When is Clipping a penalty?

[Seabass123]

And here I thought we'd be talking about football

[Chelan]

Damn, DJTT community certainly has come through on this question that I had - especially on the part of exokinetic & mostapha. I think I am understanding the general principle, however a lot of what mostapha wrote is way over my head. I'm just not that educated I guess when it comes to sound principles.

djproben wrote

The amp can only work with what the mixer gives it, so if you're clipping on the mixer it's going to sound crap even if the amp is not cranked up. But there's probably more headroom on some mixers than you think -- the numbers of LEDs on these meters are far from standardized. So it's possible that your mixer isn't really clipping even if it's in the red while another might.

deevey wrote

Amp up - Mixer master down is the best way to play it.

Those 2 bits of info make the most sense and are the easiest explanation to understand, though I still don't know if 1 or 2 red dots would indicate clipping on my mixer. Does one red dot = 2 db or 3 I wonder? The Numark M3 is obviously nowhere near the top of the line so it gives no db readout except for at the 0 mark.

As a general rule, I know and understand that clipping is bad, makes the bar or club sound bad, and is not good for your speakers as it wears them out a lot faster - good explanation on how that works by exokinetic.

mostapha wrote

Actually, you can figure it out. Find any subtractive synth plugin and generate a sine wave that does not clip when rendered. Aim for it to be as loud as possible without intersample modulation distortion or clipping, or about -3dB as a general guide if you don't know how to test for that. It doesn't really matter what frequency you use, but I'd make separate ones at 110Hz, 440Hz, and 7040Hz if I knew nothing else and wanted to be thorough.

This is where I pretty much got lost. After having said all that, is taking a store bought CD from the actual artist (not a CDR) and putting it in a CDJ or burning it to iTunes and then importing it in Traktor (at a high quality br) the same? I mean if I am using a high quality production of the music to test the clipping point on a mixer is that what you were trying to explain? Still even so if I heard the music was clipping, how would I know if it is at 1, 2, or 3 db? I have no clue what a syth plugin, intersample modulation distortion, of how to even choose the frequency at which I use.

As far as Traktor goes, I mix externally and use auto gain which I feel does a fairly good job on most tunes. I'm just always looking at the master output and making sure that it is not hitting red. It seems to me that it is a lot easier to tell sound wise when it hits the red marks in Traktor that it is definitely clipping the sound. As for all the other info that exokinetic & mostapha were discussing regarding Traktor and certain dynamic ranges and certain bit audio files I had no idea what they were referring to and that was ok with me.

The main thing I wish I could understand better is how to figure out at what db that the mixer is clipping. Even though it was explained, it made no sense to me. Is there an easier way or explanation? If not, I'll be happy knowing what I've learned thus far - keep it out of the red on the mixer so as not to send a clipped signal to the amp.

[Chelan]

I don't know how, but I just posted at 7:25 PST so it should be the most current post. But when it put my post in the thread it listed it back 2 posts and said I posted it 5 hrs ago. Anyone else having posting problems like this? I know DJTT is havig server problems the last 2 nights.

[mostapha]

Also a very good insight on Traktors negetive headroom, witch I have been expecting as the case for while, I usually run the traktor gains at -3db but that only limits the main body of sound to -3, transients will peak just below 0db, witch causes a disgusting clip, witch gets a lot worse, if you are clipping two channels internally in traktor.


The -14db suggestion I'm going to do some serious testing on as well, this seems to make a lot of sense, and the gain knobs on my behringer are surprisingly quiet.


And is it Traktors extreme bit depth (witch allows for something like 200+db of dynamic range) that allows you to run the internal traktor master gain at -40db with ought squashing the dynamic range?


...Again thanks for the insightful info!

I was talking about Traktor's master setting, not it's channel gain settings. The channel gains can be wherever you want them. I don't know where the figure 200dB of dynamic range in Traktor came from, but it's probably not far off. I think it's safe to assume that it's at least 192dB, and that's if they're using 32-bit integers, not floating point numbers…it's also a substantial bit more than basically anything you'll have after it…so as long as you've got enough gain on the next stage, you can run it about as low as you want.

Anyway, that huge figure refers to traktor's internal mixer and effects, which you basically can't clip. Even tracks mastered really hot at max gain with the EQs all the way up won't clip it. I haven't tried with an HP filter right over the kick with ridiculous resonance, but…I wouldn't expect it to clip Traktor's mixer.

Clipping the sound card outputs, on the other hand, is really easy whether you mix internally or externally. I run mine at about -14dB because that puts the channel gains on my xone at about 3 o'clock to get them to peak at 0dB when I'm using auto-gain (which works really well, btw).

