Archive for the ‘Analysis tools’ category

Toning Your Sound System

September 10, 2010
No this is NOT a typo. I did not mean to write “Tuning your sound system” because that is entirely a different subject. So what is the difference between toning and tuning?

 Here is a simple example from the muscial side: This is my son Simon. He has a guitar effects pedal that has exactly the TONE of Eddie Van Halen. One small thing though: he can’t TUNE his guitar.

A legend in his own mind

 

Sound systems also have a similar contrast between these two concepts. Tuning  a sound system (in my estimation) is where you adjust the system so that it has uniform response over the listening area, with minimal distortion, maximum intelligibility and best available sonic imaging. Tuning is about making the far seats similar to the near seats. An objectively verifiable – but verifiably unattainable goal of same level, same frequency response, same intelligilbility throughout the room. Making the underbalcony as similar as possible to the mix position (which hopefully is NOT under the balcony). It is about making sure every driver is wired correctly, still alive, aimed at the right place and cleanly crossed over to the next one. It is about making it so the mix engineer can mix with confidence that theirs is a SHARED experience. Because it an objective pursuit, the use of prediction tools, analysis tools and our ears all play important roles in the process.  It does NOT, however mean that it sounds GOOD. “Good” is subjective.

Toning, on the other hand, can’t be done wrong. It is entirely subjective. Toning a system is the setting of a bank of global equalization filters at the output of the mix console that drives the sound system. If you want to set it by ear fine. If you want to set it by 10,000 hours of acoustical analysis containing mean/spline/root squared/Boolean averaging then go for it. If I am the mixer and I don’t like it, I will change it. Too bad. I like MY tone better. Deal with it. I don’t like flat. Deal with it. I like flat. Deal with it. There is nothing at stake here. Nothing to argue about. And no need to bring objectivity, or an analyzer to the table. The global equalizer is just an extension of the mix console eq. In the end the mixer will choose what they want to eq on a channel by channel  basis and what they want to eq globally. But also in the end there is no wrong answer, because it is entirely subjective. I have worked shows where, in my opinion the mix sounded like a cat in heat. That’s my opinion, and therefore not relevant, unless asked for. I asked the mixer “Are you happy with that?” They say “Yes”.  As long as I have ensured the cat in heat is transmitted equally to everybody in the room (i.e. TUNING the sound system), my work is done.

Good toning enhnaces the musical quaility, or natural quality of transmitted sound. Good tuning ensures that the good (or bad) toning makes it beyond the mix position.

 Piano Tuning…. and Toning

One does not have to know how to play a piano to be a competent piano tuner. It is an objective pursuit. Numbers. It can be done with an analyzer and/or a trained ear. The toning of a piano, a subjective paramater, cannot be wrong. John Cage opens up the piano and scatters nuts and bolts on top of the strings. This “tones” the piano. Is it wrong? Of course not. But before John Cage plays the “prepared” , i.e. toned piano, do you think he has it TUNED?  You bet.

John Cage Prepared Piano - a subjectively "toned" piano

 Below is another example of a “toned” piano.

I always wanted to find a way to work a deer head into my music

 Below are the tools for TUNING a piano. Similar to the ones we find our artistic auto mechanics using to TUNE up our car.

Tuning Forks

Hmmm..... Digital calipers: Objective or subjective?

Strobe tuner: otherwise known as a frequency analyzer

 

Just semantics or more?

