Do I need to call in a professional to adjust hanging speakers?

The speakers are pretty much over the stairs, so scenery wouldn't have been in the way (and the only thing close to the speakers were periaktoi that were behind them, and in front of the doors).

Yesterday I had my student techs mic up 8 actors (Shure ULXs and headset mics, in case it matters) and the actors stood center and on the front edge. They all spoke in a fairly loud volume and only one student's mic started to feedback when pushed too high (it was a lower tone feedback - probably in the baritone range, if that helps). In general, we could get all eight at a decent level without any problems. I'm thinking (given my limited knowledge) that this is just a matter of being careful with the gain and levels of each mic, and not a deeper problem.

I'll post another update tomorrow after talking to the sound guy.
 
Several things strike me, you are running a great sound board with built in compressor, all sort of eq control. To control feed back ring out your mic frequency. You may also add the HPF ( high sq 1pass filter. ) and take all high end out.
Use something like RTA to find the specific freq thats givung you trouble.
Rigging- You touch and you are now liable. If your not qualified , please get one.

i wish you well.
 
I would be cautious about using the low pass filter. It would only be effective above about 8 kHz. Murky mics are not an improvement. A high pass filter takes the low frequencies out and prevents feedback at those frequencies. Use the high pass filter set to about 100 Hz on each actor's mic. Avoid boosting EQ controls, use cuts only.

Use compression sparingly, with a high threshold. Compressors can bring about feedback by increasing gain when the actor lowers their voice or stops speaking.

Remember that when multiple mics are running near feedback, you have to lower the levels of them 3 dB every time the number of open mics double. For example, you have less feedback margin with 8 live mics than you do with 4.
 
Lots of pro info here, much of which is over my head (and perhaps the OP's as well). Working from the assumption that the solution is to be found in mixing rather than installation, I might suggest that you bring in a good audio engineer / mixer for a consult, to EQ (or "ring out") the system. Then make a careful record of the settings.

re: the Legally Blonde video. I did not know that gain riding was performed on the level of syllables. Pretty impressive. Also, they need a preset page button in a better spot (like a space bar).
 
Okay, I think the main take away is that I have to make certain school admin ignores any one else's opinion on what the auditorium needs and should come to me first.

That said, the sound guy was very helpful. I explained what we did the other day and said that we don't need to move the speakers. He agreed, then went on to show my student techs some of the things they can do while mixing the show. I know just the very basics of compression, high pass filters and gating, but he was able to go into detail with the girls.

Thank you everyone for all the advice - I owe all of you a round!
 
Um, let me pose a few more questions for you here. ( I come from a 50 year background of designing, installing, tuning and operating venue systems for theater and concert uses).

1. Are the 2 speakers hanging together under separate amplifier control, or are they wired in parallel and fed from the same amp? Why this matters - gain for the center-fill cabinet(s) may need to be lower than the outer cabinet to manage feedback when actors are moving downstage, or there are mics in an orchestra pit, etc.

2. Without photos of the audience space, its hard to see if the aim on those cabinets is optimal. If standard spacer bars were used, vs. doing the math and trigonometry first, there may be improvements possible there.

3. What are the speaker models, please? From this we can look up the patterns.

4. How old are the speakers? Do they sound good-as-new, or do you hear distortion, grinding or buzzing from any of them?

5. While an installer's inclination is often to hang the box with the mfr logo readable (eg, the woofer on the bottom, tweeter or horn on top), often the reverse orientation is better suited to the room and the angles afforded by the hang position. Take pix from both top and bottom of house left, center, and right, as well as 1 from middle of house, looking up at the closest speaker in each case, and post them - that will help us help you.

6. Looking back in history - who designed and installed this the first time? Was it an organization that impresses you as knowing what they are doing? Would you want to invite them back for a look and a listen, or is it better to get a new set of eyes and ears in there?

I completely agree that someone who knows how to mix ("sound guy") may be a dangerous choice if they are not also aware of rigging safety, how to calculate dynamic vs. static loads, etc. Often a structural engineer is also necessary to ensure that the place the hanging points attach to the building are strong enough to support not just the dead weight, but the momentum and side to side motion that could result from (say) an earthquake. We think about that a lot here in California :)

Ben Stiegler
Performing Arts Audio
510/823-0850
 
Here's the auditorium (one guess as to what show we're doing). We had some feedback during our last musical, and the thought from the sound pro guy is that the inside speakers are points too far in and are going over the apron instead of completely out to the house. If we rotate each set of speakers out, the outside speakers will hit the walls. I'm a little skeptical about moving the speakers since I didn't think it was much of a problem before. I'm meeting with the guy on Monday. If it matters, we're using a Soundcraft Expression. We have a FBX 2400 Dual Feedback Eliminator that was used with our old board but is not hooked up now.

