Posted tagged ‘analyzer’

Off to Mexico for AES and SIM3 Training – Updated

April 25, 2010

I have been busy putting together new material for SIM 3 training, and AES seminar and the upcoming Broadway Sound Master Class. You have seen some of the work in progress below, but I have had to push to get things ready for showtime.  Sorry for the delay in getting more things posted and for my lateness in response to Goran. Just pushing it right now – LOTS of really good stuff coming- phase circles galore but priorities………..

AES Expo

I was invited to give a talk for the AES at the Sound Check Expo in Mexico City

This is a big audio trade show in Mexico City. Lots of  levels of gear mixed together: Pro Audio, Music Industry Audio, Guitars, Pianos, Disco lighting , and the most popular event was getting the autograph of a hot young girl singer. I am sorry but I never made it to the front of the line. :-(.

I did a talk for about 1.5 or  hours and it was like giving a speech at the United Nations. There was a faint spanish language echo in the room when I spoke, about 500 ms delayed. It was a translator in a booth at the rear and everybody in the audience was listening on headphones. Wow, this guy was fast – and good, because I even got a few laughs at my jokes. I remember doing a translated seminar once in China. 4 days without a single laugh – until I tripped and fell down on the stage – the crowd loved THAT!   OK back to Mexico. The lecture was very well attended and it was a great honor to have so many people there. We covered alot of interesting topics including subwoofers steering and fun stuff like that. I was told that this was the best attended training session of the convention (about 120 people) and that felt really good. If only I could have gotten the singer girl to join me on stage we would have REALLY filled up the place!

Here are two pics from the seminar. The first one shows me at the podium. I don’t remember the bubbles floating around the room, but you can see them in the picture. The second one shows the view in the room.

AES Sound Check Expo

SIM3 Seminar

 Next on the agenda was Meyer Sound Mexico where we held a SIM3 Training. It was the usual 4 day session, but in Mexico City the sessions are marathons. Typically we go from 10 am to 7pm, but two of the days we went past 9 pm. The Mexico city schools are some of the most interactive of all the schools I do. The students are sendiing up a constant stream of interesting and challenging questions and we cover SO MUCH material. Sometimes the order in which we cover them is a bit crazy, but we cover TONS of topics.

Working with me on this seminar was Oscar Barrientos and Mauricio Ramire(el Magu). These are expert teachers in their own right so it is great to have them to translate and enhance. My typical style, when doing a translated seminar, is to (try) keep my talking short, to make quick switches to the translators. With these guys, because they know the subject so well, they can follow the concepts and even expand on what I say when they move it into Spanish. This helps speed things along alot – because typically a translator has no audio knowledge, does not know the terms, and certainly does not know FFT analysis. (In Korea once we had a translator QUIT at lunch time the 1st day – because she was too humiliated by all the students telling her she was translating all the audio words wrong. A student, Sean Cho, took over the job and saved the seminar).

Most of the students had been to Magu’s and/or Oscar’s training courses before and a few (Eduardo Brewer from Venezuela and Jorge and Juan Carlos Yeppes) had even been to my course before. It is the ultimate honor for me to have engineers return to my course.  The advanced level of the students helped us to move along at a very fast pace.  I am always very grateful about the way i am treated in Mexico. They are SO GOOD to me.

I also had the honor of meeting Luis Pinzon. He is the only person I know with 3 copies of my book – 1st & 2nd edition ingles, and 1st edition espanol. I happily signed all 3 for him. I wish I had brought a Chinese version to give to him. That would have completed the set!  . Luis also gave me his cable checker – which is quite amazing.

I was taken to some really nice restaurants by Antonio Zacarias and also  we went for Tacos to El Charco – which I highly recommend.  Also went to a Chinese restaurant in a shopping mall near Meyer Sound Mexico – I DON’T recommend this place, unless you want to die.  Funny though ….A week later I had Mexican food in China – The Mexican food in China was better than the Chinese food in Mexico, but Mexican in Mexico and Chinese in China worked out the best.

So here are some photos from the Mexico seminar, taken by Eduardo and Hermes. I think I have the names right on the class photo – if not help me out please. Also if you have some others – please send them to me.

