Track & Field

Back in a previous life as a web developer, Friday afternoons in the office were made a little more bearable thanks to a game called Layer Tennis.  In this game, two artists trade a Photoshop file back and forth every 15 minutes for 10 rounds. Each artist creates 5 banner images from a mashup of the previous rounds plus any other inspiration they care to draw from.

I'd long wondered how Layer Tennis would be played using sound instead of images.  I told Vinnie about the game, and we came up with a longform version for our Trends in Modern Sound Design class.  I'm calling it (sound) Track & Field (recordings).  It's one part Layer Tennis, one part Guerilla Sound, and one part Telephone Game.

We setup two teams: Stephen Swift, Josh Fehrmann, Brian Svoboda, David Backovsky; and Patricia Cardona, Matt Glenn, Mark Caspary, Michael Matthews.  Each week, the team's Pro Tools session would get passed to the next member in line like a baton in a relay race.  Each designer then had 1 hour to create a 30 second audio clip, which would get placed on the master track right after the previous clip ended.  For the first week, everyone created a 30 second sound clip as a jumping off point; so actually, each team was responsible for four Pro Tools sessions, and the one you were personally responsible for that week was just based on where you were in the rotation.

We've been going at this for seven weeks now, and collectively have generated a half-hour of audio: that's 8 relay games, each with seven 30 second sound clips strung together.  We've posted them here for your entertainment... Enjoy!


Group 1, Rotation 1: Stephen, Josh, Brian, David, Stephen, Josh, Brian



Group 2, Rotation 1: Patricia, Matt, Mark, Michael, Patricia, Matt, Mark



Group 1, Rotation 2: Josh, Brian, David, Stephen, Josh, Brian, David



Group 2, Rotation 2: Matt, Mark, Michael, Patricia, Matt, Mark, Michael



Group 1, Rotation 3: Brian, David, Stephen, Josh, Brian, David, Stephen



Group 2, Rotation 3: Mark, Michael, Patricia, Matt, Mark, Michael, Patricia



Group 1, Rotation 4: David, Stephen, Josh, Brian, David, Stephen, Josh



Group 2, Rotation 4: Michael, Patricia, Matt, Mark, Michael, Patricia, Matt

Blizzard Studios

Recently, for our last class session of my Trends in Modern Sound Design class, we took a field trip across town to Blizzard Studios.  If you play video games at all, chances are good that you have played a Blizzard game at some point in your life (their products include World of Warcraft and Diablo, both of which get screen time in my house). Blizzard is known for creating immersive designs with a lot of attention to detail, and we wanted to see how their sound team handled such large and complex projects.

We all had to sign nondisclosure agreements, so I can't talk much about what we saw on our visit, but here are some things I can say:

• The sound team and the music team work side by side. The designers, composers, and engineers are in constant conversation with each other, and they all seem to agree that this makes the end result much stronger.
• The sound team has a large and growing collection of custom field recordings, which they use to create the sounds of creatures and environments. They do use commercial effects libraries, but they definitely mix in their own sounds.

While on our visit, we spent time with a number of people in the sound/music area who each took time to show us a bit of what they do and talk to us about the game sound world. Thanks to everyone at Blizzard for a great visit!

And, here's the obligatory photo of our group in front of the Blizzard Orc:

Speaker cable - critical listening tests

In the Critical Listening class, we did some intensive listening to different loudspeaker cables. I love following the audiophile discussions about cabling and I especially love that people will pay thousands of dollars for several feet of copper wire. However, there are audible differences. 

The four cables that were auditioned:

1. Apature Accusound L-SP518
2. Monster Cable - original speaker cable
3. Monster Cable - Navajo SuperFlat
4. #24 solid conductor zip cord

Josh listening at the sweet-spot.

The amplifier was a Crown D75, which was chosen because of it's very high damping factor, neutral sound, and convection cooling (no fan). 

