The Deep Story Behind DeepNote – the THX Logo Theme

This has been expounded a number of times. I thought it would be good to give a full, first-person account with all the details and maybe some previously unnoted tidbits.

But first, a word from the officials:
THX, the THX logo, and the THX Deep Note audio mark are registered trademarks of THX Ltd.

Note that the official site for all things THX is the web site of THX, Ltd. You can see and hear all the versions of the THX logo and logo theme from the beginning to the present. And check out the THX Youtube Channel. The original one that I did the sound for is "Wings". You have to picture it in a dark theater, of course, and taking up a full screen.

The story starts around 1980. In preparation for the debut of “The Empire Strikes Back”, George (Lucas) sent his audio team to inspect the sound system at the Coronet Theater - the big classic theater on Van Ness in San Francisco. I feel free to mention it by name since it was closed in 2005. The team was Tomlinson (Tom) Holman, Ben Burtt, and Gary Summers. In that era, the standard sound system was three Jensen “Voice of the Theater” speakers behind the screen, then some number of surround speakers around the theater. The team was horrified to find that (1) one speaker was turned backwards, and (2) another speaker was on its side and was not connected at all. They put it all back together, but couldn’t get it to sound like the sound system back in their studio. That launched Tom Holman’s push for a theater sound system that met the needs of the modern blockbuster films. He knew that it needed to be tunable to match the widely varied shapes and sizes of theaters around the country, and that it had to be possible to align it so that the sound was as close as possible to the sound in the professional mixing theater where the film sound is finalized. This became the first THX sound system. For “Return of the Jedi”, George insisted that all the theaters that wanted the initial 70-mm release of “Jedi” would have to install the THX sound system. At the time, that was about 160 theaters in the US. As a historical note, George used a similar tool to get the Dolby surround system installed for the release of the original “Star Wars”.

The audio branch of Lucasfilm was called “Sprocket Systems”. Compared to ILM, it was a relatively small but talented group. The manager of Sprocket Systems was Jim Kessler. Most of the task of managing Sprocket Systems consisted of writing the budget, arranging trips, staffing up for major motion picture productions, selecting projects, and the usual day-to-day efforts needed to keep a professional studio chugging along. Lucasfilm has always had a system of “promoting from within”. People were often assigned tasks that might be a bit out of their immediate comfort zone to encourage career growth. Jim Kessler was assigned the task of producing a 30-second “trailer” that announced the THX sound system, to be released with “Jedi”. Jim had engaged a professional animation company to do the work. It was going to be a very classy and dramatic piece with a slow-moving introduction, climaxing by a fade-in of a gigantic metallic “THX”. As is common in big production projects, the animation came in a bit late and a bit over budget.

At the time, I was the head of the Audio Group at the Lucasfilm Computer Division. We had just completed the construction of a large-scale audio signal processor. Most of the folks there knew that I had extensive experience with music and music synthesis. Jim came to me and asked me to produce the sound for the trailer. He said he wanted something that “comes out of nowhere and gets really, really BIG! I allowed as to how I thought I could do that. As soon as he said it, I knew I wanted to start with an atonal cluster that rose up into what the rockers call a “power chord”. My immediate influences were (1) the big chord at the beginning of the Bach Tocatta and Fugue in Dm, BVW 565, about 30 seconds in. The big chord comes back several more times in the piece (2) The end of the Beatles “Day in the Life”. The atonal cluster was heavily influenced by my work in modern music at Stanford CCRMA and at IRCAM.

I recently got in touch with Jim and asked him why I was chosen to do the theme. He said it was partly a political decision. The Computer Division was under pressure from the board and the upper management to prove our worth. This is tricky for a research group. Jim thought it would help if I could actually make some sound that ended up on the big screen. He didn't articulate this to me at the time. I'm just happy that folks liked what I came up with - Jim said that his backup composers included Phillip Glass and James Horner. Some company, hey? Not sure I can live up to that comparison.