So why do I make this distinction?  Because I have recently experienced several cases where people are confusing these concepts. In one case a guy wrote an article about how much better systems sound if they don’t have a flat response. Better to have peaks and dips. He notes that people that tune sound systems with analyzers do the clients a disservice by making thr system “flat”. Who am I to argue with this. He doesn’t like flat. OK. However, in the course of putting down acoustic analyzers for global equalization, the article never mentions the OTHER things that we use analyzers for: checking polarity, aiming the speakers, adjusting splay angles, adjusting relative level between speakers, setting crossovers, phase alignment, intelligibility analysis, treating reflections or most importantly: working to make it sound uniform throughout the room. The article compares equalizing your church sound system to your home hi-fi, which is to say TONING the system.  Maybe this guy’s approach is great for toning the system, but it is useless for tuning the sound system. The article “The fallacy of a flat system” can be found here

———————-

Then I received a question from one of my recent students from Asia:

Dear Bob:

Last week I join the BRAND X SPEAKER COMPANY seminar, they use another method to alignment the line-array system.

1) the whole line-array should be same EQ & same level.

2) they use room capture software to alignment the line-array system. They capture about 15 trace at difference mic position in the venue but not on axis speaker position and finally they sum average of the trace to 1 result then EQ it. What do you think?

————–

This was my reply:

1) the whole line-array should be same EQ & same level. 

I cannot find any good reason for this. The lower area is covered by the lower boxes, the upper area by the upper boxes. They are in very different acoustic environments, they are very much at different distances. Why lock yourself into a solution with no flexibility? If the end result is a perfect match… then great. If not…what can you do besides make excuses?

2) they use room capture software to alignment the line-array system. They capture about 15 trace at difference mic position in the venue but not on axis speaker position and finally they sum average of the trace to 1 result then EQ it. What do you think?

This solves NOTHING. The end result is the same eq to all speakers. If it was an average of 2 positions or 20,000 positions the average is still just ONE set of parameters. If it sounds different in the front than the back before you average then it will sound exactly the same amount different AFTER the average. Why bother to take samples all around the room if you are not going to do anything about the DIFFERENCES around the room? It is just a waste of time.

The only reason to use an analyzer is to get objective answers such as: is it the same or different?  Not for subjective ones such as – does it sound good?

Example: Let’s say you average 20,000 seats and put that in as the eq for all speakers. Then the mixer hears it and wants a boost at 2 kHz.  What are you going to do? You are going to boost 2 kHz or get fired. Who cares about the average now?

6o6

———-

In this case a manufacturer is using toning techniques without dealing with the tuning part. BOTH must be applied if we are going to bring the tonal experience to the people that pay to hear our sound systems.

Conclusion:

Keep an eye on both sides of the issue, but bring the right tool for the job:

Recommended system tuning attire

System toning outfit (Women only PLEASE!)

 

Toning apparel for men

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SIM3 Optimization & Design Seminar at UC Irvine

June 29, 2010

We just completed a 4-day SIM3 training seminar in the south side of southern California. UC Irvine is located very near the ocean, which makes one wonder how folks could study when the surf’s up. It is also right next to John Wayne Airport. Naturally I flew in and out of LAX, and drove the hour down to the other airport. Why? Because I live in St. Louis, which USED to be an aviation town (ever heard of Charles Lindbergh, McDonnell Douglas or TWA? – all just museum stuff now.).

Measuring, measuring, measuring

We had a good sized class of 19, including grad students and professors from UCI, some engineers for Creative Technologies ( a rental house specializing in corporate), some freelancers and two special guests: Daniel Lundberg  and Jamie Anderson. There were 3 people (not including Jamie) who had attended my seminar previously and were returning. This is, for me, the highest honor and I am very grateful for the support of Will Nealie (whose photos are shown here), Chuck Boyle and Szilard Boros.

The Venue

We were fortunate to get to do the seminar on the stage of the 300 seat Claire Trevor Theater. This allowed us to measure first in the controlled circumstance of the near-field on stage and then work our way out into the house. As an added bonus we were allowed to measure (and re-design and retune) the house system, which had an up-to-date line array type system of 8 x Meyer M1-Ds.

The class moved along very smoothly. We covered LOTS of ground and the acoustics of the hall were very favorable so that students could get a look at what real systems can do in a good hall.

