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Author Topic: FOH Frequency Response Curve  (Read 5945 times)

ZhaoLi Seow

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FOH Frequency Response Curve
« on: September 28, 2009, 01:29:06 am »

Just came back from a festival show. I noticed that all the FOH engineers tuned their system flat from 100Hz to 10+kHz. Below 100Hz, they had a boost of 6-12 dB in the sub region. Mix was bright at FOH location, but was just nicely warm when listening from outside the tent.

I will mix indoors and when I tune the system, I usually tune the system with a 18dB drop from 20Hz to 20kHz for indoor systems. I know flat doesn't sound good indoors, some people tune with a gentle roll off above 2kHz.

What do you guys tune the system to, for shows both indoors and outdoors?
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Jeremy Oswin

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Re: FOH Frequency Response Curve
« Reply #1 on: September 28, 2009, 02:58:53 am »

I've been tuning both indoors & outdoors with a gentle roll off above 2k, flat below that.  This is based on an averaging of many positions everywhere from 1 meter on axis to 3 or 4 positions throughout the audience.  The resulting frequency response tends not to be perfectly smooth in any one position, but roughly as balanced overall as any other.

Canned music and low frequency heavy instruments seem to require a significant eq boost in the low end with this tuning, and that works for me because every other instrument has that much less low end respectively.

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Charlotte Evans

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Re: FOH Frequency Response Curve
« Reply #2 on: September 28, 2009, 06:13:43 am »

I prefer to notch out the real nasties at the DSP, leaving the FOH graphic as a "grab EQ" for emergencies or for any variations between daytime/dewpoint outdoors and empty/full venue (hopefully!) indoors.
Very rarely need to hack at graphic EQ's, it usually means the set-up in the DSP needs to be looked at.

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Charlie Zureki

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Re: FOH Frequency Response Curve
« Reply #3 on: September 28, 2009, 06:31:57 am »

ZhaoLi Seow wrote on Mon, 28 September 2009 00:29


I will mix indoors and when I tune the system, I usually tune the system with a 18dB drop from 20Hz to 20kHz for indoor systems. I know flat doesn't sound good indoors,.....


 Hammer

 18dB drop? ... so... basically, you just lower the Gain?

Hammer
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Ivan Beaver

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Re: FOH Frequency Response Curve-Measurement types
« Reply #4 on: September 28, 2009, 07:54:31 am »

I would argue it depends on the type of measurement system used.

RTA or dual transfer (or other time based system).

Agreed on the RTA. Flat never sounds good-I tried for years to get an RTA system to sound good flat.

I tune (system alignment) my systems flat from around 100Hz up to as high as they system wil reproduce-typically around 12-15KHz.

The whole idea that the loudspeaker system should reproduce as accuractly as possible what if coming into it from the console.

Below 100Hz there is anywhere from a very slight boost (or none) to a pretty good suzed boost-depending on the customers needs.

Typically I use Systune or Smaart for system alignment.

While I use TEF for loudspeaker measurement-the very thing that makes it great for that, makes it lousy for system alignments.  The ability to window out except what is coming out of the loudspeaker.  Great for response graphs-but our ears are still hearing more than just the direct signal.

Systems that have a wider "window" respond to more of what our ears are hearing-therefore give a better representation.

Then there is the whole "taste" factor.
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Ivan Beaver

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Re: FOH Frequency Response Curve-20-20KHz?
« Reply #5 on: September 28, 2009, 07:59:42 am »

ZhaoLi Seow wrote on Mon, 28 September 2009 01:29

I will mix indoors and when I tune the system, I usually tune the system with a 18dB drop from 20Hz to 20kHz for indoor systems.



So your live systems are solid down to 20Hz and go up to 20KHz?  What type of loudspeaker system are you using?  Where would this be measured at?

