I have a rockford 75.2 amp thats pretty old, but still works great. I also have
a newer pioneer amp thats not hooked up. I believe it's also 75 watts x 2 .
now, I have a rockford 12" HE2 sub (the middle of the road sub, better than the
Z subs). I'm looking for a little more bass. I mainly listen to rock music but
listen to hip hop everynow and then. my question is, is there another 12" that
I could get to replace my rockford that would be better for the power I'm
giving it (both channels bridged to 150 watts). or is anythign else I get going
to prety much sound the same? thanks
-Slick Nick

The best choices for you would be to add a second HE2 or go with a ported
box. Both will give you more output with your existing power.


Paul Vina



"habibe99" wrote in message
...
I have a rockford 75.2 amp thats pretty old, but still works great. I also
have
a newer pioneer amp thats not hooked up. I believe it's also 75 watts x 2
..
now, I have a rockford 12" HE2 sub (the middle of the road sub, better
than the
Z subs). I'm looking for a little more bass. I mainly listen to rock music
but
listen to hip hop everynow and then. my question is, is there another 12"
that
I could get to replace my rockford that would be better for the power I'm
giving it (both channels bridged to 150 watts). or is anythign else I get
going
to prety much sound the same? thanks
-Slick Nick

Hm... I had a feeling about that. my problems with it are space reasons, I need
to be able to use most of my trunk. and I don't want to have to buy another
amp. cause I don't believe my rockford amp at 75 watts per channel woudl do
them any good. would they? thanks


The best choices for you would be to add a second HE2 or go with a ported
box. Both will give you more output with your existing power.


Paul Vina



"habibe99" wrote in message
...
I have a rockford 75.2 amp thats pretty old, but still works great. I also
have
a newer pioneer amp thats not hooked up. I believe it's also 75 watts x 2
.
now, I have a rockford 12" HE2 sub (the middle of the road sub, better
than the
Z subs). I'm looking for a little more bass. I mainly listen to rock music
but
listen to hip hop everynow and then. my question is, is there another 12"
that
I could get to replace my rockford that would be better for the power I'm
giving it (both channels bridged to 150 watts). or is anythign else I get
going
to prety much sound the same? thanks
-Slick Nick


-Slick Nick

Adding a second sub will do a lot more for you that changing your sub or
getting a bigger amp will. Even without adding more power it will get
considerably louder. I replaced the S12L5 in my wife's car because I killed
it for the second tim eand put in a pair of older RF DVC12s and it's louder
and better sounding.



Paul Vina




"habibe99" wrote in message
...
Hm... I had a feeling about that. my problems with it are space reasons, I
need
to be able to use most of my trunk. and I don't want to have to buy
another
amp. cause I don't believe my rockford amp at 75 watts per channel woudl
do
them any good. would they? thanks


The best choices for you would be to add a second HE2 or go with a ported
box. Both will give you more output with your existing power.


Paul Vina



"habibe99" wrote in message
...
I have a rockford 75.2 amp thats pretty old, but still works great. I
also
have
a newer pioneer amp thats not hooked up. I believe it's also 75 watts x
2
.
now, I have a rockford 12" HE2 sub (the middle of the road sub, better
than the
Z subs). I'm looking for a little more bass. I mainly listen to rock
music
but
listen to hip hop everynow and then. my question is, is there another
12"
that
I could get to replace my rockford that would be better for the power
I'm
giving it (both channels bridged to 150 watts). or is anythign else I
get
going
to prety much sound the same? thanks
-Slick Nick


-Slick Nick

Adding a second sub will do a lot more for you that changing your sub or
getting a bigger amp will. Even without adding more power it will get
considerably louder. I replaced the S12L5 in my wife's car because I killed
it for the second tim eand put in a pair of older RF DVC12s and it's louder
and better sounding.

Given that adding a second sub getting the same exact power as the original
sub, you will see a 3 decibel gain. I don't believe that adding a second sub
while halving the input of both will show much of a gain. In other words, 2
subs each getting 75 watts each is not going to be significantly better than 1
sub getting 150 watts. Any thoughs?

On 28 Dec 2003 06:26:01 GMT, HRA (BANDIT2941)
wrote:

Adding a second sub will do a lot more for you that changing your sub or
getting a bigger amp will. Even without adding more power it will get
considerably louder. I replaced the S12L5 in my wife's car because I killed
it for the second tim eand put in a pair of older RF DVC12s and it's louder
and better sounding.

Given that adding a second sub getting the same exact power as the original
sub, you will see a 3 decibel gain. I don't believe that adding a second sub
while halving the input of both will show much of a gain. In other words, 2
subs each getting 75 watts each is not going to be significantly better than 1
sub getting 150 watts. Any thoughs?

Actually, doubling the cone area (adding a second sub) should raise
the output by 3dB, even without increasing amplifier power. Adding a
second sub, and giving it as much power as the first sub will give
approximately a 6dB gain, not 3dB.
So to use your example, two subs getting 75 Watts each should be 3dB
louder than a single sub receiving 150 Watts, assuming the subs are
the same type.

Scott Gardner

Actually, doubling the cone area (adding a second sub) should raise
the output by 3dB, even without increasing amplifier power. Adding a
second sub, and giving it as much power as the first sub will give
approximately a 6dB gain, not 3dB.
So to use your example, two subs getting 75 Watts each should be 3dB
louder than a single sub receiving 150 Watts, assuming the subs are
the same type.

