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Old 10th October 2012, 07:22 PM   #1761
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Quote:
Originally Posted by Djim View Post
Click the image to open in full size.
That's 2 watts vs. 1 watt. 2nd line down is "Amplifier power of EACH loudspeaker" so each speaker gets 1 watt, 2 watts total.
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Old 10th October 2012, 07:40 PM   #1762
Djim is offline Djim  Netherlands
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Ah, I see what you mean. That calculator is indeed tricky. When you have two drivers, the sensitivity raises 3dB, like I explained earlier. So if you fill in two drivers you have to correct the sensitivity figure manually.

Click the image to open in full size.

Last edited by Djim; 10th October 2012 at 07:47 PM.
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Old 10th October 2012, 07:50 PM   #1763
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Quote:
Originally Posted by Djim View Post
Ah, I see what you mean. That calculator is indeed tricky. When you have two drivers, the sensitivity raises 3dB, like I explained earlier. So if you fill in two drivers you have to correct the sensitivity figure manually.

Click the image to open in full size.
I don't think so.....LOL.
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Old 10th October 2012, 07:57 PM   #1764
AndrewT is offline AndrewT  Scotland
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One speaker with 10W gives 100dB @ 10m
Two speakers each with 5W gives 103dB @ 10m over the frequency range defined by the cone, or mouth, separation.
Two speakers close coupled each with 10W gives 106dB @ 10m

double the power and you get +3dB.
double the mouth & cone area and you get +3dB.
double the power and double the mouth and cone area and you get +6dB.

Add second speaker to an amplifier and you do not get double the power. Some amplifiers will go into protective limiting, some will give 40% to 60% more power, some will give 60% to 80% more power, none will give 100% more power, none!
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Old 10th October 2012, 08:29 PM   #1765
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Quote:
Originally Posted by AndrewT View Post
One speaker with 10W gives 100dB @ 10m
Two speakers each with 5W gives 103dB @ 10m over the frequency range defined by the cone, or mouth, separation.
Two speakers close coupled each with 10W gives 106dB @ 10m

double the power and you get +3dB.
double the mouth & cone area and you get +3dB.
double the power and double the mouth and cone area and you get +6dB.

Add second speaker to an amplifier and you do not get double the power. Some amplifiers will go into protective limiting, some will give 40% to 60% more power, some will give 60% to 80% more power, none will give 100% more power, none!
Can you email those guys with the calculator page and tell them they are wrong.....?
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Old 10th October 2012, 08:46 PM   #1766
DrDyna is offline DrDyna  United States
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Quote:
Originally Posted by AndrewT View Post
none will give 100% more power, none!
Dan D'augustino would like a word with you Andrew!
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Old 10th October 2012, 09:38 PM   #1767
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by turbodawg View Post
Can you email those guys with the calculator page and tell them they are wrong.....?
Not necessary. Just read their website more carefully. But I agree that they could have been more clear with their explanation.

If you look to the equations involved one can find out that they are based on incoherent sources (uncorrelated sound sources). In other words, they are not acoustically coupled and each sound source (loudspeaker) plays a different sound signal. When you add two incoherent sound signals of the same sound levels the sum is +3dB, like the calculator shows.

Coherent sound signals (correlated sound sources) in phase and within the wavelength of the sound will acoustically couple. When you add two coherent sound signals of the same sound levels the sum is +6dB.

Quote from their website LINK :

Adding of two incoherent sound pressure levels or voltage levels:
Click the image to open in full size.

Adding of two values of the same level give an increase of the total level of (+)3 dB.
This equation is used for electrical adding of incoherent signals,
and for the calculation of the energy level of two loudspeakers.


Adding of two coherent sound pressure levels or voltage levels:
Click the image to open in full size.
Adding of two values of the same level give an increase of the total level of (+)6 dB.
This is obtained by feeding two side-by-side loudspeakers with the same signal.
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Old 10th October 2012, 09:53 PM   #1768
maxo is offline maxo  United States
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ok , so in the case of the SS15's
what is the best way to stack them

suppose you have 8 ss15's
does you lay them in the floor in line ( horizontally )
standing in front of them cab1 will be your leftmost and cab 8 your rightmost

or
4 cabs in the floor side to side and another row in top of them

or if you have just 4
4 in line in the floor side to side or 2 in the floor and 2 in top of them

also... i heard that some guys raise them with "mini" stage structures
the put like some kind of table 5 to 6 feet from the floor and put the subs there and the rest of the setup in top of the subs

does raising the height of the cabs affect for good or worse the spl's ?
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Old 10th October 2012, 10:05 PM   #1769
DrDyna is offline DrDyna  United States
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Quote:
Originally Posted by maxo View Post

does raising the height of the cabs affect for good or worse the spl's ?
That depends on surrounding structures. As a general idea, moving away from walls and boundaries decrease levels, but without knowing for sure what the surroundings are, it's difficult to tell if it'd be a positive or negative change as far as linearity is concerned.
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Old 10th October 2012, 10:22 PM   #1770
Mark Kravchenko --- www.kravchenko-audio.com
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I'll throw this into the mix:

Voltage sensitivity is what gets lost in most of the how loud the speakers become in comparisons people make.

Any given loudspeaker motor has a finite voltage sensitivity. Adding two motors together in any configuration does not change that sensitivity.

A 50% drop in the lowest impedance point does not give you double the power available over the speakers usable bandwidth as Andrew pointed out. A care examination of the impedance of the boxes in question will show you that where the tuning points are they are indeed very high in impedance. Therefore where the lowest and highest tuning points are placed is where it is most difficult for a normal amplifier to pour on the watts.

Remember that amplifiers are actually voltage sources. Given a steady state input signal an amplifier attempts to drive an equal amount of voltage into a varying impedance by fluctuating the amount of current. The available current has limitations based on the power supplies rating and a number of other factors.

Mutual coupling between drivers does change the expressed output level for a certain bandwidth, not across the board.

And a stack of boxes can help in more ways than one thinks. Take a look at Arts measurements with the wings on the sides of the boxes. the launch of the wavefront off of a larger baffle increases the efficiency of the system.
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