Reaching 126 dB

[Steve[_10_]]

How much amp power would I need to reach 126 dB measured at 32 meteres
away from the speakers?

[DJ Bukkake]

Steve wrote:
> How much amp power would I need to reach 126 dB measured at 32 meteres
> away from the speakers?
Hell, we broke 130 DB at an outdoor venue several weeks ago. We did it
with only 30,000 watts. The local authorities shut us down an hour
early, even though we had a sound permit for the outdoor venue.

Oh, and we broke 130 decibels at 50 to 75 meters with that power.

Sadly, I got shutdown in my second song because it was an all ages venue
and the damn promoter failed to tell any of us about that little fact.

Song 1: guy in the song says "See Deese Nuts you sluts"
Song 2: "your momma, your daddy, your sister's a hoe"

Here come the cops, "Next DJ please". I tell them, uh, is alcohol
allowed at all ages venues because nobody told me that there would be
minors here...

Oh yeah, good luck hitting 126 @ 32 meters.

[arthur[_5_]]

You had 180 Amps at your disposal? Outdoors?
Sure ya did. Must have been using Class D amps huh?

arthur


On Fri, 31 Aug 2007 19:23:58 -0500, DJ Bukkake
> wrote:

>Hell, we broke 130 DB at an outdoor venue several weeks ago. We did it
>with only 30,000 watts. The local authorities shut us down an hour
>early, even though we had a sound permit for the outdoor venue.
>

[DJ Bukkake]

arthur wrote:
> You had 180 Amps at your disposal? Outdoors?
> Sure ya did. Must have been using Class D amps huh?
>
> arthur
>
>
> On Fri, 31 Aug 2007 19:23:58 -0500, DJ Bukkake
> > wrote:
>
>> Hell, we broke 130 DB at an outdoor venue several weeks ago. We did it
>> with only 30,000 watts. The local authorities shut us down an hour
>> early, even though we had a sound permit for the outdoor venue.
>>

Uh, the guy who actually owns the sound equipment brought 15 2000 watt
QSC amps, and an ungodly amount of 18" subs and double 15" tops. It was
a royal bitch finding different circuits to run both the sound and the
light show and we had extension cords running all over the damn place.
I just provided the CD players and mixer to connect to the sound system.
This was a professional sound system that is normally rented to bands
that play in outdoor stadiums.

Then again, that is what I get for being one of the few DJs in town who
owns a Pioneer DJM-800 mixer. EVERYONE calls me when they have a big
event because the "professional" DJs want to play on the DJM-800.

You didn't think I was talking about car audio amps, did you?

[MOSFET]

Unfortunately your question is not as easy to answer as you might think. It
would say the BIGGEST factor is NOT the size/how many subs you have AND how
much power you have to drive them.

No, the biggest factor is the size of the vehicle, PERIOD.

There IS a reason why bass is so much louder in a car than in a living room.
It all has to do with the transfer funtion you benefit from in a smaller car
cabin. The smaller the car, the greater this transfer function will be.
Case-in-point. I had a pair of JL 12W3's in a '94 Stanza powered by a
single RF Power 360 (360 X 1 RMS at 4 ohms bridged). I was able to hit 132
dB. It was FRICKIN loud and the sub box resided in the trunk.

When I transfered everything to my new car many years ago, a '99 Subaru
Forester, I had about a 5 dB drop in total SPL (and I tried a number of
different cinfigurations of the sub. This surprised me at first because as
a Forester does not have a trunk and the sub enclosure was open to the cab,
I actually thought my bass would be louder. Wrong. It's all about
airspace. The Stanza was a much smaller car and it was easier to pressurize
a smaller airspace.

However, I'll take a stab. Assuming you have a stock battery and
alternator, and let's say, a Honda Accord. Two 12's and a 300-500 watt amp
should get you there no problem. Maybe even just a pair of tens or a single
15. 126 dB, in competitive SPL circles is not really THAT loud (though to
your average geezer, or wife, 126 dB would seem enough to wake the dead).
But I LOVE bass and MUST always have a car that can hit 130 without breaking
a sweat. NOT to disturb my neighbors, but so that even at highway speeds I
can FEEL the bass!

