Rational Acoustics



Kip Conner
December 6th, 2008, 10:38 PM
One of my gigs is with a singer-songwriter that plays intimate venues, but spent may years playing arena situations. During those years he got accustomed to loud stage monitors and enjoys the power that comes with volume.

Because of this loud volume the P.A. often becomes dark (sonically) because of his high volume and my adverse lower house mix volume. Many nights the monitors are equal to the volume of the room.

I have been trying to experiment with delaying the main house feed to make the stage and house volume something more uniform. Since it's a solo acoustic thing, the monitor mix and and front of house mix are similar other than the fact the monitor mix is dry. I have tried approaching this use of delay from two angles:

1. Phase Align the offending frequency band: 100-400Hz, much less delay
2. Impulse align by letting the monitor bounce off of the rear wall and delaying the Main feed to match- up to 15 ms

Each one has had it's advantages and disadvantages, but neither has given me the outcome that I want. Its a battle that I can win if I crank the main house feed to overcome and drowned out his level.

Turning it down and IEM's aren't options

Suggestions? Methodical Ideas?

Harry Brill Jr.
December 6th, 2008, 10:53 PM
Wish I had a solution for you. Combat audio is always a comprmise. You are already doing what any of us would. Get the energy that is equal level at the same time reference. I would also consider using the spectrograph with your ears to equalize the mains and monitors at the same time. If you can link the EQs and pull out some of those low mids that may help you and your artist. It will also allow your board tapes to still have that full low end. The spectrograph will train your eyes what frequencies are bothering your ears most.

Maybe Arthur has a magic bullet. Arthur?

Nicolás Suárez
December 7th, 2008, 06:29 AM
Here comes a crazy solution:

What he wants is the PA signal but "reflexed" in all the arena.

Why not to put another monitor with the main mix but with a FX unit inserted. I think that changing the pre delay, rev time, etc, and using all the signal WET will find a similar response that she hear in arenas.

Or maybe pass thru the FX unit the monitor mix.

http://xemazgz84.blogia.com/upload/20070523234712-cient-loco-1-.png

Arthur Skudra
December 7th, 2008, 01:27 PM
The magic bullet is a good set of in-ears...oh wait, can't do that here! :p

Your situation is not unique, I battle it all the time with small church clients who put a band on a stage the size of a postage stamp, for an auditorium of less than 500 seats, low ceilings and lots of sheetrock walls included! The same happens when a band sets up in a smallish bar or nightclub.

No easy answers here, because in the time domain you're dealing with separate arrival issues:
1. Acoustic energy coming from the singer & musical instrument themselves
2. Off axis energy coming from the back of the stage monitors (mostly LF and low midrange)
3. Energy coming from 1st and 2nd order reflections from adjacent rear/side/ceiling surfaces originating from same stage monitors
4. Energy coming from the direct field of mains speakers
5. Energy coming from reflections off of any surfaces adjacent to the mains speakers (including reflections from the back wall of the venue)
6. Energy from the stage monitors going into the musician's mics and mixing with the direct energy from the musician.

Depending on where you choose to place your measurement mic in the audience area, different time deltas will be evident, so you can align for the front row centre seat, but it will be very different for those seated 20 feet to the left or right, and perhaps the sound booth 50 feet back.

So not knowing what you have control over, my suggestions, in no particular order:
1. Only use high-end stage monitors that have little off axis energy. Perhaps the higher quality and intelligibility of these monitors might allow you to lower the volume level of the stage monitors a bit (cross your fingers and hope your musician doesn't notice). The biggest clue here is your mention of problems in the 100-400 Hz range, typical of the off-axis "mud" from stage monitors.
2. Careful use of the HPF on the stage monitors to limit what remaining off-axis energy you have. Your musician might complain.
3. Pay attention to late reflections coming back to the stage from your mains. Often the reason why musicians want loud stage monitors is because they want to mask the distracting late reflection coming from the rear of the venue (often exasperated by the use of poorly setup line array mains). This can be fixed by treating the rear wall, or re-aiming the main PA. Not sure if this is the case here.
4. Use stage monitors that have a trap angle so the stage monitor can be aimed "up" at the musician, minimizing reflections from the stage rear wall. However this might open up a can of worms if the ceiling is low. Nevertheless, you might bring some wood blocks of various heights to allow you to tweak the vertical aiming angle of your stage monitors.
5. Position the stage monitors so that they take advantage of the null points in your microphone's coverage pattern.
6. Put up a heavy curtain or some kind of absorption on the back wall of the stage.
7. Use front fills, even if coverage from the mains doesn't require it. My thought here is that much of the problems you describe tend to be issues at the front of the venue, and lessen at the rear of the venue (dependent of course on the size of the venue).

Once you have attempted resolving the issue in the acoustical domain as best as you can, only then start doing some tweaking in the electronic domain, but keep in mind any electronic "fix" is going to be an exercise in finding the right combo of compromise. First examine the remaining off axis response of the stage monitors, and compensate accordingly with eq and HPF settings. Next try to find a point between being on-axis to the mains, and being on-axis to the musician, and try to find a time delay that works well for the majority of the people affected by the loud stage monitors (hint, use a small hotspot at the musician's position to establish a timing reference). Hope this helps! :)

Edit: Timing the mains to a key instrument or musician on stage is nothing new, we find ourselves delaying the mains to the backline or drums (when aligning the mains to subs, it sometimes works out that way whether or not it's intended), or for many years I used a Yamaha YDP-2006 inserted on a choir mic group to delay the choir mics usually located at the rear of the stage. When the delay time is set correctly, it's amazing to hear how well the acoustic energy sums together with the mains, I sometimes add a slight HF boost to sweeten things a bit further, sometimes it's enough to overcome the energy coming from the stage. Now that we have digital mixing consoles, you can delay each input individually, allowing even more flexibility.

Harry Brill Jr.
December 8th, 2008, 06:04 PM
Great post Arthur. My inside knowledge of Kip's situation made it difficult to be objective.
I am certain Kip is doing the best he can with all of the above. He works for a touring artist that plays smaller venues, and his hands are mostly tied in regards to room treatment and equipment choice.

Harry Brill Jr.
December 8th, 2008, 07:06 PM
Arthur and I are chatting and we think you should lose the wedges and put the main PA behind Shawn facing the audience. This way he feels and hears what the audience does, but he gets the most SPL and you don't have conflicting sources anymore. Maybe this is not possible very often but maybe it is. We figured we should mention it just in case.

Arthur Skudra
December 8th, 2008, 08:26 PM
I know we're all taught that mains speakers should not go *behind* the talent on stage, but considering the simplicity of the situation here (2 mics), I think you can get away with this with minimal feedback issues (Smaart can be very helpful here), and less (or no) dependence on stage monitors. Food for thought, and perhaps something worth experimenting with.