What I always believed(and proved in my college physics class) was that if you
have one object at x decibels, and you put another one near it that is x
decibels, the sum is x+3 decibels. In other words, if you have a race car at
130 decibels, and you put another race car next to it at 130 decibels, now you
have 133 decibels. In other words, if you double the intensity I, you have a 3
decibel gain.
So that should work for subwoofers the same way, so adding a second subwoofer
powering it exactly the same as the first will yield a 3db gain.

To quote from a physics book:

"SL = 10 log I/Io (Io = I sub zero)
The SL is definined with respect to a reference intensity Io(I zero), which is
chosen to be 10^-12 W/m^2 (a typical value for the threshold of human hearing).
Sound levels defined in this way are measured in units of decibels(dB). A sound
of intensity Io has a sound level of 0dB, wheras sound at the upper range of
human hearing, called the threshold of pain, has an intensity of 1 W/m^2 and a
SL of 120 dB. Multiplication of the intensity I by a factor of 10 corresponds
to adding 10dB to the SL. We can also use dB as a relative measure to compare
different sounds with one another, rather than with the reference intensity.
Suppose we wish to compare two sounds of intensities I1 and I2:
SL1 - SL2 = 10 log I1/Io - 10 log I2/Io
which equals 10 log I1/I2"

So, if we double the intensity(by adding another subwoofer with the same exact
wattage) this yields and intensity ratio of 2. So we have 10 log 2 which equals
3.01, or, a 3dB gain by adding a second subwoofer powered the exact same.

The book goes on to say:
"For example, two sounds whose intesity ratio is 2 differ in SL by 10 log 2 = 3
dB" which is what I just said.

Jamie

While technically correct, it rarely works that way. I went from a single
Kicker S12L5 with 500 watts on it to a pair of older RF DVC12s with the same
500 wats on the pair (250 each) and it's WAY louder. I haven't measured it
yet, but you can easily tell the difference. According to your post the
difference should have been minimal, and probably less thanthat since the L5
had about 20% more cone area than a single DVC12.
Basically I'm saying two will be a lot better than one in every way.


Paul Vina



"BANDIT2941" wrote in message
...
Adding a second sub will do a lot more for you that changing your sub or
getting a bigger amp will. Even without adding more power it will get
considerably louder. I replaced the S12L5 in my wife's car because I
killed
it for the second tim eand put in a pair of older RF DVC12s and it's
louder
and better sounding.

Given that adding a second sub getting the same exact power as the
original
sub, you will see a 3 decibel gain. I don't believe that adding a second
sub
while halving the input of both will show much of a gain. In other words,
2
subs each getting 75 watts each is not going to be significantly better
than 1
sub getting 150 watts. Any thoughs?

What I always believed(and proved in my college physics class)
snip

Scott said that.

Paul, a 3dB gain is nothing to scoff at. I'm sure the difference was
substantial, but I doubt it was any more than the 3dB Bandit was talking
about.

"Paul Vina" wrote in message
news:h_EHb.680189$Tr4.1699274@attbi_s03...
While technically correct, it rarely works that way. I went from a single
Kicker S12L5 with 500 watts on it to a pair of older RF DVC12s with the
same
500 wats on the pair (250 each) and it's WAY louder. I haven't measured it
yet, but you can easily tell the difference. According to your post the
difference should have been minimal, and probably less thanthat since the
L5
had about 20% more cone area than a single DVC12.
Basically I'm saying two will be a lot better than one in every way.


Paul Vina



"BANDIT2941" wrote in message
...
Adding a second sub will do a lot more for you that changing your sub
or
getting a bigger amp will. Even without adding more power it will get
considerably louder. I replaced the S12L5 in my wife's car because I
killed
it for the second tim eand put in a pair of older RF DVC12s and it's
louder
and better sounding.

Given that adding a second sub getting the same exact power as the
original
sub, you will see a 3 decibel gain. I don't believe that adding a second
sub
while halving the input of both will show much of a gain. In other
words,
2
subs each getting 75 watts each is not going to be significantly better
than 1
sub getting 150 watts. Any thoughs?

Here's a quote on topic:

"...it should be mentioned again that the radiating efficiency of a
direct-radiator loudspeaker can be increased at low frequencies by
mounting several units side by side in a single baffle. The mutual
interaction among the radiating units serves to increase the radiation
resistance of each unit substantially. For example, two identical
direct-radiators very near each other in an infinitely large plane
baffle, and vibrating in phase, will produce four times the intensity
on the principle axis as will one of them alone."

Beranek, "Acoustics," 1st Ed., 1954, p259.

The "four times the intensity" part is a 6dB gain, which results from
adding a second subwoofer and powering it with the same amount of
power that the first sub received. (The doubling of power as well as
cone area is implied in this paragraph, not expressed.

In real life, doubling the number of speakers and doubling the total
power delivered probably won't give a full 6dB increase in SPL, but it
certainly should give more than 3db. The example given in this thread
with the two racecars isn't a good analogy, because even though you've
doubled the power by introducing the second racecar, there's nothing
in that situation that's analogous to the doubling of cone area in the
speaker example. Thus, the racecar example *would* only give you a 3
dB increase.

