be to your advantage. If is such a big word though. Have all of
your other investment bases covered, then cover that one.
Rodney
Rodney Phillips
>
> Rodney Phillips <wha...@home.com> wrote in message
> news:d%vb5.50109$Yr4.9...@news1.rdc1.tn.home.com...
> > I'm very surprised that you feel a system with your speakers sounds
> better.
> > To me it's a supply and demand issue. In all the years that I have been
> > around any audio shows, both as a paying customer and worker I have not
> once
> > heard anyone say "Man, that would have sounded so much better if the
> > low-frequency extended down to 20 Hz instead of 40 Hz." Matter of fact,
I
> > never once thought that myself.
>
> That's because they or you have mever experienced a system that will go
that
> low. Once you've experienced one that is set up and run properly you'll
> understand.
Trust me, I have experienced low-frequency audio. The production is made up
of a lot of components both audio and visual and it's the overall
combination of these components that will leave the final impression on the
audience. Low-frequency extension is but one of these components. I never
said that if you had it to turn it off. The original question was, is it
worth it? To me it's a lot of expense that must be covered somehow for a
small part of the overall equation.
>
> > My point was and is that is requires much more equipment to accommodate
a
> > frequency range down to 20 Hz, which is directly proportional to the
drain
> > on a contractor's finances. Most audio contractors that I have seen
doing
> > the regional type shows could spend $40,000 much better than chasing a
20
> Hz
> > lower end. Let's face it, I don't see a lot of posts here from DB,
Clair
> or
> > Showco. I don't get the idea that most folks here have money to burn.
>
> Yes it can cost more but if you can afford it then it's well worth it. It
> does need more power but you don't have to put out so much in the low mids
> to give the impression of bass when you have the real thing available. As
> I've said if you've never had it you won't miss it.
>
> Phildo
>
That is the whole point. Can you afford it and does the investment provide
a return to you? To me, this was never an issue of what sounds better. For
example, I have a pretty good entertainment system in my house. I paid a
little more than $12,000 for it all and I'm happy with what I have. Others
in my neighborhood have paid $50,000 and up for theirs. Does their system
sound and look better than mine? Sure it does. Would I spend the same
amount for my house? Hell no. It's not worth the extra expense for the
added benefit. That's like putting a small regional-type company's system
in a venue and letting a band perform one night. Then bring Showco in the
next night same band, engineer and crowd and run the show. Then ask the
audience which was better. I think we can figure what the response will be,
but it's not a fair comparision. More money should always get you a better
system. Can you eat and pay your bills and take your wife on vacation after
you have paid for that equipment? Business is business and it must pay your
way.
Rodney
George Gleason
Quality is always worth it compromise your quality, you compromise your
potential
George
Rodney Phillips
>
> Quality is always worth it compromise your quality, you compromise your
> potential
>
> George
>
>
low-frequency extension. A quality system is always worth it to me, and
most of those quality systems (EV, Meyer, Turbos, Apogee, etc) are going to
start dropping off below 40 Hz. Look at the graphs of the boxes.
I do not buy or use sub-grade equipment and I don't know how this whole
issue turned into a quality argument. For instance, I compete with other
testing facilities for acoustic work. We use B&K microphones exclusively in
our lab as well as B&K analysis gear. We have about $130,000 invested in
cartridges (equals out to 150 or so cartridges). That doesn't cover the
cables, preamps, power supplies, calibrators, calibration system or anything
else associated with the microphones much less the analysis gear or facility
itself. I have to price my facility against others that use what I consider
lesser quality equipment. If we were not government funded we would
probably go bust. Is it worth it to me and to the taxpayers, damned right
it is but we have human life on the line with a lot of the hardware that we
test and we do not compromise.
You have recently bought some Meyer equipment and I applaud your purchase.
I like their gear and I hope that it works out well for you. They will be
fabulous down to 40 Hz and maybe even 32 Hz. But that 20 Hz thing is going
to rock your pocketbook, believe me. Will it be worth that expense?
Rodney
Rodney Phillips
-snip-
>
> You have recently bought some Meyer equipment and I applaud your purchase.
> I like their gear and I hope that it works out well for you. They will be
> fabulous down to 40 Hz and maybe even 32 Hz. But that 20 Hz thing is
going
> to rock your pocketbook, believe me. Will it be worth that expense?
>
> Rodney
>
mentioned in another post.
Rodney
George Gleason
> You have recently bought some Meyer equipment and I applaud your purchase.
> I like their gear and I hope that it works out well for you. They will be
> fabulous down to 40 Hz and maybe even 32 Hz. But that 20 Hz thing is
going
> to rock your pocketbook, believe me. Will it be worth that expense?
