Using Audacity 2.01 to digitize my LPs. I think I’m following the instructions correctly.
After recording the LP & saving the project file, I run a HP filter for subsonic noise, then send the wave to Click Repair. My records are coming in around -5 dB on the meter. As the last edit I want to amplify or normalize tracks to -1 dB, but I always seem to have a few red clip lines that prevent that. All the clipping is on the bottom of the wave form as shown in the attached.
Even if there are no red lines the bottom of the wave forms are so close that they also prevent me from getting the volume up to the desired level for exporting. There aren’t dB scales on the bottom…does that mean they can’t be heard? Do I have to tackle each one individually & repair them in order to amplify the volume? Did a search here but couldn’t find a perrtainent answer…would appreciate your assistance.
Hello again. I am not quite clear from your postting as to when the occasional clipping is arising. It could be on the raw transcriprion, or after the application of the subsonic filter, or after the application of ClickRepair. Whenever it is, you need to get rid of it before final level adjustment with Amplify or Normalise – once the waveform is damaged it stays damaged.
I assume you know that if you select the entire track and activate Amplify (and then cancel it), it will tell you how much amplification is needed to produce a track that peaks at 0dB. Is that where you get your -5dB from? You certainly cannot make such an estimate reliably just from watching the meter as you record. So the first step is to determine properly the peak level of your original transcription. If that is more than about -3dB then it is prudent to reduce the level of the analogue input to the digitisers of your UFO 202, for example by allowing the UF 202 rather than the TT to provide the phono preamplification/equalisation.
Then do the same check after applying the subsonic filter, and then again after applying ClickRepair. This will enable you to pin down the point at which the clipping level is exceeded. I think it is very unlikely to be ClickRepair that is causing the problem, since its whole purpose is to remove peaks not to create them, and it leaves the vast bulk of the signal unmodified. However, a filter with too sharp a cutoff can certainly cause problems. I use DeNoiseLF, part of the companion software to ClickRepair, to deal with subsonic noise and hum (two separate passes) and have never had any problem with it.
To my eyes, the sample waveform shows “touching 0dB” but not “exceeding 0dB”. If that really is the case, there is, as yet, no audible damage. Therefore Steve’s advice is good - bring it down a little to be on the safe side.
OK…my brain is on a serious vacation here…I’m missing some concept or other…
Looking at the wave form of the entire song of that attachment shows the peaks around -5 dB. Steve was right in that the red line disappeared when I did a Amplify of -1, both the top & bottom of the waveform contract towards the center & the peaks go down to around -6 dB…ie, instead of increasing the volume, it’s lowered.
What I’m trying to do of course (as my last edit prior to exporting) is increase the volume to around -1.0 area…but, the amplify command won’t allow that. That’s why I thought the bottom of the waveform is what’s stopping this from occurring, since I don’t see any peaks on the top going higher than -5 dB…ie, quite a ways from the ceiling, whereas the bottom part is touching the line at the bottom. This same scenario shows up on all my LP recordings so far.
Appreciate all of you attempting to assist me…obviously, I’m misunderstanding something…but what???
Although the dB scale only has numbers above the centre line of the track, dB level exists both above and below the line.
I the posted image, the peak level is at 0 dB at the bottom of the waveform.
Audio waveforms are not always symmetrical about the centre line (as evidenced by the picture). The asymmetry may be due to DC offset or may just be that the waveform is not symmetrical.
The “Normalize” effect in Audacity has an option for removing DC offset, so it would probably be worth apply the Normalize effect to see if that makes the waveform more symmetrical.
so your saying that the audio is already at max volume, based on observing the waveform at the bottom ???
If my understanding of what your saying, that is obviously the knowledge gap that I was missing. So I’ve been mistaken in looking at the top of the scale…I should be observing the bottom …but there aren’t any scales there for me to make a good observation (or perhaps my window is not correctly configured?)
On several LPs, I’ve looked at the center-line where the DC offset should be visible but haven’t observed any. I’ve tested this by bring up the command on a couple of LPs & the wave form doesn’t move at all after applying the correction.
Sound is analogue and is caused by minute changes in air pressure on our ear drums. Positive pressure (inwards on the drum) becomes the “top” half and negative pressure (outwards on the drum) becomes the “bottom” half. That may not all be strictly scientifically correct but it should help you grasp the concept and fill that “knowledge gap”.
What I’m trying to do of course (as my last edit prior to exporting) is increase the volume to around -1.0 area…but, the amplify command won’t allow that.
Perhaps I have misunderstood what you are trying to do. You can type your own choice of amplification inot either of the linked boxes in Amplify. One of your later posts suggests that you are now doing this.
It sounds as if your problem is simply the result of an Amplify step taking you to exactly 0dB, and where the waveform touches this level it is flagged as clipping, although it has not been damaged. Apparently some DACs don’t like handling a signal that actually reaches 0dB, which is why you are advised to back off a bit from that level.
You ask about weather in the UK. It has been raining since late May, with daytime temperatures seldom reaching 20deg.C (68deg.F).