I recently received the following note from Eric Christensen:
"Hi James, I am Eric Christensen, formerly of Skywalker Art glass studio and industrial light and Magic. Back in the early 80s one of my best friends, Jim Kessler asked me to design the THX graphic logo. We were out having a cocktail so I took a cocktail napkin and pretty much drew out the logo in one attempt. I started with a T with a long right horizontal cross and place the HX underneath with an underline matching cross somewhat like a Roman numeral. Then I widely spaced small letters Lucasfilm Sound System above and below. All in all it took less than five minutes to sketch it out. Ever since I have never seen any mention of my design. So there you have it, that’s how it originated.

Eric Christensen
Lucasfilm conceptual designer"

Here is Eric's Original Design. So, here and now, let me officially thank and give credit to Eric for his brilliant design which has, indeed, withstood the test of time! Thanks, Eric.

I picked the internal working title of the piece “Deepnote” as a reference to the Douglas Adams “Hitchhikers’ Guide to the Galaxy” ultimate computer that was called “Deep Thought” that came up with the answer of 42 for the question of the life, the universe, and everything! I didn’t figure a way to work 42 into the composition. Too bad. I actually did not expect the name to stick, but it sure did – to the point where THX, Ltd. filed a copyright on the name.

I need to say here that a number of other similar-sounding pieces have been mentioned, including works by Krakatoa, Bernie Kraus, Asia, and others. Let me get something straight – I have never claimed that Deepnote was completely original! As noted, there are important antecedents like Bach and the Beatles mentioned above, and a great deal of modern and electronic music. There is, however, one important difference between my realization of this musical idea and all others – the big chord in Deepnote, based on a 37.5 Hz pedal tone (about 37 cents North of D1), is in just temperament. This is deliberate. It is why the chord sounds “bigger” than any other realization, including the Bach organ chord. Organs (and orchestras) are not in “just intonation”. This is the key secret to the power of the piece. No other realization, including most (all?) of the cool Youtube simulacra, is in just intonation. 37.5 was chosen because it is just about as low as you can get and still have people perceive it as a pitch rather than just a vibration (that would be like playing cards in a kid’s bicycle spokes), and that it is related to 600 Hz which is easy to compute with (anything with a “6” in it can be divided by 2, 3, 6, and often many others).

I asked Jim for the timings of the piece. He gave me an idea of how long the introductory section would be, then how long the big “THX” would be on the screen. I set up a few constants at the top of the C program that determined the lengths of the sections. There was INITIALTIME that ended up as 9 seconds, of which the first 4 seconds (FADEINTIME) had the sound come from silence to -12 dB. After that was 12 seconds of RISETIME for the big glissando, of which the last 5 seconds were the SPEEDUPTIME where I accelerated the ramps up to the target final chord. The chord was held 6.5 seconds (HOLDTIME) then slowly faded out for 8 seconds (FADEOUT). The astute reader will come up with a total of 35.5 seconds. Mind you, the original goal was 30 seconds, but the animation came in at 35.5.

These weren’t the original timings. I carefully programmed in the numbers Jim had given me. The day came to record the audio with the animation. This was the first time I had seen the animation. Brian Kelly was the operator in the control room. The animation was on 35mm film. The sound was to be recorded on a dubber as a 4-channel master (LCRS). He played the animation and I hit <return> just as the image came up. We immediately noticed that none of the times lined up with what Jim had told me. Among other things, I had planned on a length of 30 seconds – not 35.5. I went through and timed the actual durations of each segment, typed them into the score file, then resynthesized the piece. We were out of the theater in less than 15 minutes. Gary Rydstrom was present. He later commented that he knew at the time that something important had happened. Little did we know. After that initial recording, Brian continued to play it for group after group that came in to hear it. Generally, after hearing it for the first time, people didn’t say anything. They just filed out silently, or stayed for another playing of it. Here is the original THX logo theme and animation, just as we heard it in the theater in the B-building on Kerner Blvd in San Rafael, CA, sometime in early 1983 (not sure of the exact date).

Hmm. I noticed that the version I reference above is a bit glitchy. I don't have a copy of the original animation, but I do have a (glitch-free) copy of a stereo version of the original audio.

