Convert input sensitivity from dB to V?

[tifune]

I'm recently in the market for an amp for the first time in years, and the input sensitivity on those is very straightforward: I need 2V (or whatever) to reach peak output. My DAC puts out 2.5V, so I'm good.

But I wanted to compare that to my active monitors, KH120 and IN-8, and I see the input sensitivity is rated at 0.. -15dB (adjustable) and 94dB @1m respectively.

Why is there such a large disparity between these, and why have the manufacturers expressed them this way? Can I convert them to V? This is more for my own knowledge, every DAC I own powers these beyond comfortable levels I just don't understand the purpose of such an ostensibly large variance.

 

[sergeauckland]

As you probably know, dB is another way of expressing a ratio, so it's important to know dB relative to what.
Inputs and outputs are usually rated in dBu, which is dB relative to 0.775volts. Some may be rated in dBV, which is dB relative to 1 volt. In the now distant past, audio inputs and outputs were rated in dBm, which is dB relative to 1mW into 600 ohms, which works out as 0.775v.

The difference therefore between dBu and dBm is the impedance they are measured across. dBu is dB unloaded, in other words into a high impedance, typically 10kohms or higher, whilst dBm is across 600 ohms. The voltage level is the same.

dBV is a way of making the numbers a bit more familiar by rating it relative to 1V rather than the more obscure 0.775V.

0dBu = 0.775V
+4dBu = 1.2V (near enough) (Edited, I had mistyped 1.4v)
+8dBu = 2V (near enough)

S.

 

[tifune]

dBV is a way of making the numbers a bit more familiar by rating it relative to 1V rather than the more obscure 0.775V.

0dBu = 0.775V
+4dBu = 1.4V (near enough)
+8dBu = 2V (near enough)

S.

Thank you! Using that I think I can piece together the KH120, but the Kali is really throwing me off with the distance. Any thoughts why it's expressed as 94dB@1m ?

https://www.kaliaudio.com/s/Kali_Au...Monitor_Speaker_Full_Specifications_Sheet.pdf

 

[voodooless]

What exactly do you think you compare? The active systems have amps and speakers, and the whole system is designed to function as an optimal package.

What you are comparing two different things. The 0 to -15 is a gain adjustment for the KH120, while the IN-8 specified an input voltage for a specific output sound pressure. dBV and dBu can be converted to Vrms. In case of the IN-8, 0.3 Vrms is needed for 94dB at 1meter (via RCA). IN-8 does not specify any maximum input voltage, while the KH120 does: +24 dBu or 12.3 Vrms. So it's apples and oranges here.

Judging from the IN-8 maxSPL, the maximum input should be 10dBV or 3.1 Vrms via RCA.

 

[sergeauckland]

Thank you! Using that I think I can piece together the KH120, but the Kali is really throwing me off with the distance. Any thoughts why it's expressed as 94dB@1m ?

https://www.kaliaudio.com/s/Kali_Au...Monitor_Speaker_Full_Specifications_Sheet.pdf

94dB SPL @1m (anechoic) for +4dBu input.

94dB @ 1m from an input of +4dBu (that's 1.2v) seems to me a sensible way of specifying the effective sensitivity.
The maximum output is specified as Max SPL (Peak @ 1M): 114 dB which implies that the overload level is 20dB (114-94) above +4dBu and so the maximum input will be +24dBu which is about 13V, which is also pretty much what Pro level balanced outputs provide.

They presumably expect their 'speakers to be used with Pro or Semi-Pro kit which is normally rated in dBu so have published specs in that way.

As to distance, that's more complicated, as there's the inverse-square law as a doubling of distance reduces output by 6dB, but then that's doubled for two loudspeakers playing the same i.e. mono signal, increased by whatever the room gain will be, especially at low frequencies, so specific to the listening environment. In other words, they can't specify it any other way as it's then totally dependent on how the 'speakers get used, but at least gives a more or less standard way for comparison with others.

S.

 

[LTig]

As you probably know, dB is another way of expressing a ratio, so it's important to know dB relative to what.
Inputs and outputs are usually rated in dBu, which is dB relative to 0.775volts. Some may be rated in dBV, which is dB relative to 1 volt. In the now distant past, audio inputs and outputs were rated in dBm, which is dB relative to 1mW into 600 ohms, which works out as 0.775v.

The difference therefore between dBu and dBm is the impedance they are measured across. dBu is dB unloaded, in other words into a high impedance, typically 10kohms or higher, whilst dBm is across 600 ohms. The voltage level is the same.

dBV is a way of making the numbers a bit more familiar by rating it relative to 1V rather than the more obscure 0.775V.

0dBu = 0.775V
+4dBu = 1.2V (near enough) (Edited, I had mistyped 1.4v)
+8dBu = 2V (near enough)

S.

See this online calculator.