Why two lefts and Not Left/Right to PA from Console?

[74hc]

I ran into an odd PA system installed by a Bose Professional authorized retailer. The system they designed has two lefts from the console to the ControlSpace processor that links to a Powermatch amp. The speakers are connected to left and right outputs on the amp. The processor (digital preamp) and power amp are full stereo.

The question I have been asking myself is why would a designer/install use two left outputs going into a stereo processor and amp system? I cannot ask the retailer because they are gone, and the local sound guy that worked with them has passed away last year. No one is left that knows.

Anybody have seen this before, or have ideas on why?

The reason for asking here is that I'm being asked to provide input for improvements. This place is cheap so it will be done piecemeal, not hiring a designer/retailer for a full replacement. The PA gear is:

1- Studiolive 16 series III mixer
2- Bose ControlSpace EX-1280C*
3- Bose PowerMatch PM8500
4- Bose Panaray MA12 Column Arrays for left and right mains. Each column array consist of two columns connected together, for a total of 4, 2 for left, and 2 for right.
5- Bose subwoofer (forgot model but it's part of their professional loudspeakers although discontinued)

One of the recommendations is to go to full stereo output from the mixer, but I want to know more on why it was done this way before giving them that.

* There is also a ControlSpace CC-64 mounted on a wall but it's not used anymore since the presenter mics no longer connect to the EX-1280C, but through the mixer like everything else (singers, instruments, audio source).

 

[WayneP]

For starters, a picture of the back of the console shows it has Right, Left and Mono Sum XLR outputs. The only other left output is a 1/4“ jack labeled Monitor Out; I can't imagine anyone using that for the house. Can you clarify?

StudioLive® Series III 16 Digital Console Mixer

The 32-channel StudioLive® 16 is the most powerful and flexible digital mixer available for live sound and recording. PreSonus® gave the StudioLive 16 the works: 40 total inputs; extensive AVB networking; more recording tracks over USB than any other digital mixer; touch-sensitive motorized...

www.presonus.com

Overall it seems like a decent system (except possibly the subwoofer), unless the room is too big for it. Certainly not low-end stuff. So I’m wondering what improvements are desired.

I’d pass on the conversion to stereo. That’s for living room listening. Only the lucky few in the sweet spot will get any benefit from it, and everyone else will get short-changed, being unable to fully hear what’s panned to the opposite-side speaker.

Regards,
Wayne A. Pflughaupt

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[74hc]

The other left does come from the monitor out ports. It's balanced. The reasons I see for changing to true stereo are:

1- Audio source input which is usually from video players (running on a PC).
2- Possibly better sound from effects.
3- Just because that's one anyone who approaches it will assume how it's wired.

All of the channels on the mixer are set for center, no panning. During the pandemic era, they connected the audio source from the video player (changed from DVD to computer), but used a microphone input channel on the mixer. Back then, when I asked them why use an XLR input on this and forgoing the USB or RCA inputs, they said they could not get either to work. They didn't know there's 32 channels on a Studiolive 16 series III mixer (the previous/next buttons). I showed them, but they never changed it while running out of XLR inputs.

Oddly, the sound guy has the channel from the PC for video playback panned fully to the left. Rest are center. I asked if that was to get more volume which he confirmed. I don't think the PC can drive an XLR input well enough.

Yes, the subwoofer is not great by any means. I play bass there so I know. I use to bring my own combo amp, but now run solely through FOH since I've found my tonehammer pedal does much to overcome it. Less stuff to schlep.

As to the space, it's too big for that PA. The sound guy (RIP) put a couple of Yamaha powered speakers in the back facing forward which is not idea due to phasing issues. It can be heard in certain areas in the room. I recommended to him awhile back to put a couple of panaray columns midway on the floor and use the delay feature in the ControlSpace processor to preserve phase sync.

Those are the three change recommendation I want to make... true left/right feed into the PA system, move the PC audio to the RCA jacks, and change the speaker configuration as I mentioned.

 

[WayneP]

The only reason I can think up to use the Monitor out would be to get signal to secondary speakers, such as the lobby or a cry room. But I assume any of the Mix outputs could also be used for that, so I don’t know. You might find the answer deep in the bowels of the processor.

Regardless, what you want to accomplish should be easy by re-configuring the processor.

The computer audio issue is curious, since Channels 9-16 accept line-level inputs.

Regards,
Wayne A. Pflughaupt

Make Your Own Cables: A How-To Guide Unique Arrangements of Hymns, P&W Standards, and Original Tunes
Official Pedulla Club #45
Administrator, Official Heartfield Club #36
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Administrator, Official Pre-Gibson Tobias Owners Club
Administrator, Fretless Club #943
Big Cabs Club #23
My Basses
My Rig: Stage and FOH Friendly
Make Your Own Cables: A How-To Guide

 

[Wasnex]

Whose to say it has always been connected that way? Does it matter? IMHO no, so don't worry about it. Maybe it was intentional. Maybe it was a mistake. Maybe at some point the right out became FUBAR'ed.

