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Gear / Technical Help => Microphones & Setup => Topic started by: HealthCov Chris on August 25, 2018, 02:35:31 PM

Title: Low Freq Roll Off on shotguns?
Post by: HealthCov Chris on August 25, 2018, 02:35:31 PM
Should I be considering using the low freq roll-off on my shotguns, or keep it flat?  New the shotgun world.  Taping Papadosio tonight indoors small to mid-size box venue.
Title: Re: Low Freq Roll Off on shotguns?
Post by: tim in jersey on August 25, 2018, 03:23:47 PM
Always flat. Always.

Can always roll off the low end in post. Can't add it after the fact.
Title: Re: Low Freq Roll Off on shotguns?
Post by: EmRR on August 25, 2018, 03:36:17 PM
I'd agree, only possible exception being if you are experiencing some large low frequency transient that's overloading your preamps.
Title: Q
Post by: furburger on August 26, 2018, 06:31:05 AM
Always flat. Always.

Can always roll off the low end in post. Can't add it after the fact.


could not disagree more.

it depends on the music being recorded, but I've had great success using a lo-cut for, oh, almost 25 years.

if you end up with a recording with too much bass, it's virtually impossible to fix it in post. (whereas mids and highs are much easier)

why?

because you *feel* bass but *hear* treble

a well made lo-cut drops one frequency 12db (31 band EQ's are every 1/3 octave, or basically all the human ear can discern), and that's it.

the one for my Sonic Studios (not shotgun mics, but it goes across the board) will either pull 40, 80 or 120 down  12dB, and that's it.

and since *most* bass oversaturation is around 63 to 98hz, I keep mine set at 80.

here's a Sabbath show, recorded from the 4th row, DFC, with the lo-cut...you can listen to the mp3 samples in the comments...

if I hadn't, Geezer would have been a distorted mess, instead, this recording is *so clear*, your ears can lock onto Geezer for the entire show.

and for 400+ people snagging a Sabbath *reseed from 1999*, I'd have to say that I kinda know what I'm talking about, regardless of the haters here.

http://www.dimeadozen.org/torrents-details.php?id=626714
Title: Re: Q
Post by: robeti on August 26, 2018, 08:01:25 AM
Always flat. Always.

Can always roll off the low end in post. Can't add it after the fact.


could not disagree more.

it depends on the music being recorded, but I've had great success using a lo-cut for, oh, almost 25 years.

if you end up with a recording with too much bass, it's virtually impossible to fix it in post. (whereas mids and highs are much easier)

why?

because you *feel* bass but *hear* treble

a well made lo-cut drops one frequency 12db (31 band EQ's are every 1/3 octave, or basically all the human ear can discern), and that's it.


the one for my Sonic Studios (not shotgun mics, but it goes across the board) will either pull 40, 80 or 120 down  12dB, and that's it.

and since *most* bass oversaturation is around 63 to 98hz, I keep mine set at 80.

here's a Sabbath show, recorded from the 4th row, DFC, with the lo-cut...you can listen to the mp3 samples in the comments...

if I hadn't, Geezer would have been a distorted mess, instead, this recording is *so clear*, your ears can lock onto Geezer for the entire show.

and for 400+ people snagging a Sabbath *reseed from 1999*, I'd have to say that I kinda know what I'm talking about, regardless of the haters here.

http://www.dimeadozen.org/torrents-details.php?id=626714

Of course you can roll-off post.
What you do with your hardware (roll off 40, 80 or 120 by 12db) is exactly what can be done with software in post.

High SPL and mics that are not able to handle those is a much bigger problem that can't be fixed afterwards. Maybe that's what you are mixing up.
Title: Re: Q
Post by: opsopcopolis on August 26, 2018, 10:53:50 AM
Always flat. Always.

Can always roll off the low end in post. Can't add it after the fact.


could not disagree more.

it depends on the music being recorded, but I've had great success using a lo-cut for, oh, almost 25 years.

if you end up with a recording with too much bass, it's virtually impossible to fix it in post. (whereas mids and highs are much easier)

why?

because you *feel* bass but *hear* treble

a well made lo-cut drops one frequency 12db (31 band EQ's are every 1/3 octave, or basically all the human ear can discern), and that's it.

the one for my Sonic Studios (not shotgun mics, but it goes across the board) will either pull 40, 80 or 120 down  12dB, and that's it.

and since *most* bass oversaturation is around 63 to 98hz, I keep mine set at 80.

here's a Sabbath show, recorded from the 4th row, DFC, with the lo-cut...you can listen to the mp3 samples in the comments...

if I hadn't, Geezer would have been a distorted mess, instead, this recording is *so clear*, your ears can lock onto Geezer for the entire show.

and for 400+ people snagging a Sabbath *reseed from 1999*, I'd have to say that I kinda know what I'm talking about, regardless of the haters here.

http://www.dimeadozen.org/torrents-details.php?id=626714

So much to unpack in that post...