>
> Rodney
Guess I won't know till I spend the money and experiance it my self
hopefully by christmas I can have a ggod start on my sub system I have
budgeted 20K for a rig to use in 300 seat theaters
G
>
>
Rodney Phillips
Best of luck.
Rodney
David Shorter
> I know him but not very well.
Six degrees of separation, my arse. What a small community this business really is.
If you run into him, ask him about his VW beetle with two 18" Cerwin Vegas where
the backseat should have been (that'll get him wondering how you knew about it).
Key Audio (Kenneth Kareta)
"system capable of reproducing extended 25, 30 and 40 Hz tones"
And Why wouldn't the fan base expect Subsonic?
Music's bandwidth expands when technology expands.
Back when 4 track studios were only for the rich and famous,
and AM (mono) radios through a 4" cone on the kitchen counter, was the listening
device,
anything below 100 Hz, or above 8 kHz, was either unheard of, or marveled at.
Also remember, that the "average" record buyer/concert goer is 22 years old.
that means they were born in 1978, and the Walkman, and CD player
were introduced *before* they were 5 years old!!
Record buyers today, listen to music on digital CD's which do not have
the high frequency loss-over-time, or low end bandwidth limitations that
cassettes did.
Many are driving to work, in cars that have enough wattage in their car stereo
to light up a Las Vegas casino for an hour!
If one of them would go to a show,
Wouldn't they wonder why their favorite performers concert
didn't shake their brains out, like it does in their car?
--
Ken
Shaun
> Guess I won't know till I spend the money and experiance it my self
> hopefully by christmas I can have a ggod start on my sub system I have
> budgeted 20K for a rig to use in 300 seat theaters
Easy to do.
(4) EAW KF940 SuperSubs $5,300 retail, $3,500 my cost: $14,000
(1) Crest 10001, $6,000 retail, $2,500 street cost (used): $2,500
(1) BSS FDS-366 Omnidrive Compact Plus, $3695 retail, $2,500
(1) Shipping $500.
Unless you need 3 or 4-way top cabs, then add one more BSS 366.
--
Shaun K. Wexler,
Hellsgate Sound
www.hellsgate-sound.com
George Gleason
Shaun <hell...@home.com> wrote in message
news:39769B05...@home.com...
> George Gleason wrote:
>
> > Guess I won't know till I spend the money and experiance it my self
> > hopefully by christmas I can have a ggod start on my sub system I have
> > budgeted 20K for a rig to use in 300 seat theaters
>
> Easy to do.
>
> (4) EAW KF940 SuperSubs $5,300 retail, $3,500 my cost: $14,000
> (1) Crest 10001, $6,000 retail, $2,500 street cost (used): $2,500
> (1) BSS FDS-366 Omnidrive Compact Plus, $3695 retail, $2,500
> (1) Shipping $500.
>
> Unless you need 3 or 4-way top cabs, then add one more BSS 366.
I seeEaw wants you to use 4x arrays of these do they work well as a @x
stack each side? How portable are they(I have BH800 not the most user
friendly box ever made). BTW will be using w/ Meyer MSL3A's (2 a side )that
I just put in service .meyer prossessor for tops
George
Shaun
> I seeEaw wants you to use 4x arrays of these do they work well as a @x
> stack each side? How portable are they(I have BH800 not the most user
> friendly box ever made). BTW will be using w/ Meyer MSL3A's (2 a side )that
> I just put in service .meyer prossessor for tops
They weigh 360 lbs. each, but I can move and stack them by myself. They have
four casters on the back, you just have to tip them upright to move 'em.
Luckily, the wheel spacing is about 1" shy of the width of a 24 ft. Ryder
truck ramp, so they can be loaded relatively easily...if the ramp is not very
level (i.e. parked on level ground) then I'd have help, especially pushing
them up and down the ramp. As for portability, no problem. They're big, like
a refrigerator, so you have to plan for them, and since they are 54" deep when
layed down, they stick out pretty far from the typical stage if ground stacked
and/or there are no sound wings.