The loudspeakers were Tannoy PBM 6.5's - recently re-coned. It's sad/great/funny that these are the only passive studio monitors that we have!  Personally, I love these Tannoy's despite their rather prominent LF bump at 125 Hz. 

The sound source was a Oppo SACD player connected to a passive attenuator to control volume. 

The switch box was designed and built by Tim Brown (MFA class of 2011) based on an original design by myself. It contains 4 DPDT sealed relays in each box, connected to a controller via MIDI cables. One box is connected to the amp and the other to the speakers. The cables under test connect the two boxes together.  Admittedly, the wiring used to fanout from the switch boxes is also part of the circuit, but whatever it adds remains consistent regardless of cable under test (that wiring is #10 stranded power harness cabling visible as red/black in the picture below).

There were several music selections based on material the class was already familiar with.  

 One of the two relay switch boxes.

The controller remote.

The entire setup in action.

The results:

1. Apature Accusound - general consensus was that this cable had a colored sound but with a slight efficiency advantage (due to its thick gauge) which was more apparent at low frequencies - thus the result appeared to boost lows compared the the other three (which would be impossible - as wires can't add gain!). Some adjectives that came up were thick, full and veiled.
2. Monster Original - This was the winning cable.  Some adjectives that came up were neutral and clean.
3. Monster Superflat - There was an eerie family resemblance in sound quality to the other Monster product.  However, this cable seemed to enhance brightness a tiny bit - probably by choking off LF.
4. #24 zip - this was admittedly a throw-away entry.  I chose this to be the worst-case without melting or catching fire. Most apparent was a significant drop in level. Clearly the bottom octaves sounded loose and tubby - most likely to damping factor being severely restricted. However, the big surprise was that the stereo sound field seemed to narrow significantly.  This may be due to frequency-dependent skin-effect in the single, solid conductor.

It is important to note that the results are based on qualitative listening and not scientific measurement. This is in-line with what the class is about.  It is equally important to note that the cables themselves add no inherent sound quality changes, but what is happening here is they change the way the two pieces of equipment in the chain interact (the amplifier and the loudspeaker).   And... it's important to note that these were NOT double-blind tests. This is a class where we try and overcome personal bias without the double-blind or A/B/X methods.

Perhaps someday we will add a scientific critical measurement class. Admittedly, I could use some newer cable to better represent what's out there now - but none of these show up in professional use. Next year I will be adding in #2 or #4 jumper cables and standard-issue Belden speaker wire. Time for an 8 position switch box!

Special Guest: Son Lux

Yesterday, Trends in Modern Sound Design, my class with the graduate students, had a special guest. Ryan Lott, who creates music under the moniker Son Lux, joined us to talk about his work from a creative and technical point of view. We've been talking about Native Instruments softsampler software Kontakt a lot this quarter, and Ryan uses it extensively in his work. He was more than happy to talk about his philosophy of music and how he uses Kontakt to create music and sound that supports his philosophy.  

Kontakt is a very deep piece of software, and it's easy to get lost in the intricacies of the mechanics. Tracking down keymappings, plug-in settings, pitch changes, keyspan settings, etc. can lead one down a garden path, and Ryan tries very hard to use Kontakt as an organic extension of his musical sensibility, not as a hindrance to it. As he explained these ideas, he also walked us through some of the ways he uses Kontakt; I think we were all excited by how well he was able to keep his music sounding imperfect - we often think our music should sound perfect, so it was nice to see someone struggle and succeed at holding on to the cracks.

Ryan recently worked on the score for the film 'Looper' with composer Nathan Johnson, and some of the work that he showed us and played for us today came from that project. You can check out some videos on the making of the score here, here, and here. Ryan was able to set up a Skype conversation with Nathan, and the students asked him about how he used field recording elements in his score. Here's a shot of that session:

Nathan was Skyping in from his current project, where he was working out of the basement studio of the director.  Shortly into our conversation, as Patricia was asking a question, Nathan was interrupted when the director walked into the studio.  The director: Joseph Gordon-Levitt!  I managed to sneak a quick photo.