A number of people have asked me about the role of George in the THX logo theme or animation. I can tell you that other than launching the investigation into improving the sound in the theater, he had no role at all. This is not from being aloof or unconcerned with the project - it was just that he had his hands quite full at the time. This was March of 1983. "Jedi" was to be released in May. Anyone who has worked in the film industry will tell you that the last 6 months of production are the very definition of Hell on Wheels. Everything has to come together perfectly to make the release date. For this reason, he had delegated the entire THX Logo animation project to Jim Kessler. As far as I know, he heard it exactly once before the release of “Jedi” and signed off on it. After it gained some notoriety, Lucasfilm started taking it seriously and decided to get a copyright for it, and to have me sign over the rights. I eventually signed an agreement with LFL for a 50-50 split in the ownership (more than I expected!). Here is a scan of the original agreement. Mind you, the logo theme by itself is not a money-maker – that is, no theater pays for the privilege of playing it. Rather, they better play it or they don’t get the next LFL production! There are some relatively modest broadcast royalties – on the order of $200 a year – for playings of the logo theme on radio or TV. I don’t care – I’ll take it. It is a lot of pizzas.

For the copyright, the lawyers at LFL asked for me to prepare a score. I got out my Rapidograph India-ink pens and drafted a score. I did the whole thing from memory, so there are some errors. For instance, the top note is a bit North of an A5, not F#5. I did not note on the score that it wasn’t exactly a D-natural, or that it was in just temperament. Plus, I really didn’t quite know that the pitch range ended up between 200 and 400 Hz. Those were the target values. I had actually put in 40 Hz as the minimum and 350 Hz as the upper limit, but as the notes were chosen by random numbers, and a 1-pole ramp was used, to this day I don’t know the exact frequencies that were achieved. I had just fiddled them until it sounded about right. I wanted it to be complex enough that you couldn’t focus in on a single voice, but that one voice after another would rise up and become audible and separable, only to fall back into the cluster again.

I might mention some of the by-products of using random numbers to drive the composition. The program consisted of one big loop that went around all the oscillators in one second. In the original version, I had 30 oscillators. So, every 1/30th of a second, the next oscillator would get a new (random) pitch and a new (random) intensity, both within prescribed bounds. Until the final chord, the smoothing on the pitch was so strong that in the second that it took to come back to that same oscillator, it was no closer than maybe 70% of the way to the target value. When the big glissando starts, the oscillators got their final target values. As the glissando went on, I speeded up the frequency ramps so that they would get closer and closer to the final values. It was deliberately set so that they never quite got exactly to the final pitches, but were detuned a bit. I tried it once with perfect final pitches, but it made it sound like an electric organ. With the detuned pitches, it sounded much more full and rich. This is presumably the same reason why piano tuners always detune the double-and-triple-strung notes a bit. The final target pitches were multiples of 37.5 Hz (up to 9x) yielding a perfect just-intoned chord.

Now for some of the unintended side effects. One problem is that sometimes the random frequency selection didn’t do what I wanted. Often, it seemed like all the pitches were rising, or all the pitches were falling – they didn’t just randomly move up and down like I wanted. You would have to run off 3 or 4 different scores until you got one you liked.

Another problem was one I didn’t anticipate at all – the folks at Sprocket Systems lost the original recording. Please understand that this is not simple carelessness. It is perfectly understandable and happens more than anyone wants to think about. The number of insignificant-looking little spools of mag (magnetic) stock running around Sprocket Systems at the end of a major motion picture production is staggering. I don't know for sure, but I estimate that there would have been upwards of 10,000 little spools of recorded sound. I have no doubt that if we went in to the hundreds (thousands?) of boxes of stored mag stock in the LFL archives, somewhere among them would be the scrap of stock with the original Deepnote recording. In any case, I had to come in a week later to re-record it. That’s fine, but I didn’t write down the “seed” for the random-number generator. It was set from the date and time, and thus was always different. When I came in to record a replacement, they complained that it didn’t have the same conspicuous bass note that dominated the sound as it raced down to 37.5 Hz. Recall that the amplitudes of the oscillators were set randomly – not just the pitches. It took a number of times through the process to (randomly) get one that didn’t have wacky pitch contours but also had a strong bass note. It still wasn’t as strong as the original, but it would do. So, the “original” deepnote is lost forever.