I use two per side, and they are UNGODLY loud. I was concerned when I ordered
them, about how they would perform using only 2 per side, rather than 4 as
recommended. Remember, these subs are designed for huge stadiums, not small
gigs! I can cover over 8,000 people outdoors with my system, using only
30,000 watts of Crest power on FOH (and running at about 15% avg). Next year
I will buy 4 more, to have 4 per side (as if I need more subbass!) but then
again I'm a SPL masochist. You definitely want the BSS Omnidrive 366 for
processing the subs...you have about an 11 ms delay to apply to the top cabs
for alignment. You could feed the 366 the stereo mix, let it run the subs,
feed the M3-A processor for the MSL3A's, and have two full-range outputs for
delay speakers. Incidentally, I'd opt for one more pair of MSL3A's, and run 3
per side atop the pair of KF940's. You can run the KF940's upwards of 300 Hz
if you need to, so selecting a crossover point is a simple matter. That
system would be very similar to what I run, except I use the Omnidrives
exclusively, with my top cabs. (Geez, you would have a system with nothing
but 12" mid/low and sub drivers). If you get into 10001's like I have, you
could run all six drivers in parallel at a 1.33 ohm load, and the subs would
be a 2 ohm load. One of your 8002's would work for highs.
Rodney Phillips
"Key Audio (Kenneth Kareta)" <k...@keyaudio.com> wrote in message
news:397373C7...@keyaudio.com...
> I have had some R&B rentals that have spec'd a
> "system capable of reproducing extended 25, 30 and 40 Hz tones"
Any system is capable of producing those tones. The question is at what
amplitude.
>
> And Why wouldn't the fan base expect Subsonic?
Subsonic??
>
> If one of them would go to a show,
> Wouldn't they wonder why their favorite performers concert
> didn't shake their brains out, like it does in their car?
Auto cabs have resonant frequencies that produce the characteristic booms
that we hear when these idiots drive by. That boom is quite a bit above 20
Hz.
> --
> Ken
>
> Rodney Phillips wrote:
>
> > To each his own. I just don't see it as a demand of the fan base or
> > promoters. If it was, I suspect that more systems would accommodate it.
> >
> > Rodney
As I said above, to each his own.
Rodney
Rodney Phillips
>"Shaun Wexler" <hell...@home.com> wrote in message
news:397694F8...@home.com...
-snip-
>I measured sustained 120-122 dB at 20 Hz, at 108 feet from the stacks,
using 40 Hz lowpassed pink noise >during a soundcheck "power test" a couple
weeks ago. No shit.
>Shaun K. Wexler,
>Hellsgate Sound
>www.hellsgate-sound.com
I would very much like to get my hands on a couple of these cabinets and
check them out. Might have some application for them. About how much would
one expect to pay for a pair?
Rodney
David Shorter
> Auto cabs have resonant frequencies that produce the characteristic booms
> that we hear when these idiots drive by. That boom is quite a bit above 20
> Hz.
Oof, oof, wump, wump, instead of boof, boof, thump, thump and bang.
That's what you get from a misaligned vented box, deliberate or otherwise.
Denny Strauser
I've heard more "rattle - rattle; buzz - buzz" from cars that are
loosing their screws and bolts from the "oof, oof, wump. wump" than any
"boof, boof, thump, thump, bang."
That's what you get from a misaligned rattletrap of a car, with a stereo
that costs more than the car.
Denny Strauser
KentElltt
ServoDrive)
>> Well, anyone with Servodrive subwoofers can do 28hz with no problem.
>
>I don't want to put your product down, but in all the years I worked with
>audio systems I encountered 1 system that was using the product.
>
The ServoDrives were never terribly common, although I couldn't figure out
why. I've used them on a few gigs over the years. Our show wasn't
sub-intensive-- there was never any intentional reaching for the bottom octave,
no eq boosting or processing of subs. But the ONLY rig I had to intentionally
roll off the low end below 40 hz was Servo-Drive equipped. Yes, they go
extremely low, and with a minimum requirement of boxes and power. The
particular rig had 4 Servo-Drives (2 per side) tucked under the stage for 8000
seats outdoors, powered at only 300 watts/cabinet. The low end was intense
enough on the stage to freak the band out. The only reason I could figure out
for the Servo's not being widely used is that (at least the early versions)
required routine maitenance (re-building) at earlier intervals than the
industry was used to.
This particular experience with Servo's should serve to point out something
you might want to consider in your quest for 20 hz response, regardless of
manufacturer. Pattern control becomes difficult at low frequencies, with most
single- or small-multiple subs radiating at essentially 360 degrees. This can
become a major on-stage problem in larger venues. In order to produce
significant 20 hz at the back of the room, you're going to be shaking the stage
to bits (due to the inverse square rule). And the only practical way to get
pattern control at low frequencies is effective baffle size. A stack of 8
decent-sized subs may have some directional control-- one or two subs isn't
likely to.
I'm sure that's part of EAW's spec of stacked subs, as well as increasing
the mouth size of the subwoofer horn.
You don't think directional contol of low frequencies could be a problem?