Again, I'm meeting with him on Monday and will press him on the details and possible solutions. My uneducated gut is that it is not the placement of the speakers.
View attachment 15857
My take is that the speakers need to be father out from the stage, as someone DS CTR is standing in the cone of the speakers. Also you might be better off with a RT,CTR,LT speaker hang
 
My take is that the speakers need to be father out from the stage, as someone DS CTR is standing in the cone of the speakers.

You aren't in the flame of the speaker standing at downstage center. You're on the edge of the pattern off of those cabinets. Those cabinets are pointed toward the middle of the center seating section.

Bringing the cabinets farther into the room will turn a non-issue into an awkward audience experience. That's a pretty wide L/R split to begin with. Move it into the crowd and tilt down and now someone in the far right of your vision is being heard from above your head in your left ear.

In an ideal world, it would be a center cluster with coverage of the whole room, L/R fills to pick up the far left and right seating and to add a little envelopment to the acoustic signature of the system (not intended for proper stereo or LCR mixing), and front fills to bring the acoustic image down to ground level for the people seated near the front. In this case, you would probably have to cut a chunk out of that cloud and hang the cluster above the cloud shooting through fabric or metal perf.

The benefits of which would be marginal if you have someone opening a bunch of mic's on the lip of the stage, gained up for students who are still learning how to project while also trying to get enough headroom to ride the vocal mix above the pit orchestra. Only so much can be done to protect someone from improper mixing technique.
 
Um, let me pose a few more questions for you here. ( I come from a 50 year background of designing, installing, tuning and operating venue systems for theater and concert uses).

Hello,

I work at a school theater that sort of looks somewhat like this. We are lucky in that we have more fabric hanging in the space. NTL, we still had feedback issues along the way.

I know you question was about the difference between the district maintenance guys and hiring a sound company. The simple answer is to hire the sound company.

As for digging into more details about the problem goes...

Ben Stiegler asked very good questions. I also wanted to know what the house looks like and what area/people you are trying to cover.

I realize that we all should walk/listen to your space to really know how to help you. Of course, that is not possible.

I will be speaking from the experience of my space and intuition. One thing I have noticed with new sound engineers is that no matter how successful the last events was, they will want to change something. Sound is very subjective. You might be able to eliminate all the feedback, and your sound could be much worse than it is now.

My intuition made me wonder if more smaller speaker over the audience might help. I also wondered if there is a location pattern of the where the feedback occurs. I meant where the performers are standing onstage when the system is most likely to generate feedback. That will give you some clues as to how to treat the speakers and levels. I also wondered if the feedback tends to come from a younger performer who has projection difficulties. That will clue you in if your problem may be the mics themselves. Idea - You might want to rent a sound system on stands and move those speakers around to see if you can get what you want.

In our space, the first step to solving our difficulties involved getting a new sound board. In our case an LS9-32. This provided 16 outs , and the feature that the board and a computer can record the settings for each "scene" or type of event. Fast forward to today. We have new drivers in place of the old source of the feedback and we run 10 channels of output that the audience can hear. We tune/time each channel. We use experts and computer based (iPad) tools for balancing the system. The mics matter too. Each mics need to be tuned to each the performer each show.

After all that, the biggest "sell" is still the time it takes to do mic checks everyday as part of the tech rehearsal process. 12 mics still takes a minimum of 30-45 minutes of tech rehearsal time. 20 or more mics can run 1.5 - 2 hours if you are using a pit/live musicians for the first time. You will have to learn what this takes in your space. You will get better at this, but since the performers always change, so do the needs of the mix.

Best of luck,

John

The other thought I don't think that has been covered is how the stage montors are placed.
 
It is important to remember that all systems will feedback. The question is, can you get acceptable headroom before this occurs? Before spending a dime on changing things, I would want to borrow an experienced soundboard op, who knows theater, to assess that there is indeed a problem, or if the solution is simply the mix/eq and expectations. Although there is some serious math behind sound, you best sound people are people who can also think in the abstract, and visualize what they are hearing.
 
A quick update - things are working much better, mainly because of the tutorial from the sound guy -the girls are already much better at setting the levels and jumping on problems. The guy did find a possibly related problem - the antennas that we had on the catwalk are no longer there, and in fact had been mysteriously cut off. Grrr. We've made adjustments - moving the receivers, and the purchase of some used equipment with a working antenna system -so we should be fine for the production.

One thing that I want to do by the end of the year is to get a full inspection of the place, which probably hasn't happened since the auditorium opened about 20 years ago. But I'll save that post for after the show when I've had a moment to breathe.

Thanks again for all of the advice!
 
Make sure the sound specialist knows what he is doing. By re-aiming your existing speakers you could end up with some serious phasing issues on each side. The ones pointing in do look like they aim in a lot, but that maybe to balance phasing on the sides with the outside throw speaker. The speakers on the side of the stage are OK, but a center fill or a center cluster system overhead could help your situation a lot.
 
