Question for Brad & Joe Re: LP Filtering

Posted: Tue Jan 29, 2002 6:56 am

I've been present at a number of pro mastering sessions for major label commercial release projects, and each time always noticed the mastering engineer applying a Low pass filter around 20Khz. Is this a case of getting rid of frequencies you can't hear that are using up headroom, so you remove it to gain more overall volume on single mixes for radio?. Is there a specific reason for LP filtering a track for Radio?. If so, at what frequency do you Mastering Gods concider the upper limit of usefull Khz regarding Broadcast/Domestic systems and what db/octave would you apply the filter at this frequency.
Many Thanks
Bearclaw. Smile

Posted: Tue Jan 29, 2002 7:19 am

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Posted: Tue Jan 29, 2002 11:36 am

Bearclaw,

I think we had this same question a few weeks ago. So I'll try to give a more interesting answer this time. There are no rules. Some may use HPF all the time to make sure there is no low rumbly stuff to muddy up the song. The Duntech monitors we use are extremely accurate in the low end so I have the luxery to able to hear what is going on and if adjustments are needed. It depends on the mix, the song the and to some extent the format. There is a lot more low end (40hrz and lower) on many of the newer records, especially heavy rock. Finding the balance between the right amount of low end but to not get in the way of the mids and highs and still have the punch on smaller speakers is the trick. And whaterver works is the right thing to do!

Posted: Tue Jan 29, 2002 1:22 pm

Just to follow up on my last response:

In my haste I thought you asked about HPfilters because I get that question regularly. As far as Low Pass Filters goes regardless if its vinyl or CD I would rarely use them. Remember that there is a lot of good stuff up there! Harmonics that put an air around the music. Vinyl has the ability to playback those extended high frequencies that I want to hear. Low end is the bigger problem with vinyl. So HPF are more common. As always it depends on each particular mix, but as a generall rule I don't use them unless there is a specific need for them.

Posted: Fri Feb 08, 2002 4:18 am

Thanks for clearing that up guys. Very Happy

Posted: Mon Mar 03, 2003 3:02 pm

I find a really nice ^analog^ LPF helps smooth the harshness of digital recordings. I'll back it off as low as 16k. Analog recordings I rarely touch though. I think analog tape naturally diminishes SMOOTHLY on the top due to wear. I started doing this when a few clients preferred using their vinyl releases transferred to CD as opposed to their CD masters on their CD releases. Upon inspection I found a steep yet smooth roloff from 12k up. So, I've implemented this technique as somewhat of a digital cure-all. It doesn't always sound better on nice monitors, though it seems to carry much better through lesser systems.

Dr.Spok Wink

Posted: Tue Mar 04, 2003 12:36 pm

For vinyl cutting I usually filter at 12hZ & 16.3 KhZ. The high pass to prevent rumble, the low pass to protect the cutter head.

For CD, I use filtering only for artistic purposes.

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