Digital "overs" and clipping

walshi

New member
Hi all,

I've read thousands of times not to go over 0dB in a digital environment (I'm using a delta 44 and Samplitude) or else the finished mix will have horrible distortion etc when the signal clips. However, I've never actually heard this distortion so far even though I know I've gone over 0dB, this is usually when I burn a cd as a test mix before I finalise my mix. Anywho, I decided to purposely hammer a test mix and I created a single kick drum beat at -0.6dB then one at +2.4dB then +5.4db then 8.4dB! When I played this back through my monitors I didn't hear any distortion at any level? The red clip lights came on in Samplitude and the main meter readout gave me the correct figures right up to +8.4dB. I proceded to burn a disc and play it back on a cd player...Guess what...NO distortion heard again? Just a kick drum getting progressively louder?

Am I missing something basic hear? I know it sounds stupid but I WANT to hear this dreaded digital distortion!!

Any thoughts or pointers would be well received

Paul

www.lancasterbombers.co.uk
 
When you say 0dB, do you actually mean "0 dB" or "0 dBFS"???

Digital overs occur at 0dBFS -- that is final - beyond 0 dBFS you have no more bits with which the waveform can be represented....

0dB on the other hand, is typically calibrated to about -15dBFS on a lot of digital gear.

So if you're seeing peaks at around +8 dB - you HAVE to be looking at peak meters not calibrated to 0dBFS.... you could NEVER see a +8dB signal without distortion.

More on gain/signal/metering in this ARTICLE.......
 
My system does exactly the same thing. I haven't worked it out exactly yet but it's the soundcard. I transferred a sonar work file with one of my mixes on, to my mates computer who is using horrible on board sound, and it sounded AWFUL. Distortion on loads of tracks. had to take the level right down on everything to compensate.
 
Bruce, the meters in a lot of software programs can accurately tell you how much you're clipping by. I imagine it's because of the extra room allowed by 32bit processing of 24bit audio.

walshi, a couple things...

1) You might need to get your ears checked :) Seriously, what are you monitoring on? I discovered limiting on one of my first mixes, when I was just monitoring on some crappy speakers and didn't really know what I was doing....I pounded the hell out of my mix and at the time thought it sounded fine. Now I listen back on it and laugh. Wicked distortion. And remember, digital "distortion" doesn't always sound like "distortion"...distortion is a common term used to describe any sort of wave form distorting.

2) You might just be chopping off peaks, which won't always sound bad...in fact it's almost the same thing as what a limiter does. Anyhow, this is typically the sign of a bad mix. Take a look at your raw mixdown, is it full of giant spikes all over the place? If you do then...keep on practicing! :)

3) There could be a screw up somewhere in the software. I doubt it, but it is possible. Try a different software meter. I once discovered a flaw in n-Track's meters when the option to tell you how much you're clipping by was turned on. When I compared n-Track's meters to pinguin audio meters the difference was pretty big. Point being, never trust nothin, heh.

Slackmaster 2000
 
It would also depend where in the signal chain the meters are reading from! Maybe your s/w also allows you to choose the meter's frame of reference (PEAK, dBFS, VU) -- all will read the same signal at different levels....
 
I'd also try it with another waveform... I'd assume that a kick (especially if not a 'real' one) might be more forgiving than other 'longer sounds'...

Maybe you have swome 'softclip' featur on in your machine?

Just ideas...

aXel
 
Thanks - on closer inspection

Thanks for your replies,

I guess slackmaster's post was the nearest! I think it was my ears!

I loaded the waveform into soundforge and zoomed up close...There it was! a waveform that looked liked "Devils Tower" from "Close Encounters of the Third Kind"!!! A completely flat top on the main attack!

volltreffer was also right regarding the length of the sound. All I used to experiment was a single Kick sample off the Alan Parsons sound check 2 CD. I guess I should have used a short section of an actuall song and hammered the CD with that.
 
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