From HTPC to PRO - Home Theater Forum and Systems -

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post #1 of 3 Old 10-27-14, 12:33 PM Thread Starter
Join Date: Sep 2011
Posts: 26
From HTPC to PRO

Gentlemen, and girls too,

I am hoping a few of you' all might part with some of that hard earned knowledge and help me venture into live sound so I might help those that set up for Worship get a more relaxed sound at church. After a few years of tweaking my system at home and getting pretty close to duplicating a "like I was there" sound, thanks very much in part to REW, I have joined the team at church.
They have not skimped on the equipment, they have installed a set of JBL arrays on ether side of the platform, the amps are controlled by Soundweb DSPs, and they have a newly installed Yamaha CL3. Of course everyone claims the system was installed professionally, at the risk of offence, REALLY! I suppose installing is one thing dialing it in is another.
So here goes my first question if I may, why in an auditorium the size of a basketball gymnasium, (that's actually what it is) would you use a HPF and roll everything bellow 300hz down to nada? What is it that I don't know?

Thanks in advance,
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post #2 of 3 Old 10-27-14, 04:50 PM
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Re: From HTPC to PRO

Simple: To keep everything from sounding muddy. The fact is, the more instruments and vocalists you have on the stage, the more what is essentially “bass management” is needed.

The problem is that most musicians and singers like to hear themselves with a full, rich sound - which translates to lots of low end. Inexperienced sound men like it, too. However, if everyone’s instrument and voice is generating an abundance of lows, what you end up with is muddy sound.

For example, ever been to a show where you saw a pass player on stage but you couldn’t pick a single bass note out of the din? Next time pay attention to what you hear when the singer is talking between songs, or when a keyboard or guitar opens a song. You’ll most likely hear lots of bass from them.

Bottom line, you don’t - can’t - EQ a full band the same way you would if there were the only a single instrument on the stage. For instance, with a solo singer playing a guitar or piano, you’d need a nice full low end to balance out the sound. But when a bass guitar is added, the piano or guitar no longer needs to carry the bottom end, so the lows need to be EQ’d out.

Keep in mind that the lowest fundamental on a guitar (open E string) is 80 Hz, which is right in the middle of a bass guitar’s range. And an 88-key keyboard can generate fundamentals below 20 Hz (more than an octave below a 4-string bass). Well, everyone can’t be the bass player. These other sources need to be high-passed to let the bass instrument carry the bottom end alone.

You’re into home theater, right? You can translate some of that training over to live sound. Specifically, considering the ultimate goal and purpose of a high-fidelity audio reproduction system: It should sound natural, only louder, shouldn’t it? To that end, listen to say, the acoustic guitar totally unamplified, then through the PA. Does it sound deeper (read more bass) through the PA? Well, that’s not the way an acoustic guitar sounds naturally. Reduce the bass so that it sounds as natural as possible.

Same thing with vocals: Do they sound deeper through the PA than without it? That’s not the way voices sound naturally. Reduce the bass. (No kidding, I’ve worked with female vocalists who asked for more bass!)

So, it sounds like whoever set up your system knew exactly what they were doing. Three-hundred Hz is a good figure to HP voices and most instruments on stage to keep things sounding clean (or maybe 200 Hz at most). And vocals especially, there’s nothing going on below that point anyway.

The drums would be the exception. High-passed at 300 Hz they’ll sound like cardboard, so you probably want to high-pass wing toms at maybe 100 Hz and floor toms at 80 Hz. Again, listen to each piece of the kit unamplified. The kick drum often has the lows exaggerated, but there’s not one in the world with 40 or even 60 Hz fundamentals!

If you manage to get the other instruments under control, you still have the problem of lows generated from the stage itself, via the monitors or backline amplifiers. Lows from these sources needs to be limited as well. However, with in-ear monitors becoming more popular, this is becoming less and less of a problem.

On the flip side, if the church’s bass player isn’t that good, adding some lows across the mixing board is a good way to hide his inadequacies...

There are acoustical considerations with the high-passing as well, given that your auditorium is a basketball court between services (read “reverb-chamber”), but I’m less familiar with that except to know it exists. For that reason you may feel the need to high pass the bass guitar much higher than you normally would, in order to keep it sounding reasonably clear and concise. Possibly the same thing with the drums as well.

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post #3 of 3 Old 10-27-14, 09:47 PM Thread Starter
Join Date: Sep 2011
Posts: 26
Re: From HTPC to PRO

Thanks Wayne
Sounds like mid bass in live sound if not kept under raps can destroy the clarity of the soundstage. That could be why the setup has no mid bass at all, erring on the caucus side. but delivering a very tinny sound.
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