problem with AMPLIFY

HI-Recently I recocorded several audio tape albums at a very low input level thinking it will be ok to AMPLIFY them to -0.1db before saving .I did this,but found it wasnt so easy & laid back…The recordings sounded very dull.(even worse than DOLBY)so now i record at about -0.3db peak, then AMPLIFY them to -0.1db.They now sound crisp & clear,you learn as you go!!.mickthefish.I use AUDACITY 2.0.1.WINDOWS XP.

I don’t know what’s going on but the recording volume shouldn’t affect the “tone” unless you the level it too high and you’re clipping. If the level is too low, you can get noise problems but it shouldn’t make the recoding “dull”.

How are you connected to the computer? I hope you are not using the mic input on a laptop…

How low is “very low”? -6 to -3dB is usually about right. The idea is to leave some headroom so that you don’t “try” to go over 0dB. So, if you’re shooting for -3dB and you hit -1dB you are OK. Bu, if your recording hits 0dB, it’s very likely that it was trying to go higher and is clipped.

The ONLY reason for a high recording level is for a better signal-to-nose ratio. In the analog tape days it was important to keep a hot signal to overcome tape hiss. But with digital recording, you have a much lower noise floor and it’s not so important and the recording level has zero effect on any noise that already exists on the tapes. When you are digitizing analog tape or records, the sound card’s noise floor is usually way below the noise on the source so a low recording level isn’t usually an issue.

The important thing with digital is that you don’t go too high and clip… Tape soft-clips when it saturates and the tape record/playback equalization also helps to soften the distortion. But, digital hard-clips so you never want to go “into the red” with digital recording.

Pros (recording at 24-bits with low noise ADCs) usually record at -12 to -18dB.

With an analog source it’s virtually impossible to adjust the level precisely for 0.3dB peaks… There’s lots of variation from recording-to-recording (and from moment-to-moment) unless your analog signal is clipping, or unless the tape was pushed into saturation (clipping) while recording. If the tapes are saturated the peaks will be constant and predictable.

And practically speaking, there’s not much point in amplifying by 0.2dB. But if you are going to do that, nothing bad happens if you amplify to 0dB. WAV files and DACs, etc., can’t go over 0dB, but nothing bad happens until you actually try to go OVER 0dB. It’s simply a numerical limit… For example, with 16-bits you can have numbers between -32,768 and to +32,767. If you need numbers bigger than that you need another bit. In a 16-bit file, those numbers represent 0dB.

…if you make an MP3, some peaks will get higher and some lower. So if you normalize to 0dB and make an MP3 and then load it into Audacity, you’ll see red for potential clipping. But, it’s NOT clipped because MP3 (and Audacity internally) are not limited to 0dB. Under some circumstances that MP3 could be clipped by the DAC when played, but I’ve never heard of that being audible, and we already know that MP3 is lossy anyway. And, if you want to prevent that, you generally have to normalize to around -1dB.

Some audiophiles also worry about “Inter-sample overs” where the reconstructed analog audio from the DAC goes over 0dB. But, I believe that’s an imaginary problem since there’s no hard-numerical limit on the analog DAC output, only on the DAC’s digital input. (And again, if you are worried about that 0.1dB probably isn’t enough headroom.)

Thanks DVDdoug I’ve learnt a lot from your reply to my problem with AMPLIFY.howevever shouldnt the AMPLIFY -0.1db also bring the recorded volume of a clipped over recorded file down to -0.1db,ive tried this & checked the spectograph envelope & it does appear to work with no adverse effects…mickthefish.(PS-the files i was talking about were almost flatlining to be honest!!.)