[Cellotron]

Originally Posted by audiovisceral

From many of the posts on here, I understand that in many cases, loudness in commercial mastering is attained predominantly through A/D clipping.

This is not entirely correct information. Many (if not most) pro ME's do not clip their ADC the majority of the time - and some never do. Some ME's when clipping also prefer to clip at a digital gain stage instead of at the input of the ADC. Others prefer to use various digital limiting algorithms (either in hardware or plugin), some of which in fact do not "flat top" to the same extent that digital clipping does at all.

For my own work I use all these methods when very high average level has been requested by the client. What individual or combination of techniques works best is entirely determined by the nature of the material on the track and the goals. Some techniques lead to more distortion, some techniques lead to more lost transients - you need to balance out what suits the track and aesthetic goals the best.

I gather that clipping via this method, with a high end A/D converter can generate positive harmonic distortion that sounds more musical than simply clipping ITB.

I don't think it has anything to do with the practice generating "positive harmonic distortion" - instead I think that some high peak transients are going by so quick that when the tops are flattened out the resultant square wave is so quick that it doesn't offend the ear as noticeably. Some ADC's have analog front ends which simply have more headroom (resulting in less distortion when pushed) than others. Still - as soon as you're overloading them there will in fact be some form of distortion happening - whether minor or not.

It's how this 'driving' process takes place that I don't understand. How do you feed the signal back into a sound card A/D at a level high enough to make it clip by the A/D, but not by the unit doing the feeding?

First off is just sensible gain staging - having a healthy but completely undistorted signal level through the entire process chain. With today's equipment this luckily is fairly easy to achieve. Next a lot of ADC's used in mastering have input attentuators on them - for my own setup all I have to do is turn the attenuator on my Mytek Stereo96 up so that the level at the input is going over what would be digital zero at it's output - and voila! - you have clipping at the input. What you have to do is monitor at the output of the ADC (I have a live loop back from my DAW to a seperate DAC so I can do this) and listen to hear at what level things start to noticeably distort so you can set this point properly. Usually clipping at the ADC works best when you're just chopping off the very highest transient peaks.

For example, if the sound is coming out of a limiter and you set the limiter output to greater than 0, the limiter would clip the signal, not the A/D, would it not?

I'm not sure what you're asking here -in general digital limiters are used after clipping at the ADC and not before.

Most analog compressors/limiters (and even a few eq's) have output gain controls so you can increase gain after their processing allowing you to send more signal to equipment after them.

Generally I never have to do this to have enough level to optionally overload my ADC - I usually just have to open up the input attenuator so that it goes from just green lights glowing to the red ones firing off occasionally.

Also, I'm going to go ahead and surmise that the A/D on my Delta 1010 is probably not going to sound all that awesome clipping-wise

My guess is that it (just like many converters out there - including the PT HD192) will sound like @ss when it is clipped. There's only one to truly tell though - and that's to run some tests yourself.

Based on that, what sort of low-end/budget/entry-level A/D converters suitable for clipping currently exist, model and money wise? Obviously, I'm not asking what Sterling uses here ...

Lavry, Mytek, Benchmark, Apogee - all make stuff that can work for this that isn't priced as premiumly as other options. You should expect to fork out at least around $850 for 2 channels unless you find a deal on something used though.

Anyway - I think the sound quality of your music will ultimately much better in the long run if you do not clip it. But as these kinds of disclaimers seem meaningless in this day and age - I hope the above "helps"

Best regards,
Steve Berson