#Decibel relative scale in negative movie#

DVDs typically sound softer than Blu-rays and that dodgy movie rip you grabbed from the internet may have a shockingly bad volume level. Volume Warĭon't worry if the comfortable listening level on your home theatre system is -40dB, but your mate listens to his system at -16.5dB - these values are all equipment and source dependent.

At any point you can add 6dB to double the percieved volume, or remove 6dB and halve it.ġdB is loosely defined as the smallest change in sound level that is noticeable to your average human ear, but because dB is logarithmic, a 6dB increase is double the volume and requires four times the power to achieve. This doesn't have to be a hard limit - some home theatre amps have the headroom to happily go into positive numbers without the average listener hearing distortion, but generally you'll be having a nice word with some police officers if you run your speaker system at this sort of volume.īy starting at 0db (the highest safe power level), we can make accurate changes to how loud the volume sounds. Put simply, home theatre amplifiers use 0db as a reference level for how much volume they can output before distortion becomes audible (or the loud parts of the sound wave are clipped). Some modern knobs may still be marked with numbers, but they'll be 'backwards' compared to the old school devices, with 0 as the loudest setting and 10 or 100 as the softest. If a computer starts at 0 and multiplies by 10, the answer is still 0, so the point of reference has to be different for digital audio systems. These knobs are telling a computer or circuit to adjust the output voltage and, as we all know, computers work on math.

They generally turn slowly or have some resistance which helps in making tiny changes very easy. Some of them turn through an arc, and others are auto-centering. These days, home theatre amps have digital knobs. You'll still find knobs like these on some types of pro audio equipment, but in a modern home theatre it'll be much less common. These knobs usually worked electrically, changing Volume Units (VU) rather than dB.

#Decibel relative scale in negative full#

The lower the number, the lower the volume, all the way down to full mute. The Volume Knobīack in the day, most volume knobs on amplifiers went from 0 to 10. There are several types of decibel, including dBm, dbV, dBu and dBFS, but they're out of scope for this quick tutorial. If they are the same amplitude, then they are said to be 0dB apart. Decibels are used to compare the amplitude of two audio signals or power/voltage levels.