pucho812

Clipping converters
« on: August 13, 2018, 08:19:00 PM »
I read a lot of so called mastering guys.  They all talk of clipping converters.  I can only assume they are mis-using the terminology, or something.  Am I missing something here?
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.


JohnRoberts

Re: Clipping converters
« Reply #1 on: August 13, 2018, 08:26:01 PM »
Early A/D convertors behaved badly then saturated (they rolled over to 0 again, FS rail to rail loud clicky stuff). Modern convertors are more well behaved so saturation (clipping) is relatively clean with quick recovery and no unexpected artifacts.

Not good practice (IMO) but what would I know about music these days?

  JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

Gold

Re: Clipping converters
« Reply #2 on: August 13, 2018, 09:07:22 PM »
Nope, you heard right. Lots of MEs do it. There are long threads on GS about which converter clips best.  I don’t do it on a regular basis but if extreme level is needed sometimes there is no choice. Sometimes it actually helps. The distortion can give a snap to the leading edge which helps on some material.

pucho812

Re: Clipping converters
« Reply #3 on: August 13, 2018, 09:10:08 PM »
 Doesn't that give you digital distortion ? or is it just a matter of over driving the Analog stages
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

EmRR

Re: Clipping converters
« Reply #4 on: August 13, 2018, 10:04:09 PM »
I don't think there's been any hip-hop or rap done without converter clipping in mastering in 2 decades, it's expected as part of the process. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

Gold

Re: Clipping converters
« Reply #5 on: August 13, 2018, 10:36:22 PM »
I don't think there's been any hip-hop or rap done without converter clipping in mastering in 2 decades, it's expected as part of the process.


Yeah, it’s part of the sound.  Clipping a Prism AD2 is a sound that is part of the lexicon so to speak.

You are clipping both the analog and digital stages.

pucho812

Re: Clipping converters
« Reply #6 on: August 14, 2018, 12:49:37 AM »
Sounds awful to me.  lol
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

Gold

Re: Clipping converters
« Reply #7 on: August 14, 2018, 02:25:00 AM »
Sounds awful to me.  lol

Not if you do it right. 

Rochey

Re: Clipping converters
« Reply #8 on: August 14, 2018, 08:57:22 AM »

There are still plenty of products on the market that use old converters that have horrible saturation behaviour. (Rollover, where it goes from max positive to max negative, is one of the most horrid).
The last converter I worked on (PCM1865) was defined very clearly to "clip like an opamp", so  you'd clip at 0x0FFF (24 bit) until the signal comes back within range.

However, there are a few arguments to avoid doing this

A) Go much above the input signal range and you'll start shorting the signal through the device ESD diodes to the supply rail.  Not good for your source
B) THD near clipping increases exponentially. Given the extended dynamic range of mastering ADC's, you have more dynamic range than you have THD. Better to sacrifice 2 or 3 dB of headroom and get both good SNR and THD.
C) Why commit distortion to a recording? Wouldn't you be better recording clean and adding distortion as a post process?

Expat Audio Home: http://www.expataudio.com

JohnRoberts

Re: Clipping converters
« Reply #9 on: August 14, 2018, 09:51:10 AM »
There are still plenty of products on the market that use old converters that have horrible saturation behaviour. (Rollover, where it goes from max positive to max negative, is one of the most horrid).
The last converter I worked on (PCM1865) was defined very clearly to "clip like an opamp", so  you'd clip at 0x0FFF (24 bit) until the signal comes back within range.
Not surprising, the customer expects it to clip cleanly or doesn't even think about it.
Quote
However, there are a few arguments to avoid doing this

A) Go much above the input signal range and you'll start shorting the signal through the device ESD diodes to the supply rail.  Not good for your source
prudent design could limit over drive capability with design of analog side input stage.
Quote
B) THD near clipping increases exponentially.
not sure what you are describing. Some analog paths saturate fairly suddenly, some over a small range. I would expect saturation in a A/D convertor to be more sudden, than gradual. Note: there is one digital console with a soft limiter built into the mic preamp that some customers apparently like.
Quote
Given the extended dynamic range of mastering ADC's, you have more dynamic range than you have THD.
not sure what this means?
Quote
Better to sacrifice 2 or 3 dB of headroom and get both good SNR and THD.
that is the classic trade off between noise floor and saturation. For years operators with a little(?) digital knowledge hit the convertors hard to avoid quantization noise. This is not an issue with modern convertors that have an analog sounding noise floor.
Quote
C) Why commit distortion to a recording? Wouldn't you be better recording clean and adding distortion as a post process?
Mastering is the last step of the process where we stick a fork in it...  In my personal opinion clipping is undesirable, but they aren't mixing for me as their paying customers.

