EQing the Room? Or the speakers?
nigel_pearson_au
Posts: 14
Hi. I am new to the DriveRack world - finally got a 260 for a price I could afford! (had to sell my car though)
I will be using this in a church that currently has a mix of speakers: left FoH is a Quest QS350 (plastic 12 + horn), right is a JBL Eon 15P, and rear fill is some old 70v vocal boxes. I chose those FoH because of all the ones I could scrounge, they had the flattest measured nearfield response.
At the moment, I have a 1/3octave EQ that I calibrated over a few hours using some demo computer software. I measured in the middle of the room. Apart from some "bass booming" that an operator cut (and I partially re-boosted), I am happy with the results. Reading/leading/preaching sounds much warmer and more natural (through a good small condenser mic).
I am hoping that the 260 will give even better results, but I am troubled by the FAQ advice. e.g.
1) you cannot/shouldn't EQ the room, and
2) pointless to Auto EQ with people in it.
Ignoring the whole "we should improve the room first" advice for now, isn't it true that for most of the listeners, the room effects far outweigh the speaker peaks and troughs?
Likewise with Auto EQing a full room. A hundred-ish people are like some soft furnishings and a small pool full of jelly. That absorbs some sound, and not evenly. I wanted something like the Auto EQ because I could quickly do those sort of adjustments in a populated building!
At the moment, I am tempted to use the GEQ and AFS to counteract the room, the output-specific PEQs to slightly balance the speakers.
Comments?
I will be using this in a church that currently has a mix of speakers: left FoH is a Quest QS350 (plastic 12 + horn), right is a JBL Eon 15P, and rear fill is some old 70v vocal boxes. I chose those FoH because of all the ones I could scrounge, they had the flattest measured nearfield response.
At the moment, I have a 1/3octave EQ that I calibrated over a few hours using some demo computer software. I measured in the middle of the room. Apart from some "bass booming" that an operator cut (and I partially re-boosted), I am happy with the results. Reading/leading/preaching sounds much warmer and more natural (through a good small condenser mic).
I am hoping that the 260 will give even better results, but I am troubled by the FAQ advice. e.g.
1) you cannot/shouldn't EQ the room, and
2) pointless to Auto EQ with people in it.
Ignoring the whole "we should improve the room first" advice for now, isn't it true that for most of the listeners, the room effects far outweigh the speaker peaks and troughs?
Likewise with Auto EQing a full room. A hundred-ish people are like some soft furnishings and a small pool full of jelly. That absorbs some sound, and not evenly. I wanted something like the Auto EQ because I could quickly do those sort of adjustments in a populated building!
At the moment, I am tempted to use the GEQ and AFS to counteract the room, the output-specific PEQs to slightly balance the speakers.
Comments?
0
Comments
no, again not what was said, It's a painful experience being subjected to an auto eq pass...it takes, in the case of the 260 with high precision, 2-3 minutes sometimes, which seems like hours if your being subjected to it. Kind of like standing next to a jet plane on takeoff.
Obviously if the room is empty it will have totally different acoustics then when full of warm water bags...but good luck getting them to understand being sonically bombarded for what seems like endless punishment..THAT is what were saying. It is pretty much understood by most seasoned engineers that the RTA measurement platform is flawed in that it only takes into consideration frequency dependent volume. True measurement schemes like SMAART, or Praxis or Systune take more factors into consideration like impulse response and time alignment and a number of other factors.
What we have found the RTA based auto eq useful for is flattening the response of the speakers so that they represent all frequencies equally, and in that way excite the room less. A good baseline flat preset derived form flattening the response away from any and all reflective surfaces that skew the measurements can be used as a tool to see what a room is doing to the sound...correct sound manipulation would then mean finding the correct speaker for the coverage and room, and or creative speaker placement and room treatment to deal with the acoustic issues. once all that has been exhausted only then is equalization brought to bear to solve the remaining issues.
Look, I realize that your options are limited here...just realize that hacking the sound to pieces with equalization is not the best way to get clarity and these practices are tradeoffs at best.
More in the morning... middle of the night here
gadget
A center cluster would be best because left and right speakers cause sonic chaos where the horn patterns interact.. but two 90 degree patterns gives 180 degrees of coverage and most likely sprays sound on the walls and ceiling.
G
Now,
1) as good speakers continue to get cheaper, the ones we can afford will become flatter*. Imagine speakers that, in a given volume of air, are as good as a reference mic. (e.g. +/-2dB). Ignoring a dB or two of bass boundary effect, does that mean we don't need to EQ it?
2) For me (and my usage), speakers vs room EQ is direct vs echo/reverb;
2A) For those who are close to the FoH, they hear mainly the direct impulse from the speakers. The echo/reverb comes in 0.25 sec later and hangs around for another .6 sec, but it is nowhere near as loud. Usually they won't even hear the echo/reverb.
2B) For those who are up the back, they hear some direct impulse and some reflected, then some echo/reverb which might be half the volume of the initial sound. For something sharp like the drummer tapping in, they will hear it, but otherwise it is just some muddiness.
If I only EQ for the speakers to be flat, I am greatly helping those in the front rows, and slightly those up the back - the starting impulse of what they hear.
If I could theoretically EQ for just the room, I am helping reduce the reverberant energy, greatly helping the non-impulse part for those up the back.
If I EQ the middle of the room, I am trying to compromise - maybe some improvements for front (mainly direct impulse), and some for those that hear lots of reverb.
Of course, everything in the real world is compromise. The hard part is matching the science to the effect (psychology)?
(*) In 20 years time, all active speakers could have servo-coupled bass and have CPUs with microphones to feedback real-time correction data, and little "error" LEDS on the panel that tell you when they need to be dusted, or the cones/surrounds/windings replaced. But I digress.