Squee factor aside, the visit with Ryan and the brief chat with Nathan were really terrific.  I know that I came away from the morning inspired, and I suspect the students did too.  Thanks, Ryan, for a great morning!

Field recording at Black Star Canyon

Last week, my Trends in Modern Sound Design class (which has all six MFAs and a few other students) got up early to truck out about 40 minutes into the desert-y mountains on the east side of Orange County. The class is a rotating topics course, and this year, we decided to take a field recording trip.  Black Star Canyon is fairly quiet (except for the occasional jet or bird chirp), and we wanted to take advantage of the quiet to record some larger machinery sounds.  We settled on two sets of sounds: an old quirky car and smashing machinery.

I divided the class into four groups: near-field recording, mid-field recording, far-field recording, and special projects (including contact mics). Each group had two students and was tasked with strategizing and assembling everything they'd need to make the recording. They assembled cable, microphones, recorders, batteries, tape (sticky, not magnetic), and other necessaries for their particular responsibility.

On the morning of the session, we assembled on campus and caravanned out to the Canyon. First up was an old (200,000+ miles) car with worn tires and busted shocks.  Then, an old beat-up air conditioner.  Then, a lamp.  Each time, the groups strategized and worked together to get the best recordings they could.

Right now, each group is editing their data, cleaning it up, labeling files, adding metadata. When they're all done, we're going to add the sounds to the UCI Sound Effects Library and make them public for all of you.  Until they're done, however, here's a video diary of our trip to amuse you:

Cable length and sound quality

In Critical Listening, we did some intensive evaluation of what cable length does to sound quality -- both at line and speaker levels. The class found the damping factor demonstration to be particularly noticeable (how low DF drastically reduced bass punchiness). Everyone was able to quantify what they heard happening before we discussed the technical reasons (how it's not the cable that is coloring the sound, but rather the way the cable interacts with the electronics and devices at each end).

In this photo you can see the hundreds of feet of cable all strung together:

And the final test was AES digital audio at extreme cable lengths. Dropouts, jitter, pops and muting all came to the party!

Editing Tape!

Yep... in Critical Listening class we actually learned all the alignment, setup, mechanics, operation and editing of reel-to-reel tape.   The format is pretty much headed towards the dead media list but it is such a joy to listen to all that it adds.

In this picture, Matt is experiencing the legitimate, old-school bliss of editing with his ears and not a silly waveform picture on a screen!  Everyone was blown away by just how good a 15i.p.s., 45-degree edit sounds - no pops or clicks - and an auto-magic crossfade. We also listened in great detail to tape compression/saturation and compared it to the Waves Kramer Master Tape plug-in -- of which we were all quite surprised as to just how similar it was to the real thing.

On Women in Sound Design

It doesn’t take a genius to figure out that Sound Design and its related fields are lacking anything close to a gender balance. The vast majority of designers in MFA programs are men. The vast majority of designers in the freelance world are men. The vast majority of people who work sound on Broadway, work for sound-related companies, work in sound design training programs, or work on the sound crews in regional theaters are men.

It’s a shame.  And we all know it.

So, why aren’t there more women working in sound?

The answer is not because women can’t ‘do’ sound. There are some great women sound designers out there: Janet Kalas, Liz Atkinson, Veronika Vorel, Jana Hoglund, Elisheba Itoop, and the Tony-nominated Cricket Myers all do excellent work (and to my ears, the percentage of women sound designers who are talented is vastly higher than the percentage of men sound designers who are talented).  There are great women working in non-design capacities: Liz Coleman & Bridget O’Connor in NYC and Amy Wedel at Baltimore Center Stage are all highly skilled. There are talented women working in the business side of sound: Ellen Juhlin at Meyer Sound is a constant fixture at conferences and events worldwide (and, of course, let’s not forget Helen Meyer herself!). MFA programs around the country are adding women sound designers to their faculties.  Eileen Smitheimer at U. Delaware, Victoria Delorio at DePaul, and EunJin Cho at Louisiana State are some of the few female sound design professors, but they’re joined in the (academic) gown this year by two exceptional women: Amy Altadonna at UMass-Amherst and Sarah Pickett at Carnegie Mellon University.  Each of these women proves every day that women CAN ‘do’ sound.

