VO-BB - 20 YEARS OLD!

paulstefano · Posted: Sun Dec 06, 2015 7:23 pm Post subject: Roll off switch?

Got a tech question would appreciate advice. I have a highway next to the house. Inside my booth it comes in as a steady rumble. I run a high pass filter at about 125 hertz and that eliminates it nicely.

But...I just picked up a new mic that has a built in 80 hertz roll off switch and my voice sounds best with it engaged. If I use my normal 125 high pass after using my new mic will I lose something? Will I effectively be rolling 205 off? Is the effect cumulative?

Thanks

Paul
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vkuehn · Posted: Sun Dec 06, 2015 7:56 pm Post subject:

There is probably no TOLL GATE on your recording set up, so experiment and find out what happens... no added cost except the value of your time. No, it is not going to 80 hz to 125 hz and end up cutting all the way up to 205 hz.

Having said that, most filters express themselves as the KNEE VALUE and the audio may be affected on above the 80 or above the 125, but as a decreasing value as you get further past that knee point.

Filters (in the digital world) are funny animals. In your DAW you may find that you not only have a choice in the frequency of the filter, but it may also offer you the choice of doing a BUTTERWORTH, Blackman, Hamming, Blackmann-Harris or Hann algorithm for the math that drives the filter. And who knows what happens if your 80 hz filter is using one algorithm, and your 125 hz filter is using some other filter.

Also consider this: you may want to do some filters at the very end of your list of steps. If you do a "brickwall" filter as some folks call it to remove everything below 80 or 100 or 120, and then you do some additional processing, and then look at the Spectral Display, you may find that a bunch of new garbage below your original cutoff of low frequency trash has re-appeared because you ran a compressor following the filter process. And that can screw up your noise floor reading on an audio book.

Mike Harrison · Posted: Mon Dec 07, 2015 5:28 am Post subject:

Using a microphone's roll off switch is a "permanent" EQ. Just as using EQ to eliminate background noise is not a good solution because doing so can/will also remove frequencies that are desirable in the voice, the same is true – in this case – of a low frequency roll off: some male voices can possess frequencies as low as 80Hz or below. So, obviously, using a roll off filter could affect the sound of your voice.

If you are able to analyze the sound of your environment and determine the frequency range of the traffic rumble and discover that it is not in the range of your voice, using EQ to address only that range MAY solve the problem.

Something else that may help: assuming the traffic rumble comes from one direction only, consider using a highly directional (shotgun) mic, pointed away from the direction the rumble comes from, and maybe a couple of freestanding ClearSonic Sorber panels between the back end of the mic and the source of the noise.

As a side note, if there is a background noise issue of any kind that cannot be effectively handled, I would recommend never using compression.
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Male Voice Over Talent
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paulstefano · Posted: Mon Dec 07, 2015 5:35 am Post subject:

Thanks Mike. I think I can figure that out when I have some time. So, if I'm understanding correctly, you are suggesting to NOT use the Roll off switch, and try to just notch out those specific frequencies of the highway rumble, if and only if they don't cross over some frequencies of my voice?
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Mike Harrison · Posted: Mon Dec 07, 2015 5:40 am Post subject:

Yes. And see the short paragraph I just edited into my previous post while you were replying.
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Mike
Male Voice Over Talent
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paulstefano · Posted: Mon Dec 07, 2015 5:44 am Post subject:

Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

I haven't read every reply so pardon me if this has already been covered.

My understanding is that most post production engineers aren't concerned about any frequencies 80hz or below, which they will probably shave off anyway. Just make sure you are rolling off the correct amount of dbs of those frequencies. In my experience most roll-off switches on mics make too drastic of a cut, with the exception of (IMO) the CAD E100s.