The worst case I ever saw involved a show in the round, with multiple small
ground-stacks ringing the stage. Some frequencies exhibited a peak SPL 15 dB
higher on stage than at any seat in the audience.
(Seats in the audience were covered by only 1 stack-- but at frequencies where
the speaker stacks were essentially omni-directional, the stage was covered by
maybe 30 stacks. Not a chance of the band hearing anything over the bleed from
the PA.)
The "20 Hz Quest" also needs to remember that a lot of rooms won't support 20
Hz (or even 40 Hz) , no matter how much power you're capable of pushing.
Without solid walls, the low-frequency energy will be transmitted directly
through the walls, but really won't be that audible in the room. Outside the
building, they'll hear it.
Kent Elliott
Key Audio (Kenneth Kareta)
> Any system is capable of producing those tones. The question is at what
> amplitude.
Completely understood.
Actually, looking at the rider in question,
it says "Capable of full audience coverage, with sustained tones to 35 cycles".
> Subsonic??
It was meant facetiously, talking in "Car stereo lingo".
> Auto cabs have resonant frequencies that produce the characteristic booms
> that we hear when these idiots drive by. That boom is quite a bit above 20
> Hz.
I've actually seen kids pop the little side windows out of their RTV seals by
attempting test tone tests as high a 80, and as low as 15, with a DB meter,
by closing the doors to protect their own ears.
--
Ken
Rodney Phillips
> Rodney Phillips wrote:
>
> > Any system is capable of producing those tones. The question is at what
> > amplitude.
>
> Completely understood.
> Actually, looking at the rider in question,
> it says "Capable of full audience coverage, with sustained tones to 35
cycles".
>
I can see that as a somewhat reasonable request.
>
> > Subsonic??
>
> It was meant facetiously, talking in "Car stereo lingo".
>
> Ken
>
I will admit that I'm not familiar with their lingo, but subsonic sound is
somewhat of an oxymoron. Infrasonic perhaps?
Rodney
John Halliburton
of Science physics
lessons on real requirements to produce the levels that have been talked
about in this thread.
Sorry that it is a bit late, but Tom doesn't access the newsgroups.
Good reading,
John Halliburton
Production Manager, Servodrive, Inc.
Shaun Wexler wrote:
> Rodney Phillips wrote:
>
>> <snip>
>>
>> I have not heard the KF940's. I assume that these are the boxes
>> that
>> require a 25 Hz high-pass filter be used with. According to their
>> literature the response of an array of four will be down 10 dB at 21
>> Hz.
>> That 20 Hz is hard to come by.
>
> Consider that four KF940's can produce 154 dB peaks...at -10 dB that's
> 144 dB at 21 Hz (although the peak calculation is a full bandpass
> rating). The highpass can be set at 18 dB/oct at 25 Hz, or 24 dB/oct
> at 21 Hz. Consider 144 dB at 21 Hz, with a 24 dB/oct rolloff = 120 dB
> at 10 Hz...96 dB at 5 Hz. These drivers are so stiff, you can stand
> on them with your feet without damage...and they are loaded into an
> enclosed chamber at the end of a 13 ft. long folded horn, with a
> sealed back chamber.
>
> I can guarantee that the 16 Hz slider on pro EQ's that go that low
> will be fully functional using KF940's, even without a dbx
> 120X-DS...just that adding <30 Hz subharmonics brings out something
> most people have never experienced. They key is to not overdo it and
> cover up the fundamentals higher up.
>
> I measured sustained 120-122 dB at 20 Hz, at 108 feet from the stacks,
> using 40 Hz lowpassed pink noise during a soundcheck "power test" a
> couple weeks ago. No shit.
>
>> Would be nice if it would work out that way. Maybe with some
>> combination of
>> boxes and subs it will.
>>
>> Rodney
>
> --
> Shaun K. Wexler,
> Hellsgate Sound
> www.hellsgate-sound.com
>
Hi
I couldn't agree more about the effect adding the missing VLF part of
the
spectrum has on essentially any kind of music, we have been saying this
for 15
years. Adding just "enough" is part of the trick and where you start
bringing up the
bottom too.
When someone starts talking about really high bass SPL's I sometimes ask
"what
did you measure this with" as the equipment to measure this kind of SPL
is
rather un-common. Too often discussion of SPL's turns into something
similar to a bunch of
gearheads talking about horsepower, an arm waving argument having very
little to
do with reality. This situation is made worse by manufacturers who
routinely claim the
acoustically impossible.
Ears are a lousy judge of "dB", even if "experienced".
