The dB Metering Scale

So it's come to this eh? You have no friends, no social life to speak of and so had nothing better to do than start reading about dB scales. Welcome to the lonely world of music production technology.

If you have been wondering why dB is used or why the maximum level is marked as 0 dB and values below it in negative dB then read on. Unfortunately the dB scale can't be explained in a single sentence. It's worth noting that going over 0 dB on a peak meter is only a problem if this happens on the Master mixer track (see 'Levels & Mixing', for an explanation), or on a Insert track routed directly to a audio interface output.

What is dB?

The peak meters in FL Studio are displayed in and against a dB scale. dB stands for deci (or tenth) of a Bel (unit of sound or electrical pressure named after Mr A.G. Bell). If you start reading around about dB it will become apparent that the dB scale has been used for many different physical measures - dB (SPL), dB(u), dB(v), dB(V), dB(m), dB(VU), dB(FS) and more! Probably not a great idea as this has lead to a lot of confusion and a number of different formulae for calculating dB.

The dB scale used on audio equipment is a relative scale. That is, the values displayed are relative to the 100% volume limit imposed by the audio output device or audio file (wav, mp3 etc). It is impossible to have more than 100% since that, by definition, is as loud as the equipment or digital audio file can go. One exception to this rule is inside FL Studio where the audio exists as numbers in 32 Bit float format. The Hint bar shows this percentage (%) as faders/knobs are moved or when the mouse cursor is placed over the scale. If we assume 100% = 1 then all levels then are relative to this reference value of 1. For example, if the level is at 50% of the maximum volume, the level is 0.5. The value is transformed into dB according to the following formula:

Calculating dB

20 * log(X/Y) where:

In this case the reference level was 1, however it could be any other level that you are comparing the signal to (say 0.1/0.25). Try entering some of the following into Google, 20*log(0.5), 20*log(1) and 20*log(2).

...time to go outside, find someone, anyone and have a conversation about squirrels. Squirrels are cute, have tiny brains that weigh about 6 grams and so can't comprehend the dB scale. Squirrels are your friends!