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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: Cheesecadet on March 09, 2013, 06:10:46 PM

Title: 80Hz High Pas Filter Question?
Post by: Cheesecadet on March 09, 2013, 06:10:46 PM
I posted this in ask the tapers but thought this section may be more appropriate.

I am curious if running the 80Hz High Pass Filter on my Shure FP24 pre is going to eliminate a substantial amount of bass from my recordings or is that setting almost negligible? 

Any input or experience with this pre and/or setting is helpful.

Thanks
Title: Re: 80Hz High Pas Filter Question?
Post by: page on March 09, 2013, 06:35:56 PM
depends on the type of music. Stuff that has an electric bass has a lot of potential on dropping the deep/funk notes, but not the higher stuff. Stuff that is brass or accoustic will be left largely intact (except for a tuba which will sit around 80hz at it's lowest). Kick drums hover around 100hz IME.

If the rolloff was starting under 50hz or (bet yet) 40hz, there isn't much harm in running it if you think you'll get wind or lots of floor rumble, but otherwise it's a crap shoot.

edit; typo
Title: Re: 80Hz High Pas Filter Question?
Post by: Cheesecadet on March 09, 2013, 07:15:50 PM
So would it be ok for typical jamband stuff and bluegrass?
Title: Re: 80Hz High Pas Filter Question?
Post by: page on March 10, 2013, 12:13:37 AM
So would it be ok for typical jamband stuff and bluegrass?

not optimal that high up but doable, best engaged for outdoor high wind stuff if your dead rats are left at home or expecting high winds.

anything else, just use a broad EQ later.

Title: Re: 80Hz High Pas Filter Question?
Post by: Chimney Top on April 17, 2013, 05:42:02 AM
The first few weeks I had the mixpre I used the 80hz filter... should NOT have used this, particularly for a hip hop/electronic concert.  Any way to boost the frequencies or 'restore'?
Title: Re: 80Hz High Pas Filter Question?
Post by: Duncan on April 17, 2013, 06:23:57 AM
Is there ever a time when it's preferable to not record using a filter over just EQing in post?

Duncan
Title: Re: 80Hz High Pas Filter Question?
Post by: DSatz on April 17, 2013, 08:11:40 AM
This depends entirely on your equipment--the overload margins of each item (at both their inputs and their outputs), and where the filtering could be applied in the circuit. A very strong disturbance at low frequencies, such as from wind, could cause overload distortion which you wouldn't be able to equalize out.

For example, some condenser microphones when struck by moderate wind might not be overloaded themselves--but then their signals could overload the inputs of your preamp. In that case, an in-line filter just before the inputs of the preamp could save the recording, while later filtering or equalization would be useless. (Also, using pads rather than filters might allow you to find the best filtering choice in post-production.) But if the microphones themselves are overloading due to the disturbance, a filter or pad at the input of the preamp would be too "late" to help.

Does that way of thinking about things help you make sense of the situation?

About reversing the effect of a filter: It's possible in theory, but in practice it's often best to compromise. If the filter was 12 dB/octave below 80 Hz, try restoring about half of that loss first (and maybe only down to 40 Hz--not all the way to 20) to see whether you can be satisfied that way. If you correct for the filter completely, you'll add a lot of low-frequency noise along with the music. Also, any thumps or bumps that you picked up would get amplified to a degree that might cost you a woofer or an amplifier fuse. So go easy on this approach until/unless you're sure that it's safe and that it's what you really want sonically.

--best regards
Title: Re: 80Hz High Pas Filter Question?
Post by: runonce on April 17, 2013, 08:28:55 AM
I posted this in ask the tapers but thought this section may be more appropriate.

I am curious if running the 80Hz High Pass Filter on my Shure FP24 pre is going to eliminate a substantial amount of bass from my recordings or is that setting almost negligible? 

Any input or experience with this pre and/or setting is helpful.

Thanks

Are you finding your recordings to be be to bassy?

These sort of adjustments are always best done in post - there isnt much to be gained by doing it live.

But yes - I think 80 would be pretty noticeable.
Title: Re: 80Hz High Pas Filter Question?
Post by: Duncan on April 17, 2013, 09:39:56 AM
Does that way of thinking about things help you make sense of the situation?

Yes that makes sense

Cheers

Duncan