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Multi-Way Conventional loudspeakers with crossovers

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Old 27th March 2006, 07:06 PM   #1
nikita is offline nikita  Canada
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I have a 87.8 dB/1W sub. What is the equivalent dB for 2.83 Volts?
Thanks
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Old 27th March 2006, 07:10 PM   #2
owdi is offline owdi  United States
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That depends on the impedance of the sub. In general, every time you half the impedance you gain 6db. So the 4ohm would be 93.8db at 2.83v.

Dan
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Old 27th March 2006, 07:34 PM   #3
e-side is offline e-side  Netherlands
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Quote:
Originally posted by owdi
That depends on the impedance of the sub. In general, every time you half the impedance you gain 6db. So the 4ohm would be 93.8db at 2.83v.
I'm not sure about that.

2.83 V = 1W @ 8 Ohm;
2.83 V = 2W @ 4 Ohm;
2.83 V = 4W @ 2 Ohm etc.

When you double the number of Watts, SPL increases with 3 dB.

So if your sub has a SPL of 87.8 dB @ 1W and it's impedance is 8 Ohms, then SPL @ 2.83 V (= 1W @ 8 Ohm) = 87.8 dB

If the impedance is 4 Ohms, then the SPL @ 2.83 V (= 2W @ 4 Ohm) = 87.8 + 3 = 90.8 dB (half the impedance means the double of watts at a given voltage level, so +3dB)
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Old 28th March 2006, 01:38 AM   #4
Ron E is offline Ron E  United States
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As I posted at Parts Express to your question there:

Many manufacturers dB/W values are actually 2.83V ratings.

Since not all manufacturers rate them the same way, the only good way (short of actually measuring them yourself) to do this comparison is to do a apple/apples comparison using calculated (not rated) values.

calculate dB/W as: dB1=112+10*log10(9.614e-10*Fs^3*Vas/Qes)
Calculate dB/2.83V as:
dB2=dB1+10*log10(8/Re)

Vas in liters
Re is DC resistance of coil, not the rated ohms.
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Old 28th March 2006, 01:40 AM   #5
David Gatti is offline David Gatti  Australia
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Why not use something like Unibox?
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