The class progresses in complexity over the 4 days, beginning with measuring a processor, then on to a near field single speaker, adding a subwoofer , near field arrays, distributed arrays and then out in the house where we design a full system and tune it. All the while the progression of complexity is underscored by the theory behind the data. The number one focus point of a SIM3 seminar is understanding what the data says and WHY they data says that. Proper diagnosis must ALWAYS come before treatment, and all treatments need follow-up testing. If they don’t work then get started on a new diagnosis. SIM school tunings are never rehearsed so when something shows up on the screen, we all are seeing the data for the first time. There are always surprises and this was no exception.

In the course of the tuning here we found that our original design had too much coverage for the room. If we had gone to MAPP On-line or even used a simple protractor on the plan view of the room this could have been seen in advance. But PURPOSELY we did not use those tools to find the answer. It is better for the learning process to see how unkowns can be decoded by the analysis methods. The “Main” array was 2 x UPJ-1P in a coupled point source, located at the house left stage edge. Our goal was to cover evenly across the room – a straight horizontal line along the 3rd to last row. As we measured the 1st speaker across the row we could see that it cover ALMOST the entire width…. almost. Adding the 2nd speaker was WAY too much, leaving it off, left us 4 seats short of the aisle. Conclusion: Our design was flawed. (This made it just like a REAL gig except that the designer’s ego was not at stake).

 It is much better (as a learning experience) to use the SIM 3 Analyzer to prove the design was wrong and to force us to consider the optimization options that had the highest prospect for success. If only we could wave a magic wand an turn this 80 degree speaker into a 50 degree speaker!  Oh….. WE CAN!     In this case we rotated the UPJ-1P horn on the 1st speaker (they are 80×50 rotatable) so that we got 50 degrees of horizontal coverage for the “A” speaker (the longer throw). This covered enough of the room to make a successful, smooth transition to the B speaker. Then we added the “B” speaker – too wide again until we rotated its horn as well. The end result was even coverage across the straight line  of the 3rd to last row within 1 dB.  The process involved measuring on axis, at crossover and off axis until the splay angles were optimized, the eq’s set (individually and together), levels set and delayedso they were phase-aligned at the crossover. Then we added the subwoofer to the array in both an overlapping and non-overlapping mode (different delays were needed for this). Finally we added a small delay speaker to extend the coverage evenly into the corner. We even took a few minutes to show the effects of adding excess delay (the side effects of the Haas Effect) and watched as the coherence and combined level at the delay location became worse than if the delay speaker had been turned off. This is always an eye-opening moment at my seminars. 

Tuning (and retuning ) the Line Array

Because the class moved along so quickly we had the luxury of extra time to take on the house system. This system is made  available for students to re-design, re-hang, re-angle, re-tune, re-etc…….  This particular config had been specified by a student AMA (against medical advice) so the professors were quite interested to see how it would look under the scope. The answer:  ________________________flat line.

The horizontal orientation was the most severe in-tilt I have ever seen (OK I am pretty new to this but I have seen a FEW systems). It was such an inside job that the Left side of the PA missed most of the…………. left side.  The mix position was in the very rear of the house right side. From a horizontal standpoint the left speaker was pointed at the right wall IN FRONT of the mix position. If you are having trouble visualing this here is a pic to help.

Horror-zontal aim points for the PA

So we measured and found that the left cluster was more than 6 dB louder on the house right than on the left. Obviously the speakers would need to be opened outward. 

Before- ONAX A vs OFF A - Off mic is near top row at the last seat on house Left

We had, however, spent the previous 2-speaker tuning  focused on the horizontal plane interaction between the pair. Here we had 8 boxes in the vertical plane– that is what we wanted to see – and we had 5 mics running from top to bottom in a diagonal line where the speaker was pointed.  As it stood, nobody knew what the current vertical angles of the cluster were. We had the 8 boxes wired in 3 zones 3-3-2 as an ABC array. It was offered to bring down the array and see the angles – then we could play in MAPP and see the response…….NO, NO, NO. Much better to turn it on and see what we have. This way we can learn how to hunt down an array in the wild. We know these 3 subsytems are out there – but where?

