Stereo onstage monitors / mono mains?

dfahrner · Post by **dfahrner** » Sat Sep 01, 2012 12:58 am

This was often a problem with early sampled pianos and other instruments, when the keyboardist wanted to have stereo monitors on stage (for the best sound) while sending a mono mix to the PA (which is almost always mono). Stereo L/R channels mixed to mono would result in a strange "boxy" sound, with missing frequency ranges, if the original samples were not carefully recorded and phase coherent. Solutions were kludgy (reversing one channel, making it 180 degrees out of phase) or expensive (external processing that could continuously adjust phase of the signals). Are the L/R outputs of the KRONOS phase coherent? Could they be summed to mono at the PA for this kind of application? When using the L/Mono output only, are the L and R channels simply summed, or is more processing done to make sure there is no phase cancellation?

I experimented with an SGX-1 piano sound, by using a stereo delay insertion effect and running the L and R outputs to two mono mixer channels; and then with no delay on one side, adjusting the delay on the other. It sounded best to me when there was no delay; as I increased the delay on one side, I could hear phase cancellation at various frequencies. It sounded like the outputs (at least from the SGX-1 engine) are phase coherent, and that summing the KRONOS L and R outputs to mono for the PA would work. ???

df

1jordyzzz · Post by **1jordyzzz** » Sat Sep 01, 2012 6:24 am

i didn't have much knowledge or experience regarding this thing

but at the last time i gig with kronos, i sent stereo into the mixer using a DI box... the +of the sgx engine (or a problem if you prefer

) is that it has a stereo perspective.. when you play a real grand, the lower keys will sound louder in the left and the higher key will sound louder in the right... because of that, i sent kronos on stereo... but another problem is that the PA configuration is left and right... for people who sits too close to the left speaker will hear lower piano notes sound louder, and vice versa... but if you send SGX engine on mono, well you didn't have much dynamic.

Post by **Sharp** » Sat Sep 01, 2012 12:25 pm

Haven't heard of anyone work like this in a long long time. This is a "Guitarists" way of thinking.
My opinion is your rig is wired up wrong, or being operated wrong.

Your rig should be wired for a stereo setup, and any mono instruments are simply not panned on the mixer. This is the only way mono and stereo signals can work together without causing the Phase problems you have.

Regards
Sharp.

johnnydr · Post by **johnnydr** » Sat Sep 01, 2012 12:50 pm

I been running my keyboards and modules stereo into my Samson mixer, for my own stage monitoring, then I send the headphone output to a DI,then to the FOH. Sounds wonderful on stage

tmatos75 · Post by **tmatos75** » Sat Sep 01, 2012 12:51 pm

Sharp wrote:Haven't heard of anyone work like this in a long long time. This is a "Guitarists" way of thinking.
My opinion is your rig is wired up wrong, or being operated wrong.

Your rig should be wired for a stereo setup, and any mono instruments are simply not panned on the mixer. This is the only way mono and stereo signals can work together without causing the Phase problems you have.

Regards
Sharp.

??????

dfahrner · Post by **dfahrner** » Sat Sep 01, 2012 3:50 pm

Sharp wrote:Haven't heard of anyone work like this in a long long time. This is a "Guitarists" way of thinking.
My opinion is your rig is wired up wrong, or being operated wrong.

Your rig should be wired for a stereo setup, and any mono instruments are simply not panned on the mixer. This is the only way mono and stereo signals can work together without causing the Phase problems you have.

Regards
Sharp.

Thanks for your sympathetic response, Sharp, but I think you read my post "wrong"...and I don't know why a guitarist would think like this, I've been wiring and operating keyboard rigs for about 40 years, my rig is stereo, mono instruments wouldn't be panned on the mixer (if I had any mono instruments), etc., etc.

Anyway, the potential problem is when my stereo mix has to go through a mono PA for more volume / coverage, wihich must be a common situation for current keyboard players: most keyboard instruments are stereo these days, most players like to have stereo monitoring onstage, and most PAs are still mono. I say "potential problem" because I haven't really noticed any phase problems, and am just asking if the KRONOS stereo outputs are phase coherent (as they seem to be from my delay experiment) and are simply summed to mono when only the L/Mono output is used...so I repeat my question...

df

Post by **Sharp** » Sat Sep 01, 2012 8:26 pm

Thanks for your sympathetic response, Sharp, but I think you read my post "wrong

This is basic 101. When you send a stereo signal down a mono system, it's going to give phase problems. It's a simple fact and I'm confident that you understand this perfectly.

This means you know exactly what the cause of your problem is, and you should know the solution. Forget about inverting waveforms or delays.

You can either....
1: Stop sending a stereo signal down the mono system and play in mono.
Or
2: Wire the rig in stereo just like everyone else does.

