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Posted by on Jun 28, 2013 | 8 comments

Tutorial: A compressor in Pure Data

Compressors have become more than just gain control units, they can be just as important as EQs in shaping a sound and sometimes even more so. For the mathematically inclined, a compressor works with a transfer function, or in plain speak, it changes its input in a predictable way. The controls of a compressor help specify this transfer function. The most common controls include: threshold (specifies when the compressor kicks in, usually in decibels), ratio (the amount a signal is compressed once it crosses the threshold), attack (the time taken for the compressor to begin compressing once the signal crosses the threshold), release (the time taken for the signal to return to ‘normal’, i.e., for the compressor to stop having an effect) and make-up gain (a post compression gain). It is quite common for a compressor to have other controls like specifying an alternate side-chain signal, filtering of the side-chain signal, choice between RMS and peak detection or look ahead (where the signal is delayed and then compressed).

Building a compressor in Pure Data (or Max) can be fairly straightforward – depending on the functionality you are looking for. For the purpose of this post I will include the following controls:

  1. Threshold
  2. Ratio
  3. Attack and release (with a unified control to keep things simple)
  4. A choice between peak and RMS detection
  5. Make-up gain
  6. Lookahead

A typical compressor works by analysing the input signal and applying a reduction in gain to this same input signal based on the parameters specified (threshold, ratio, etc). A simplified schematic:

SimpleCompSchema2

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Posted by on Apr 30, 2013 | 3 comments

Pure Data Wavetable Synth – Part 9 (Fin)

Part09-01For those of you who just want to play around with the finished project, there is a download link at the bottom of the article. Despite all of this, I’m still relatively new at Pure Data and the Max language. To those who chime in with corrections or clarifications in the comments, you are most appreciated! If you’re new to PD, make sure you check the comments section for clarifying info provided by generous souls.

Last time, we implemented a three stage filter section with independent LFOs to sweep the center/cut-off frequency of each one. Today, we’ll finish up this patch by adding two last features…an anti-aliasing filter and the ability to record to the hard drive directly out of the patch. If you’re somehow just finding this series of tutorials, or you haven’t finished the previous steps, might I suggest you look those up here? This will also be the last time I’ll remind you to setup your MIDI controller in Pure Data before opening your patch. ;)

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Posted by on Apr 25, 2013 | 6 comments

Pure Data Wavetable Synth – Part 8

Part08-01aDespite all of this, I’m still relatively new at Pure Data and the Max language. To those who chime in with corrections or clarifications in the comments, you are most appreciated! If you’re new to PD, make sure you check the comments section for clarifying info provided by generous souls.

We’re picking up steam here. The synthesizer is essentially done. What we’re doing in the last two projects is adding features to make it a little more fun. Today, we’ll be adding in a 3 stage filter section. We’re going to route our synthesizer output through a hi-pass filter, then a band-pass filter, and finally a low-pass filter. It will pass through each of them in series, but we’ll be able to turn the filters on and off. Just to make things a little extra interesting, we’ll incorporate an LFO into each filter to sweep the center frequency (which we’ll also be able to turn on and off). You’ve completed the previous seven tutorials…right? ;)

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Posted by on Apr 23, 2013 | 1 comment

Epic Sound’s Guide to SFX Relaunched

 

2013-06-cropped

A wonderful resource for budding and veteran sound designers is the list of ways to make certain sounds that Epic Sound has been hosting for many years.  Recently it got an update which is worth checking out.  Epic Sound was nice enough to send us over a nice Q & A about the relaunch:

 

David Filskov’s Guide To Sound Effects Relaunched

Sound designer David Filskov’s Guide To Sound Effects has just been given a major overhaul, with a cleaner look, new search options and backend improvements for quicker updates.

Here’s what David himself has to say about it:

 

Q: First of all, what is The Guide To Sound Effects?

DF: It’s a list – a big one! – of interesting ways of making sound effects. It has lots of ideas, ranging from how to make the always-handy sound of alien egg sacks, swinging swords, rat shrieks and scary weapons – and many, many more.

The ideas come from sound designers from all over the world – and as far as I’m aware, it’s the biggest list of sound design ideas available anywhere online.

 

Q: How did The Guide to Sound Effects get started?

DF: I’ve worked as a sound designer since the late ’90s, and I’ve always been on the lookout for new ways of creating sounds. Back then there weren’t many hands-on guides available to sound designers, so I started to compile my own list of the best / most interesting approaches to making new sounds.

At the time, I was part of a mailing list called VGM which a lot of brilliant sound designers subscribed to – and whenever I saw an interesting idea there, I made sure to jot it down. I also added my own ways of making sounds – and gradually, the list grew to what it is today.

At first, it was just meant for personal use, but I figured that these ideas could perhaps inspire other sound designers too, so I decided to share it.

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Posted by on Apr 23, 2013 | 2 comments

Pure Data Wavetable Synth – Part 7

Part07-01Despite all of this, I’m still relatively new at Pure Data and the Max language. To those who chime in with corrections or clarifications in the comments, you are most appreciated! If you’re new to PD, make sure you check the comments section for clarifying info provided by generous souls.

Today is “amplitude” day in our wavetable synthesizer series. We’re going to be implementing amplitude modulation, as well as a method to control the ADSR envelope of our individual voices. Do I need to say this next part again? Well, I will just in case. This is part 7 in this series of tutorials. Reading parts 1 through 6 before tackling today’s tasks is encouraged. As with the last two tutorials, make sure you connect your MIDI device and configure it in PD before opening your patch. MIDI input and control won’t work otherwise.

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