MOSFET


"Steve" > wrote in message ...
> How much amp power would I need to reach 126 dB measured at 32 meteres
> away from the speakers?
>

[arthur[_5_]]

I'm impressed. Never gave an ounce of brain power to how one
would go about creating synthetic jet engine blast on a lawn. ;

Do they hand out ear protection at these noise shows?

cheers


On Sat, 01 Sep 2007 02:49:09 -0500, DJ Bukkake
> wrote:
>
>Uh, the guy who actually owns the sound equipment brought 15 2000 watt
>QSC amps, and an ungodly amount of 18" subs and double 15" tops. It was
>a royal bitch finding different circuits to run both the sound and the
>light show and we had extension cords running all over the damn place.

[DJ Bukkake]

arthur wrote:
> I'm impressed. Never gave an ounce of brain power to how one
> would go about creating synthetic jet engine blast on a lawn. ;
>
> Do they hand out ear protection at these noise shows?
>
> cheers

No, hearing protection, but they should have passed it out. They even
had some stupid kids standing directly in front of the stacks of
speakers. Their parents should have been arrested for letting them get
that close. Then again, the police let them cross the barricade....

[Steve[_10_]]

MOSFET wrote:

> There IS a reason why bass is so much louder in a car than in a
> living room. It all has to do with the transfer funtion you
> benefit from in a smaller car cabin. The smaller the car, the
> greater this transfer function will be.

So are you saying that bass in a car such as a Mini Cooper or even a
Mazda Miata, for example, would be louder?

My car is a 2006 Toyota Corolla by the way.

[MOSFET]

Yes, correct.

But with a Miata, the soft-top would absorb a TREMENDOUS amount of the
sound.

With a mini-Cooper, a single 10 with a 500 watt amp might get you 135 dB.

MOSFET

"Steve" > wrote in message ...
> MOSFET wrote:
>
> > There IS a reason why bass is so much louder in a car than in a
> > living room. It all has to do with the transfer funtion you
> > benefit from in a smaller car cabin. The smaller the car, the
> > greater this transfer function will be.
>
> So are you saying that bass in a car such as a Mini Cooper or even a
> Mazda Miata, for example, would be louder?
>
> My car is a 2006 Toyota Corolla by the way.
>
>

[Captain Howdy[_3_]]

Are you totally sure ?


In article >, "MOSFET"
> wrote:
>Unfortunately your question is not as easy to answer as you might think. It
>would say the BIGGEST factor is NOT the size/how many subs you have AND how
>much power you have to drive them.
>
>No, the biggest factor is the size of the vehicle, PERIOD.
>

[arthur[_5_]]

There is an optional fiberglass top for the Miata. We own one and
never remove it cuz we do not have a place to store it. One of the
downers of apt living. Nearest friends with house and property are 4
miles away.

The real issue with a tiny car, sans trunk, is nil storage space. We
have a trunk lid rack for touring beyond a week.



I think it is easy to understand the concept of large space is to
think "dilution". The volume of the speaker cone oscillation is
diluted by the volume of the space to which it connects. The effect
is greatest at low frequencies and less at high frequencies

arthur


On Sat, 1 Sep 2007 22:52:23 -0700, "MOSFET" >
wrote:
>But with a Miata, the soft-top would absorb a TREMENDOUS amount of the
>sound.

[GregS[_2_]]

In article >, Steve > wrote:
>How much amp power would I need to reach 126 dB measured at 32 meteres
>away from the speakers?

You said speakers. Lets assume one 100 dB efficient driver.
You would need 100,000 watts. Probably bass, so adding
more drivers can drastically reduce the power required.
If you had a bank of 4, you could resuce that to 25,000 watts.

greg

[GregS[_2_]]

In article >, (GregS) wrote:
>In article >, Steve > wrote:
>>How much amp power would I need to reach 126 dB measured at 32 meteres
>>away from the speakers?
>
>You said speakers. Lets assume one 100 dB efficient driver.
>You would need 100,000 watts. Probably bass, so adding
>more drivers can drastically reduce the power required.
>If you had a bank of 4, you could resuce that to 25,000 watts.

