Effect amplify - denegrate sound at some amt?

[cfmoore]

For two track stereo wave files recorded at 24bit 44.1hz, when uning the effect amplify

Does the sound quality begin to denegrate prior to 0.0

Is there an amount of decible increase without affecting sound quality?

Should peak amplitude be less than 0.0db?

[waxcylinder]

No, it should not degenerate before 0db - but as soon as it hits 0db then is degrades with a vengeance, into "clipping".

This is a feature of digital recording which is very unforgiving in this respect - unlike old analogue tape which enabled the occasional foray into the red zone on the meters without causing sound damage (this is down to the physics of the medium).

WC

[steve]

For the very best sound quality, set your default project rate to 32 bit - this allows a huge amount of volume scaling with completely negligible errors (those extra 8 bits prevent "rounding off" discrepancies). If you require your final show to be 24 bit or 16 bit, there will be a tiny (very tiny) amount of noise added when you convert (down-sample) due to "dithering" but this is no worse than you would get if everything was at 24 bit as the 24th bit (LSB) can not be an accurate value anyway (it has to be either 0 or 1).

If you try amplification in the order of 50 dB (a huge amount) you may notice degradation of sound quality, but even at 16 bit this will be quite small - at 32 bit it will still be negligible.

I generally keep amplitudes a little below 0.0 dB - before the final export I will normalize to -0.1 dB as some players / format converters do not always handle 0.0 dB properly.

During editing I usually tend to keep a few dB's of headroom (in the order of -6 dB) as it makes apply effects easier. One exception to this is if applying compression type effects when it can be useful to know exactly what the peak amplitude is, in which case I will normalize to 0 dB.

[kozikowski]

Nothing happens to the audio signal before 0.0. but if your speaker or headset amplifier is right on the brink of collapse, it doesn't take much to push it over the edge.

It takes about an 18dB increase in audio signal for you to hear double volume--that's the audio signal doubling three times. So if you crank your amplifier up good to your ears, you may be putting a tremendous strain on the electronics. Modern amplifier clipping/damage can sound almost as entertaining as timeline/edit clipping.

Koz

[steve]

Nothing happens to the audio signal before 0.0.

Not true - the amplify effect does have an effect on sound quality, but it is usually so small as to be insignificant. However if extreme amounts of amplification are used (in excess of 50 dB) then with 16 bit audio the effect is clearly audible. As an experiment, try amplifying a 16 bit sound by -70 dB, then amplify it again by +70 dB - it is not the same, there is noticeable noise added. Now try the same test with a 32 bit sound and amplify by -100dB, then amplify it again by +100dB - the resulting sound is almost identical to the original (there is still a tiny amount of added noise, but it is in the region of -90 dB)

It takes about an 18dB increase in audio signal for you to hear double volume

I still don't understand where you get that figure from - in most cases an 18 dB increase sounds considerably more than double volume to my ears.

[cfmoore]

My thanks to you all for all of the great info. I have learned a lot but also gained some understanding about what I learned.

I was concered that an amplified effect increase of 5 to 8 db would denegrate the sound. I am the guy with the question about low recorded volume levels via the turntable.