Smashed Up – a Parallel Compression Tutorial

Introduction

Welcome to the Resoundsound parallel compression tutorial. We often use compression to beef things up. The more we compress, the thicker the sound gets. The tradeoff is of course compromising the natural dynamics and nuances of the sound.

This is where parallel compression (also called “New York compression”) comes into play. It’s one of the most powerful techniques in mixing – it allows us to go really heavy on the compression and beef things up without destroying the original peak transients.

This is useful for a lot of things – but I find it especially good when working with heavy, compressed music such as drum&bass and dubstep.

Parallel compression reduces the dynamic range in a different way from regular compression. It’s referred to as upward compression as opposed to regular downward compression. This means parallel compression brings up the quieter sounds and details where as regular compression brings down the highest peaks.

This upward compression effect is achieved by blending together an uncompressed and compressed versions of the same signal. The dry signal provides the transients and natural character where as the compressed version reinforces the low level audio and contributes weight and fatness.

I mostly use parallel compression on drums, but it’s often used on vocals and bass, and can be applied to pretty much anything – even the entire mix.

 

Brief History

The origins of this technique have been a subject of some debate. According to some it originated way back in Motown when they needed something to make the vocal hold it’s ground in a busy mix. Music before Motown – such as Frank Sinatra‘s – had been all about the vocals. The singer was traditionally mixed really up front and sounding quite natural – only with added reverb.

With Motown music this changed – the music was very much about the rhythm. They pushed up the drums and other instruments in the mix. This lead to the vocal getting drowned. They needed a solution where the music comes through loud, but without compromising the vocal delivery. Some say this is how parallel compression was invented, and it does make sense to me. Applied on vocals it made them stronger, bringing up the low level details and making every little nuance come through properly.

A lot of New York based studio engineers were relying heavily on parallel compression in the 70’s and 80’s (hence the term “New York compression”). This is what brought the technique out to a wider scene and made it popular.

 

Before We Begin

I am using Logic Studio for the purposes of this tutorial – apologies to those of you on different platforms.  The principles are the same, however, and I am doing my best to keep everything as simple as possible so that the ideas will translate better to other platforms.

I’m using the terms “dry channel” and “smash channel” here to refer to the uncompressed and compressed channels.

The most common use of parallel compression involves hitting the compressor really hard using high ratios and thresholds. This is what we are doing in this tutorial as well, but bear in mind every situation is different – you can go as hard or subtle as you like.

 

Step One – Set Up the Dry Channel

Set up a drum loop on an audio track. For this tutorial I’ve created a version of “Soul Pride” break.

Here is what it sounds like to begin with:

Step 1: Set Up the Dry Channel

 

As you can see and hear there is quite a lot of dynamics happening – there are a lot of low level ghost snares and other low level noise. We are going to use parallel compression to bring up these low level sounds (including the tails of the louder hits) and give the drumloop some power.

 

 

Step Two – Set Up the Bus Send

Next up we need to set up a bus send on the dry channel. The idea is to get a copy of the signal sent to a bus channel  (aka smash channel), where the compression then takes place.

In Logic all you need to do is to click on an empty send slot and choose a bus – Logic then creates the channel for you automatically and it will show up in the mixer.

Step 2: Set Up the Bus Send

 

[box type=”info” style=”rounded” border=”full”]An alternative approach (and the only one on some platforms) is to create a copy of the audio channel itself and use that as the smash channel. I prefer to send to a bus though: the advantage is that you can send several audio tracks – for example the entire drum kit – into a single bus for parallel compression. It also keeps the arrange from getting cluttered.[/box]

 

Step Three – Smash It

Load up a compressor on the smash channel. Set the compressor to literally smash the incoming signal. It’s a good idea to solo the smash channel at this point for adjusting the settings.

Here is what our example smash channel sounds like on solo:

I’ve hit the compressor hard with loads of gain reduction here. You don’t have to go this extreme, but a pretty hefty compression effect is required in this case to achieve our goals.

I’ve used a short attack setting here which makes the transients (snares especially) sound very clicky and unpleasant. However this will serve to give the finished thing some extra “snap” and “punch” when mixed in with the dry signal in modest amount.

Step 3: Smash It

 

An explanation of the most important parameters in detail:

  • Ratio: Heavy, heavy, heavy. The 1:19 ratio here gives the kind squashing we need here.
  • Attack: Usually best kept fairly short – especially if the transients are good in the original signal. Many times it’s best to leave it at zero. In this case I thought the transients on the dry version sounded a bit soft so I used an attack of 10ms for that extra bit of “snap” to add to the mix.
  • Threshold: In parallel compression the idea is usually to get the compressor working on those quiet low level signals, so we need to slam the threshold properly. The example hits -20dB of gain reduction.
  • Release: This is something you should play around with. It really depends on your source material and the tempo you are working in. Sometimes pumping is what you want, but always try to aim for a release time that reinforces the original rhyhtm.
  • Use make-up gain to compensante for gain reduction.

 

Step Four – Adjust the Volume of the Smash Channel

Now bring down the volume of the smash channel to zero and start bringing it back up slowly. In most cases you don’t want to mix in the smash channel too much – just enough to give it that extra fatness. If you push it too hard, you will start losing the original character of the sound. Sometimes really nice effects can come out from this though. Always experiment!

Adjust the Volume of the Smash Channel

 

Listen to the finished version of our break:

And the same thing with the compression turned on and off a couple of times:

Notice how the compression pulls up the quieter drum hits and gives the whole thing subtle power? That’s what it’s all about. The transients that would be affected in regular compression are still there, too.

A Potential Problem

Processing a copy of a signal on another track with plugins may cause latency on some platforms. Even the slightest delay will cause phase-shifting and result in warped sound/loss of frequencies.

Most modern host platforms have a plugin delay compensation feature to prevent this these days, but at times you might still run into plugins that refuse to co-operate with the host on this.

In Logic you can turn on the plug-in latency compensation option under Preferences > Audio > General. This will assure everything will stay perfectly in phase – at least when working with built-in plugins.

Fortunately there is a way to deal with this even when automatic compensation isn’t an option:

Create a copy of the dry track and set that up as the smash track (instead of sending into a bus). The compressor will still create latency, but you can now manually nudge the audio backwards slightly to make up for it.

 

Take It Further

This tutorial only covers a very basic starting point for parallel compression. You should try experimenting with different variations once you get the hang of it. Here are a few ideas:

  • Different compressors provide different results. The unique characters of different compressors become really apparent when pushed to the limit so it’s definitely worth trying this out with parallel compression.
  • EQ the smash channel very differently from the dry channel – very nice for basslines.
  • You can also set up several smash channels, each with different EQ/compression/FX.

 

Hope you enjoyed the tutorial, have fun and please use the commenting feature for any questions or comments.

If you thought the tutorial was helpful, please consider sharing it through Twitter, Facebook or other means provided!

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  • As an additional resource, I’ve just discovered Voxengo has a free plugin which acts as a cure for plugins that don’t report the latency they cause back to the host. Have a look…

    Voxengo Latency Delay

    “Latency Delay is an auxiliary AU and VST plugin which allows you to compensate latency produced by any audio plug-ins, instruments and processes which produce latency but do not try to report it to the host. Latency Delay introduces 10000 samples latency itself and delays the audio signal by 10000 minus the specified amount of samples or milliseconds. Please note that audio host application should support the latency compensation itself for this plug-in to function properly. “

  • Alejandro Lobos Kunstmann

    Saw the images, heard the examples, did it. Perfect. Now I have to master it. Cheers for the EXCELLENT ARTICLE! Loved it.