Thats wrong.
This time I got 124 dB at 24 meters with 10,000 watts.
134 dB at 24 100,000 watts
Without getting exact, I, guessing about 50,000 needed for 126 @ 32 mtrs.
Get about a set of 10 drivers, and you can reduce that about 10 dB power or
5000 watts.

greg

[arthur[_5_]]

Speaking power, 3db is 2x,and 10db is 10x so your ratios are correct
for 124 to 134 but for 127 the power required would be 20k watts
assuming 10k is correct ... therefore 50k watts must be incorrect.

db is logometric as I assume you know.

arthur

On Tue, 04 Sep 2007 12:42:32 GMT, (GregS) wrote:
>Thats wrong.
>This time I got 124 dB at 24 meters with 10,000 watts.
> 134 dB at 24 100,000 watts
>Without getting exact, I, guessing about 50,000 needed for 126 @ 32 mtrs.
>Get about a set of 10 drivers, and you can reduce that about 10 dB power or
>5000 watts.
>
>greg
>
>
>

[Barry & Nikki]

I was able to reach 137.3 Db in my convertible 95 Trans Am with only a
single 10" Rockford Fosgate and a Punch 60 amp at a local Kenwood Db drag
race quite a few years ago. I sure wish I had the JL Audio 10 that I have in
there now when I was at that comp. I know I would have hit a LOT higher. Not
even the judges could believe I only had one amp and one sub in an Obcon
box.



"Steve" > wrote in message ...
> MOSFET wrote:
>
> > There IS a reason why bass is so much louder in a car than in a
> > living room. It all has to do with the transfer funtion you
> > benefit from in a smaller car cabin. The smaller the car, the
> > greater this transfer function will be.
>
> So are you saying that bass in a car such as a Mini Cooper or even a
> Mazda Miata, for example, would be louder?
>
> My car is a 2006 Toyota Corolla by the way.
>

[GregS[_2_]]

In article >, "Barry & Nikki" > wrote:
>I was able to reach 137.3 Db in my convertible 95 Trans Am with only a
>single 10" Rockford Fosgate and a Punch 60 amp at a local Kenwood Db drag
>race quite a few years ago. I sure wish I had the JL Audio 10 that I have in
>there now when I was at that comp. I know I would have hit a LOT higher. Not
>even the judges could believe I only had one amp and one sub in an Obcon
>box.

One woofer ?

http://www.danleysoundlabs.com/images/Matterhorn%20Finished.jpg


>"Steve" > wrote in message ...
>> MOSFET wrote:
>>
>> > There IS a reason why bass is so much louder in a car than in a
>> > living room. It all has to do with the transfer funtion you
>> > benefit from in a smaller car cabin. The smaller the car, the
>> > greater this transfer function will be.
>>
>> So are you saying that bass in a car such as a Mini Cooper or even a
>> Mazda Miata, for example, would be louder?
>>
>> My car is a 2006 Toyota Corolla by the way.
>>
>
>

[Barry & Nikki]

Yes as I stated ONE single 10" woofer was all I had hooked up to the amp.
The stock Trans Am door and rear speakers are hooked to the head unit and
were basically turned off for the competition so as not to blow them.



"GregS" > wrote in message
...
> In article >, "Barry &
Nikki" > wrote:
> >I was able to reach 137.3 Db in my convertible 95 Trans Am with only a
> >single 10" Rockford Fosgate and a Punch 60 amp at a local Kenwood Db drag
> >race quite a few years ago. I sure wish I had the JL Audio 10 that I have
in
> >there now when I was at that comp. I know I would have hit a LOT higher.
Not
> >even the judges could believe I only had one amp and one sub in an Obcon
> >box.
>
> One woofer ?
>
> http://www.danleysoundlabs.com/images/Matterhorn%20Finished.jpg
>
>
> >"Steve" > wrote in message ...
> >> MOSFET wrote:
> >>
> >> > There IS a reason why bass is so much louder in a car than in a
> >> > living room. It all has to do with the transfer funtion you
> >> > benefit from in a smaller car cabin. The smaller the car, the
> >> > greater this transfer function will be.
> >>
> >> So are you saying that bass in a car such as a Mini Cooper or even a
> >> Mazda Miata, for example, would be louder?
> >>
> >> My car is a 2006 Toyota Corolla by the way.
> >>
> >
> >

