morningfert.blogg.se - Decibel examples

If is it -6dB, then it is half the size it was before. If the voltage is +6dB, it is twice the size as it was before. These examples also show that it is possible to have positive and negative decibels. So, we could say the output is now -6dB (below what it was before). This means we are halving the voltage (because 6dB is a factor of 2). Remember decibels are always relative to something, in this case, to what it was before we doubled (added 6dB to) the level.Įxample Two: same scenario, but this time we lower the volume by 6dB. That is, relative to what the level was, it is now 6dB higher. Otherwise, just skip the calculator and read the examples below to help understand how decibels are used.Įxample One : you increase the volume on a mixer or amplifier by 6dB: this is actually doubling the voltage that will appear at the output (because 6dB is a factor of 2 – see table).

The easy ones to remember are x10 = 20dB, x100 = 40dB and x1000 = 60dBįor those who want to see other ratios and decibel values, you can use this simple calculator.

Double the voltage (x2) changes the output by 6dB (see examples below).

There are some interesting points highlighted by this table: (I’m not showing the formulas or calculations because I reckon most people skip over them anyhow, and if you like formulas any search engine will give you as many as you like) But without getting into formulas etc, we need to accept the following summary of linear ratios of voltages and decibels. (Note: power measurements (like the power differences in an amplifier) use a similar but different formula). When we are talking about audio levels, we are looking at voltages, or sound wave amplitudes.

A small change in decibels relates to a different change in the ratio of the two levels being compared. Also, a doubling in the side length does not double the area – it is a lot more than the double! This is an example of a non-linear relationship – in this case, a small increase in the side relates to a different increase in the area. In this example, you can see that increasing the side measurement does not have an equivalent increase in area, but a larger increase. Another example of a non-linear relationship is between the side of a square and the area of a square.

This is because our range of hearing is so vast, that to use a linear scale we would be using figures from 0 – 1,000,000!Ī secret to understanding decibels is to note that decibels are non linear. So why use a decibel? You might have noticed that the volume control on most HiFi amps is marked in decibels, as is the markings on mixer level controls. For example, the line out of mixer might be at -10dB, this usually means it is 10dB below 0dB. Unfortunately, what it is relative to is often not mentioned when stating a decibel reading. There is no absolute level called a decibel. A decibel expresses a ratio.

A decibel uses a logarithmic scale, not a linear scale like volts or watts – see below.

A Bel is a very large unit, so the prefix deci (one tenth) is used. What is a decibel?Ī decibel is a tenth of a Bel, a unit of level, named after Alexander Graham Bell. But first, some basic questions and answers about decibels. These articles give a practical understanding on using decibels in audio work. Decibels are widely used in audio, and often misunderstood.