I don’t recommend working on systems where you don’t know where the speakers are pointed, but it is important to be able to find where they actually ARE pointed – even if you have a piece of paper (or I-pad) to show you. The learning experience here was the process of finding. Here is a pic to get the idea of where the mics were:

Mic placement strategy

Terminology sidebar – ONAX (On Axis), X (Crossover), VTOP (Vertical top),VBOT (Vertical bottom).

Before we get to any tuning, we dummy checked each mic and speaker to make sure we had everything wired right. In the course of this we set the delay compensation for each mic and they ran from around 50 ms to 13 ms so we are looking at near seats that are around 12 dB closer (a ratio of 4:1) than the rear seats. The array will need to overcome this difference in proximity.   

So we began with just the upper system “A” on (the top 3 boxes). We compared Onax A, VTOP and XAB positions. VTOP (around the mixer ) was a disaster. No HF, no coherence and the far side much louder than the near side.

Original angles - ONAX A vs VTOP

UCI M1D R1 - VTOP A Solo -before EQ

 

Perfect mix area!!!!! XAB was down slightly from ONAX A so now we knew (vertically) where “A” was pointed: Too low.

Before- ONAX A vs XAB

The cluster was already very high so we can’t move it much.  The real answer would need to be getting some up-angle in the array. This would require some real-world rigging and this was not going to happen in our short time frame so it does not seem that we will fully solve the mix position.

Onward. We moved the ONAX A mic up and down a row and found that our original position had the most level – we had found the center of A. We eq’d it and stored it as a reference level.

Next begins the search for B. We looked at the ONAX B mic and moved it up and down until we found its high-water mark. The level at B was stronger by about 3 dB (compared to A). It was also about 3 dB (70%) closer. This made it obvious that the splay angles chosen for this array were wrong. How did we know?  The job of the different splay angles is to create a matched level at different distances. Here we were seeing that as we got closer, it got louder – the expected propeties of getting closer to a symmetric, non-directional source, not one that is creating asymmetry in the vertical plane. We eq’d the B system and reduced its level 3 dB.

Next up was the bottom two boxes, system “C”.  This system covered the front rows REALLY well. It was 7 dB louder than at the back and we were still in the 4th row.  It got even louder up closer but we gave up.

Before- ONAX A vs ONAX C

Conclusion: The cluster system needed to generate around 12 dB of level difference from top to bottom. It actually achieved 3 or 4 dB.  Time for the cluster to come down and redesign the system.

Redesigning and retuning the Line Array

We have no drawings of the room. Not even a napkin sketch. The UCI internet is not getting through to my laptop. We are going to have to go it alone. 

This is what we know (a) the cluster is too low, we have more than enough angle to reach the bottom and we need 12 dB more level at the top than the bottom. This means that the splay angles for the C section need to be at least 4x wider than the A section.

So how do you design a line array with no Manufacturer Official Line Array Calculator, no Mapp On-line, no drawings? We need to know the angle spread from top to bottom, and the difference in range from top to bottom. So we looked at the existing angles and found that the overall angle spread was 40 degrees. We know that was more than wide enough. We know we have a 4:1 distance ratio.

So we need 35 to 36 degrees of spread – we have 8 boxes (7 splay angles) – the average splay angle will be 5 degrees. (5 deg x 7 = 35 deg). We know the widest angle we can get for an M1D is 8 degrees. If we have 8 degrees at the bottom and 2 degrees at the top (a 4:1 ratio) we will approach our 12 dB range ratio. Add ’em up  (2-2)-3-(6-6)-(8-8) = 35 degrees. System A = is 3 boxes at 2 deg (a 6 deg speaker), 3 deg splay to system B (a 12 deg speaker) and then on to C (a 16 deg speaker).  Here is a picture of the design in progress: Yes – that is the AS-BUILT paperwork under my hand.