Scott Gardner



On Sun, 28 Dec 2003 20:34:22 -0500, "Mark Zarella"
wrote:

Paul, a 3dB gain is nothing to scoff at. I'm sure the difference was
substantial, but I doubt it was any more than the 3dB Bandit was talking
about.

"Paul Vina" wrote in message
news:h_EHb.680189$Tr4.1699274@attbi_s03...
While technically correct, it rarely works that way. I went from a single
Kicker S12L5 with 500 watts on it to a pair of older RF DVC12s with the
same
500 wats on the pair (250 each) and it's WAY louder. I haven't measured it
yet, but you can easily tell the difference. According to your post the
difference should have been minimal, and probably less thanthat since the
L5
had about 20% more cone area than a single DVC12.
Basically I'm saying two will be a lot better than one in every way.


Paul Vina



"BANDIT2941" wrote in message
...
Adding a second sub will do a lot more for you that changing your sub
or
getting a bigger amp will. Even without adding more power it will get
considerably louder. I replaced the S12L5 in my wife's car because I
killed
it for the second tim eand put in a pair of older RF DVC12s and it's
louder
and better sounding.

Given that adding a second sub getting the same exact power as the
original
sub, you will see a 3 decibel gain. I don't believe that adding a second
sub
while halving the input of both will show much of a gain. In other
words,
2
subs each getting 75 watts each is not going to be significantly better
than 1
sub getting 150 watts. Any thoughs?

In Paul's situation, a 3 dB gain was all he could expect, since he
doubled the cone area WITHOUT increasing the total power delivered
(500 Watts). Sound like that's about what he got.

Jamie (Bandit) is claiming that doubling the cone area AND doubling
the power delivered will only give a 3 dB increase, which is simply
wrong. He would be correct if we were talking about point-source
energy sources, like his textbook describes, but with loudspeakers at
low frequencies, cone area has an effect as well as total power. Note
that this phenomenon does not apply to tweeters. This is because the
speakers must be mounted close together (relative to the wavelength
being produced) for the synergistic effect to take place. Subs are
dealing with very long wavelengths, so this is easy to do. Tweeters
produce energy with such a short wavelength that even if you put them
side-by-side, you probably still wouldn't get the effect.

Scott Gardner


On Sun, 28 Dec 2003 20:34:22 -0500, "Mark Zarella"
wrote:

Paul, a 3dB gain is nothing to scoff at. I'm sure the difference was
substantial, but I doubt it was any more than the 3dB Bandit was talking
about.

"Paul Vina" wrote in message
news:h_EHb.680189$Tr4.1699274@attbi_s03...
While technically correct, it rarely works that way. I went from a single
Kicker S12L5 with 500 watts on it to a pair of older RF DVC12s with the
same
500 wats on the pair (250 each) and it's WAY louder. I haven't measured it
yet, but you can easily tell the difference. According to your post the
difference should have been minimal, and probably less thanthat since the
L5
had about 20% more cone area than a single DVC12.
Basically I'm saying two will be a lot better than one in every way.


Paul Vina



"BANDIT2941" wrote in message
...
Adding a second sub will do a lot more for you that changing your sub
or
getting a bigger amp will. Even without adding more power it will get
considerably louder. I replaced the S12L5 in my wife's car because I
killed
it for the second tim eand put in a pair of older RF DVC12s and it's
louder
and better sounding.

Given that adding a second sub getting the same exact power as the
original
sub, you will see a 3 decibel gain. I don't believe that adding a second
sub
while halving the input of both will show much of a gain. In other
words,
2
subs each getting 75 watts each is not going to be significantly better
than 1
sub getting 150 watts. Any thoughs?

Seems I'm missing the point here. I didn't realize that what you said was
being debated. In any case, yes, you're correct. Who was disagreeing with
it?

"Scott Gardner" wrote in message
...
In Paul's situation, a 3 dB gain was all he could expect, since he
doubled the cone area WITHOUT increasing the total power delivered
(500 Watts). Sound like that's about what he got.

Jamie (Bandit) is claiming that doubling the cone area AND doubling
the power delivered will only give a 3 dB increase, which is simply
wrong. He would be correct if we were talking about point-source
energy sources, like his textbook describes, but with loudspeakers at
low frequencies, cone area has an effect as well as total power. Note
that this phenomenon does not apply to tweeters. This is because the
speakers must be mounted close together (relative to the wavelength
being produced) for the synergistic effect to take place. Subs are
dealing with very long wavelengths, so this is easy to do. Tweeters
produce energy with such a short wavelength that even if you put them
side-by-side, you probably still wouldn't get the effect.

Scott Gardner


On Sun, 28 Dec 2003 20:34:22 -0500, "Mark Zarella"
wrote:

Paul, a 3dB gain is nothing to scoff at. I'm sure the difference was
substantial, but I doubt it was any more than the 3dB Bandit was talking
about.

"Paul Vina" wrote in message
news:h_EHb.680189$Tr4.1699274@attbi_s03...
While technically correct, it rarely works that way. I went from a
single
Kicker S12L5 with 500 watts on it to a pair of older RF DVC12s with the
same
500 wats on the pair (250 each) and it's WAY louder. I haven't measured
it
yet, but you can easily tell the difference. According to your post
the
difference should have been minimal, and probably less thanthat since
the
L5
had about 20% more cone area than a single DVC12.
Basically I'm saying two will be a lot better than one in every way.