Recently at the shop I was diagnosing a problem on a new product and
had on my
old aircraft carrier head phones (just good hearing muffs now) and had
the
Chevin 6000 amp maxed out driving the box , with my head in the horn
poking
around.
An experienced FOH mixing engineer was there (and he is a guy who likes
it loud)
came in wincing with his fingers in his ears. I turned it off and he
says,
"Wow, was that 150 dB?".
I grinned and said you wanna see how loud that really was?
And he said, "Sure, its got to be 145 at least. "
I got the B&K 2204 sound level meter out which has a peak hold setting,
another pair
of hearing protectors and cranked the system back up. Where he was sure
it was 150 dB
was actually about 128 dB (off by a factor of more than 100) and we had
to get the meter
within a foot or two of the horn to find 140 dB.
He was humbled, and whenever I have done this it has been the same.
People generally over estimate how loud speakers are. A measurement is
not the
same thing as a calculation or marketing department guess.
I'm not saying you couldn't measure 122 dB at 108 feet as described but
it is
maybe worth looking into a little closer.
Due to the size of the wavelength, even a good sized pile of these
boxes(the 940's) would
not have appreciable directivity at 40 Hz, so you are dealing with
something
that is primarily a point source.
For a device to produce 122 dB at 108 feet (~33 meters) at say 40 Hz
represents the output of a 72 inch
diameter piston moving 3 inches peak to peak, unless you are moving that
much
air, you can't make that sound level. This is a significant amount of
air
displacement, like 12,215 cu/in or about 61, 18" drivers at 1 inch p/p.
The same SPL at that distance represents about 11,170 acoustic Watts and
if the
speaker system were say 30% efficient, would need 37,233 Watts RMS from
the amps.
Don't forget that pink noise has +6dB peaks so you need 148,933 Watts
worth of
amplifier power not to clip.
If you were one meter from a "point source" producing this acoustic
power, the
sound level would be 152 dB avg., 158 dB peak
While the post didn't mention the number of boxes being measured, I
would
imagine it is less than the 38 boxes needed not to exceed the power
handling
limits of each box.
On the other hand if sound were coming out higher up in the spectrum,
the horn
would be large enough to produce significant directivity which is
manifested in a
rising response caused by the tightening radiation pattern.
If one looks at normal Hf horns, one sees lots of horns which have 10 dB
or more
increase in level on axis over the same acoustic power from a point
source.
If the speaker while electrically band passed at 40 Hz were producing
any
harmonic distortion, those components would all be at higher
frequencies, in the
range where there may be significant directivity and if enough higher
than the
fundamental actually raise the SPL.
What does the spec sheet say?
The spec sheet refers to "groups of 4 or more" in several places and
while not
actually saying so, I would assume, given the issue of horn mouth size,
the
response spec (+ - 3 dB 24 to 300 Hz) is met in a group and not
singly.
The spec lists sensitivity as 109 dB 1w 1m (24 to 300 Hz) and power
handling at
1 kW.
If the drivers had NO power compression or other nonlinearities, it
would
produce 139 dB, the figure listed as long term output. Given that pink
noise
has a built in 6 dB peak to avg. ratio, the peak fig of 145 is assumed
as well.
On the other hand since after a few seconds at rated power all drivers
exhibit
power compression, typically loosing -5 to -9 dB or more of output, to
me the
phrase "long term" and 139 dB in the same sentence is exceedingly
optimistic.
For a point source, 109 dB 1w 1m also represents 50 % efficiency which
is very
high even for a horn, let alone one with such a tiny mouth and at such a
low
frequency (again maybe they mean as a group where the mouth area is
added up).
Personally I suspect the high equivalent sensitivity rating and other
SPL's is
partially due to it (an array) having significant directivity in the
upper
ranges making it measure somewhat higher than it would if the
sensitivity were
measured in the 24 to 80 Hz range where the real "woofing" is going on.
I find it interesting that they fail to print a response curve (as it
isn't a
given that a lf horn has flat response) and
while Live Sound in general isn't famous for being at all "hi fi", the
word
distortion is also never mentioned, even if it is an important factor on
quality.
Since so much of how a speaker will sound is often evident in basic
measurements, they should include them for those that care.
Hopefully this venue is also not an "unofficial EAW forum" and is more
of an
open technical discussion, on the "Live sound board" if one questions
the
technical spec.'s on EAW product, one gets' their posts pulled, and as
in my case, threatened to be permanently barred from posting.
Tom Danley
Director of Research and Development
Sound Physics Lab / Servodrive inc.
Phildo
> Hopefully this venue is also not an "unofficial EAW forum" and is more
> of an
> open technical discussion, on the "Live sound board" if one questions
> the
> technical spec.'s on EAW product, one gets' their posts pulled, and as
> in my case, threatened to be permanently barred from posting.
