PEACE clipping meter question!

[Robbo99999]

According to the clipping meter in PEACE, how come I have to run a -6.5dB pre-amp if my total EQ curve only seems to need -4.3dB, however it's really only in this particular song (lots of bass) that the clipping meter is triggered to such an extent that it requires more negative preamp than the sum of my EQ filters suggest? I'm aware that the 'prevent clipping' tick box in PEACE automatically & coarsely adjusts negative preamp to prevent clipping, but I've fine tuned it by putting in manual values until it triggers and it's that -6.5dB that is required, when really it should only be -4.3dB required. You can see from the following screenshot:

Does anyone know why the PEACE clipping meter is requiring such a large offset in this particular song (and a few others to lesser extent) & why above the "total of the EQ curve"?? Does this mean the PEACE clipping meter is inaccurate and showing clipping when there can't be any, or does it somehow detect clipping that is not fully described by the EQ curve (maybe something to do with intersample overs?)?

 

[RayDunzl]

You have a +5 and a +3 boost...

The signal doesn't necessarily occur spread out like on the frequency graph, The boosts can stack when those frequencies occur simultaneously.

+5 and +3 (electrically) comes out (to my surprise) to be a maximum of +10.78dB.

Since the +3 rides on some attenuations, maybe it is able to do the fancy math and come up with -6.5dB for a "safe" number.

Calculator: http://www.sengpielaudio.com/calculator-coherentsources.htm

 

[Robbo99999]

Thanks for the reply, although I don't fully understand, if what I think you're saying is true then wouldn't that mean that if there was no EQ and just being run stock then there would be digital clipping if a 0dBFS tone was played that incorporated every single frequency on the curve at the same time? Because I don't really understand how a +5dB boost at 20Hz can combine with a +3dB boost at 6000Hz to push it over the limit.

I don't really know what you mean by boosts stacking, because the total EQ curve is showing the max boost at any given frequency already? The total EQ curves show I have to give -2.2dB more headroom than the max point on the curve, which I don't understand.

How do you mean "+3 rides on some attenuations"? What do you mean by adding coherent signals in that link?

EDIT: all the instructions I've read regarding EQ, including the Oratory1990 headphone EQ's (who's an audio professional) show that they just take the total EQ curve and put in a negative preamp so that max point on the total EQ curve doesn't go above 0dBFS. Whereas the clipping meter in PEACE is telling me that for certain songs I have to put an extra -2.2dB preamp on top of what would normally be expected. I still don't understand why? I'm just saying this because I'm not sure if you've noticed I've already put in a negative preamp according to these 'normal' instructions.

 

[RayDunzl]

Thanks for the reply, although I don't fully understand, if what I think you're saying is true then wouldn't that mean that if there was no EQ and just being run stock then there would be digital clipping if a 0dBFS tone was played that incorporated every single frequency on the curve at the same time?

Yes, but that doesn't happen.

Much of what you listen to is down -20dB or so for the individual parts.

Modern bass often presses the limits of the aggregate, and the engineers will "clip" the extremes of the higher frequencies along for the ride.

Example:

At the top, you can see how the higher frequencies seem to be trimmed from going in theiir positive direction (clipping) when the bass nears maximum excursion.

The lower graph shows the "peak" values of all frequencies in the whole recording. No frequency yields 0dB on its own.

 

[RayDunzl]

I don't really know what you mean by boosts stacking, because the total EQ curve is showing the max boost at any given frequency already?

It shows the max boost for individual frequencies.

It does not show the resulting increase in voltage due to the boosts should they occur simultaneously.

Above, only 88Hz goes above -20dB, but the waveform is nearly clipped when multiple frequencies occur simultaneously (music).

 

[Robbo99999]

Yes, but that doesn't happen.

Much of what you listen to is down -20dB or so for the individual parts.

Modern bass often presses the limits of the aggregate, and the engineers will "clip" the extremes of the higher frequencies along for the ride.

Example:

At the top, you can see how the higher frequencies seem to be trimmed from going in theiir positive direction (clipping) when the bass nears maximum excursion.

The lower graph shows the "peak" values of all frequencies in the whole recording. No frequency yields 0dB on its own.

View attachment 76327

Hmm, there's some stuff here that I don't understand, and I'll have to ask you tomorrow, because it's too late for me think clearly on it, not only within what you're showing there, but how that translates to PEACE somehow 'potentially' taking this into account when "no one" else is taking this into account when applying negative preamp to EQ curves. I'll concede there could well be some things for me to learn here, but I don't understand why no one else is doing it when it comes to their EQ (even guys like Oratory1990).

I'll read your post again tomorrow and will try to ask some sensible questions.

 

[Robbo99999]

It shows the max boost for individual frequencies.

It does not show the resulting increase in voltage due to the boosts should they occur simultaneously.

Above, only 88Hz goes above -20dB, but the waveform is nearly clipped when multiple frequencies occur simultaneously (music).