The problem is not that there aren’t ANY women who can ‘do’ sound. The problem is that there aren’t ENOUGH women who can ‘do’ sound. The cause for that, I think, is easy to identify: the institutionalized chauvinism inherent in almost every field that could factor in to an interest in sound design.  Consider these various ways that a young person might be first introduced to sound and sound design:

• Working on stage crews in school or at local music clubs. Stage crews are often male-dominated, and chauvinism is rampant.
• Composing music. While music performance is much more fairly balanced by gender, composition is still dominated by men.
• Theater Design, except for costume design, is still a male-dominated field (we have eight design faculty in design at UCI, only two of which are women), and it’s easy for educators to overlook interested students who don’t match their image of what a designer should look like.
• Science and the scientific mind. Despite early test scores that reflect equal intellectual aptitude in math and science, girls are often left behind in science classes at an astronomical rate. After many years of work by dedicated educators, this trend is starting to change, but there’s still a lot of work to do in this area.

Say you’re a young woman with an aptitude for sound.  In order to discover sound design, you have to thread a gender needle. Maybe you’re good at science, but you have to get through school without giving up. Maybe you’re a bright composer, but you have to have the right opportunities to shine. Maybe you’re technically inclined, but you need to convince the crew chief that you’re not a weakling full of dead weight before you can go near the sound console.

Solve for XX (that’s a chromosome joke…)

If we want to bring more women into sound design, we need to attack on all of these fronts simultaneously, and while none of us can do everything, each of us can help in our own way. At UCI, here’s what we’re doing to promote women in sound:

• Cultivate undergraduate sound designers of both genders. Our first contact with undergraduate students is usually through a class called Drama 50D: Introduction to Sound Design, and it is usually during that class that undergrad students start to discover sound design. We’re very alert to any and all aptitude for design in the class, and we work very hard to fight against the tendency to focus on men during technical discussions.
• Graduate student population. Even though our program is still fairly young, we have a strong history of women in our sound design program. In the last four classes to leave UCI, we’ve had three women (Cory Carrillo, Noelle Hoffman, and Beth Lake), all of whom are doing excellent work now that they’ve left UCI. Having a high rate of women in the program has a number of benefits unconnected to the women themselves: 1) a visible plurality of women is another way to indicate to undergraduate students and potential MFA students that women are welcome in our program, and 2) a plurality of women serves as a deterrent for the men in the program (faculty, staff, and students) to accidentally lapse into chauvinist behaviors.
• Recruiting. Understanding that young women lack the institutionalized support to discover sound design (see the previous section), it’s unsurprising that women are deep in the minority of the application pool. Because of the lack of support that women in sound, science, and/or design often get, we operate under the assumption that the average woman applying to our program has had less experience, mentorship, and encouragement than the average man. That doesn’t mean that she’s any less talented; rather, it just means that on average, she may not appear as strong as the male applicants.  To counter this, when we recruit, we take an extra-close look at female candidates, digging deeper to see if what may appear to be an unqualified candidate is actually a diamond in the rough. (I want to be quite clear here – we do not practice any sort of Affirmative Action, and we would not accept an unqualified woman instead of a qualified man. We simply make an extra effort when reviewing female applicants.).

