This page briefly explains the specifications of the speaker (SP).

​Enclosure

The number and type of speaker units are indicated.
Please see this page for details

​Rated Input

​It shows the rated power value that this speaker will accept. It is mainly used to calculate how many connections can be made to AMP.

​Rated Impedance

The impedance (Ω) is shown to determine whether it is for input impedance or low impedance. (See here for information on high impedance and low impedance.) The input value (W) changes depending on the impedance (Ω). The "Rated Input" value described above is not necessarily used.

​Sensitivity

This value is mainly used to compare SP sound volume (power to sound conversion ability). If a large amount of power is input to the SP, it will output a loud sound, and the farther away from the SP, the quieter the sound will be heard. To compare the SP volume, you need to fix these two values and compare them.This value is sometimes called "Sound Pressure Level" .

Power Handling Capacity (PHC)

This indicates the maximum watts of input that the speaker can tolerate.
This is often mistakenly thought to represent the maximum volume, but the maximum volume is calculated from this value and the sensitivity as the maximum sound pressure level.

However, In the case of a low impedance system, it is not necessarily true that the speaker can withstand the output of an amplifier with the same maximum output as the PHC. This is because when the system is actually used, the level of the sound source input to the AMP is not constant. The PHC only assumes that the input source is at a constant level (the rated level of the amplifier). To operate the system safely, you need to keep the input level constant to some extent using a compressor, etc. For information on compressors, see this page.

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Maximum Sound Pressure Level (Max SPL)

This represents the sound pressure level 1m away from the speaker when PHC is input to the speaker.

MaxSPL is calculated using the following formula.

                                  MaxSPL (dBspl, 1m.1W) = Sensitivity (dBspl,1m/1W) + 10logPHC(W)

Relationship between Sensitivity, PHC and MaxSPL

As the formula above shows, PHL is not MaxSPL. MaxSPL involves the sensitivity.

Let's clarify the difference between Sensitivity and MaxSPL.
These are both sound pressures 1m away from the speaker.
The difference is the input value to the speaker.
   Sensitivity: Input to the speaker is 1W
   MaxSPL:     Input to the speaker is PHC

The blue SP and red SP shown in the diagram below have different sensitivity and PHC values.
Please check the relationship between sensitivity, PHC, and MaxSPL.

Here, the relationship between Sensitivity and Handling Power Capacity (HPC) is shown in the graph on the right. 
The Sensitivity is the sound pressure level (SPL) at 1W input. This is the value of sensitivity itself. The MaxSPL is SPL when PHC value is input.

The actual sound pressure level (SPL) in operation is between the sensitivity and MaxSPL. This can be calculated by subtracting the level attenuated by the amplifier knobs or attenuators from MaxSPL.

Please see here for how to subtract sound pressure when the listener is more than 1m away from the speaker.

How much SPL output the system actually requires will depend on the customer's operations and ambient noise levels.
Please refer to this page for information on SP installation for buildings PAs or commercial PAs.

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Frequency Response

This shows how SP affects the input signal on frequency. Being flat means that the SP has no effect on the input signal and outputs the same as the input signal. This is one of the ideal SP conditions. 

The above figure shows the frequency characteristics of the two SPs. The SP on the right has a flatter frequency response than the SP on the left. This SP is good for listening to music.

​This is Horn SP. From this SP, the input signal around 1kHz to 2kHz is emphasized and output. This band is the main band mainly included in voices. In other words, this is an SP that can emphasize and output voices.

This SP cannot be said to have good sound quality for listening to music. This is because it cannot output enough high and low frequencies. However, if the purpose is to output large announcements, it can be said to be a suitable SP.

Frequency characteristic diagrams are often not included in specifications; only numerical values are listed. In that case, the frequency band and allowable dB difference are written.

For example, it is written as "500Hz to 5kHz (10dB)".
This 10dB is the allowable dB difference. In the diagram above, this is the vertical width of the pink band.

The frequency characteristic value changes depending on this allowable dB difference. The larger the allowed dB difference, the wider the frequency range. The width of the two red dashed lines is the frequency range.