Ah right, I'm getting closer to understanding now, the voltage, that triggered the beginning of my understanding.....because for example Amir tests at 2V output on DACS, maximum output, and that's just on a 1kHz (IIRC)....so yes you couldn't have 2V being output by say 1kHz and say 4kHz at the same time. What this means for music is where I would struggle to visualise, but again I'll have to ask some more sensible questions tomorrow when I'm fresh.

 

[RayDunzl]

I don't really understand how a +5dB boost at 20Hz can combine with a +3dB boost at 6000Hz to push it over the limit.

 

[RayDunzl]

how that translates to PEACE somehow 'potentially' taking this into account when "no one" else is taking this into account when applying negative preamp to EQ curves.

But they do...

My Room Correction EQ demands -3dB to start, and when that isn't enough, you can subtract more.

 

[Robbo99999]

View attachment 76336

Although that scenario could still happen without any EQ at those points on the curve, so whilst I can see how the frequencies combine, I don't see how this clipping is not happening all the time when EQ is not even applied. I'm still not getting away from the fact in my mind that the 'normal' negative preamp I've been using is already levelling the playing field back to a more than neutral situation (because most of the points on the curve are well below 0dBFS and only one miniscule frequency even remotely close to 0dBFS), so given this I fail to see how this problem is not worse and not occurring all the time when no EQ is used.

 

[Fluffy]

@RayDunzl your examples are mistaken. I don't have Peace but I use EqAPO in its basic form. It doesn't matter what combined filters you have, it just matters which one is the largest boost, and you should set you pre-amp according to it. Here is a signal of 105hz+6khz normalized to -0.1 dbfs:



Now I'll add +5 db at 105hz and +3 db at 6khz:



It gives me exactly 5 db of gain above odbfs:



A loopback recording in audacity will give me a clipped signal:



Setting a -5 db pre-amp will eliminate the clipping:

 

[Robbo99999]

@RayDunzl your examples are mistaken. I don't have Peace but I use EqAPO in its basic form. It doesn't matter what combined filters you have, it just matters which one is the largest boost, and you should set you pre-amp according to it. Here is a signal of 105hz+6khz normalized to -0.1 dbfs:
View attachment 76345


Now I'll add +5 db at 105hz and +3 db at 6khz:
View attachment 76344


It gives me exactly 5 db of gain above odbfs:
View attachment 76343


A loopback recording in audacity will give me a clipped signal:
View attachment 76342


Setting a -5 db pre-amp will eliminate the clipping:
View attachment 76341
View attachment 76340
View attachment 76339

This would be my normal understanding, this is how I did it.......I'm not sure why the clipping meter in PEACE is indicating something different though.

 

[Fluffy]

I don't use peace so I don’t know either. But you can try making a loopback recording in audacity to verify if there is actually digital clipping.

 

[Robbo99999]

I don't use peace so I don’t know either. But you can try making a loopback recording in audacity to verify if there is actually digital clipping.

If you have a look at my screenshot in the first post of this thread you can see the Equaliser APO window that you also linked, it's showing -2.2dB for Peak Gain (one of the red circled areas I circled in the screenshot)....I'd normally run that so it was at 0dB, but it was the clipping meter in PEACE that for some reason asked me to run it at an addition -2.2dB. Yeah, so I'm not doing anything different to you in your approach with Equaliser APO, just that the PEACE clipping meter seems to be firing off when it shouldn't....although that's what I'm trying to get to the bottom of. I had thought I was onto some answers with Ray's examples, but your screenshots show different conclusions to Ray's, so I don't know why the disparity there.

 

[Fluffy]

Maybe there is some additional gain somewhere in your chain? A loopback test can help verify if that meter is accurate.

 

[Robbo99999]

Maybe there is some additional gain somewhere in your chain? A loopback test can help verify if that meter is accurate.

What kind of additional gain though? I mean I run 84% Windows volume and ideally -4.3dB negative preamp on top of that to account for the the EQ curve total as seen in Equaliser APO.......yet PEACE clipping meter would show clipping still. I mean where else in the system is there gonna be additional gain, I've not got anything else in the chain.

 

[Robbo99999]

@RayDunzl , could you come back at Fluffy on the question he asked you in this post (https://www.audiosciencereview.com/...ace-clipping-meter-question.15071/post-473757) because that seems to be the key to answering the questions. I have a feeling you haven't really seen what I've done in my screenshots in the first post of this thread, so I'm thinking you've got your wires crossed, but not sure.

 

[Fluffy]

Well then I guess we need another Peace user in here…

 

[Robbo99999]

Well then I guess we need another Peace user in here…

Well I had one PM me already, he said he saw the PEACE meter firing off when it "shouldn't" based on how we understand to use the Analysis Panel in Equaliser APO (I'd normally run Peak Gain at 0dB, PEACE wanted me to run it at an additional -2.2dB):

So whatever it is, it is something inherent to the PEACE clipping meter that is either mistakenly showing clipping where there is none, or it's taking in some other factors into account that truly shows clipping....it's not some strange thing just happening to my specific audio chain, it's something about PEACE.

 

[Fluffy]

Maybe it's calculating reconstructed peak or something like that. basically "rounding" clipped waveforms to show were the wave would actually peak if it weren't for limiters. Though it's pretty useless, so I'm not sure why would it do that.