Calculating the splay angles based on range ratio

The new angles were put into the cluster and up it went – pretty much as high as it could reasonably go (about a foot or two higher than before) and we resumed measuring. This went very quickly now. The center point of each subsytem was easy to find since they each were made up of a symmetric angle set. The center of A was at cabinet #2, the center of B was at # 5 and the center of C was between 7 and 8. Each system was eq’d separately and levels set. The level tapering needed to bring the lower systems into compliance was 1 and 3 dB respectively, a far cry from the 3 and 7 dB previously. The systems were combined – first A & B and then C was added and a very uniform frequency response and level was created over the space. The level from front to back (back being the top row) was now 1 dB. The mix position still sucked – but we knew we could not save that without a rigger.

Reworking the angles

 First we looked at the ONAX A position, and EQ’d it. This will be our level/spectral standard going forward.

The next step was to look at the response at the mix position. We expected that things would not be improved much here since we were not able to aim the array up high enough to hit here……..and we were not disappointed.  Well I mean we were not surprised.

After- A at ONAX A Compared to A at VTOP

After - Response of A solo at ONAX compared to B solo at ONAX B

 The EQ applied is slightly different for A and B respectively. The difference is minor because both “speakers” are comprised of 3 elements. The splay angle is different which creates a different summation gain of 3 dB – the correct amount to compensate for the difference in distance.

After- A at ONAX A Compared to AB at ONAX A

Above – You can see the addition at A that occurs when B is added. The response shows no loss but the gain varies with frequency. As frequency falls, the percentage overlap increases and the addition increases. At 8 kHz the percentage overlap is so low that we see no addition. By contrast, at 125 Hz we see 6 dB addition. All frequencies between show gain values between 0 and +6 dB. This is a great example of 3rd order speaker behavior.

After- AB at ONAX A and ONAX B

After- AB at ONAX A ONAX B and XAB

 

After- HF ZOOM - AB at ONAX A ONAX B and XAB

 Above is a zoomed look at the uniformity of the HF levels.

Combined System A+B  EQ

Once A and B are combined we look at the LF region to see where the coupling was shared in both directions. Frequencies that were boosted in all locations can be equalized by matched filters in the A and B sections. In this case a 160 Hz filter was applied. Below we have a zoomed in comparison of before and after the AB Eq was added.

After- AB at ONAX A -Combined system EQ

 The screen below shows how we have restored the Combined AB response to the same shape as our initial A solo reponse.

After- AB at ONAX A -Combined system EQ compared to solo A EQ

 The AB sytem is now complete

After- AB with combined EQ at ONAX A ONAX B and XAB

Combined System: Adding (AB) + C

Now that AB is complete we turn our focus to C. Speaker C (2 boxes) was EQ’d as a soloist and it’s level set to match the ONAX A standard. The solo EQ response appears below.

After- C at ONAX C EQ and Level
The response below shows the full combined response ABC at ONAX A and C positions, giving us a clear view of the difference between top and bottom (not much!). The distance ratio between these two locations is around 8 dB!

After- ABC at ONAX A and ONAX C - top to bottom compared

 Finally we sell the full system ABC at its 3 main locations.

After- ABC at ONAX A, B and C

Was this the best way to design a system? I would not recommend it, if you have the option of drawings etc. But in the end we still have to test it – and that is where the final design comes from. In this classroom setting we made the tuning process drive the design. What we learned from our data was translated into an updated design and this was then measured. The result was a winner. This process, in a few hours was a distillation of 25 years of work for me. Everything I I ever learned about design came from the process of trying to tune an existing design, and learning from it.

There are additional class photos which will be placed in the “Seminars” Page on the right of this blog page.

and finally………………….

I did manage to bring home some good data from this tuning so I will add those to this post later. Soon… I promise.