Is this a straight line drop from 20Hz to 20K or does it flatten out somewhere or does it look more like a phase response curve of a bandpass filter-but with amplitude in place of degrees?    
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Kristian Johnsen

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Re: FOH Frequency Response Curve
« Reply #6 on: September 28, 2009, 08:33:31 am »

I THINK he meant that he starts out with the 20 Hz slider at o dB and rolls off progressively until the 20 kHz slider is at -18 dB.
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Scott Helmke (Scodiddly)

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Re: FOH Frequency Response Curve
« Reply #7 on: September 28, 2009, 10:12:31 am »

It's a pretty good question I haven't gotten around to raising, especially with respect to line arrays which usually start out with extremely big lows compared to highs.  How much do you flatten out the response when system tuning?  I've even heard of people under-reporting the number of cabinets to the DSP (Meyer array correction) to leave the lows/mids still hotter than the highs.

Dick Rees

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Re: FOH Frequency Response Curve
« Reply #8 on: September 28, 2009, 10:21:53 am »

ZhaoLi Seow wrote on Mon, 28 September 2009 00:29

Just came back from a festival show. I noticed that all the FOH engineers tuned their system flat from 100Hz to 10+kHz. Below 100Hz, they had a boost of 6-12 dB in the sub region.


How do you know this?  Did you ask or receive documentation?  Were you just looking at a graphic?  Were the system DSP settings posted for all to see?  If not I assume this is an assumption on your part.

Quote:

Mix was bright at FOH location, but was just nicely warm when listening from outside the tent.


In other words, it seemed brighter inside a highly reflective environment where the highs bounce around like berserk kangaroos and not so much outside where the reflections were on holiday.


Quote:

I will mix indoors and when I tune the system, I usually tune the system with a 18dB drop from 20Hz to 20kHz for indoor systems. I know flat doesn't sound good indoors, some people tune with a gentle roll off above 2kHz.

What do you guys tune the system to, for shows both indoors and outdoors?


I use my ears and do what it takes to get it to sound right to me.  Sometimes it goes by the book, sometimes I need to add a new page......
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Gene Hardage

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Re: FOH Frequency Response Curve
« Reply #9 on: September 28, 2009, 10:33:41 am »

Dick Rees wrote on Mon, 28 September 2009 10:21


I use my ears and do what it takes to get it to sound right to me.  Sometimes it goes by the book, sometimes I need to add a new page......



Yes & yes.

When using my full "A" rig I have an Ashley EQ handy that could be inserted in the vocal sub group if needed.  So far that has not been the case but I have not had to use this rig inside a horrible hall yet - mostly outside stuff.  I don't have any measuring tools except the two on the side of my head.
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Chris Boschen Leonard

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Re: FOH Frequency Response Curve
« Reply #10 on: September 28, 2009, 10:46:09 am »

+1 on dealing with the major variations using the DSP paraEQ. The DSP is waaaay more suited for making precise adjustments than a graphic, especially when you are working inside a SMAART window with inverted traces, so you can match the amplitude and Q of the filter to correct the trace.

When I tune a system, indoors or out, I am going for as flat a response as possible across the frequency range of the speakers. I do this via the DSP paraEQ, until SMAART shows acceptable traces. The dual 30 band KT Eq's I usually use on mains (I work mostly with small systems & clubs) are for the FOH, and are left flat. If the FOH wants a low end bump, they can hit the KTs. Essentially, the FOH gets two layers of processing: mine, and theirs. My DSP EQ settings smooth the response to a good starter setting, and then FOH talent can hack to their heart's content on the KTs if they want or need something different, for whatever reason.  

I like to give a BE enough rope to hang themselves in style.
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ZhaoLi Seow

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Re: FOH Frequency Response Curve
« Reply #11 on: September 28, 2009, 11:22:38 am »

Well, I use Smaart for my measurements and to clarify, i have an imaginary line that is drawn at say +12dB at 20Hz and end at -6dB at 20kHz and i tune the system to match that line. It doesn't mean i have that line on the sliders on the GEQ. it's the system response shown on the smaart frequency analysis. Of course there is no system that is able to produce the extremes of 20Hz or 20kHz, and I will roll off the bass at a reasonable frequency and not push the trebles to extreme.

anyway, at the festival, I had the chance to observe the various artist's FOH engineer tune the system and look at their overall response curve. These are engineers for world class acts that have hits that top billboards.

