Negative peak limiting.

[ultima]

Negative peak limiters do just that ...limit the negative peaks, but what for?
Im really curious why that would be done to a signal!?

I reckon they are used in broadcasting?

Does anyone know what these are used for at all?

thanks.

[Bob Olhsson]

The most common broadcast processors use what they call a "phase rotator" to keep whatever phase is the loudest positive. It's a trick that allows a broadcast signal to be its loudest while operating within legal levels of modulation.

Phase rotation can make innocuous clipping not only audible but distorted enough to cause a reduction of volume on the air. It's the main reason modern clipped CDs often sound so wimpy and small when played next to older rock titles.

[robdarling]

Is the phase rotation a dynamic process? Is it actually flipping phases or is it just evaluating both phases at the detector circuit?

[Bob Olhsson]

It has to actually flip it. It's done using an all-pass filter. Does very ugly things to out of phase stereo stuff too so checking mono remains an ultra important part of mixing.

[robdarling]

nasty. now I understand why old Springsteen and U2 tracks feel so much much better next to the new one on twofer Tuesday back to backs.

thanks for the info bob.

[groove guru]

It's funny that you guys are talking about phase rotation now. I've never heard of it until last week. As I was looking through a recording mag, there was an article about "radio ready" mixes where they discussed all of the broadcast processors. They also mentioned some type of "clipper" thas is used which is also new to me.

I'd like to know more about getting a mix ready for radio play compared to normal cd productions. Give up the secrets if you got them!

[Brad Blackwood]

This article by Frank Foti and Robert Orban might shed some light...

[groove guru]

Thanks for the link Brad, that was a very interesting article.

[Bob Olhsson]

Originally posted by robdarling
nasty. now I understand why old Springsteen and U2 tracks feel so much much better next to the new one on twofer Tuesday back to backs.

Kind of amazing that we've got a generation of A&R and management folks who don't seem to listen to, or if they listen, don't want to do anything about what their artists sound like on the air. It isn't an "audiophile" issue, it's a pure "balls" issue.