Paul Vina



"BANDIT2941" wrote in message
...
Adding a second sub will do a lot more for you that changing your
sub
or
getting a bigger amp will. Even without adding more power it will
get
considerably louder. I replaced the S12L5 in my wife's car because
I
killed
it for the second tim eand put in a pair of older RF DVC12s and it's
louder
and better sounding.

Given that adding a second sub getting the same exact power as the
original
sub, you will see a 3 decibel gain. I don't believe that adding a
second
sub
while halving the input of both will show much of a gain. In other
words,
2
subs each getting 75 watts each is not going to be significantly
better
than 1
sub getting 150 watts. Any thoughs?

Bandit 2941 was missing the point. Here's his quote:

"So that should work for subwoofers the same way, so adding a second
subwoofer powering it exactly the same as the first will yield a 3db
gain."



He's recognizing the 3 dB gain from doubling the power, but ignoring
the additional 3 dB gain from doubling the number of speakers.

Scott Gardner



On Sun, 28 Dec 2003 23:33:38 -0500, "Mark Zarella"
wrote:

Seems I'm missing the point here. I didn't realize that what you said was
being debated. In any case, yes, you're correct. Who was disagreeing with
it?

"Scott Gardner" wrote in message
...
In Paul's situation, a 3 dB gain was all he could expect, since he
doubled the cone area WITHOUT increasing the total power delivered
(500 Watts). Sound like that's about what he got.

Jamie (Bandit) is claiming that doubling the cone area AND doubling
the power delivered will only give a 3 dB increase, which is simply
wrong. He would be correct if we were talking about point-source
energy sources, like his textbook describes, but with loudspeakers at
low frequencies, cone area has an effect as well as total power. Note
that this phenomenon does not apply to tweeters. This is because the
speakers must be mounted close together (relative to the wavelength
being produced) for the synergistic effect to take place. Subs are
dealing with very long wavelengths, so this is easy to do. Tweeters
produce energy with such a short wavelength that even if you put them
side-by-side, you probably still wouldn't get the effect.

Scott Gardner


On Sun, 28 Dec 2003 20:34:22 -0500, "Mark Zarella"
wrote:

Paul, a 3dB gain is nothing to scoff at. I'm sure the difference was
substantial, but I doubt it was any more than the 3dB Bandit was talking
about.

"Paul Vina" wrote in message
news:h_EHb.680189$Tr4.1699274@attbi_s03...
While technically correct, it rarely works that way. I went from a
single
Kicker S12L5 with 500 watts on it to a pair of older RF DVC12s with the
same
500 wats on the pair (250 each) and it's WAY louder. I haven't measured
it
yet, but you can easily tell the difference. According to your post
the
difference should have been minimal, and probably less thanthat since
the
L5
had about 20% more cone area than a single DVC12.
Basically I'm saying two will be a lot better than one in every way.


Paul Vina



"BANDIT2941" wrote in message
...
Adding a second sub will do a lot more for you that changing your
sub
or
getting a bigger amp will. Even without adding more power it will
get
considerably louder. I replaced the S12L5 in my wife's car because
I
killed
it for the second tim eand put in a pair of older RF DVC12s and it's
louder
and better sounding.

Given that adding a second sub getting the same exact power as the
original
sub, you will see a 3 decibel gain. I don't believe that adding a
second
sub
while halving the input of both will show much of a gain. In other
words,
2
subs each getting 75 watts each is not going to be significantly
better
than 1
sub getting 150 watts. Any thoughs?

Jamie (Bandit) is claiming that doubling the cone area AND doubling
the power delivered will only give a 3 dB increase, which is simply
wrong. He would be correct if we were talking about point-source
energy sources, like his textbook describes, but with loudspeakers at
low frequencies, cone area has an effect as well as total power. Note
that this phenomenon does not apply to tweeters. This is because the
speakers must be mounted close together (relative to the wavelength
being produced) for the synergistic effect to take place. Subs are
dealing with very long wavelengths, so this is easy to do. Tweeters
produce energy with such a short wavelength that even if you put them
side-by-side, you probably still wouldn't get the effect.

I was just going by the rule that doubling intensity gives a 3dB gain. I
figured that putting another subwoofer next to the original with the same
amount of power would serve to double the intensity. But, it seems that cone
area behaves similarly yet independently of the intensity, ie 3dB for doubling
it.

Scott Gardner wrote:

Actually, doubling the cone area (adding a second sub) should raise
the output by 3dB,

http://www.installer.com/tech/conearea.html

http://www.installer.com/tech/conearea.html
it has nothing to do with CONE area and power doubling!


Scott Gardner wrote:

Bandit 2941 was missing the point. Here's his quote:

"So that should work for subwoofers the same way, so adding a second
subwoofer powering it exactly the same as the first will yield a 3db
gain."

He's recognizing the 3 dB gain from doubling the power, but ignoring
the additional 3 dB gain from doubling the number of speakers.

Scott Gardner

You're right - I chose my words poorly. The first 3 dB increase comes
from the doubling of input power, and the second 3 dB increase comes
from adding a second subwoofer in phase with the first, "correlated",
as you described in your tech notes. The doubling of cone area is a
by-product of adding the second sub, not the source of the 3 dB
increase.