In Conclusion

Every few months, I have another conversation with a different colleague about women in Sound Design, both professionally and at UCI.  During those conversations, most of what I’ve written here comes up, and I’m happy to have the conversation multiple times to keep the topic at the forefront of our thought. I typically wouldn’t write something like this on the blog; it’s a sensitive subject, and I’m sure I’ve rubbed someone the wrong way. However, we’ve recently started classes for the year, and for the first time since we’ve had a full roster of sound design MFA students, we only have one woman student. The dearth of women is not for lack of trying, but in the last two years, we have not found any women that we thought were ready for UCI Sound. Maybe we’re looking in the wrong places?

At any rate, I’ve been thinking a lot about this, and I wanted to take a time to reaffirm our commitment to women in sound design and to confirm that I am looking forward to having more women join us in the future.  If you’re a woman sound designer (or a man, for that matter), and you are interested in UCI Sound, please drop me an email of introduction and let’s talk.

(note: the views expressed above are entirely my own and do not reflect the views of UCI, UCI Drama, or the UCI Sound Program)

Special Guests: Nagel and Frears

Yesterday was a day full of special guests here at UCI.  In Trends in Modern Sound Design, a rotating topics class for all MFA Sound Designers, we welcomed Andrew Nagel. Andrew works with L'Acoustics, a manufacturer of high end loudspeakers. L'Acoustics is based up in Ventura County, so it was an extra-special treat for Andrew to come down and visit with us down in Orange County. He talked with us for three hours about his career path from freelance design through consulting and ending up at L'Acoustics, his thoughts on education versus real-world experience, and some products that L'Acoustics has developed recently as they try to build market share in the theater market. He also invited us up to L'Acoustics in the future, and I'm hoping we're able to make that happen soon!

Mark, Brian, Matt, David, Andrew, Josh, Patricia, Michael, and Stephen

In the afternoon, we inaugurated the new Design Colloquium Series with a talk with Will Frears. Will is a busy theatre & film director, primarily based out of NYC, but he's in town working on Build at The Geffen Playhouse, which is currently in previews.  We invited him down to talk about his career and thoughts on the theatre with our students. We had a good turnout - not only were the designers present, but we had some actors and some undergrad directors. Will spoke for about 90 minutes, answering questions, telling stories, and providing advice to the actors and designers as they start to build their career. He had a lot to say, and we were glad to have him down.

Will Frears (left) talks with Head of Directing Jane Page and Sound Design Student Josh Fehrmann after the Colloquium.

Thanks to both Andrew and Will for taking the time to come down and talk to us!

Rational Acoustics SMAART Training.

Rational Acoustics SMAART Training.

(A.K.A Adventures in Becoming a Better Sound Communist)

As the summer of 2012 slowly came to an end, we at UCI Sound decided to jumpstart our thinking machines by hosting Jamie Anderson from Rational Acoustics for a three day SMAART training class.  Though I have a Louisiana public education, I am not spelling Smaart wrong.  SMAART stands for Sound Measurement Acoustical Analysis Real Time. It is a brilliant piece of measurement software that we use here at UCI to understand and quantify what our systems our doing in the room they are in. Smaart is an industry standard in measurement software and, as we learned, it can serve as a valuable tool for system design and optimization. Over the course of three days we learned a tremendous amount about theory, application, and use of the software.

Day 1 began with an exploration into the fundamentals of sound. This was a wonderful opportunity to review and revisit many of the topics we discussed at the Meyer Seminar earlier in the summer. It is always great to have a refresher and further understanding the physical properties of how sound works.  Jamie broke down the system design timeline into six parts. He also reminded us that often as sound practitioners we are thrown into the creative process at various points along the process.

The six points to good system alignment are

1.                    Concept/Artistic goal- (What are the artistic needs of the piece of art? What story does the system need to help tell?)

2.                    Venue Evaluation/ Modification- Where is the performance taking place? What are the acoustical/physical limitations of the space?

