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In Reply to: Re: Multiple monitor mixes( how to get enough seperate outputs) posted by BCRock on January 14, 2002 at 03:03:46:
That is excellent advice. Especially about keeping the stage volume down. You might want to consider buying powered monitor speakers. I have had good luck with the HotSpot vocal monitors and I also like the Yamaha MP5 for a powered keyboard monitor (put it right in front of the keyboard player aimed at his head). Otherwise you will need to buy more amps. You might also want to consider using headphones for your drummer.EQ on a monitor is to prevent feedback, you want to cut (never boost) the frequencies that tend to feedback. The smile eq curve is a great way of detecting B*S* artists. Nobody with the slightest clue about sound would use a smile eq.
Peace,
Phil Ouellette
Follow Ups:
Further thoughts on monitor eq.Roll off the low frequency on all monitors (under 100 Hz) as much as your musicians will let you. Low frequency is omnidirectional and too much will swamp your other monitors and make your FOH mix sound bad. No instruments (or vocalists) beside the bass player and the kick drum are going to have much energy below 100 Hz anyways (and they rarely need to be in a monitor mix).
When ringing out a monitor I will usually turn the mic around and point it at the monitor speaker. I then slowly bring up level on the aux send until you just start to hear the feedback begin to ring (carefull, don't let it get away from you). Chop the offending frequency about 3 to 6 dB. An RTA really helps speed this up since it lets you see which band is ringing. Do this once or maybe twice more and then stop. Hopefully you will have gained at least 6 db of usable gain before feedback which is a lot (the difference between having to eat the mic and being able to back off a few inches). Don't overdo this or else the monitor can end up sounding so chopped up that it doesn't do the vocalist much good.
General note, be sure you engage the low cut (or high pass) switch on all your vocal mics. Doing this will reduce the amount of stage noise they pick (drums and bass mostly), plus has the additional benefit that you will be less likely to see your woofers jump out onto the stage if a live mic gets dropped.
Further unsolicited advice: Make sure that every vocalist using a monitor can see down the throat of the horn or else they will not be able to hear themselves. It is amazing how many times moving a music stand or getting people to stand in front of the monitor speaker eliminates problems with the monitors.
Phil
Thanks for all the good advice, it helps. I never realized I
should notch feedback frequencies for the monitor mixes. That
helps alot. I guess I must have phrased that second question
wrong though, because I was asking about the EQ for the whole
system (31 band eq back by the main amp). Should this eq for
the whole system be basically flat then? One of the other guys
thinks the low and high ends should be rolled off for more clarity.
Thanks again for the excellent help. -Brian
EQ's are used on main speakers for two very different reasons.
1. Correcting uneven frequency response in the speaker system.
2. To avoid exciting troublesome frequencies in a room.In fact due to these different requirements it is not uncommon to see two eq's used in series on a single speaker system, one is used to clean up the frequency response of the speaker (and is never changed again after being setup), and the second is used to compensate for room effects. I would only consider using 31 band eq's since the 15 band eq's are not selective enough. Best of all is to use parametric eq's, but these can be tricky to setup.
Smoothing out the roughness in your speaker systems frequency response, especially around the crossover frequencies will help eliminate feedback problems and will also make the speaker sound a lot better. What you are trying to do is tame the bigger spikes and make the response generally smoother, not flat. It isn't possible (or even desirable) to make a speaker system ruler flat, you just don't want any big spikes in the response. You would expect that the crossover in your speakers would take care of this issue, but the reality is that lower cost speakers don't pay as much attention to this so you usually have to do some cleanup. Plus as soon as you add a subwoofer to your system you are totally on your own when it comes to getting a smooth response.
Note: Real speakers (as apposed to marketing fluff) roll off at both the low and the high ends (this is what the smile eq is trying to compensate for), but the reality is if you boost these frequencies enough to make the response flat you are going to have a harsh sounding high end and your system will probably clip on low notes. Not a good situation at all. Remember cut only, never boost with an eq.
To eq a system properly requires a certain amount of test gear. The best solution is to use either a TEF or a SMAART audio analyzer system. These will let you see the actual output of the speaker and eliminate reflections from the room. These are big buck solutions and take training to use. If you can find someone who has one of these it would be worth it to pay them to setup your eq for you (and then put a locking cover over your eq so no one, including you, will mess it up).
Most pro audio shops will have an RTA which has a set of level LED's (like a vu meter) for each frequency slider on your eq. The problem with an RTA is that it doesn't distinguish between the direct sound from the speaker and the reflections from the room. To sucessfully use an RTA to eq a speaker you really need to do it outside, in a large flat area (no nearby buildings).
Alternatively you could buy a test CD that has test tones on it and a Rat-Shack sound level meter and adjust it yourself. Don't worry that much over 10 KHz. The low-mid and midrange is where your system really needs to shine.
The issue of problem frequencies in a room is caused the fact that every room resonates at certain frequencies (determined by the physical dimensions of the room). This is the reason why certain notes will sound really boomy in some rooms and not in others. The idea is to identify the resonant frequency of the room and then reduce the amount of energy you put into the room at that frequency.
You can do this pretty easily with an RTA. Play pink noise through your system at about 95 dB (make sure the room is empty or people will complain) and then mute the pink noise. Watch the RTA display to see which band in the low-mids (under 800 Hz) takes the longest to drop. This is the fundemental resonant frequency of the room, do it a couple of times until you are sure you have the right band then cut that frequency 6 db on your eq. Do this again only this time looking in the high-midrange band (1000 - 8000 Hz), and this time only cut by 3 dB. Do this once or twice more looking for other problem frequencies (only cutting by 2 to 3 dB) throughout the entire audio range. Avoid doing this too much (especially in the area between 1 to 4 KHz) or your vocals will start sounding thin.
After you are done listen to a music CD that you know well. Does it sound OK? If not reduce your adjustments (put them closer to flat) until you are happy with the sound.
P.S. A round room is the worse possible audio space followed closely by a square room. If you are forced to perform in these kinds of spaces, spend as much time beforehand as possible figuring out the problems in these rooms.
Phil
Great way to put it up. I would also say, knocking out the lows (below 100-150 Hz) is a great way to keep the power of the amplifiers for frequencies that help the person needing the monitor.
An even better way is to have a high-pass filter at around 100-150Hz,
this also helps reduce stage noise (less boom) & helps with phase problems between monitors & FOH speakers. Because they are too close to the speakers & surrounded by stage noise the musicians don't notice the difference.
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