>
too stuck up their own asses. Give me the anarchic freedom of usenet any
day.
Pity we don't get more of the posters from the live-sound board here though.
Phildo
George Gleason
usefull Thak You for your efforts
george Gleason
Rodney Phillips
> of Science physics
> lessons on real requirements to produce the levels that have been talked
> about in this thread.
>
> When someone starts talking about really high bass SPL's I sometimes ask
> "what
> did you measure this with" as the equipment to measure this kind of SPL
> is
> rather un-common. Too often discussion of SPL's turns into something
> similar to a bunch of
> gearheads talking about horsepower, an arm waving argument having very
> little to
> do with reality. This situation is made worse by manufacturers who
> routinely claim the
> acoustically impossible.
>
My experience as well. I often picture some manufacturers with a
strip-chart hooked to a microphone, calibrated of course :-), and a fire
extinguisher attempting to get that one blip on the paper to advertise as
their "continuous SPL capability".
I've noticed the same thing regarding the thermal specifications of some
drivers. They must test them in freezers. I had about 20 large, 5"
diaphragm, R-H compression drivers several years ago that we used in a
long-duration test. We were told they had a thermal spec of 2 hrs using
pink-noise at their rated output. After 30 minutes my SPL started to drop.
We shut down and found about half of them burned to a crisp. We had to
mount the magnets to aluminum plates and actively cool them with GN2 to make
them last. Even then, we had several fatigue failures in the aluminum
diaphragms. We had some Community M4's in the same test. We ran them at
250W for 6 hours at a time with pink noise and no cooling. Not one failure.
We had one coil short down to 2 ohms, but it was still driving. Toughest
drivers I ever used.
>
> Ears are a lousy judge of "dB", even if "experienced".
> Recently at the shop I was diagnosing a problem on a new product and
> had on my
> old aircraft carrier head phones (just good hearing muffs now) and had
> the
> Chevin 6000 amp maxed out driving the box , with my head in the horn
> poking
> around.
> An experienced FOH mixing engineer was there (and he is a guy who likes
> it loud)
> came in wincing with his fingers in his ears. I turned it off and he
> says,
> "Wow, was that 150 dB?".
> I grinned and said you wanna see how loud that really was?
> And he said, "Sure, its got to be 145 at least. "
> I got the B&K 2204 sound level meter out which has a peak hold setting,
> another pair
> of hearing protectors and cranked the system back up. Where he was sure
> it was 150 dB
> was actually about 128 dB (off by a factor of more than 100) and we had
> to get the meter
> within a foot or two of the horn to find 140 dB.
I'm surprised that he didn't suggest that you send the meter in for service
:-)
> He was humbled, and whenever I have done this it has been the same.
> People generally over estimate how loud speakers are. A measurement is
> not the
> same thing as a calculation or marketing department guess.
Very true. I have a PWT that is used for sonic fatigue testing of large,
5'x5', panels. It is powered by four 30,000 acoustic watt, pneumatic
sources. It is a thermal-acoustic facility so there are lamp banks on one
wall of the wave duct which create a bit of leakage. Outside the test
section at a distance of 10' or so we measured 145 dB with exponential
averaging using an averaging time of 8 seconds with B&K equipment. We have
allowed some people to approach the area, with proper hearing protection of
course, but few people will advance that far before retreating. It is a
very imtimidating experience. The overall SPL at the middle of the test
panel is 170 dB for a 45 second linear average.
>
> I'm not saying you couldn't measure 122 dB at 108 feet as described but
> it is
> maybe worth looking into a little closer.
As I posted earlier in this discussion, I would like to get some of those
and put them to a test. I would never dispute someone's measurement claim,
but it is hard to believe. Maybe EAW will send me a few for evaluation, or
maybe not.
I've always wondered about some of the horn-mouth sizes and the frequency
response claims of several horn-loaded subs. I've got a 29 Hz horn with a
mouth cross-section of 50 sq ft. I designed anf fabricated a 50 Hz
termination for a PWT that had a cross-sectional area of about 30 sq ft and
that was less than I had calculated for the requirement. Since it was for a
PWT, I chopped it a little early to make the fabrication easier.
It's unfortunate that any group would act that way. Children will be
children and sometimes the truth hurts.
Rodney
Phildo
> Very true. I have a PWT that is used for sonic fatigue testing of large,
> 5'x5', panels. It is powered by four 30,000 acoustic watt, pneumatic
> sources
Any chance you could make a subwoofer out of it?
