What type of speakers...speakers on sticks, line arrays or side stacked horizontal arrays?

You must address Time, Energy and Frequency. You cannot just EQ a system to make it work in a room. Sometimes EQ alone will make it worse.

Now, when it comes to loundess, you are correct, Fletcher Munson curves show that we hear differently at 85dB vs 100dB. People will generally tighten up a space. Forseeing the future comes with experience.

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Speakers, stands & venue

I am usually working with a pair of speakers on adjustable tripod stands. I don't always use the same equipment as I engineer at different venues. The speakers are usually 12"/15" cabinets. Some of the brands I work with are EV, Mackie, JBL, StudioMaster.

It'd be good to use a more scientific method of knowing how high to position speakers rather than my estimation based on the angle of the horn and reach.

Most of the venues are in a hall (square or rectangle shaped) often with high ceilings. Sports halls tend to sound the worst!

The problem I have is that further into an event, the overall sound becomes 'muddy'. Musicians say that they cannot hear themselves especially acoustic guitar players and the keyboard player. I don't always use individualised monitors but I may have to add more monitors?

My concern is that the overall sound lacks clarity when all musicians are playing full throttle and the audience are singing along too. Clearly increasing the overall gain to overcome the body absorption in the venue isn't the solution as the whole mix then sounds harsh and can lead to potential feedback issues too.

Is there a particular frequency band that is affected as more people fill a venue and the temperature increases?

Ok, I see where you are coming from.

Get the horns above heads of those standing in the front. That is about all you can do if you are using stands.

Now, most small two-way boxes do not throw far evenly. If you were to look at the dispersion of frequencies on a plot, you will find most of the time, unless your two-way box has a large format HF driver, you will find 30' to be about where they poop out. Now, most economical two way boxes also do not have a HF and LF that stays together in the far field. With line arrays, it is the midrange that does not hold up, unless the HF and MF drivers are in a co-entry horn like a VDOSC, Adamson, etc.

You must also consider the inverse square law. Check this out: [[url=http://[/URL]="http://hyperphysics…"]Intensity Measurement Example[/]="http://hyperphysics…"]Intensity Measurement Example[/]

If the musicians are wanting to hear themselves out of the mains while performing on stage. forget that. They are correct. They cannot hear enough highs, because they are off axis and they shouldn't. All they are hearing is the mids and lows radiating from the speaker. This radiation is reduced by using wood boxes instead of plastic, and using a horn-loaded midrange. They need monitors.

Your musicians should learn to mix themselves onstage and the PA should fill in the gaps for the sound in the room to sound complete.

A good solution for the acoustic people who can't hear themselves (assuming you can't afford a Bose L1 for each of them) is the TC Helicon Voicesolo monitors. They standmount, and get much closer to the ear. Whether they are cheaper overall than a set of in-ear monitors per person is debatable.