[Mariachi]

Okay... here's my take on it if you had a spherical speaker

If you have a 100 db per watt @ 1 meter point source speaker

Then you would have to calculate the ratio of the sound SPL @ 1 m and
@ 10 m

A spherical wave emitting power source has intensity at radius r
I - intensity
P - power
r - radius

I = P/(4*pi*r^2)
I(1m) = 1 Watt / (4 * pi * (1m)^2) = .0796 Watt / m^2

I(10m) = 1 Watt/ (4 * pi * (10m)^2) = .000796 Watt / m^2

I(1m)/I(10m) = 100

This tells us that the intensity drops by a factor of 100

If the intensity drops by a factor of 100 then the energy of the sound
wave drops by a factor of (100)^(1/2), which is 10
If the energy drops by a factor of 10, then the amplitude of the sound
wave drops by a factor of (10)^(1/2), which is 3.162.
If the amplitude drops by a factor of 3.162, then the RMS pressure
level of the sound wave will drop by a factor of .707*3.162, which is
2.236

SO ...

SPL = 20 * log(p/20micropascals)


SPL ratio is
SPL ratio = 100 db / SPL(@10 m)
>>find SPL(@10m
p1 - rms pressure at 1 m
p10 - rms pressure at 10 m

SPL ratio = log(p1/20microPa)/log(p10/20microPa) = log[(p1/20micPa)-
(p10/20micPa)]
10^(SPL ratio) = (1/20microPa)(p1 - p10)
10^(SPL ratio)*20microPa = p1 - p10
p1/p10 = 2.236
p10/p1 = 1/2.236

divide both sides by p1
[10^(SPL ratio)*20microPa]/p1 = 1 - (1/2.236) = 1 - .44722 = .5528

what is p1?
100 dB = 20 * log(p1/20micPa)
10^(100/20) = p1/(20micPa)
p1 = 2,000,000 micro Pascals
p1 = 2 Pascals

solve for SPL ratio

10^(SPL ratio)*20microPa = (.5528)*p1 = .5528*2 = 1.1055
10^(SPL ratio) = 55277.3
SPL ratio = log (55277.3)
SPL ratio = 4.7425

100 db / SPL @ 10 m = 4.7425

So at 10 m, you have 100 dB / 4.7425 = 21.08 dB

If perhaps it takes double the wattage to get a 3 dB increase at 1 m,
then
10 * log (2^n) + 100 = SPL @ 1m
n - number of times wattage doubled
n = log base2(Current Wattage/1 Watt)

What is the SPL @ 1 m if they SPL at 10 m has to be 126 dB
4.7425 = SPL @ 1 m / 126 dB
SPL @ 1 m = 597.555 dB (huh? probably because of non-focused sound or
possible mathematical error)

anyways... moving on

10*log(2^n) + 100 = 597.6 dB
10*log(2^n) = 597.6 dB - 100 dB
log(2^n) = 49.76
2^n = 10^49.76
2^n = 5.7544E49
n = log base2(5.7544E49) = log (5.7544E49)/log(2) = 165.3

165.3 = log base2(Current Wattage/1m) = log base2(Current Wattage)
2^165.3 = Current Wattage = 5.7544E49 Watts
(which is the same thing as 2^n)

So you need 5.744E49 Watts of power if you have a point source speaker
( i think i have a mathematical error somewhere)... seems overkill

[Mariachi]