Certainly open to doing some tuning, but suiting everyone is hard. Churches are multi-purpose buildings. People get married in them, want to hear each other singing in them, like the buzz when lots of people are talking after the service. A dead sounding space isn't a happy space!
Heh. Evening band actually just did that. New mixer + speakers probably installed this week:
http://www.questaudio.net/products/q_motion/qm-12fr.php
Sadly, they will spray just as much as the current horns. I am debating hanging them in the roof so that their 90° is front to back, and their 60° becomes a non-overlapping left to right in two blocks. Slightly concerned about losing the "focus" though. (I always find speakers up above sounds weird. OK for background music, but not for live band or talk)
The speakers we used from 1993-2009 were 15" with piezo horns. Top-end sounded crappy, but the horns were at least directional (90 x 20ish degree). Some people said they were too directional.
More directional speakers (line arrays) could help, but building isn't really large enough to warrant that.
Ceiling is high, and speakers are aimed down enough to mostly avoid it, but yes comb filtering and other reflections are manifest.
Conversely, stereo imaging is nice too. When a bride gets to process down the aisle with a nice piece of recorded music, or when we pan individual drums in the kit, it definitely adds something.
Kinda wish we could choose. Like a mono output to a middle box or cluster, and stereo to the sides for the few things that we want to wrap around us. Maybe dbx can supply a firmware patch for the 260 to allow "surround" routing
Every room has a point of no return, a saturation point where additional spl becomes sonically destructive. No amount of eq is going to solve that..
In a large room, with a known power output you can determine the total amount of absorption by measuring the average pressure throughout the room..this total absorption can then be used to calculate the reverberation time using the Sabine formula.
In a small room this fails miserably where a large part of the spectrum of interest lies in resonant modes of the room that don't overlap but may be isolated ...
Therefore system equalization will do little for these isolated modes and destroy all that is good with the world around it...
Every speaker manufacturer strives to make their speakers flat in speaker response...because large frequency aberrations (sometimes even small ones at bad points) can cause aberrant feedback. Some have better results than others. Speakers that sound great out of the box are few and far between, and those that process nicely are more often then not, now locked out so you can't mess with the settings. From all that I have learned on this great sojourn one theme is always focused on when the big boys come to talk, that there is no substitute for pattern control, speaker placement, and system tuning, and that is a flat frequency response, all speakers in phase and aligned properly....
I think these are answered with the small room reverb quotient from above...
Yes, stereo image can be nice for those in the center who can hear both channels... but what about those on the outsides that completely miss those guitars panned full left or those toms panned left and right...
Center clusters with proper pattern control aimed on the warm water bags with reverence (pun intended) to the level the room can sustain before it degenerates into chaos will do more to foster the one thing that is most important in church setting...spoken word intelligence...you can always bring in speakers on a stick if you want to do that, but for the majority of what a church is, the above statement will do more to make you look good than all the equalization in the world...
These processors are available now.. from dbx and others...
Gadget
Be well
And, the more "reverently" radiated water bags are packed in there, the more we have to turn it up, and the more reverb dominates. Hmmm.
Full pan is bad - I have rarely done it, although in an echoish space, most people will hear something :-)
Very true. For the mid/vocal range, less speakers (and room EQ?) is the aim.
Though, for the band, a sub is their aim. Sigh.
I guess it is too late for me, now that I finally have a 260, but what models, wouldn't that make routing of low bass impossible?
(processor splits stereo mix into Left/Centre/Right, which then needs to have something like a "3x4 (2band)" filter?)
480 (4 in 8 out) discontinued
4800 an amazing box with virtually strait wire sound also 4x8
the new SC 32 offers 32 IO's and flexible routing
but these are all well above the cost of the 260
There are some inexpensive multichannel processors that are not dbx...
BBE has a 4x8
Peavey has a 4x8
Behringer has a 3x6
all priced well under the 260 but without all the features
If your mixer has an extra aux send perhaps you should look into aux fed subs.. the process can really tame bass down by limiting the number of sources the sub can reproduce...
G
Dennis
Interesting idea, Dennis (though I suspect an impulse or burst might work better than continuous pink noise?)
I am worried about the differences in height, though. Eventually the trigonometry gets you - you can easily delay for source and speakers in a plane to the listeners' heads, but when the speakers are 6 to 12ft above the speaker's head, aren't the extra distances going to spoil the time alignment?
(although the former sounds like primitive room EQ to me
I did have a good look at the Behringer DCX2496 specs. An extra input and maybe a better PC config tool, but a lot less useful stuff.
All these could do my proposed trick with AUX feeds, or a subgroup'd mixer I guess.
It would be tidier if all the routing could be done in the processor, though. e.g. something that is panned fully left in the mixer outputs is only output from the DR's L output, something 3/4 left would be equally output from L and Center, and something un-panned would only be routed to the Center output.
Some high-end surround production mixers did actually have a joystick to do that for discrete 4.0/5.1 outputs, and I'm sure current DAW setups can also, but the $$$ and learning curve on those is huge.
Here in the real world, I guess I will have to dream of an A-union-B routing upgrade for my '260.
For this explanation, lets tempoarily ignore your rearfills. For someone sitting in the rear of the room, the elevation of flown speakers in relation to preacher is not that noticeable or distracting. For someone in the front row right in front of preacher and right underneath speakers flown at a 12' trim height, it could be very distracting. It could be that the acoustic sound of preacher's voice won't be loud enough for alignment purposes and you might want some very small frontfill or lipfill speakers. Align the frontfills to preacher's head, and then align the flown L&R speakers to the frontfills. Before I go any further, I would like to see a diagram of the room with all speaker positions and dimensions.
Dennis