Uh... I think they've sussed this out, @sloop. While your observation is not to be dismissed I think it's important to remember that "phase" is a frequency-domain phenomena that exists when identical signals combine (or arrive at a common location) in a way that is not time-synchronous at a particular frequency. Normally this occurs when 2 loudspeakers (or an architectural/scenic reflection) both cover a portion of the audience area.

The center frequency of the resulting comb filter is based on the physical distance between loudspeakers/reflective surface.
 
Uh... I think they've sussed this out, @sloop. While your observation is not to be dismissed I think it's important to remember that "phase" is a frequency-domain phenomena that exists when identical signals combine (or arrive at a common location) in a way that is not time-synchronous at a particular frequency. Normally this occurs when 2 loudspeakers (or an architectural/scenic reflection) both cover a portion of the audience area.

The center frequency of the resulting comb filter is based on the physical distance between loudspeakers/reflective surface.

Exactly what I was trying to convey. Changing the spread of the speakers could cause phase issues. Just because you have a "professional" advising you, doesn't mean its going to work. I have seen a lot of "professionals" screw up big time.
 
@JDI had a Beyer DT108 with a spare mic element glued in place on the outside [Rear] of its boom mounted microphone. It was a little heavy out on the end of the mic boom and required a little extra effort when snugging down the tilt-lock. They were wired with their polarities electrically additive but, as they were reversed / 180 degrees out of phase physically, they combined to reduce ALL electro-magnetic and HVAC noise entering the comms system while making it extremely easy to converse with the assistant LX when confirming mid-scene / mid-act physical repatches of the single-conductor hard-patches.

Why ever would you need to do that?

The 108/9 series have *noise-cancelling mics* -- both sides of the mic are open to the air, and since you're only on one side, you're (mostly) all that comes out.
 
Why ever would you need to do that?

The 108/9 series have *noise-cancelling mics* -- both sides of the mic are open to the air, and since you're only on one side, you're (mostly) all that comes out.
@Jay Ashworth When you're in a room with 100 1970's vintage British Strand JTM series dimmers of a variety of sizes up to 6 Kw's and you're leaning into a telco-style, single conductor hard-patch to physically unplug and re-plug 120 VAC load circuits not only between performances but during performances while many circuits are active and many dimmers are dimming and / or fading, the coils of your dynamic mic are in close proximity to the magnetic fields being radiated from the single conductor load cables of your hard-patch. I understand what you're saying about airborne noise. The electrical cancellation of the two elements was to negate magnetic coupling and the associated unbearable hum it would induce into the unbalanced mic input of their Electro-Vox production intercom system of the day, originally custom fabricated by Electro-Vox of Montreal, Quebec, Canada.
With apologies if I did not explain this sufficiently clearly in my post.
Toodleoo!
Ron Hebbard.
 
Oh. The problem was EM noise, not acoustic.

Yeah, I can see that.
@Jay Ashworth To further clarify, this was back in 1977 thus some of the exact quantities of load circuits are becoming fuzzy in the crevasses of my mind. There were approximately 400 to 500 load circuits emanating from the telco-style hard patch. Smaller dimmers had 3 or 4 load receptacles per dimmer with larger dimmers having 6. I can't recall any dimmers having more than 6 load receptacles. As much as possible, cables remained plugged and loads were switched 'on & off' by switch-rated Heinneman (SP?) magnetic breakers with the aid of color-coded tape. The Stratford Festival operates as a rotating rep'. In 1977 they operated 3 venues physically scattered about the city. My first season, the bulk of my time was spent in their main building with its thrust stage. Again from memory, I believe we opened the 1977 season with 3 or 4 productions in June or late May then proceeded to add 3 or 4 more productions in August for a total of 6 or 8 productions running in their rotating rep' through to the end of their season in late September / early October with shows which opened the season being dropped from the rep' as the end of our season approached. The same pattern applied across all three venues with many of the acting company performing in all three venues with matinees in one venue followed by evening performances in others on a regular basis. In the first half of the season, booking time for maintenance was difficult as all facilities were booked solid until ALL productions were open and running in rep' when things settled down to 10 & 12 performances per week by virtue of cross-casting of Equity performers and only periodic understudy rehearsals being slotted into the schedule. I offer this to help you appreciate why physical re-patching of the telco-style load leads was often necessary during performances: There are only so many dimmer receptacles physically available on the hard-patch, even with the addition of out-board plugging boxes. [60 Amp rated 'cube-taps' if you prefer to envision them that way] Eventually you end up having to physically shuffle load circuits during rehearsals and performances thus the need for the board operator to receive confirmations of the completion of re-patches prior to executing his next cue. Nobody plans to intentionally shuffle single conductor loads while they're live and under load. Nowadays the term 'Arc Flash' leaps to mind.
Toodleoo!
Ron Hebbard.
 

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