Thanks for inviting me to Mexico, and I hope I can come back soon —actually I WILL be back in Mexico this Novemeber – but it  a cruise vacation – so I won’t be working 🙂

Until next time,

Hasta luego y Buena Suerte

6o6

 
Mexico SIM3 Class 2010

6o6 is getting some hands on experienceNow we know who was reading email during class

Yes this is supposed to make sense..........

Magu, Oscar, Paco and 6o6

Eduardo, Magu, Hermes, 6o6, Oscar and the bald guy

6o6

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A Concise Article on Cardioid Subwoofer Arrays – by Steve Bush

March 25, 2010

This article  Tech Talk: Building Directional Subwoofer Arrays

Working toward consistency. was posted just today on the ProSoundWeb by Steve Bush.

Well written, concise, plain English and NO MATH!

 (lo siento que no es Espanol pero tiene fotografias).

I need say no more.  Geez.  That was the easiest post I ever did!

6o6

Cardioid Subwoofer array in an arena

Training at Disney Animation II: Size Matters

February 28, 2010

In the world of animation the world can be as big a basketball and a basketball can be as big as the world. In the real world, size matters. Not in the animation world. In the world of animation audio, size does not seem to exist either. Low frequencies don’t have a wavelength in ProTools. Sure they look all stretched out compared to the HF samples but there are no worries that they are too big to fit in the hard drive. This is not just an issue for this particular studio, but rather studio world in general. Such spaces are controlled environments. Acoustically sterile. Tracks can be synthesized, spliced, re-sampled to another frequency range, mixed with another track from across the world with little regard for the acoustics of the space. The physical nature of acoustics is far removed from the thoughts of people in these quiet spaces. Those of us in live sound never have the luxury of NOT thinking about the affects of the local acoustics, and the loudspeakers that fill them. Live sound people live in an acoustic combat zone – battling the interaction of multiple speakers, open microphones, stage noise, reflections and more.  Studio sound folks can isolate and control sounds to create a clean sound or, if desired, purposefully create an acoustic combat zone for the listeners.

Things we need to know to do our job, and things we accept and move on

Digital audio is pretty much magic to me. Sure it is 1’s and 0’s, a clock frequency and sample rates and all but I don’t visualize shift registers and memory locations as a filter. I turn a knob on my digital parametric and I look at the result on the analyzer. Its amplitude and phase responses are indistinguishable from the analog filters that I understand down to the resistors, capacitors and op-amp feedback loops. The end result is that I accept the digital filter as functionally equivalent and move on to do my job – set the filters to the best shape for the application. Each of us has unique areas that we accept and move on from in order to specialize in our area of interest. Don’t ask me to operate your mix console artistically, but I will be happy to show you lots of interesting things, scientifically,  about what happens to the signal in its custody.

In the world of studio mixing, the focus is on acquisition and manipulation of the “media”:  a recorded bit stream of audio. Once captured the media is free of the constraints of physical size until its final delivery to the audience. The only place where size matters is in the differences between the mix room and the showroom. Here is where an interesting set of proportions play out: a tiny minority of listeners (the mixers) will do the vast majority of the listening  in the small space of the studio, The vast majority of the listeners (the audience) will do a tiny minority of the listening (perhaps even just once – rather than 100’s of times like the mixer)  in the showroom. So the link between the rooms is critical. We have a very short window for people to experience the details the mixers worked so hard to create in their controlled studio environment.

My job here was to train the engineers in how to operate the analyzer. The analyzer measures differences – this is pretty much its entire capability: differences in level, time, distortion, phase, added noise. This is exactly the tool needed to link the studio and the showroom. But the tool is useless without the knowledge of how the differences are shown, and the vital link as to how those differences are perceived. Night and day differences can be shown on the screen – that have no perceptible sonic difference. Conversely we can enact audible differences that will be invisible to our analyzer. It is going to be important to know the difference.

It was not surprising to me that media/engineers there have spent little time considering the acoustical physics at play. It is not their job. The acoustics of the rooms and the speakers are provided by others. Unless there are gross deficiencies in the mixing room setup they can move ahead with their work. Each individual knows which rooms they like – but the central criterion for these engineers is how well the mixing rooms predict the listening experience in the showroom. It is possible with extensive ear training to be extremely competent at hearing the translation, and memory mapping the difference in order to anticipate the effects. It is highly improbable, in my opinion, that one can figure out how to affect these two different spaces in order to make them the most similar, without a thorough understanding of the physical nature: the size, shape, speed of sound, and the mechanisms in our human anatomy related to our sonic perception. A mix engineer predicts the translation, a system and/or an acoustical engineer affects the translation. The system engineer’s role is to help the mix engineer’s predictions come true.