PHILDO WANT !!!!!!!!!!!!!!!!!!!!! :>)
Phildo
Rodney Phillips
>
> "Rodney Phillips" <wha...@home.com> wrote in message
> news:aUil5.109080$Yr4.1...@news1.rdc1.tn.home.com...
large,
> > 5'x5', panels. It is powered by four 30,000 acoustic watt, pneumatic
>
> Any chance you could make a subwoofer out of it?
>
> PHILDO WANT !!!!!!!!!!!!!!!!!!!!! :>)
>
> Phildo
>
>
It would be pretty distorted, but one could do it. Seriously, some of these
sources are used, at reduced power levels, in some theme-park attractions.
The particular setup that I was talking about only takes about 1500 W of
electrical power. I run the whole thing from two QSC EX4000's. It also
takes 12,000 SCFM of air, which is a little harder to come by.
Rodney
Chris Buckley
experiment in an electronics class, we cooled a 2N107 germanium
transistor with liquid nitrogen and got thing to pass over 1000 watts
before it burned out. I just thought I'd through that in.
jim and robin calderwood
haven't followed this thread but here is some low end for you to drool over.
Check out the picture at the web site. What music group would you most like
to see use a pair of these?
http://www.arl.mil/ARL-Directorates/ISTD/aat/MOAS.htm
The Mobile Acoustic Source (MOAS) is a pneumatically driven 56 ft long
fiberglass horn designed to be a high amplitude acoustic source. The source
of airflow for MOAS is a rotary compressor driven by a 150-hp diesel engine.
This gives a maximum flow rate of 1200 cubic feet per minute a a pressure of
7.5 pounds per square inch. The airflow passes through a Wyle WAS-3000
modulator, which is electrically driven to produce the fluctuations in the
airflow. The modulator is remotely operated due to the output intensity of
the source. The fiberglass horn is designed to match the impedance between
the modulator and the atmosphere over the frequency range of operation. The
frequency range of operation is 10 to 500 Hz with a maximum output level of
145 dB with minimal distortion. These characteristics allow for the system
to reproduce the acoustic signal in frequency and amplitude from most
potential acoustic targets. The system can broadcast single tones, multiple
tones, or tape playbacks. The system can be operated off of hard power,
generator, or inverter. The trailer can be easily compacted to allow for
transportation on any commercial highway.
Specifications:
Frequency Range: 10-500 Hz
Output Level: 145 dB (re: 20 m Pa)
Output Signal: Single Tone, Multiple Tones, or Tape Playback
Remote Operation
Utility:
Low Operating Cost Acoustic Target
Long Range Detection (5-15 km)
Countermeasures
Low Frequency Active Noise Control
David Shorter
> Sorry if this has already been posted. I've been away for awhile and
> haven't followed this thread but here is some low end for you to drool over.
> Check out the picture at the web site. What music group would you most like
> to see use a pair of these?
>
> http://www.arl.mil/ARL-Directorates/ISTD/aat/MOAS.htm
It has been.
They're pneumatically driven and aren't meant for audio.
Mind you, there are some bands that I would like to see
playing into the large end. :-)
Rodney Phillips
news:399656A7...@ihug.co.nz...
> jim and robin calderwood wrote:
>
> > Sorry if this has already been posted. I've been away for awhile and
> > haven't followed this thread but here is some low end for you to drool
over.
> > Check out the picture at the web site. What music group would you most
like
> > to see use a pair of these?
> >
> > http://www.arl.mil/ARL-Directorates/ISTD/aat/MOAS.htm
>
> It has been.
>
> They're pneumatically driven and aren't meant for audio.
>
> Mind you, there are some bands that I would like to see
> playing into the large end. :-)
>
> --
>
> Regards,
> David Shorter
That's what I tried to explain to the music-tv guys that contacted us about
letting a band play through our afore mentioned setup. They had an idea of
setting a world record for the loudest rock concert. I explained to them
that, although you can tell what song is playing, it is highly distorted and
frequency-limited. They didn't seem to care. We tried to do it, but the
effort was squashed by our head-shed.
Rodney
Rodney Phillips
"jim and robin calderwood" <ca...@psnw.com> wrote in message
news:%csl5.10845$dl3.5...@news-east.usenetserver.com...
> Sorry if this has already been posted. I've been away for awhile and
> haven't followed this thread but here is some low end for you to drool
over.
> Check out the picture at the web site. What music group would you most
like
> to see use a pair of these?
>
> http://www.arl.mil/ARL-Directorates/ISTD/aat/MOAS.htm
>
At full power those sources take an air-flow of 3000 scfm at about 35 psig
and will output about 30,000 acoustic watts, or about 165 dB. At the higher
SPL's the distortion gets very high.
