I'm convinced that if I really ever NEEDED to have a stereo system again, I will buy a second Bose PAS. It's just that good and THAT easy.
As it is ..... most of my venues do not benifit from the stereo field, and since I monitor through the kb speakers (in stereo)at least I always hear the stereo signal in my face. In the immediate area near the stage, stereo DOES enhance some things, but so far - having the wide dispersion, clear sound and terrific range of the Bose tower has been a superior choice for me.

Next time I am in a situation that can "show off" the stereo spread, I might try to see how the system sounds by using my JBL/Sub setup as the other half of the field. It'll consist of the Roland Sub and 2 stacked EONg2 10s on top. That'll make a small tower on the other side. Hmmmmmm......

(I know it's just more "fluff" .... I definatly don't need it yet)

Not to convince you otherwise or anything, but the benefit of stereo isn't just what comes out of your stage monitors but what the audience hears. The stereo audio reduces phase cancellation that is inherent with all summed audio outputs, and it forces separate portions of your audio to reflect within the room from various angles towards the audience. I find that stereo adds a great amount clarity to the overall sound because of the phase reduction.

The only way to test and prove this to yourself is to run a stereo PA system in a room and try playing music from a CD player and/or your keyboard through it both in mono and stereo and see if it makes a difference to your ears when sitting where the audience sits.

Hey guys,

I thought this was a nice article on the subject.

http://www.mcsquared.com/mono-stereo.htm

mike

Uncle Dave,

How well do you think the PAS would work in a 250 person Church? I'm not thinking of music here but as a voice PA for the preacher. In order to get acceptable volume levels from the pastor we have to sit right on the edge of feedback. Also the people that are hard of hearing say they can hear but not understand. Do you think it would add any clarity over a conventional PA?

Tom

Yes it was - thanks for posting it. While the author makes a strong argument for mono in this article, he/she leaves out any consideration of phase cancellation in summed audio outputs from stereo instruments like keyboards. They also don't discuss something I call the "mono myth" - no band is truly able to perform in mono unless they are all vertically piled on one another. Just by the natural arrangement of the instruments on stage, be it a small band or an orchestra and especially the latter, there is a natural stereo audio spread. The acoustics of the room then reflect those sounds and blend them.

We all have two ears, not to belittle anyone with trouble hearing, and the only natural way for us to hear the exact same thing in both ears is for a single sound source to be coming from straight ahead, directly overhead, or directly behind the listener. Otherwise we listen for two distinctly different sounds, which is probably why our ears are on either side of our head instead of being planted on the front of our heads like our eyes. So I would argue that stereo sound is the most natural way for us to listen to music because it's the most natural way for it to be presented. As a one-man-band I'm aware that I am being compared to traditional bands when I perform, so I want the most natural and comparable sound possible. My keyboard sounds best in stereo so that's the way I've chosen to amplify it - if my competition chooses to perform in mono (they often do) then so much the better for me.

Hey Jim,

What exactly do you loose when there is phase cancellation due to summing the outputs of stereo instruments? I know you loose direction or placement or soundstage along with some effects but does the original sound source change? In other words, you play a grand piano sound, the original signal is stereo, and if you were to sum the stereo outputs, it no longer sounds like a piano or sounds like a very sick piano or whatever?

This whole mono-stereo thing can really perplex me (if I let it). I had a whole slew of questions back when Roel was helping Terry out with is mono-stereo recording issues. But I held back...Tech-talk doesn't always appear to be popular here.

If you've got the time to explain, I'll definitely listen.

mike

The Yamaha P120 and P90 "stage piano" do not have any mono piano samples, so if you don't plug it into a true stereo system live you get a rather thin, edgy, attack only type sound in mono. It's a dilema
So I am thinking thin mono Bose PAS won't be suitable and that I may have to go with a pair of Bose 802s or a pair of Italian FBT 10" powered cabinets to keep the piano in stereo and avoid the phase cancelation that stereo piano samples get when put through mono.


[This message has been edited by rintincop (edited 02-09-2004).]

In keyboards, the most common side-effect of phase cancellation is when you perceive some notes on your keyboard to be louder than others or if you hear an unintended chorusing or flanging effect.

In layman's terms, phase-cancellation means that when a sound is played along with an inverted phase of itself, the two signals cancel each other out. All audio signals are airwaves that move up and down, so by adding a slight delay to a signal, you change when the up/down movement happens. If the "up" hits at the same time as the "down" does of the same sound, the result is silence. This principle is what is used in the noise-cancelling headphones by Bose and others: a microphone picks up the ambient sound and then combines that sound with a phase-reversed copy of itself in the actual headphone sound so that you hear no ambient sound at all. Some companies are even trying to design new car mufflers based on this principal. Here's a link to another non-technical explanation with diagrams.

We often hear audio phasing, sometimes called chorusing or flanging, used as an audio effect when a small amount of delayed signal is added back with the original signal. I'm sure you've heard recordings that used a flanger where the sound seems to thin until it nearly disappears and then comes back (if you haven't then listen to the bridge in the Doobie Brothers song "Listen To The Music" where the singer says "like a lazy flowing river"). As the signal gets closest to optimum cancellation, the sound reduces in volume and sounds like it's being "choked off" only to return as the phase-cancellation passes.

A phase inversion occurs whenever a minutely delayed copy of a sound is recombined with it's original sound. This can happen in keyboards when the left/right stereo signals are combined into mono. It's never perfect cancellation (which would result in silence), but it's usually pretty noticible... certain notes on the keyboard won't have their usual full tone while others will seem to jump out.

Hope that helps...

[This message has been edited by The Pro (edited 02-09-2004).]

Thanks Pro!

I've got comments but they'll have to wait (work calls).

mike

I think the PAS will shine in a church for voice ! It's so clear and present, in all areas of the room.
Remember, I used to be a big supporter of stereo, but this system is changing things. The benfits outweigh the negitives in almost every venue so far. It all depends on placement. I can definatly see how a second tower could be a nice addition, but not that often.