Speaker Sensitivity

[abailey]

Ok I have searched everywhere but can not find the answer to my question so I am going to try here. I need to compare sensitivity of 2 different loudspeakers. One is given at 1w/1m and one is given at 2.8v/1m. All would be okay if they were both rated at 8ohms but they are not. One is rated at 89db 1w/1m and is 4 ohms. The other speaker is rated at 86db 2.8v/1m and is 6 ohms. How do I make the conversion so I can compare them correctly? Thanks.

[Æ]

Here, try this.
http://www.sengpielaudio.com/calculator-efficiency.htm

Ok I have searched everywhere but can not find the answer to my question so I am going to try here. I need to compare sensitivity of 2 different loudspeakers. One is given at 1w/1m and one is given at 2.8v/1m. All would be okay if they were both rated at 8ohms but they are not. One is rated at 89db 1w/1m and is 4 ohms. The other speaker is rated at 86db 2.8v/1m and is 6 ohms. How do I make the conversion so I can compare them correctly? Thanks.

http://www.sengpielaudio.com/Calculations03.htm

[JRT]

Ok I have searched everywhere but can not find the answer to my question so I am going to try here. I need to compare sensitivity of 2 different loudspeakers. How do I make the conversion so I can compare them correctly? Thanks.

1st is rated at 89 dB at 1 Watt at 1 meter with 4 Ohm nominal impedance.
2nd is rated at 86 dB at 2.83v at 1 meter with 6 Ohm nominal impedance.

Convert the power sensitivity rating to a voltage sensitivity rating.

Volts = SquareRoot(Watts * Ohms)

Your first example is rated at 89 dB at 1 Watt at 1 meter and has 4 Ohm nominal impedance.

Do the math with the above equation and you will find that 2 Volts across a 4 Ohm load draws 1 Watt.

So a corresponding measure of voltage sensitivity is 89 dB at 2 V at 1 meter.

You should be using the same reference voltages and distances.

To adjust to like voltage:

Change in SPL = 20 log (V2/V1) dB ; where V1 is the initial voltage and V2 is the new target reference.

20 log (2.83/2.00) = 3.02 dB increase.

So the 89 dB at 2 V at 1 meter sensitivity
is also 89+3= 92 dB at 2.83 V at 1 meter.

A very similar equation can adjust for propagation distance from a point source.

Change in SPL = 20 log (d1/d2) dB ; where d1 is the initial distance and d2 is the new propagation distance.

So if you needed to shift propagation distance from 1.0 to 4.0 meters...
20 log (1.0/4.0) = -12 dB change in SPL at the ear
when that ear is moved further away to 4x the initial propagation distance.



.

[Paul O]

For reference..
2.83v = 1w into a 8ohm load.
2.83v = 1.33w into a 6ohm load
2.83v = 2w into a 4ohm load

Using the speaker that is rated at 1w/1m is the baseline...

To get the 1w rating of the 6ohm speaker, this formula says it only need.. Volts = SquareRoot(Watts * Ohms) = 2.45v.

And the change in SPL is.. SPL = 20 log (V2/V1) = -1.25db

So the actual 1w/1m rating of the driver would be 84.75db

[Chris Roemer]

Here, try this.
http://www.sengpielaudio.com/calculator-efficiency.htm



http://www.sengpielaudio.com/Calculations03.htm

If you're building a passive XO, you want to compare everything at 2.83v.

The 6n speaker is 86dB @ 2.83v (this is about 1.2w).
The 4n speaker is 89dB @ 1w, which is 2v.
At 2.83v its sensitivity will be 92dB, which is 2w.
So, connected to a passive XO, the 4n driver will play 6dB louder than the 6n driver.

If these are subs, and you're driving them with a plate amp, you should compare these at 1w (not forgetting that most amps can push more watts into lower impedances).
The 4n speaker is 89dB @ 1w.
The 6n speaker is 86dB @ 2.83v, which is 1.2w.
At 1w, it will produce 85dB.

So, connecting them to an amp, the 4n driver will play 4dB louder than the 6n driver, given the same amount of power.

[abailey]

Thanks for all the responses guys. This helps. It is also good knowledge for future projects I am working on.