Also, as you pointed out, the overall 6 dB gain is a theoretical
maximum. The actual increase will likely be less, although how much
less is impossible to tell. I would still predict the overall gain to
be at least 4-5 dB.

Interestingly enough, the post of mine you quoted below was the only
one where I described the phenomenon correctly, attributing the second
3 dB gain to doubling the number of loudspeakers, and not mistakingly
referring to it as "doubling the cone area".

Scott Gardner


On Mon, 29 Dec 2003 17:00:11 GMT, Eddie Runner
wrote:

http://www.installer.com/tech/conearea.html
it has nothing to do with CONE area and power doubling!


Scott Gardner wrote:

Bandit 2941 was missing the point. Here's his quote:

"So that should work for subwoofers the same way, so adding a second
subwoofer powering it exactly the same as the first will yield a 3db
gain."

He's recognizing the 3 dB gain from doubling the power, but ignoring
the additional 3 dB gain from doubling the number of speakers.

Scott Gardner

I didnt mean to sound like I was picking on you Scott.
There were several posts by several people that were
worded wrong, I chose your posts to respond to although
I meant it for everyone that had the same claim.

I have explained that so many times on RAC in the past
decade I eventually made the tech page to save me from typing it
all over again and again....

Scott Gardner wrote:

Interestingly enough, the post of mine you quoted below was the only
one where I described the phenomenon correctly, attributing the second
3 dB gain to doubling the number of loudspeakers, and not mistakingly
referring to it as "doubling the cone area".

but you must not have read my paper !!

1. Adding one sound to another sound of the same amplitude (volume) will
gain you 3dB.
2. Adding one sound to another sound of the same amplitude and correlated=

will gain you 6dB.
(correlated means exactly the same phase, and likely to occur with the lo=
ng
wavelength of bass notes in our cars)=85

it IS NOT a facto of doubling the speakers OR doubling the power to the
speaker!!

Eddie Runner
http://www.installer.com/tech/conearea.html

On Mon, 29 Dec 2003 21:34:32 GMT, Eddie Runner
wrote:

I didnt mean to sound like I was picking on you Scott.
There were several posts by several people that were
worded wrong, I chose your posts to respond to although
I meant it for everyone that had the same claim.

I have explained that so many times on RAC in the past
decade I eventually made the tech page to save me from typing it
all over again and again....

Scott Gardner wrote:

Interestingly enough, the post of mine you quoted below was the only
one where I described the phenomenon correctly, attributing the second
3 dB gain to doubling the number of loudspeakers, and not mistakingly
referring to it as "doubling the cone area".

but you must not have read my paper !!

1. Adding one sound to another sound of the same amplitude (volume) will
gain you 3dB.
2. Adding one sound to another sound of the same amplitude and correlated=

will gain you 6dB.
(correlated means exactly the same phase, and likely to occur with the lo=
ng
wavelength of bass notes in our cars)=85

it IS NOT a facto of doubling the speakers OR doubling the power to the
speaker!!

Eddie Runner
http://www.installer.com/tech/conearea.html


Yep, there were several caveats that were listed in the paragraph I
quoted from "Acoustics" that I didn't explicitly address. The
speakers must be facing the same direction, and close enough to each
other for the synergistic effect to take place. (This is trivially
easy for subwoofers, almost impossible for tweeters.)

I would assert that "adding one sound to another sound of the same
amplitude" is equivalent to doubling the input power, **as long as**
you're still within the linear operating region of the subwoofer. Of
course, it's still only a theoretical maximum of 3 dB, and will depend
largely on the loudspeaker.

To paraphrase the "Acoustics" quote, with some of the caveats
emphasized-- Two speakers, identically powered, close to each other,
producing bass frequencies, and in-phase with one another will produce
four times the sonic intensity (+6 dB) along their principle axis when
compared to a single loudspeaker.

Scott Gardner

Where did you get the Baranek book??
Other than me and Nosaine I didnt think anyone else
had that book... ha ha

Scott Gardner wrote:

On Mon, 29 Dec 2003 21:34:32 GMT, Eddie Runner
wrote:

Yep, there were several caveats that were listed in the paragraph I
quoted from "Acoustics" that I didn't explicitly address. The
speakers must be facing the same direction, and close enough to each
other for the synergistic effect to take place. (This is trivially
easy for subwoofers, almost impossible for tweeters.)

I would assert that "adding one sound to another sound of the same
amplitude" is equivalent to doubling the input power, **as long as**
you're still within the linear operating region of the subwoofer. Of
course, it's still only a theoretical maximum of 3 dB, and will depend
largely on the loudspeaker.

To paraphrase the "Acoustics" quote, with some of the caveats
emphasized-- Two speakers, identically powered, close to each other,
producing bass frequencies, and in-phase with one another will produce
four times the sonic intensity (+6 dB) along their principle axis when
compared to a single loudspeaker.

Scott Gardner

Actually, doubling the cone area (adding a second sub) should raise
the output by 3dB,

http://www.installer.com/tech/conearea.html


Where in your tutorial do you refute what was said about adding cone area by
adding a second sub?

you MAY get 3db when you add another cone
BUT, adding the cone area IS NOT WHY you get 3db!!!!!!!