Basically, you need to turn the master down to give yourself some headroom at your soundcard output whether you're mixing internally or externally and basically regardless of what sound card you're using. The problem arises from converting from traktor's huge dynamic range internal signal to the 16 or 24-bit integers that your sound card expects. Since you're starting with 16-bit files the vast majority of the time, if you use 24-bit output, you can run it down to -48dB with no loss of dynamic range that wasn't noise anyway…you just have to be able to turn it back up in a DJ mixer of FOH mixer so a really wild transient, software f*up or unplugged cable doesn't cause your wide-open amp to clip or blow up.

In a more general sense, this issue is kind of what gain staging is all about. You want to find the limiting factor for dynamic range in your system. Because 16-bit audio files represent 96dB of dynamic range without any processing tricks and vinyl records–even ignoring the loudness war–are probably a bit less than that based on what I've read, the limiting factor is probably your original files…which is exactly how it should be. You can't recover lost dynamic range…ever. You can just destroy it.

If you peak over 0dBV at any point without adequate headroom in whatever comes next, you throw away information that you'll never get back, and you probably cause distortion. On the other hand, it's perfectly okay to run things a bit cold and just turn it back up later. Depending on the quality of your gain circuits and cables, you might add some noise…but a bit of white noise sounds a lot better than a bit of clipping…mostly. In some cases, with certain types of analog gear, a couple dB of "gain overlap" (essentially, overdriving a gain stage) can sound really good. And it's safe to experiment with that a lot of the time. But Traktor's output and DJ mixers are almost always not the place to be doing that. Most transistor-based amplifiers aren't the place to do it either, though some of them can sound good.

In general, though…if you don't have time for a thorough sound check, the benefits don't outweigh the risks. Just do it 'right' (aiming for 0dB out of the DJ mixer max is not a bad thing) and don't worry if you go a dB or two over…just don't get ridiculous.

The complication comes when you're spinning with other DJs who don't understand levels as well. If you're opening and you have time to talk to the sound guy, figure out what he wants…he can probably tell you how things are set up and where he wants you peaking. If he says to run the mixer into the red…I'd ask him why…otherwise, you should probably just listen to him. If there's not a sound guy…well…talk to the promoter. Ideally, you can do it right, but keeping the night going is most important. Just make sure people know what's going on so that you don't set the sound system for a good volume when you're peaking at 0dB and then get blamed when the next guy comes on, slams the channel gains up, maxes the bass EQs, and causes the subs to blow, catch fire, or attain sentience and start raping people.

[exokinetic]

OMG

Thank you so much for this post!


Going to change the way I gain stage traktor for sure. I always ran my mixer to never allow peaks to go above 0db, so that will work exactly the same as before, but now I understand the concept behind what traktor is doing.


And in my post I was referring to the master output on traktors software, and I run external mixing. I'm also a big fan of the auto-gain.

Thanks again for the detailed info!

[gogomillard]

I don't know how, but I just posted at 7:25 PST so it should be the most current post. But when it put my post in the thread it listed it back 2 posts and said I posted it 5 hrs ago. Anyone else having posting problems like this? I know DJTT is havig server problems the last 2 nights.

hahaha same here. it happened to me a few minutes ago. said i posted at six pm (nine pm now here in memphis)

[gogomillard]

hahaha same here. it happened to me a few minutes ago. said i posted at six pm (nine pm now here in memphis)

and now it says 11pm.

[Tango 179]

Very informative thread thanks everyone. I have been trying to wrap my head around gain for a while now.

[mostapha]

This is where I pretty much got lost.…

The reason I told you how to do it with a sine wav is that a sine wave is a pure tone at one frequency with no natural overtones. It's really easy to hear when it starts to clip, because you're start hearing higher octaves of that note almost immediately, which is what clipping sounds like.

That's the only reason I said to do it that way.

I think the only other major misleading detail is that 440Hz is the A above middle-C. And an octave represents a doubling of frequencies. I don't know why I always use As for tests like that on electronic things…I just do…kinda like how I don't really know a guitar is in tune until I hear an open G major chord…just one of those things.

[Chelan]

Hey mostapha,

I know what you are talking about now when you refer to a sine wav. Very glad to have learned. Thanks. My next question is do you think I could use a sine wav found on YouTube to test the clipping level on my mixer? I noticed there are many on there at different frequencies.

If not, how is the best way to go about obtaining one to use for a test? And still further yet, since my mixer is not marked at all, is there anyway to find and estimate at least at the db level in which the sine wav starts clipping?