3.                    System Design/Equipment choice- Make sure you have the right equipment for the job.

4.                    Equipment Verification/Installation-Once the equipment is installed verify that it works. SMAART is a great tool for verifying problems within the signal chain.

5.                    System optimization/ Tuning/ Voicing- The process of voicing a system to meet the artistic goals and demands of a production. For example, a rock show might want to have a heightened low end to provide that “punch” to the kick and the bass.  This is where Smaart really excels. Using the various forms of measurements, Smaart gives the designer valuable information that can aid in tuning/ alignment.

6.                    Realization, Use, Adaptation- We have all seen the engineers at FOH constantly looking at their RTA or Transfer Measurements. Because we don’t work in perfect environments the sound is constantly changing. We have to be able to adapt the system to the conditions of the night. Every show is different. Smaart is a great tool to monitor and understand system response during the show. Especially with the use of wireless microphone a system tech could literally walk around with an iPad and capture traces all around the space for reference. The possibilities are endless.

During day one Jaime said that the goal of the training was to become a better “Sound Communist.” We want everyone to get the same show. Yes..... this is impossible, but I feel it is a great thing to strive for.  So, embrace/ strive for equality in your systems. Day one was filled with a ton of information about the Smaart interface and some techniques on getting better measurement data.

Smaart does two forms of measurements. The first is single channel measurement. These measurements are absolute. A spectrum measurement is one type of single channel measurement. For example a mic would go into Smaart and analyze the frequency response of the speaker at that given location in the space. These measurements measure frequency and amplitude. The time domain is excluded.

Smaart also performs dual channel measurements. These measurements help dive into the guts of a system. They can help solve problems within the time domain as well as show the differences in frequency response from what is being sent to what is actually being produced though the air.  The transfer function is a great example of a dual channel measurement.  In this measurement, a reference input signal is compared to a measurement on the output (i.e. direct pink noise from a console is sent into Smaart as a reference and out of the speaker. The second channel would be a microphone measuring that signal out in the house). Smaart then compares the differences of the two signals to formulate a transfer function. The phase response and spectrum response of the data are then graphically represented within Smaart.  What makes this measurement so powerful is it takes the time domain into account. With this information we can decipher the phase response and arrival times of sources. We can even determine the polarity of a speaker using the impulse response.

At the end of day 1 a lot of our minds were blown at the fact that Smaart will easily average numerous traces. This is useful and gives the engineer a better understanding of the average response of a system in a given area. The process of averaging is done by taking multiple traces in a given area; then, within a menu in Smaart, the user can select those individual traces and average them together. A graphical average will appear and show the overall trend of response.  The averaging feature is quite useful in showing any big issues within a system. Going after the big issues is much more effective than going after the small stuff because every seat is different.

Jaime has a great phrase for discussing prioritization: “Rocks, Pebbles, Sand, ……Beer.” In order to be better sound communists, we should tackle the big problems first. Once the big problems are solved, then we can work on the little things if we get the time. Of course, beer must happen after a long day of alignment. Do make time for that.

Day 2

The second day was where we really learned how to utilize Smaart. In the morning, we took many different measurements and put Smaart through its paces. Here at UCI, we often use Smaart for tuning. Jamie showed us many tips and tricks of better navigating the interface. After our measurement calisthenics and lunch we started utilizing Smaart to set crossovers and exploring the impulse response trace.

The Impulse response measurement is a powerful measurement. It is a dual channel IFT measurement that measures amplitude over time. Why is this useful? Well an impulse response can show your arrival times of reflections, other speakers, other drivers, and even polarity.

 

(Above is an example of an impulse response measurement. The large spike is the first arrival of sound. The smaller spike represents a later arrival.)