Mark Zarella wrote:

Actually, doubling the cone area (adding a second sub) should raise
the output by 3dB,

http://www.installer.com/tech/conearea.html


Where in your tutorial do you refute what was said about adding cone area by
adding a second sub?

you MAY get 3db when you add another cone
BUT, adding the cone area IS NOT WHY you get 3db!!!!!!!

Not sure what you're getting at here. Are you suggesting that the
(theoretical) 3dB increase occurs only when the total system power is
doubled, but not when the cone area is doubled?

I think Scott was varying one parameter at a time in his analysis. In other
words, keep total system power constant and double the number of speakers
(identical to the original). Then double the amount of power but stick with
just one speaker. His mistake was that he was then adding the result,
assuming linearity.

Huh? If you had 1 sub ay 75 watts and then switched to 2 of the same size
at 37.5 watts it would be louder. What exactly are you talking about? If
it isn't the cone area that's making it louder, what is?


Paul Vina



"Eddie Runner" wrote in message
...
you MAY get 3db when you add another cone
BUT, adding the cone area IS NOT WHY you get 3db!!!!!!!

Mark Zarella wrote:

Actually, doubling the cone area (adding a second sub) should raise
the output by 3dB,

http://www.installer.com/tech/conearea.html


Where in your tutorial do you refute what was said about adding cone
area by
adding a second sub?

Huh? If you had 1 sub ay 75 watts and then switched to 2 of the same size
at 37.5 watts it would be louder. What exactly are you talking about? If
it isn't the cone area that's making it louder, what is?

Power compression differences would play a role, maybe even a substantial
one depending on the sub and frequency response of the subwoofer system.

Mark Zarella wrote:

Not sure what you're getting at here. Are you suggesting that the
(theoretical) 3dB increase occurs only when the total system power is
doubled, but not when the cone area is doubled?

NEITHER!!!

You get the 3db for the simple reason that two like sounds combine.
it has nothing to do with doubling the power or doubling the cone area!
(other than the power or cone area make the sound in the first place.)

I can have a speaker with an 8 inch cone and a speaker with a 15 inch
cone, the 15 may not be louder... so cone area alone is not a factor...

I can have a speaker being driven with 100 watts and when I increase it
to 200 watts I may not get 3dB more ...

BUT, if I have one sound and add another sound the same SPL then I
WILL get 3db!!!

See your way of doubling the cone or doubling the power MIGHT NOT
GIVE ME 3DB.... But my way ALWAYS DOES!!!!!

And, if I were to add two like sounds that were correlated
(in phase perfectly, very likely for bass in a car) then we would increase
6db!!

the 3db for cone doubling and another 3db for power doubling is a MYTH.

I did write a paper to explain this some time ago, please review it
if you have the time http://www.installer.com/tech/conearea.html

Eddie Runner

when two sounds combine it gets louder, it has nothing directly
to do with only cone area....

One 12inch makeing 100db and another 12 making 100db
will combine to make 103db...

by the same token a 15 inch making 100db and an 8 inch
making 100db will combine to make 103db....

SEE!!!! We did not double the cone area and still got the 3db

It has NOTHING to do with cone area!!!!
it simply has to do with combining sounds...

Eddie Runner

Paul Vina wrote:

Huh? If you had 1 sub ay 75 watts and then switched to 2 of the same size
at 37.5 watts it would be louder. What exactly are you talking about? If
it isn't the cone area that's making it louder, what is?

Paul Vina

Not sure what you're getting at here. Are you suggesting that the
(theoretical) 3dB increase occurs only when the total system power is
doubled, but not when the cone area is doubled?

NEITHER!!!

You get the 3db for the simple reason that two like sounds combine.
it has nothing to do with doubling the power or doubling the cone area!
(other than the power or cone area make the sound in the first place.)

This is the same thing though. Two like sounds combining is the same thing
as doubling the cone area (note: all else being equal, which as you pointed
out before, is a difficult proposition in the real world). Oftentimes,
modeling loudspeaker output consists of treating the cone as an infinite
amount of point sources. Whether you double cone area or double the number
of cones, you're doubling the number of "point sources". In effect, you've
got the same thing going on. So to say it has nothing to do with doubling
the power or cone area is not correct. It has everything to do with it.

I can have a speaker with an 8 inch cone and a speaker with a 15 inch
cone, the 15 may not be louder... so cone area alone is not a factor...

That's correct. There are other variables at play. But there's an
interdependence between all of them.


I can have a speaker being driven with 100 watts and when I increase it
to 200 watts I may not get 3dB more ...

You probably won't. Power compression is a key reason.

BUT, if I have one sound and add another sound the same SPL then I
WILL get 3db!!!

Assuming the wavelength is long enough.

See your way of doubling the cone or doubling the power MIGHT NOT
GIVE ME 3DB.... But my way ALWAYS DOES!!!!!

Not sure what you mean here. Doubling the power or cone area WILL ALWAYS
yield a 3dB increase, assuming everything else is held the same. That is,
same power output, same enclosure size/tuning characteristics, etc.

And, if I were to add two like sounds that were correlated
(in phase perfectly, very likely for bass in a car) then we would
increase
6db!!

the 3db for cone doubling and another 3db for power doubling is a MYTH.