Main issue is that's not how the low cut works. It's a high pass filter, removing everything below the selected filter at a set q

It is absolutely doable to remove in post, that's the whole point of parametric equalization.
Title: Re: Low Freq Roll Off on shotguns?
Post by: goodcooker on August 26, 2018, 11:28:17 AM

Shotguns typically have less low end response than other pattern mcs (YMMV) and are used from farther back, limiting the need to roll off bass due to proximity to the subs. Do it in post production work in a controlled environment when you can hear what you are doing if you do it at all. I usually do roll off alittle low end but I use mics that have a ton off low end response that goes really far down.

Unless way too much bass content is overloading your preamp due to excessive SPL levels there is absolutely no reason to do it in the field.
Title: Re: Low Freq Roll Off on shotguns?
Post by: robeti on August 26, 2018, 11:34:41 AM

Shotguns typically have less low end response than other pattern mcs (YMMV) and are used from farther back, limiting the need to roll off bass due to proximity to the subs. Do it in post production work in a controlled environment when you can hear what you are doing if you do it at all. I usually do roll off alittle low end but I use mics that have a ton off low end response that goes really far down.

Unless way too much bass content is overloading your preamp due to excessive SPL levels there is absolutely no reason to do it in the field.

Excellent post. I suggest topic starter takes this advice.

 :cheers:
Title: Re: Low Freq Roll Off on shotguns?
Post by: Walstib62 on August 26, 2018, 01:09:20 PM
Should I be considering using the low freq roll-off on my shotguns, or keep it flat?  New the shotgun world.  Taping Papadosio tonight indoors small to mid-size box venue.


There is no one size-fits-all answer to this question. You would need to check the specs of the roll-off for the specific mic. Bass roll-off circuits reduce-not generally eliminate-low frequencies at at a given dB/octave curve. Each mic will have a specific curve. The frequency at which the roll-off begins to occur is called the corner frequency.  Normally the low frequencies can be re-boosted in post, depending on the roll-off curve.

These filters can be very useful in eliminating unwanted rumble (from A/C units or excessive subwoofer reverberation).  Without the roll-off engaged, you may need to set your gain so low that you lose some dynamic range in the mid and high frequency range. If, as mentioned above, the low frequencies are at such a high magnitude that the input stage or A/D clips, the results are very unpleasant and may result in an substandard recording.

Shotgun mics generally operate as cardioid mics at lower frequencies, so a shotgun would not be immune to such low frequency "overload" issues. Engaging the roll off may be appropriate or may not be necessary, depending again on the spectral range of the environment.





Title: Re: Low Freq Roll Off on shotguns?
Post by: DSatz on August 28, 2018, 04:01:33 PM
A cuppla things:

[1] Yes, many/most shotgun microphones have deliberately curtailed low-frequency response. It's not inherent in the way that shotgun mikes work; rather, it's a design choice on the part of the manufacturers, since the primary application for shotguns is dialog recording, and nothing much below about 80 Hz is likely to be desired in that application.

[2] In some shotguns this filtering is switchable and in others it's not. The switchable ones often have more extended low-frequency range to begin with, since the user can always switch on the filter if need be. Other mikes may use increased diaphragm tension, which improves the overall resistance to wind and handling noise, but "bakes in" the low-frequency limit.

[3] It's already been pointed out that low-cut switches on microphones are NOT like single-band controls on a graphic equalizer; the rolloff goes all the way down at a fixed number of dB per octave. Attached is a set of frequency response curves for a professional shotgun microphone that has two separate, switchable low-frequency filters (which may be cascaded), plus a treble adjustment to compensate for heavy-duty windscreens.

[4] In theory you can undo the effect of any filter in post-processing. But the more you cut a range of frequencies and later "re-boost" them, the greater the risk of audible noise in that range of frequencies. The "re-boosting" process restores the original frequency balance, but can't tell the difference between the desired signal and the inherent noise of the channel, so it inevitably amplifies the noise by the same amount--kind of like Dolby noise reduction applied in reverse.

This tends to support the "don't use the filter unless you're pretty sure that you need it" point of view.

--best regards
Title: Re: Low Freq Roll Off on shotguns?
Post by: achalsey on September 17, 2018, 10:05:07 AM
^ :facepalm:  This thread is a month old and was going fine.  There is no need to instigate.  Leave it alone.
Title: Re: Low Freq Roll Off on shotguns?
Post by: tim in jersey on September 18, 2018, 01:50:43 AM
^ :facepalm:  This thread is a month old and was going fine.  There is no need to instigate.  Leave it alone.

You are absolutely right. Removed. Thanks for being the voice of reason.