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...


EmRR

Re: Clipping converters
« Reply #10 on: August 14, 2018, 10:03:13 AM »
C) Why commit distortion to a recording? Wouldn't you be better recording clean and adding distortion as a post process?

Mastering is the last step of the process where we stick a fork in it...  In my personal opinion clipping is undesirable, but they aren't mixing for me as their paying customers.

While you guys are raising these questions, I'm telling you IT IS AN OPERATIONAL STANDARD within particular genre, and has been for a very long time.  It's all over everything you hear in those genre.


Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

JohnRoberts

Re: Clipping converters
« Reply #11 on: August 14, 2018, 10:12:12 AM »
While you guys are raising these questions, I'm telling you IT IS AN OPERATIONAL STANDARD within particular genre, and has been for a very long time.  It's all over everything you hear in those genre.
I am not raising this as a new question... Long before there were A/D convertors people saturated their analog audio paths, so good design involved fast/clean overload recovery.

The customer is always right, even when.....

While I avoid listening to some genres of music intentionally, from what I hear blaring out open car windows as they drive by, clipping on top of clipping is acceptable to many listeners.

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

Gold

Re: Clipping converters
« Reply #12 on: August 14, 2018, 10:23:33 AM »
Making a technical argument against clipping is  a situation where things around here get hilarious. Non users pulling numbers out of space to describe sound. Yeah, right.

Script

Re: Clipping converters
« Reply #13 on: August 14, 2018, 10:48:08 AM »
I wake up to the sound of music
AD converter comes to me
Speaking words of wisdom
Let it clip

Let it clip, let it clip, let it clip, yeah, let it clip
There will be distortion
Them dudes don't give a...(bliep)
 8)

JohnRoberts

Re: Clipping converters
« Reply #14 on: August 14, 2018, 10:55:49 AM »
Making a technical argument against clipping is  a situation where things around here get hilarious. Non users pulling numbers out of space to describe sound. Yeah, right.
I find both sides of this debate(?) humorous... that horse left the barn a long time ago.

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

Gold

Re: Clipping converters
« Reply #15 on: August 14, 2018, 11:07:01 AM »
It like a luthier saying someone isn’t playing their  guitar right .  Who cares?

Rochey

Re: Clipping converters
« Reply #16 on: August 14, 2018, 11:40:00 AM »
John,

this is what i'm talking about:
At high amplitudes, the THD swamps the N in the THD+N :)

My recommendation with customers designing audio systems is to only allow brief transients (where clarity etc isn't really a requirements) to enter that space.

Finally - I still don't understand why you would distort using the converters instead of in a post processing algorithm?
Expat Audio Home: http://www.expataudio.com

Gold

Re: Clipping converters
« Reply #17 on: August 14, 2018, 12:09:09 PM »
Finally - I still don't understand why you would distort using the converters instead of in a post processing algorithm?

Because professionals are able to make decisions and commit to them. Maybe it sounds better? Maybe the engineer wants to hear the finished sound before committing to the rest of the processing?

That graph illustrates perfectly why you would do it. The sharp rise in distortion happens right below 0dBfs. Material with strong transients like hip hop for instance will stay clean except for the heavy transients like bass drum or snare drum. The added distortion fools the ear into thinking the 6db you just lopped off is still there.
« Last Edit: August 14, 2018, 12:16:53 PM by Gold »

Pip

Re: Clipping converters
« Reply #18 on: August 14, 2018, 12:20:26 PM »
Mastering engineers I work with will, depending on the request of myself or the artist and it is a technique some use at their own discretion, hit certain converters hard, clipping them, usually rhythmically on the downbeat so it is musical. It is not a constant or random over.
Pip
New York City
http://geosonixlab.com

Gold

Re: Clipping converters
« Reply #19 on: August 14, 2018, 12:29:45 PM »
I've never had a client request that I do it or don't do it. They will say they want it louder. How that happens is my job.  Anticipating the level that is expected and delivering it is also my job.


 

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