It most certainly is not a myth. You're simply failing to keep the other
variables constant.

when two sounds combine it gets louder, it has nothing directly
to do with only cone area....

One 12inch makeing 100db and another 12 making 100db
will combine to make 103db...

by the same token a 15 inch making 100db and an 8 inch
making 100db will combine to make 103db....

SEE!!!! We did not double the cone area and still got the 3db

It has NOTHING to do with cone area!!!!
it simply has to do with combining sounds...

It DOES have something to do with cone area. You can't just presuppose that
the 15 and the 8 will both output 100dB. There has to be a REASON for the
same sensitivity, because cone area does in fact contribute to the output
level. In the real world, we tend to notice that larger cone area yields
higher output level when the enclosure size is optimal such that the system
tuning is identical between the two cases. I suggest you read Richard
Small's 1970 paper on the subject. It's short enough to even hold your
attention.

Actuallly, for both of those examples, the total increase could be as
high as 6 dB, if the speakers in question were reproducing bass notes,
were located close together, and were in-phase.

Scott Gardner

On Tue, 30 Dec 2003 16:42:54 GMT, Eddie Runner
wrote:

when two sounds combine it gets louder, it has nothing directly
to do with only cone area....

One 12inch makeing 100db and another 12 making 100db
will combine to make 103db...

by the same token a 15 inch making 100db and an 8 inch
making 100db will combine to make 103db....

SEE!!!! We did not double the cone area and still got the 3db

It has NOTHING to do with cone area!!!!
it simply has to do with combining sounds...

Eddie Runner

Paul Vina wrote:

Huh? If you had 1 sub ay 75 watts and then switched to 2 of the same size
at 37.5 watts it would be louder. What exactly are you talking about? If
it isn't the cone area that's making it louder, what is?

Paul Vina

that is absolutely correct!!

Scott Gardner wrote:

Actuallly, for both of those examples, the total increase could be as
high as 6 dB, if the speakers in question were reproducing bass notes,
were located close together, and were in-phase.

Scott Gardner

On Tue, 30 Dec 2003 16:42:54 GMT, Eddie Runner
wrote:

when two sounds combine it gets louder, it has nothing directly
to do with only cone area....

One 12inch makeing 100db and another 12 making 100db
will combine to make 103db...

by the same token a 15 inch making 100db and an 8 inch
making 100db will combine to make 103db....

SEE!!!! We did not double the cone area and still got the 3db

It has NOTHING to do with cone area!!!!
it simply has to do with combining sounds...

Eddie Runner

Paul Vina wrote:

Huh? If you had 1 sub ay 75 watts and then switched to 2 of the same size
at 37.5 watts it would be louder. What exactly are you talking about? If
it isn't the cone area that's making it louder, what is?

Paul Vina

While your statements may be true, we still need a baseline for observation
and comparison purposes. To say that combining two identical "sounds" will
result in a 3db SPL increase (over just one) is stating the obvious.

I think everyone following this discussion would agree that power and piston
area both play a role in the final SPL. However, the question is: what SPL
increase will we achieve by introducing an identical second subwoofer into a
system, and driving it with the same power as the first? We need to start
somewhere. Then we can discuss the effects of other factors (ex: power
compression).

Kevin Murray


"Eddie Runner" wrote in message
...
when two sounds combine it gets louder, it has nothing directly
to do with only cone area....

One 12inch makeing 100db and another 12 making 100db
will combine to make 103db...

by the same token a 15 inch making 100db and an 8 inch
making 100db will combine to make 103db....

SEE!!!! We did not double the cone area and still got the 3db

It has NOTHING to do with cone area!!!!
it simply has to do with combining sounds...

Eddie Runner

Paul Vina wrote:

Huh? If you had 1 sub ay 75 watts and then switched to 2 of the same
size
at 37.5 watts it would be louder. What exactly are you talking about?
If
it isn't the cone area that's making it louder, what is?

Paul Vina

Mark Zarella wrote:

Not sure what you're getting at here. Are you suggesting that the
(theoretical) 3dB increase occurs only when the total system power is
doubled, but not when the cone area is doubled?

NEITHER!!!

You get the 3db for the simple reason that two like sounds combine.
it has nothing to do with doubling the power or doubling the cone area!
(other than the power or cone area make the sound in the first place.)

This is the same thing though.

No its not.... you cant double the cone area without doubling the motor
and the cone mass and a whole bunch of other variables.... You cant magicly
double the cone area and even if you did it would not guarantee a 3db
increase.... SO its NOT the same thing... Doubling the cone area MIGHT
give you 3db... doubling the sounds WILL give you 3db increase!! (correlated
gives you 6db)..

See the difference??
your way is MIGHT
my way is WILL
!!!!!!!!!!!!!!!!!!!!!

Not the same thing at all..

Two like sounds combining is the same thing
as doubling the cone area (note: all else being equal, which as you pointed
out before, is a difficult proposition in the real world).

all of what being equal???
Equal voice coil, equal magnets, equal suspension, equal cone weight???
???? Equal power??? How do you know its equal???

And what if it is NOT EQUAL???
What if one speaker is an 8 inch and one speaker is a 15 inch???
it could still be a 3db increase if they combine sounds!!
Then again it might not be!!

The common myth that doubling the cone area gets you 3db is
all full of holes!!