Day 3

Day three was a practical application day.  Instead of sitting around and talking theory, we came up with some practical applications for using Smaart. Before we began, Jamie made a point to discuss reference microphones. Thru the whole seminar, we were using various measurement microphones at various price ranges. The lesson we learned was that though these microphones have a difference in frequency response, noise floor, and price, they can still get the job done for measurement. The frequency response curves for every microphone had differences in the high end past 5k. This difference in frequency response is minimal to the difference in response one would get by moving the microphone and inch in any direction. Also, Smaart can import data correction curves to flatten out the response of a microphone. So…in the live environment an $89 microphone will perform quite well for measurement.  Where you do run into problems is that the sensitivity and noise floor of cheaper microphone is often less desirable than the more expensive quality measurement microphones. Yet, as a grad student on a budget, it was comforting to hear that an $89 microphone could get the job done.

The Smaart training seminar was an amazing opportunity that allowed us to further familiarize with the powerful tool. More importantly, we were reminded that the journey to good sound is a constant leaning process. We learned a ton and it was a great way to start off the year. I know all of us will utilize the things we learned for the rest of our careers. A big thanks goes out to Jamie Anderson and all at Rational Acoustics for an amazing three days of learning. This has helped us grow as artist, sound practitioners, and sound communists. Thanks for the fun.

-Josh 

A year after his passing... a quote that rings true...

It's technology married with liberal arts, married with the humanities that yields us the result that makes our heart sing.   -Steve Jobs  1955-2011

Using Shotgun Mics Indoors...

...might be a bad idea, according to this interesting piece I read this morning.  Check it out four yourself; I'll post a bit of it here to whet your whistle...

I have been researching an idea that I have been hearing for a while:

It’s not a good idea to use a shotgun microphone indoor.

I want to check this question out and, eventually, make some tests. Here we go!

Audio GL

Some really cool 3D sequencing software that's still in beta.

Ain’t Nothin’ But a Phase Thing

Last week, UCI hosted the Meyer Sound seminar on Fundamentals of System Design, Implementation & Optimization, led by Steve Bush. For all of us involved, this was an excellent opportunity to return to the basics of system design and ear training for live sound. Steve started at the ground level and took us through the process of critical decision-making, at a pace that allowed everyone in the room to stay on board.

The first day was spent reinforcing the basics. Steve set up combinations of UPJ arrays, UPJ & M1D subs, & M1D sub arrays, and demonstrated the results both aurally and visually in SIM. We did a lot of listening to comb filtering and polarity reversal with pink noise to get our ears acquainted with those sounds. Steve drilled us on wavelength and period recognition, asking questions like:

Q: If Period = 1/Frequency & Frequency = 1/Period, what is the period of 100 Hz?

A: 10ms. 

Q: What happens if two 100hz sine waves are sent to the same speaker with one delayed 5ms?

A. Complete cancellation

The underlying point of the exercise was to reinforce the importance of loudspeaker placement when designing systems, allowing us to speedily approximate the basic interaction between two speakers at any distance from each other. Just remember: 100hz is a mini cooper, 1kHz is a hoagie, and 10kHz is your pinkie finger.

Steve heavily reinforced the causes and effects of phase in all stages of system design. He set up a situation in which one source of pink noise was split and sent to a single speaker, and one feed was delayed an unknown amount. By examining a combination of the frequency and phase traces in SIM, we were able to see correlation between the frequency of the first dip in the combing and the 180º phase cancellation point. We would then double that frequency to determine the frequency of the next peak, then find the period of that peak to determine the delay between the two sources. For instance, if the dip is at 500, the peak would be at 1k — therefore, there would be 1 ms of delay present.

To demonstrate some of these effects, Steve set up a fairly typical tuning situation with a single UPJ and an M1D sub. Typically when tuning these speakers, you typically insert some form of high pass filter on the UPJ & low pass on the M1D sub. As Steve demonstrated, however, these filters introduce a shift in the phase curve of each cabinet — specifically, these 2^nd order filters used within the Galileo 616 processor create a 90 degree phase shift at the cut frequency for each speaker. In other words, if the two filters are set at the same frequency, they create a 180º phase difference at this crossover point. The solution? Steve merely flipped the polarity on the sub, “turning the nulls into peaks and the peaks into nulls.” This shifted the cancellation point of the two speakers upwards in frequency, to a range that the subwoofer does not cover — in other words, there was no perceivable cancellation!