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Dick Rees

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Re: FOH Frequency Response Curve
« Reply #12 on: September 28, 2009, 12:17:42 pm »

ZhaoLi Seow wrote on Mon, 28 September 2009 10:22

.

anyway, at the festival, I had the chance to observe the various artist's FOH engineer tune the system and look at their overall response curve. These are engineers for world class acts that have hits that top billboards.




I learned long ago not to confuse "entertainment" with music (sound).
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Karel 'Charly' Will

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Re: FOH Frequency Response Curve
« Reply #13 on: September 28, 2009, 01:26:09 pm »

Hi,

Magu offered me his goal for system tuning: flat from as low as possible till around 100Hz, then a ten dB roll off till 1kHz, then flat again till as high as possible.
That's remarkable similar to what some of my more experienced colleagues are doing for rock and dance.
I notice that when I tune a system by ear, I get a result that is mostly flat as a ruler, but with a 10 - 12 dB bump below 100Hz. I think that gives me a much more hifi sound, better suited to folk, pop, ...

I guess rock and dance need that extra low mid in order to make the music being felt, where folk, pop, ... benefit from the extra clarity in systems that were tuned "flat".

Just my 0.02
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Jason J Raboin

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Re: FOH Frequency Response Curve
« Reply #14 on: September 29, 2009, 01:18:58 pm »

For me it depends on the act.  For louder rock a 6-12 db boost below 80 and a gentle roll off starting at 2k sounds good to my ears.

For the folk act, I am looking for flat, with a 3-6 db dip in the 2-4k range.  The size of that dip seems to depend on the quality of the PA as well as how much high end the PA puts out.  The less "air", the bigger the dip.
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Timo Beckman

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Re: FOH Frequency Response Curve
« Reply #15 on: October 14, 2009, 03:18:51 pm »

I just start out with finding the x-over point between the main system and the subs (-6db point on the low end of the main). put in the low pass filter on the subs and take aa look at the freq responce of the system (sub and main) . Most of the time you see a dip appear in the 80 to 125/160 region of the pa meaning you have a combing problem (most systems i do have system settings for the tops  and as long as they are ok i do not worry about them ). Then apply delay on the subs and play around with it untill the dip is gone . Also i look at the phase trace before i do this and after the hole is gone .
Most of the time the subs are aligned with the mains at that time . After that i try to flatten the mains on all the areas where the freq responce is going above a centre line over the full freq responce of the system using gentel q factors on the parametric eq's .
I try to flatten the sound as much as possible so that what ever you do on the mix board comes out of the system .
After that i take a measurement of the mains at the possition of any delay/fill system there and try to match that to the mains in phase freq. responce and level .
I use a combination of smaart sat-live and my main analyzer is SIM3 with 6 DPA4007's wich gives me a lot of possibilities to verify all that i'm doing .
Greetz from a rather cold and windy place in the netherlands .
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Christian Tepfer

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Re: FOH Frequency Response Curve
« Reply #16 on: October 14, 2009, 06:37:49 pm »

Well, I basically don't care what frequency response I have on FOH.

I care about "does it sound good". When I measure the outcome it depends heavily on the source material, the room and the audience.

On PA systems I take what I get and try to mix accordingly. Makes no sense to try to push a system beyond the limits.

Eric Snodgrass

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Re: FOH Frequency Response Curve
« Reply #17 on: October 14, 2009, 08:15:18 pm »

Christian Tepfer wrote on Wed, 14 October 2009 15:37

Well, I basically don't care what frequency response I have on FOH.

I care about "does it sound good". When I measure the outcome it depends heavily on the source material, the room and the audience.

On PA systems I take what I get and try to mix accordingly. Makes no sense to try to push a system beyond the limits.

+1
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Eric Snodgrass
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Re: FOH Frequency Response Curve
« Reply #17 on: October 14, 2009, 08:15:18 pm »


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