Rodney
Jeffrey D Sobel
wha...@home.com says...
> At full power those sources take an air-flow of 3000 scfm at about 35 psig
> and will output about 30,000 acoustic watts, or about 165 dB. At the higher
> SPL's the distortion gets very high.
>
> Rodney
>
>
>
Oh, yeah. Well if these things are so darn loud, why does the bottom
picture show a guy cupping his hand to his ear and learning toward the
horn as if he's straining to hear it? ;)
I've heard about people working in acoustics labs running high-spl
chamber tests in which ~140db of low-freq was aimed at a secured soda can
and the paint peels off, then the can disintegrates. Anyone got video
footage of stuff like that?
JDS
John Halliburton
interesting projects at Servodrive in the past. I figured it was on topic, and
certainly is
an interesting read.
John
Hi all
.... but we(Servodrive.) built a system under a NASA subcontract for a sonic
boom
simulator which had been thought to be impossible at the time.
This was featured on the TV show "beyond 2000" as "The speakers from
Hell".
This was a combination of speaker systems and a flow modulator I
designed set up outside an old house on a air force base outside
Atlanta. It could produce 132 dB minimum (~2 pounds per sq. foot) on
the outside wall of a house (from 2 meters away) from 5 KHz down to 3 Hz
and was capable of producing the equivalent sonic boom expected from the
NASA space plane.
The "boom" was problematic for NASA as the size of the plane produced a
bigger and more low pitched sound than a fighter.
This was noticeable as a distinct KAA.....BOOM., the wave shape from a
sonic boom is a spike up and sawtooth shaped decay, through and past
zero to negative pressure and then a fast spike recovery to zero (with
some over shoot).
Such a "sound" was expected to be a problem for things like windows,
houses, peoples nerves etc. and they needed a way to test for that..
At full level, doing swept sine testing with the TEF machine, we were
able to move the middle of the old house's wall about 15 inches peak to
peak at about 5 Hz (its resonance) and by "teasing" various other
resonance's, we took off a part of the siding and were eventually able
to produce a loud CRUNCH from under the house which was when we stopped
playing around (hey this job sucked bad other wise so we got a little
goofy at times).
Any way, the point was that the low frequency system had a volume
displacement of about 50 cu/meters per second (at DC) and at 3 Hz, had
the equivalent displacement of an 8 foot by 12 foot piston traveling 18
inches peak to peak
Airflow was provided by 12, 5 hp 3ph fans, two in each modulator. Rather
than run at high air pressures (which produces a very high background
noise level) and a class "A" valve, I used much larger volume, much
lower pressure and a push pull Class A valve.
If interested in the transducer, look up patent 5,140,641 at
http://town.hall.org/patent/patent.html
As a side note, it turns out you can hear 3 Hz if its loud enough, the
threshold of hearing at 3 Hz is about 110 dB (if I remember correctly)
and since this could go +22 dB louder, was audible
Standing in front of the system at full tilt, doing a slow sine sweep
from 100 down to 3 Hz was a memorable experience.
It felt good when it stopped.
Tom Danley
Sound Physics Labs / Servodrive
Rodney Phillips
news:MPG.14010c271...@news.tranquility.net...
> In article <lMwl5.110161$Yr4.1...@news1.rdc1.tn.home.com>,
> wha...@home.com says...
>
> > At full power those sources take an air-flow of 3000 scfm at about 35
psig
> > and will output about 30,000 acoustic watts, or about 165 dB. At the
higher
> > SPL's the distortion gets very high.
> >
> > Rodney
> >
> >
> >
> Oh, yeah. Well if these things are so darn loud, why does the bottom
> picture show a guy cupping his hand to his ear and learning toward the
> horn as if he's straining to hear it? ;)
>
Well, you get used to it after a while.
>
> I've heard about people working in acoustics labs running high-spl
> chamber tests in which ~140db of low-freq was aimed at a secured soda can
> and the paint peels off, then the can disintegrates. Anyone got video
> footage of stuff like that?
>
> JDS
>
>
We have destroyed soda cans for demo's, but we never had a video camera that
had a frame rate fast enough to capture it. We have access to one now that
has a rate of 500 frames/second. We are planning to try it again as soon as
we get our test chamber empty. We cement the can into our horn by its
bottom and then expose it to the acoustics. We use a level of 172 dB which
is pretty close to the launch pad environment for a shuttle launch. The
can, opened of course, does fatigue and rip apart after very few seconds.
Never lost the coating though.
Rodney