We also practiced arraying 2 UPJs, but in a different style than has been done here at UCI recently. Steve decided to treat one of the two cabinets as the main source, with the other acting as a kind of a fill that expands the width of coverage of the first. The measurement process went as follows:

1.  Capture the response of the main cabinet on-axis in SIM.

2.  Shift the captured trace down 6dB.

3.  Move the mic toward the coverage limit of the horn, until the live trace matches the -6dB one. This is the “-6dB point” of the horn.

4.  Mute the main speaker and bring in the fill.

5.  Adjust the placement of the fill until it matches the -6dB response of the main speaker. This means that the coverage of the speakers crossover at the -6dB point of each.

6.  Unmute the main speaker and tune the delay of the fill until the responses match.

7.  EQ the fill as necessary

Effectively, this creates the illusion of a single UPJ that has the extended coverage of an additional UPJ horn in one direction. Very cool, and definitely something we will want to experiment with.

One of the most interesting topics we covered was the phase response of a single loudspeaker within itself. Steve definitely blew a few minds in the room when he talked about the slow response of the woofer of a cabinet when compared to the tweeter. He also covered the use of all-pass filters in tuning. All pass filters provide no change in the frequency response of a signal, but merely introduce a delay in the signal. Steve explained that Meyer tunes the phase response of its cabinets by splitting the input signal into frequency ranges and inserting all-pass filters in such a way that the higher frequency ranges are delayed to arrive more in time with lower ranges  — effectively evening out the phase response of the cabinet. In the case of the UPJ that he used for the demonstration, the phase deviation is no more than 540º. Steve also mentioned that all-pass filters can be useful tools when matching the phase response of two speakers made by different manufacturers — but he also warned us that misuse of the all-pass filters can result in significant problems in other areas of tuning.

Steve touched on numerous methods of arraying subwoofers to allow directional control of the low frequencies. A sub-gradient array consists of two subs facing forward in a single-file line, with 3.5’ of separation. The rear sub is delayed to the front one, and then the polarity is reversed on the rear sub. This effectively creates strong cancellation in the rear, allowing the overall volume to be pushed without affecting those behind the array as much. An endfire array is a similar setup, except that the front sub is delayed to the back one, and there is no polarity flip. This creates constructive interference in the front, and destructive in the back. Endfire arrays can also consist of more than two subs in a line. Steve also showed examples of arrays-of-arrays with subs — for instance, a line of endfire arrays across the front of a stage.  He cautioned us on the use of these sub arrays, though, as even the smallest problem (like an XLR wired with reversed polarity) can completely destroy the effect.

One of the goals for the seminar was to practice our newfound skills on the rep system of the Claire Trevor Theater. The rep system includes:

 

•   Two line arrays, each with (8) M1Ds & (1) MID sub, on either side of the proscenium

•   (2) arrayed UPQs serving as the center

•   (2) MM-4XPDs at the rear of house serving as fills for the FOH mix position and the handicap seating

Steve decided to leave one of the arrays set up in the rep position, and experiment with the other one for comparison. We lowered the array to try new splay angles and heights and listened to how each set of boxes interacted with the room. It was a rare and unique opportunity to go through the steps of tuning a line array while Steve talked us through what we were hearing.

This seminar was an incredible experience for all of us at UCI. Steve was a wonderful teacher who gave some of the best-worded examples and definitions for fundamental concepts I have heard to date. He did a fantastic job of translating the results of SIM measurements into aural examples, and he explained everything in a manner that everyone, at every pace, could grasp. We really can’t wait to try out what we learned in the fall! Thank you to everyone involved and we hope to do this again soon!

^Patricia & Matt