The relative analyzer: Human and machine

Disney animation’s purchase of the SIM dual-channel FFT analyzer creates an opportunity to open a window into the physical nature of sound. The analyzer’s renderings are purely objective, and only displays what physically exists, i.e. – no prediction, no simulation. This does not mean it displays things exactly as we hear them. It measures relationships – some of which we experience directly, some indirectly. For example, let’s listen to a recorded violin track. ProTools can show us the sampled waveform over time of the track – amplitude vs. time. The analyzer can show us the spectral content over frequency, the relative levels over frequency over a given period of time. ProTools can (or at least could someday) show you this as well. That is still the easy part because we still have a one-dimensional rendering of the signal – level/freq. This can also be done with a Real-Time-Analyzer – the king of one-dimensional audio analysis.

Where the analyzer breaks out on its own is in the relative response: the response of the violin at my ear – compared to its own response in its recorded electronic form.  The analyzer can see peaks and dips, how much time it took to travel, how different the arrival time is over frequency (phase over frequency), how much HF was lost in the air, how much energy the room reflections added to the low end, how much noise was added to the signal and more. These modifications to the waveform all come from physical realities, and therefore, the best solutions come with an understanding of the physical nature.

The analyzer sees the difference between an electrical signal an acoustical. Humans can’t do that  unless they have an XLR input in addition to their ears. We hear only the end product, complete with its acoustical effects. We are, however, doing our own version of relative analysis. When we hear the violin track we are comparing it in our brain to our memory file of violin sounds. This history file gives us a variety of reference points to consider: how close we are to the violin, how big the room is, how live the room is, whether the violin being mic’d or a pickup, the presence of nearby surfaces that create a strong reflection to mar the tone, and much more. If the violin sounds close, we have the perspective of being on stage. If it has a long reverberation tail we are cued to believe that we are in a large reflective room. If the picture in front of us is a distant violin playing outdoors our brains will know we will have an implausible scene.

Two other relative analyzers for humans (and other animals) are used for localization.  Binaural localization compares the signals at the left and right ears for arrival time and level. Sound from the left side arrives earlier and louder at that ear and we localize the sound there. For vertical localization we use the comb filter reflection signature of our outer ear to determine up and down. The outer ear is asymmetric in shape and therefore a different set of reflections guides the sound into our ear from above than below. We compare the reflection structure riding on the incoming signal to the memory mapped signature set in our heads and match it up to find the vertical location.

The FFT analyzer operates differently: give it any two signals and they can be compared. Differences in time and level over frequency are directly shown. The analyzer does not need to know what a violin sounds like to know if it is being accurately reproduced. Whatever sound is generated can be the reference for comparison.

The next level is the relative/relative. We can compare the response at one location to another – or at a given time to another – or both. We can look at the studio response in multiple locations, look at the studio compared to the theater etc.  Our human analyzer has this capability as well but this is a considerable challenge to get specific data. One can walk around a room and observe the differences, or you can play your reference track at the studio and then take it to the theater. While it is not so difficult to walk around and hear differences in overall level,  gross frequency response characteristics and spot a strong peak here and there, it is very difficult to pinpoint a cause such as 2ms difference in arrival between two speakers or a 3ms reflection off the console.  It is possible that a person walking around the room can find these things and more by ear alone and propose the best solutions. I could win the lottery too. The probability of success go up greatly if we add the analyzer results to the data set ( we don’t have to stop listening and walking) and supplement our ears with information that we cannot directly experience. Our ears never directly say: The time gap between the direct and reflected sound is 8 ms.  They hear it. The data is in there – but you can’t access it. With our analyzer this number pops right out and the resulting peaks at 125 Hz, 250 Hz , 375 Hz and up will be as clear as the Himalayas.  But in order to get these answers, we will need to know enough about acoustics behavior to have this info at our fingertips.

To be continued