The original C program was 322 lines of code. The “orchestra” file (written in an extinct language we called “Cleo”) was 248 lines. That file specified the design of the oscillators and envelope generators, the spatialization, and the patch out to the four output channels (LCRS). The original spatial placement just placed each voice in a different speaker, so each speaker had 6 or 7 voices. At the beginning, only one speaker’s worth was sounding. This gives the atonal cluster this curious balance between being transparent and opaque. You think you are hearing into it, but only here and there can you actually pick out an individual voice (without some help). It took about 4 days to write the code and "tune" the composition. It went so quickly because of the huge volume of code already written to run the ASP, including the Cleo language and all the real-time drivers, plus the fact that the ASP did the entire synthesis in real time. All the oscillators, envelope generators, mixing busses and spatialization routines had already been programmed. It was "just" a matter of plugging it all together and writing the compositional program to drive it all. With the real-time synthesis, one day was enough to "tune" it to get the piece to sound like I had envisioned it the minute Jim described what he wanted.

In 2014, the THX people asked me to redo the theme using modern audio standards. This included a 48K sampling rate, 24-bit samples, and modern formats, including stereo, 5.1, 7.1, and the Dolby “ATMOS” 9.1 bed (7.1 with two overheads). Since the ASP no longer existed, I rewrote the system using a modern workstation and C++. It took about a week to program the synthesis engine and another week to “tune” the piece. Additionally, they wanted three different durations – 30s, 45s, and 60s. The big question for me is what did I want to change?

I had always wanted to increase the number of voices. The 30-voice choice was determined by the ASP. Given the freedom of pure software synthesis, I could pretty much choose any number I wanted. I found out pretty quickly that increasing the number of voices beyond a certain level didn't help - it just made it sound like mush. That is, you lost the effect of the odd voice drifting up where you could follow it then diving back down into the soup. I found also that hearing it in a surround speaker system helped the clarity quite a bit. That is, with 5-speaker surround-sound, I could use more voices before it got muddy. I ended up with a somewhat weak rule of about 10 voices per channel, then hand-adjusted each format.

I have had a number of questions about what compositional system or synthesis software did I use. The answer is quite simple for the 2014 remake - the whole thing was one purpose-built C++ program that does exactly one thing - synthesize the THX logo theme. I could have done it in, say, Supercollider or Max MSP but I didn't. I just started coding and 2 weeks later delivered the product to the THX folks. There was quite a bit of tweaking after that. They had a number of suggestions that did, indeed make it better. Even on my laptop, I could resynthesize new versions of it in no more than 2 minutes for all versions (they were all generated at once). And this time I printed out the random number seed and incorporated it into the output file names so I could always perfectly recreate a given version.

One of the things we never got around to doing was what we called “Rockin’ the Logo” – that is, combining live performance with the playback. I produced various versions of the theme (up to 5 minutes in length) that were tuned to concert D – still just intonation, but at least on a note of the standard A-440 scale. I had the idea that the live music would play around an A7 chord during the atonal cluster then would get buried by the big chord, forming the biggest V-I progression in the world. I imagined one Jazz version, one Funk version, and maybe one pseudo-gospel version. The possibilities are endless. Maybe I’ll try it sometime myself. Better yet, you folks try it and post the results on Youtube or something.

I have endlessly enjoyed the various versions of the theme that folks have made, from the Tiny Toons “THUD” to the eyeglass-breaking Simpsons, and all points in between. For me, the vocal version by Mach Kobayashi is absolutely stunning.

So, that’s the story of Deepnote, the THX logo theme, and I’m stickin’ with it!

Here are some related links:

THD Deep Note Part I - Twenty Thousand Hertz Podcast - Kevin Edds
THD Deep Note Part II - Twenty Thousand Hertz Podcast - Kevin Edds
Interview and video from THX, Ltd.
Article in FastCompany
CISION Article
MXDX Interview
VOX/RECODE article

My friend and colleague, Ge Wang of Stanford/CCRMA has a new book out:

"Artful Design"/

In case you're curious, here is a PDF excerpt of the THX Deep Note section, including visualizations and an emulation in ChucK:
THX Page from "Artful Design"

Here is the ChucK code:
ChucK code for THX replica

Finally, here is a "one stop" webpage that links to the above:
THX Summary Page

Unapologetic Commercial Pitch

In conjunction with THX, Ltd., I am offering numbered, signed 8.5x11 prints of the THX Logo Theme score. These embossed prints are on Strathmore textured paper and are suitable for framing. You may order one HERE.