
Recreating the THX Deep Note (2009) - citywide-fondue
http://earslap.com/article/recreating-the-thx-deep-note.html
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vortico
Here's what the THX note would look like in creative sheet music notation.
[https://twitter.com/THX/status/1000077588415447040](https://twitter.com/THX/status/1000077588415447040)

DEEPNOTE from NYSTHI for VCV Rack does this in a virtual modular environment.
[https://github.com/nysthi/nysthi#deepnote](https://github.com/nysthi/nysthi#deepnote)
You could create this with other modules too, like E-Series E340.

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djmips
There's seems to be a THX contest on currently and I found this version quite
remarkable. [https://youtu.be/ZRvJW4-izLs](https://youtu.be/ZRvJW4-izLs)

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ElCapitanMarkla
that is amazing haha

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sien
That's really neat.

There is a very good 20 000 Hz podcast on the creation of the THX Deepnote:

[https://www.20k.org/episodes/thxdeepnote](https://www.20k.org/episodes/thxdeepnote)

[https://www.20k.org/episodes/thxdeepnote2](https://www.20k.org/episodes/thxdeepnote2)

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MPetitt
If you’re interested in the history of stuff like this be sure to look into
Beaver and Krause
([https://en.m.wikipedia.org/wiki/Beaver_%26_Krause](https://en.m.wikipedia.org/wiki/Beaver_%26_Krause)).
If you recognize the THX sound then you’ll also probably recognize the last 30
seconds of Spaced
([https://youtu.be/2xKO3KAtDZ0](https://youtu.be/2xKO3KAtDZ0)). They started
off as early Moog salesmen showing off equipment and ended up introducing many
famous musicians like George Harrison, the Doors, and the Byrds to electronic
music. They also scored for movies such as The Graduate, In Cold Blood, Point
Blank and Rosemary's Baby. True pioneers in the space and good music to boot.

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Ironchefpython
The version on the official site (worth a few clicks if you have headphones)

[https://www.thx.com/deepnote/](https://www.thx.com/deepnote/)

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another-cuppa
Headphone? Deep Note was made for speakers.

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Jaruzel
And mixed for at least a 5.1 soundfield. The low frequency start absolutely
has to come from the subwoofer, or the whole effect is lost.

I have deepnote as an AC3 audio file, along with a lot of other sound clips
such as the original Dolby Digital trailers (the steam train is my favourite),
and when ever I'm tweaking the audio in my Home Cinema I always fire them all
up and give the house a good shake :)

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another-cuppa
It doesn't necessarily have to come from a subwoofer. Dolby specifically
states that the LFO channel does not have to correspond to a physical speaker.
The LFO channel only exists to ease retrofitting a subwoofer into old cinemas
(in that case they would simply wire the LFO to a subwoofer and be done). But
any other channel can contain bass information and in practice a new cinema
will use a bass management system to route bass from all channels into their
subwoofers. In theory a cinema could also have no subwoofers at all and send
all bass to the mains and drop the LFO. It all works.

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basil-rash
Link to the real one seems to be dead. Here's a version I found on youtube:
[https://www.youtube.com/watch?v=uYMpMcmpfkI](https://www.youtube.com/watch?v=uYMpMcmpfkI)

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basil-rash
Edit: someone else posted a much better version,
[https://www.thx.com/deepnote/](https://www.thx.com/deepnote/). My link fails
in comparison. Also, that website is actually pretty cool.

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juanuys
Prior discussions:

2014:
[https://news.ycombinator.com/item?id=7537674](https://news.ycombinator.com/item?id=7537674)

2009:
[https://news.ycombinator.com/item?id=725564](https://news.ycombinator.com/item?id=725564)

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jacquesm
This has been on HN several times in the past:

[https://hn.algolia.com/?query=Recreating%20the%20THX%20Deep%...](https://hn.algolia.com/?query=Recreating%20the%20THX%20Deep%20Note&sort=byDate&dateRange=all&type=story&storyText=false&prefix&page=0)

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thu
Maybe someone here can help.

A few years ago I tried to implement what is shown on that page but without
using something like SC, i.e. I was generating list of samples directly. I
recall I was stuck trying to find how the 2nd order resonant Low Pass Filter
(BLowPass [1]) was working.

Any good pointer to help me write it would be appreciated. I didn't spent much
time reading SC source but I think it was not very clear for me without much
sound synthesis knowledge.

1\.
[http://doc.sccode.org/Classes/BLowPass.html](http://doc.sccode.org/Classes/BLowPass.html)

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TheOtherHobbes
A typical implementation is simple - a couple of single sample delays, a
couple of multiplications, some addition.

Deriving the coefficients and the design is not simple. There is math.

[https://ccrma.stanford.edu/~jos/filters/Two_Pole.html](https://ccrma.stanford.edu/~jos/filters/Two_Pole.html)

A characteristic equation called the Transfer Function defines what a filter
(actually any circuit) does using polar complex numbers to represent the
frequency and phase of an arbitrary input signal.

Basically the TF says "If you put a sine wave in, the circuit will change its
amplitude and phase like this" \- across all possible frequencies.

Filters are usually designed with a combination of poles and zeroes.

Poles are low-pass building blocks. Zeroes are high-pass building blocks.

Poles are a polynomial on the denominator of the Transfer Function, zeroes a
polynomial on the numerator.

When you have your continuous Transfer Function you apply something called a
z-transform, which gives you a form you can turn into a difference equation,
which is basically the core equation for the filter, and another set of
equations for calculating the coefficients.

Instead of deriving this from scratch you use standard forms which you can
find on sites like the JOS tutorial I linked to, and dspguru.com.

But you do need to have some idea how all of this works - and also when this
nice simple model stops working. (E.g. digital filters have issues close to
the sampling rate, so good designs compensate for this and don't just use the
difference equation blindly.)

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thu
Thanks a lot. It seems this remains quite a challenge to turn those into
working code though !

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jancsika
Here is one done in Pd:

[https://www.youtube.com/watch?v=Rz1uNLHorEs](https://www.youtube.com/watch?v=Rz1uNLHorEs)

The little GUI allows you to change all the parameters, like the partials of
the final chord and the range of the glissando for each voice.

But I think the sound would only "lock in" by recording an actual cello and
using that for the source of the oscillator. (A friend of mine suggested a
cello harmonic which seems right given the timbre of the opening texture.)

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jancsika
There's also the issue of how far each voice travels from its initial randomly
chosen state to its goal frequency.

It sure sounds to me like the original algorithm sought to choose initial
frequencies that would be farthest from the goal frequencies. In other words,
a lot of voices traveling several octaves from low to high while others go low
to high. But I haven't tested that.

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rocky1138
The one at the end that fits in the size of a tweet sounds better than all of
them, IMO. Including the original.

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xtagon
The early part (with the most randomness) sounds very similar to the prop
buzzing noise multirotors make.

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milansuk
I would never have thought there is a C code behind this masterpiece.