Anything less than that are your only wasting your time as there is nothing else that addresses the problem.

and I don't know why a guitarist would think like this

That's a reference to a discussion I've had many times with Guitarists in bands. Most of them haven't got a clue, yet think they are experts because they have been playing years.

Soon as you start talking Phase to them, you can see the lights just switching off in their eyes.

Regards
Sharp.

SanderXpander · Post by **SanderXpander** » Sat Sep 01, 2012 9:42 pm

I haven't seen a mono PA in years, I don't get how this would be "most PAs" by any stretch of the imagination. But I agree something still needs to be worked out for when you do encounter such a situation. My personal best option would just be to just run the Kronos mono from the L/Mono output in such a case.

roblof · Post by **roblof** » Sat Sep 01, 2012 10:23 pm

SanderXpander wrote:I haven't seen a mono PA in years, I don't get how this would be "most PAs" by any stretch of the imagination. But I agree something still needs to be worked out for when you do encounter such a situation. My personal best option would just be to just run the Kronos mono from the L/Mono output in such a case.

While the PA systems usually are wired in stereo, most live mixing is done in mono since stereo is next to impossible to mix in most venues as it normally wouldn't make any sense soundwise.

As usual there are exceptions to this, but in genral mono is still the king.

I wonder how a live mix in a thx surround theatre would sound if we were placing the leslie in the middle of the room?

Post by **Sharp** » Sat Sep 01, 2012 11:11 pm

Hi roblof.

You mix by what you hear.

While a mono instrument will come out the other end in mono, this is only if the signal is not process by an effect, which is almost never.

A voice going through a simple reverb automatically becomes a stereo signal.

Same goes for most Guitar effects, Chorus delay and so on.

It has nothing to do with mixing in stereo. It's about performing with a stereo signal and avoiding phase issues.

Regards
Sharp.

danmusician · Post by **danmusician** » Sat Sep 01, 2012 11:38 pm

SanderXpander wrote:My personal best option would just be to just run the Kronos mono from the L/Mono output in such a case.

+1

I'm a solo performer using a Bose L1 system for live performance. I practice in my studio with stereo monitors. I just use the L/Mono out into my Bose. I've noticed subtle differences in my backing tracks and even the pianos when in mono, but my wife doesn't hear it. She certainly has heard my stuff more than anyone other than me so she is certainly familiar with it. So, I stopped worrying about it.

dfahrner · Post by **dfahrner** » Sun Sep 02, 2012 12:43 am

OK, one more time: how is the L/Mono output from the KRONOS generated? The manual says that this "gives you a mono summation of the stereo signal". If it's just the summed L/R outputs, from the same sources, with no additional internal signal processing, that means the KRONOS sounds have been very carefully generated and sampled so that they are "phase coherent", with mininal phase problems when mixed to mono. Why would mixing ("summing") the L/R outputs to mono at the PA mixer be any different?

And every guitarist what a "phaser" is...

df

SanderXpander · Post by **SanderXpander** » Sun Sep 02, 2012 5:06 am

I think you'd be fine except when using chorus on your patches (which is standard on more of them than you'd think). However, I still don't get why you would ever even take the risk of phase problems. If you absolutely must have stereo monitoring and mono FOH, why not use the headphones output for your monitor hook up.

Also, I don't see how this is different from any synthesizer since they started going stereo back in '85 or so.

tmatos75 · Post by **tmatos75** » Sun Sep 02, 2012 5:31 am

Sharp wrote:Hi roblof.

You mix by what you hear.

While a mono instrument will come out the other end in mono, this is only if the signal is not process by an effect, which is almost never.

A voice going through a simple reverb automatically becomes a stereo signal.

Same goes for most Guitar effects, Chorus delay and so on.

It has nothing to do with mixing in stereo. It's about performing with a stereo signal and avoiding phase issues.

Regards
Sharp.

????
Sharp,
No offense, but it's becoming apparent that you either don't understand the questions being asked, or you don't know what you are talking about.

tmatos75 · Post by **tmatos75** » Sun Sep 02, 2012 5:41 am

roblof wrote:
SanderXpander wrote:I haven't seen a mono PA in years, I don't get how this would be "most PAs" by any stretch of the imagination. But I agree something still needs to be worked out for when you do encounter such a situation. My personal best option would just be to just run the Kronos mono from the L/Mono output in such a case.
While the PA systems usually are wired in stereo, most live mixing is done in mono since stereo is next to impossible to mix in most venues as it normally wouldn't make any sense soundwise.

As usual there are exceptions to this, but in genral mono is still the king.

I wonder how a live mix in a thx surround theatre would sound if we were placing the leslie in the middle of the room?

Roblof is 100% correct. All PA's are stereo, but almost all live mixing is done in mono, especially if it's a large venue.

By the way, my setup is exactly as you described yours....
I mix in stereo for my personal monitors and I send a mono signal to the FOH mixer.