On Sep 20, 8:28 pm, Mariachi > wrote:
> Okay... here's my take on it if you had a spherical speaker
>
> If you have a 100 db per watt @ 1 meter point source speaker
>
> Then you would have to calculate the ratio of the sound SPL @ 1 m and
> @ 10 m
>
> A spherical wave emitting power source has intensity at radius r
> I - intensity
> P - power
> r - radius
>
> I = P/(4*pi*r^2)
> I(1m) = 1 Watt / (4 * pi * (1m)^2) = .0796 Watt / m^2
>
> I(10m) = 1 Watt/ (4 * pi * (10m)^2) = .000796 Watt / m^2
>
> I(1m)/I(10m) = 100
>
> This tells us that the intensity drops by a factor of 100
>
> If the intensity drops by a factor of 100 then the energy of the sound
> wave drops by a factor of (100)^(1/2), which is 10
> If the energy drops by a factor of 10, then the amplitude of the sound
> wave drops by a factor of (10)^(1/2), which is 3.162.
> If the amplitude drops by a factor of 3.162, then the RMS pressure
> level of the sound wave will drop by a factor of .707*3.162, which is
> 2.236
>
> SO ...
>

126 dB = 20 * log(p/p0)
10^(126/20) = p/p0
p = 10^(126/20) * p0
p@10 m = 39.905 Pascals
p@1m/p@10m = 2.236
2.236 = Pascals
p@1m = 89.22758 Pascals

SPL @ 1m = 20 * log (89.22758/p0)
SPL @ 1m = 132.99 dB

10*log(2^n) + 100 = 132.99 dB
10*log(2^n) = 132.99 dB - 100 dB
log(2^n) = 3.299
2^n = 10^3.299
2^n = 1990.7 Watts
2^n = Current Wattage of speaker

ANSWER
Power of spherical speaker = 1991 Watts

that makes a lot more sense

[Mariachi]

On Sep 20, 8:57 pm, Mariachi > wrote:
> On Sep 20, 8:28 pm, Mariachi > wrote:
>
>
>
> > Okay... here's my take on it if you had a spherical speaker
>
> > If you have a 100 db per watt @ 1 meter point source speaker
>
> > Then you would have to calculate the ratio of the sound SPL @ 1 m and
> > @ 10 m
>
> > A spherical wave emitting power source has intensity at radius r
> > I - intensity
> > P - power
> > r - radius
>
> > I = P/(4*pi*r^2)
> > I(1m) = 1 Watt / (4 * pi * (1m)^2) = .0796 Watt / m^2
>
> > I(10m) = 1 Watt/ (4 * pi * (10m)^2) = .000796 Watt / m^2
>
> > I(1m)/I(10m) = 100
>
> > This tells us that the intensity drops by a factor of 100
>
> > If the intensity drops by a factor of 100 then the energy of the sound
> > wave drops by a factor of (100)^(1/2), which is 10
> > If the energy drops by a factor of 10, then the amplitude of the sound
> > wave drops by a factor of (10)^(1/2), which is 3.162.
> > If the amplitude drops by a factor of 3.162, then the RMS pressure
> > level of the sound wave will drop by a factor of .707*3.162, which is
> > 2.236
>
> > SO ...
>
> 126 dB = 20 * log(p/p0)
> 10^(126/20) = p/p0
> p = 10^(126/20) * p0
> p@10 m = 39.905 Pascals
> p@1m/p@10m = 2.236
> 2.236 = Pascals
> p@1m = 89.22758 Pascals
>
> SPL @ 1m = 20 * log (89.22758/p0)
> SPL @ 1m = 132.99 dB
>
> 10*log(2^n) + 100 = 132.99 dB
> 10*log(2^n) = 132.99 dB - 100 dB
> log(2^n) = 3.299
> 2^n = 10^3.299
> 2^n = 1990.7 Watts
> 2^n = Current Wattage of speaker
>
> ANSWER
> Power of spherical speaker = 1991 Watts
>
> that makes a lot more sense

of course there is no such thing as a spherical speaker, so the
intensity of the sound would not dissipate as much as 1/r^2, because
the sound waves are more focused. Once you know the relationship
(correlation factor) of the sound wave rms pressure dissipation as the
distance from the speaker increases, then you could figure out how
much wattage the speaker would need at any distance away to produce a
certain SPL.

In other words,
Once you get the divergence angle (the half angle) of the sound wave
protrusion from the speaker, then you can solve the problem.