I used to work sound and play bass in what was the best band in our city. (No I'm not telling.) An opportunity arose to acquire one of the best bass players that I have ever had the opportunity to work with. From that point I became the sound guy, and I did my best to make the band sound the best I could with the equipment I had wherever we played.
We were given the opportunity to open a show for Billy Ray Cyrus. (Long before Hanna Montana became the slut of the south.) The show was at a very large venue in front of more than 10,000 people. Their sound engineer was more than happy to hand over full control of the sound system to me when our band played. He helped me get everything set up during sound check, showed me where the effects and other needed controls were on the 96 channel console they brought and then politely stepped aside and let me completely control our bands sound without interference. It all depends on the sound company's policies and whether it is a union venue or not. Union run venues we played would not even let me bring my own equipment onto the stage. They did everything but play the show for us.
Our guitar player has had two bad sound man experiences in a row and is insisting that he won't play any more gigs-including those already booked, unless we have our own person mixing and setting up that "knows the band's sound" because "we deserve the best".
Oh... and yes their are "sound guys" that don't know the difference between 4 kHz and 40 Hz. All they know is that they have a lot of money invested in all of this assume gear that can set off a seismograph in the next county and they want to use it to impress themselves and others. Their is a guy that I know locally that owns a crap load of sound gear and hires out to local festivals and events. He cannot even hear well without hearing aids. If he has a problem with his system or changes out a power amp, he calls me to fix it. Just last month he asked me why his monitors sounded so muffled. I found that every one of the horns in his monitors were burned out, and he couldn't tell what the problem was. So... ???
I have pointed out that an equal share of our take wouldn't be enough to hire even a marginally competent person.
^ This is exactly what I did. I took my responsibility very seriously. I read books and really studied the technical side of what it takes to make "good" sound. At one point I could identify a feedback frequency just by the sound of it and correct it immediately. There are too many aspects of why sound does what it does in different situations to really get into that.
Having your own sound guy does have advantages when it come to subtle things like adding different effects at various parts during a particular song or songs or using things like a vocal echo at just the right moment for a certain effect.
Knowing the bands "sound" is really not the way it works though. The sound perceived by your audience is never the same from one day to another. It is never the same form one venue to another. And it is diffidently never the same from one PA system to another.
His response was pretty childish and personal and insinuated that I didn't care how we sounded.
He is a guitar player, know for their "soap opera garbage"

not a sound engineer. Ask him to pick up a copy of the Yamaha Sound Reinforcement Handbook and read it until he completely understands everything in it then he will be qualified to competently critique the bands sound at any given time or venue...
I'm sorry... I didn't intend to write a book, I just get carried away when responding to some of the posts here. I still remember all of the drama that goes with trying to merge all of the egos and find a balance where knowledge, talent and opportunity can come together to make awesome music for ALL to enjoy...