6o6

New York Trainings – Updated with Pics

May 19, 2010

I am in NYC this week for two rounds of classes: SIM3 training in Brooklyn and the Broadway Sound Master class on the NYU campus in the East Village. The SIM class is at City Tech in Brooklyn – which is where John Huntington teaches. We have several of his students joining the class which is really nice. This trip marked a first for me – even though I have been coming to NYC quite regularly since 1984 this was the 1st time I ever set fot in Brooklyn. We arelocated over by the legendary brooklyn bridge and I can see it from the school – so hey – I can add another borough to my list……Manhattan, Queens – been 2 places there – La Guardia AND JFK – wow, and now two places in Brooklyn – City Tech AND Peter Luger – the famous steakhouse.

We are halfway through the class and pretty much right on schedule. Looking forward to the BSMC this weekend – always a great learning experience for me

****** John Huntington was kind enough to take some pics of the seminar.

6o6

Macau COD Tuning: Day 4 (Work in progress)

May 8, 2010

 Note: I have completed day 5 at the time of this writing – I am posting this work in progrees so that the posts will come out in the right order – I will fill this one in ASAP

Bus level adjustments for equal level

One of the major components of an LCS-based system design is the managment of buses. Buses are they way signals are routed to provide a particular effect. In this case there is a desire to sometimes operate the mains with a high vertical image, sometimes low and sometimes in the middle. In this case this can be achieved be relative levels between the Melodie Mains (high) and Soundbeam Mains (low). To get the middle vert positon we use both. But we don’t want it to get LOUDER just because we move into both speakers – we only want to move the image – if we simply combine then it will get louder.

A dedicated bus (when properly calibrated) can provide a means to send signal up or down without level change. In this case three buses – Hi – Mid – Low are set to different level combinations of the two main outputs – to achieve the same COMBINED response. Sounds easy enough with a 2-part combination but it can get tricky when multiple parts are in play.

A secondary set of buses was created for the surrounds. These moved the sound outward AND control the vertical – in 3 parts. High overhead surrounds for the middle and lower areas, low overhead surrounds for the outer perimeter , and lateral surrounds that cover everybody. This makes for a tricky set of crossovers and bus level combiniations. In the end, matched acoustic levels were created in buses that allow the surround signal to move out, and up as needed. Signals assigned to the high bus go up and out, the low bus go out, and the “all” stretches out AND up, but keeps the same level as it doubles its quantity of devices. To do this we do a series of measurements and adjust the drive levels to compensate for the actual combined acoustic levels in the house – it is NOT a simple matter like – take away 6 dB and done. The fact that the different devices overlap their patterns in the seating area from DIFFERENT directions means that simple addition does NOT apply.

expand constell zone parts – the constellation zones were touched up and we got the speakers needed to measure them.

Subwoofer Delay Steering

The subwoofer system is a hybrid of two distinct array types: coupled point source and quasi-coupled line source. I call the latter “quasi-coupled” because the 3m spacing leaves them coupled down at their low range (30-60 Hz) and stretching toward uncoupled at the top end (80-120 Hz.)  The fact that they are all above the pool in the central fly space means that we have no worries about the near-field response before the line pyramid and fully combined. As it turns out, all audience members will see fully finished array performance.

Our seating area is 270 degrees of a circle. The center +/- degrees we will call “front” and the side 90 degrees “side”.  The design intent is for the coupled array to concentrate on the middle zone and the line source to take the sides. Since the front would be well covered by the coupled array it was hoped that we could steer the line asymmetrically toward the rear part of the sides.

We went to MAPP and ran a series of calculations. The 3m spacing (dictated by structural beam spacing in the grid) is pretty wide to work with delay steering. The 100 Hz range breaks up pretty badly before we get much of an effect on the bottom range. The biggest challenge was the extreme narrowing in the center. Even if we got it to bend toward the back, it was WAY too narrow.  Instead we focused on a symmetric spreading strategy which combined delay and level tapering to give a very even spread over the range of 30-80 Hz. The outers were turned down in level and delayed the most.  Config was -4,-3,0,-3,-4 dB (from outer to center to outer ) and 3,2.25,0,2.25,3 ms.