On the other hand 2 equal sounds however is not all full of holes...
it WILL get you 3db or 6db if correlated...

Oftentimes,
modeling loudspeaker output consists of treating the cone as an infinite
amount of point sources. Whether you double cone area or double the number
of cones, you're doubling the number of "point sources". In effect, you've
got the same thing going on. So to say it has nothing to do with doubling
the power or cone area is not correct. It has everything to do with it.

NO!
Its not the fact that the cone area doubles.
Its the fact that the sound doubles!!

MAYBE (and maye not) when you double cone area you get 3db!
But ALWAYS when the sound doubles you get 3db!

Not sure what you mean here. Doubling the power or cone area WILL ALWAYS
yield a 3dB increase, assuming everything else is held the same.

Everything else??
Your statement is missleading and flawed!
doubling the INPUT power to the speaker is likely to not give you
a 3db increase, you just said it as well....

Cone area IS NOT WHY the sound is louder!!
We could do it with a smaller cone or a larger cone or NO CONE AT ALL!

Blaming it on CONE AREA or POWER or BOTH is a flawed
way of looking at something thats very simple....

IF! and I stress IF!
your second speaker is the same size and IF it puts out the
same dB as the first one which is already playing then you
would get 3db, and you would be doubling your cone area.

BUT, and I stress BUT!
you could also get the same3dB without doubling your cone
area! You could get it if a smaller or larger speaker was
playing the same sound or you could get 3dB if a fat lady
was singing the same song at the same level... See, it has
nothing to do with cone area!!!

You COULD!
You MIGHT!
But it wont always!!
read this http://www.installer.com/tech/conearea.html

Eddie Runner

You get the 3db for the simple reason that two like sounds combine.
it has nothing to do with doubling the power or doubling the cone
area!
(other than the power or cone area make the sound in the first place.)

This is the same thing though.

No its not.... you cant double the cone area without doubling the motor
and the cone mass and a whole bunch of other variables.... You cant
magicly
double the cone area and even if you did it would not guarantee a 3db
increase....

I never claimed you could. In fact, I agreed with you on this point earlier
in the thread. But, in order to understand what's going on, it's often
useful to analyze the output of a system, any system, when changing just one
variable. The real life consequences may or may not reflect this analysis.
In this case, I think there is an application where this analysis reflects
the real world - for instance, adding the second sub, even if total system
power remains unchanged, is illustrative of this effect. However, you can't
use your oversimplified "adding an identical second source" analysis,
because it doesn't apply - the two sources aren't identical.

SO its NOT the same thing... Doubling the cone area MIGHT
give you 3db... doubling the sounds WILL give you 3db increase!!
(correlated
gives you 6db)..

See the difference??
your way is MIGHT
my way is WILL
!!!!!!!!!!!!!!!!!!!!!

Not the same thing at all..

Your way is "will" only under certain circumstances. It's not applicable
for others (see above). That's why it's useful to know the underlying
cause, rather than simplified shortcuts that aren't generalized for all
cases.


Two like sounds combining is the same thing
as doubling the cone area (note: all else being equal, which as you
pointed
out before, is a difficult proposition in the real world).

all of what being equal???
Equal voice coil, equal magnets, equal suspension, equal cone weight???
???? Equal power??? How do you know its equal???

In real situations, it's difficult to keep everything equal. But in the
case of adding second sources, you can keep everything you listed above
equal. You can selectively vary power in the process and arrive at all
kinds of answers - answers which you have a more difficult time predicting
using your one nongeneral way of looking at things.


And what if it is NOT EQUAL???
What if one speaker is an 8 inch and one speaker is a 15 inch???
it could still be a 3db increase if they combine sounds!!
Then again it might not be!!

Not only might it not be, but it's highly unlikely that it would be! First
of all, the freq response would probably be entirely different. If it was
not, then the sensitivity would probably be entirely different.


The common myth that doubling the cone area gets you 3db is
all full of holes!!

I agree that it's misused, but it's not full of holes. The theory stands
true. The problem is that many people apply it in the wrong way.

Oftentimes,
modeling loudspeaker output consists of treating the cone as an infinite
amount of point sources. Whether you double cone area or double the
number
of cones, you're doubling the number of "point sources". In effect,
you've
got the same thing going on. So to say it has nothing to do with
doubling
the power or cone area is not correct. It has everything to do with it.

NO!
Its not the fact that the cone area doubles.
Its the fact that the sound doubles!!

So then you're pointing out the obvious. All you're saying is
dB=10log(P/P0). You've said nothing but doubling a quantity is going to
yield a 3dB increase in that quantity. That applies to anything. I'm
talking about speakers. I'm talking about WHY the sound doubles. The
physical cause of the sound doubling. Quibbling over whether your units are
differential or logarithmic does not address this at all.

"Mark Zarella" pam
wrote:

Gosh isn't it interesting at how some folks need to argue things that might be
better spent on more productive issues. Mark is right but there is one area in
this discussion, not Mark's that needs a minor correction:

....sigh.....
SO its NOT the same thing... Doubling the cone area MIGHT
give you 3db... doubling the sounds WILL give you 3db increase!!
(correlated
gives you 6db)..



I think Eddie means combined "coherently". Two identical sounds will always be
"correlated". They can be nothing else if the are the 'same.'