mono vs. stereo PA

Posted: Mon Dec 17, 2001 1:59 pm

I've been designated as the one to learn the ropes in Sound Reinforcement at my place of employment. So far, I've done sound for Joe Lovano, Leo Kottke and Tommy Makem, so I'm not a complete novice. I just feel that way sometimes. I'd like to appeal to the collective wisdom regarding the advisability of Mono vs. Stereo PA setup. The principal components in our system are a Mackie 1604 VLZ Pro mixer, Mackie SRM 450 powered speakers for mains and JBL Eons for monitors.

Posted: Thu Dec 20, 2001 6:05 pm

Depending on the room and the audience, I have never seen the benefit of stereo mains. The only people that can hear it are those in the center of the audience.

Posted: Fri Dec 21, 2001 8:14 am

I'm about as far from being an expert on PA systems as you can get, but....Having said that, it seems to me that the decision would depend on how close the audience is to the system and how wide the audience is. If the audience is in close and/or wide, then mono would seem to be the best choice. If the audience seating is mostly centered or further back from the performers, then stereo might be worth a try, although nothing too dramatic as far as panning goes.

RO Admin Joined: Mar 20, 2000 Posts: 4332 Location: Canada

Hi, I will give this one a whirl, been mixing live for thousands of hours. I was front loaded and stereo before stereo was cool. Had allot of guys tell me "the audience can't tell the difference" or "it's a waist of money having to buy extra eq's x/over/etc. I once had a discussion with a pretty respectable sound man in a club. He bet me that the audience couldn't tell the difference. I said "your on" so I did a bunch of A/B with the entire audience. "what do you like better" I asked. It was a hands down. They all could tell.Here's the biggest thing about going stereo. more freq control, cleaner more pleasing volume, less eq'ing. My example is like comparring a honda V6 fuel injected to a straight 4 cylinder weber carb motor.
In stero you can get much louder without it becoming painful. Your mids somehow blend in much better which results in less eq'ing, way better imaging etc. The idea in live mixing (or mastering I guess) is to try and keep all freq coming at you at the same time. (For my taste... bass ahead a bit) In mono, no matter what size the room is, the bass always seems to be delayed more. This makes the upper mids appear harsh because it's the first thing your ear hears.(our ear are most sensitive to these freq).To warm things up, alot of sound men start messing with the eq... right? wrong... In stereo I always set a PA to be almost flat by using the individual speaker volume controls from amps and crossover points. I try and keep the upper mids as flat because they give excitement to the mix and help define the bass. Using different options rather than the eq IMO always produce sweeter and waaaayyy punchier mix's.Another tip...some rooms create standing waves in just one part of the room (beams, corners etc). Stereo PA system can eq that side to compensate.Time delays & crossover settings make an interesting topic. (maybe we should do a live mix forum)Hope this helpsStereo is always better. Cool

Posted: Thu Jan 03, 2002 9:57 am

The one issue I have with stereo PA is when your sitting on the farther left or right of the stage. If the instruments are panned pretty hard to match stage placement you can't hear the far side instruments. This is especially bad in rectangular rooms that are wide and shallow. I was at a show once where I never heard the keyboards because they were on the other side of the stage. The FOH mixer really needs to keep in mind the entire audience when mixing and not just mix for themselves. So I think yes stereo is cool BUT don't overdo it.

RO Admin Joined: Mar 20, 2000 Posts: 4332 Location: Canada

Never use individual note panning effects in a live situation. The reason for going stereo is NOT for panning effects. The only thing I ever panned (in perfect situations) were toms. Most "useful" keyboard patches are chorus effects and they usually rotate so that won't matter much. Plus, alot of those wild panning things on keyboards modules etc. get whacked out when you go mono. IMO the less panny or whirly sounds the better. They cause huge phase problems and take away from the vocals. Still setup, plugin and pan the board and all the stereo instruments "stereo" (hard left/right but stay away from doing the obvious that effect the audience. Out board effects like delay's and reverb work better in mono. Stereo sounds way better.

Posted: Thu Jan 03, 2002 12:23 pm

Hi Bigtree,I'm just a bit confused by what you mean. If you don't pan anything then you're just sending a mono mix to 2 channels of EQ, Amps etc. I also have to agree with Harvey. It all depends on the room, instrumentation etc. on how to approach a live stereo mix.I ran sound professionally for ten years. Because of time, budget and spinal constraints I used a mono setup so I haven't had experience mixing live stereo myself, however I have had experience in the audience and been disappointed more than once because something was panned too hard to the other side of the venue and I didn't hear an instrument in the mix. Plus 70% of the rooms I worked were either odd shaped or acoustiacally nasty so stereo would have been hard to use or lost in the reflective mess and stage volume.

Posted: Fri Jan 04, 2002 4:47 pm

Not to mention, if the artist has prerecorded backing material that isnt optimized for mono, it's going to cancel/sum and generally sound like crap, especially in the mids. I check my mixes in mono all the time, but I really hate mono live.

Posted: Wed Jan 16, 2002 3:21 pm

Stereo: no, it doesn't work live
Left/Right panned sound: yes, it sounds better.Sorry to be confusing, but I've had this argument a hundred times.Real stereo -- the way your ears do it -- is based partly on volume and partly on phase difference.As lots of people have told me (at great length), if you pump out real stereo, then it will only be correctly phased for the people sitting in the middle, and people to the left and right will get part of the sound out of phase, which will make it sound weak.On the other hand, the pan controls on mixing desks only pan by volume -- they don't introduce phase shifts, so they don't create this problem. What this is doing is creating two monaural sound sources, each of which is in phase with the other, and which, in principle, someone would be able to place as separate sources based on their own phase cues.Someone with superhuman hearing might be able to hear this, but for most of us it would sound like stereo because the volume cue of loud on one side and softer on the other would cover over the subtle phase cues from the two speakers as separate sound sources.This works great for pseudo-stereo effects like stereo chorus, and for spreading a bands sound. However, for playing back stereo tracks which have been recorded using phase-stereo techniques such as Emagic's Dirmixer or Waves stereo phase stuff, or by using coincident pair microphones, there would be phase cancellation.So, paradoxically, a stereo recording is better played back live in mono, while mono instruments are better gently panned across the two speakers.

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