We measured across the bowl and the results were sufficiently uniform – and similar tp the prediction that we moved on to the coupled cluster.

Coupled Cardioid Sub Array

Cardioid steering investigation for the coupled array  3 forward – 2 rear firing (pol reverse, 4 ms, -2.5 dB)

Macau COD Tuning: Day 3 (work in progress)

May 8, 2010

 Note: I have completed day 5 at the time of this writing – I am posting this work in progrees so that the posts will come out in the right order – I will fill this one in ASAP

The #1 goal for today was to get 1/4th of the room operational for so that Pierre could get initial Constellation data. Constellation needs to gather data, and then go off line crunch a lot of numbers. If we can get Pierre started, then he makes progress – quietly, while we continue making progress noisily.

As often happens, once Pierre got into the physical space, he revised the room division strategy for Constellation. Not a big thing, but we would need to expand our quantity of speakers. As it turned out, it was close to the end of the session when we had everything in place, but no one had lost any time.

One of the interesting findings was in the horn-orientation of the UP-Juniors. These boxes have a “Vari-O” horn, which can be turned 80×50 or so, one direction or the other. They had been specified as 50 vert and 80 hor – when  the cabinets were lying on their sides. (the opposite of the standard config.) Paperwork suggests that the units were special ordered this way – so either they were never turned at the factory – or they got turned twice. One of the great things about an install that has had around a year of delays is no-one can remember and the folks who put them in have gone to the old-folks home.  In any case we became suspicious when we were verifying the cabinets – verificiation is done by moving the mic along a line to each sequential speaker. they should matct. In this case a few inches closer or further made a big diff in the horn range, which we were measuring near its bottom edge…..hmmm , very touchy. I raised the prospect that ONE of the cabs might be turned wrong – turns out they ALL were. That kept folks busy for a while as we moved on to other things

Day 3 – work in progress – more soon

UPJ horns tilt

merge upper surr

lower surr 1

lower surr 2

adds to clust

Macau COD Tuning: Day 2

May 7, 2010

Day 2:

Day 2 was spent finishing the tuning process for the Main arrays (to the 1/2 point) Now that we have done all 4 arrays we will copy the the settings over to the other side and then verify the symmetry of the other speakers. We are setting that part aside, moving on instead with tuning other systems and leaving all of the symmetry verification for later.

This tuning is a multi-part affair, for a very multi-purpose, multi-channel system. While the Main system and subwoofers will be used in a fairly traditional manner, the surrounds will be used as spatial image movement, surround envelopment and also as reverberation enhancement: the Constellation system.   I will be staying here after the SIM tuning, to help with the Constellation calibration. In total I will have 8 nights on site. 

Pierre Germain and Steve Ellison of MSLI will be joining me for the Constellation (Pierre on day 3 and Steve on Day 4). Acoustically the room is quite dry – a bit surprising considering we have a 5,000,000 gallon swimming here – OK I COULD NOT RESIST. – There are 10,000 absorption panels, each about 2×2 meters, 4 inch thick (at least). The reverb time is under 1 second in the high end, quite amazing for a room of this volume. We will be extending the reverberation with the Constellation system, recirculating the sound through hanging mics and back through the extensive speakers around the room.

Our mission today wwas to make progress on the mains and also to get a 25% slice of the room’s surround/constellation speakers so that Pierre could be kept busy upon his arrival tomorrow. Most of this was accomplished.