Figure out how it's currently configured. I.E. make sure both lefts are doing exactly what you think they are doing. Maybe they are and maybe they are not.

After you are certain what is going on, consider what changes will make the system better. Try the changes and confirm everything is working as you intend.

 

[Wasnex]

The sound guy (RIP) put a couple of Yamaha powered speakers in the back facing forward which is not idea due to phasing issues. It can be heard in certain areas in the room. I recommended to him awhile back to put a couple of panaray columns midway on the floor and use the delay feature in the ControlSpace processor to preserve phase sync.

Adding or relocating and delaying speakers sounds like a good idea.

 

[Mike Caldwell]

I've walked in to plenty of installations for service call work, upgrades, ect and after digging into them sometimes what your looking at makes sense and other times it's the result of too many hands trying to fix a problem that maybe did not exist in the first place.
This is a big guess but maybe at first the mono sum XLR output was feeding the main system and the 1/4 plug that is now in the monitor left output was plugged into a mix out that was feeding another zone somewhere and at some point a few helpful hands reaching behind the mixer changed some connections.

As for the computer audio that issue could have been or still is from the left right output of the computer directly being connected to a balanced line input where the left right lines are wired to the + - of the balanced connection causing lots of cancellation issues.

 

[74hc]

I think I figured it out after mulling over it all yesterday afternoon. It likely so there are two separate faders for mains left and right, although in a ad-hoc way. The Presonus mixer only has one main slider for both left and right mains out. The monitor ports have a fader (round knob) on the mixer. This makes sense because they have feedback problems. The choir mics are not in the center, but off to the right of the right main speakers. Adding to the feedback problem is the right main speaker is mount behind the mics, and the bottom of the column array is about chest high on me.

To answer Mikes point, I did ask the sound guy before he past away why the two left outputs are going to the PA system, and not the standard left and right outputs. He replied the authorized Bose retailer who designed and installed it did that way, and that they don't need stereo. At that time, I felt there was more to it than that, but I didn't know what.

I received an email asking if I would take over that guy's job. It would be unpaid and likely range from 10 to 40 hours per week. They would probably tell me is voluntary for now, but could be paid later. I'm not going to fall for that. It's a church with Sunday services, and events during the week (weddings, funeral, christian classes, and conferences). The room is a large rectangle shaped one with a seating capacity of 350 people according to the fire marshal.

I'm going to reply back and decline. I'm just a mediocre bass player with hearing aids that has little to no sound experience.

 

[Mike Caldwell]

I think I figured it out after mulling over it all yesterday afternoon. It likely so there are two separate faders for mains left and right, although in a ad-hoc way. The Presonus mixer only has one main slider for both left and right mains out. The monitor ports have a fader (round knob) on the mixer. This makes sense because they have feedback problems. The choir mics are not in the center, but off to the right of the right main speakers. Adding to the feedback problem is the right main speaker is mount behind the mics, and the bottom of the column array is about chest high on me.

To answer Mikes point, I did ask the sound guy before he past away why the two left outputs are going to the PA system, and not the standard left and right outputs. He replied the authorized Bose retailer who designed and installed it did that way, and that they don't need stereo. At that time, I felt there was more to it than that, but I didn't know what.

I received an email asking if I would take over that guy's job. It would be unpaid and likely range from 10 to 40 hours per week. They would probably tell me is voluntary for now, but could be paid later. I'm not going to fall for that. It's a church with Sunday services, and events during the week (weddings, funeral, christian classes, and conferences). The room is a large rectangle shaped one with a seating capacity of 350 people according to the fire marshal.

I'm going to reply back and decline. I'm just a mediocre bass player with hearing aids that has little to no sound experience.

I'm going to say this install was never really finished when it was claimed to be "finished".

Personally I think there has and is this selling point of vertical column speakers that they do not feedback, you put a mic with some gain on it like a choir mic in front of a speaker and it will feedback...sorry BOSE!

It's any ones guess how that mixer is set up at this point.

 

[walterw]

I'm going to reply back and decline. I'm just a mediocre bass player with hearing aids that has little to no sound experience.

good call; i wouldn't even suggest any changes

this install is obviously a mess (the "bose professional authorized retailer" was probably just a guy who sold stuff), and unless you're ready to rip it all apart and rebuild the system the right way, the moment you touch a knob or unplug a cable everything that goes wrong from then on will be Your Fault

This place is cheap so it will be done piecemeal, not hiring a designer/retailer for a full replacement.

then it will never be right and will never sound good. at the very least they need to get a pro to come out and evaluate what they have

 

[Mike Caldwell]

good call; i wouldn't even suggest any changes

this install is obviously a mess (the "bose professional authorized retailer" was probably just a guy who sold stuff), and unless you're ready to rip it all apart and rebuild the system the right way, the moment you touch a knob or unplug a cable everything that goes wrong from then on will be Your Fault

then it will never be right and will never sound good. at the very least they need to get a pro to come out and evaluate what they have

YES......