The secondary Main system is the Sound-Beam 2 (SB-2) . This is what it sounds like – a parabolic dish speaker system with 20 degree coverage over almost its entire operating range. There are 8 units and they cross their beams in the center of the room, giving secondary coverage to the opposite side of the room. So each seat is covered ABOVE  at a 66ms distance by the Melodie array and also by the 2x distant SB-2.  The controlled pattern of the SB-2 allows it to be used selectively across the pool with minimal self-interference – (readers of my book will note that this is the ultimate Point-Destination array – but since it maintains its control over its full range, it comes out the other side of center able to achieve isolated coverage on the far side. If there are set pieces in the middle, then things will get interesting for sure, but this secondary source alloows for vertical image movement (the SB-2s appear much LOWER to the listener than the Melodies – which are nearly overhead to the front rows.

So Day 2 was spent CAREFULLY aiming the SB-2s. I MEAN CAREFULLY.  One of the interesting aspects of the SB-2 is its pattern is the ultimate in symmetry – a circle. We overlapped them slightly (-4 dB  to -4 dB) along the center line in order to make sure they met above and below – visualize a binocular pattern – two circles, slightly overlapped at the center.

After finishing the beams we proceeded on to three of the 4 levels of perimiter surrounds/delays/ constellation speakers. We equalized and level set the individuals. The combination would have to wait for Day 3……….

Macau COD Tuning: Day 1

May 5, 2010

I am currently in Macau. If you don’t know where Macau is, study up on the history of the Portuguese Empire. Macau,  the #1 gambling destination in the world has now reverted back to ownership by the People’s Republic of China and like all gambling operations serves as a funnel of money back to the local government, and local billionaires. 

So here I am tuning a large sound system that will play it’s part in a theatrical spectacle whose mainstage is a 5 million gallon swimming pool.  If you have trouble visualing that well…… big. REALLY big. The show is “in the round” with 270 degrees of raked seating around the pool.  The speaker positions are almost all above the audience, most of them in the ceiling, so that there can be unobstructed vision to the pool and the many acrobats, and other flying objects that come in and out of the pool. The only speakers NOT above the audience are BELOW the audience and BELOW the water. I won’t be tuning those, as it turns out, but I really would like to.  :-(.

The installation is in the “City of Dreams” Casino/Hotel complex. It is a Melco property. The show designer is Dragone, famous for “O” at the Bellagio, “La Reve” at the Winn and Celine Dion’s show when she was doing her long run at Caesar’s Palace.

Ths system was designed by  Francois Bergeron & Vikram Kirby of Thinkwell. This is my 2nd project with Thinkwell. We did ZED for Cirque Du Soleil in Tokyo. Francois Bergeron of Thinkwell and I go WAY back and amoung other things we did the Tokyo Disney Sea project together.  The install company is Solotech (Montreal, Vegas) and my contact here is Bob Barbagallo. We worked together here in Macau 3 years back to put in the other big show in town: Zaia (Cirque) at the Venetian.

The sound System

So what we have are 8 clusters of 7x Meyer Sound Melodie speakers. Each of these covers from “the beach” (the front row) to  nearly the top row. The cluster is broken into A-B-C sections of 2-2-3 elements. The tuning follows the typical A-B-C methods described here and in my books but the differential between A-B & C in this case is barely discernible.  Why? Because the shape of coverage is nearly symmetrical. The difference between the farthest seats and the nearest seats is on 10%.  71 ms to the farthest and 64 ms to the beach.  Therefore the setting were nearly the same top to bottom.  The splay angles between the 7 boxes were 4-6-6-6-6-4. The 4’s on the outside sharpened the outside edges a bit to keep away from a reflecting wall at the top and reflection water (imagine that!) at the bottom.

The EQ was divided into two modules – a common EQ for all 3 and then another stage for the other two. Most of the work was done in the common eq with minor stuff done in the singles. 1 dB of level taper was all that was needed to get uniform top-bottom level.

The first day of tuning was spent on the main arrays. On the 2nd day we will be taking on the secondary mains: soundbeams which shoot across the pool and cover the opposite side of the hall. These help to keep the vertical image down and can be brought in and out to provide image movement.

It is noon here. Time to sleep and get ready for our next round starting 11pm tonight.