Mastering Techniques - Using A Compressor - Part 1 - Mastering Media Blog

Wednesday, 20 August 2008

Mastering Techniques - Using A Compressor - Part 1

There are still more things I want to cover in the area of general DIY Mastering, but I've decided it's time to start posting some specific information up here to help people get to grips with common mastering techniques. So this is the first in a new series of posts headed "Mastering Techniques", which will run alongside the DIY Mastering posts. I'm going to cover things like level-matching, EQ, stereo width adjustment and so on, but I think the subject most people struggle with is compression. Often people have been told that the answer to any number of problems is compression, but don't know what they're trying to achieve, or how to get there.

This post started to get much too long, so I've decided to split it into several sections, this is Part 1...

Know What You Want

In my opinion, the most important thing when using compression is to have a clear goal. You'll see lots of explanations of compression saying things like "a compressor reduces the dynamic range of it's input", but I don't find these very intuitive, and prefer the explanation I was given as a trainee:

Compression is used to make things louder

There can be all kinds of positive side-effects of this process, like making things sound fuller, richer, more controlled or punchier, but at the end of the day, especially in mastering, it's all about loudness. NOT excessive loudness, but something musically beneficial.

Mastering engineers almost always use a limiter somewhere to boost level, but the problem with this is that mixes very quickly sound crushed or distorted using only limiting. Using some gentle compression first means the limiter doesn't have to be hit so hard, giving a more natural sound. More on limiters in a later post.

The ideas here apply equally to compressing individual instruments or voices in a mix, incidentally, but you'll need different settings, usually. First we need to recognise a harsh fact of life:

Not all compressors are created equal

The best analogue compressors cost thousands of pounds. However there are some really good software plugins these days which cost far less. For example if you're looking for emulation of a traditional analogue compressor in a mix, complete with "musical" pumping, I really like Sonic Timeworks Compressor X. Would I use it for mastering ? Probably not. However there are high-quality compressors available on a DIY budget which are suitable for mastering - the TC Electronics System 6000 is a mastering "industry standard", and many of it's algorithms are available as plugins for their Powercore system, for example. Many people also use plugins by Waves or Izotope, and discussions rage about whether it's really possible to master with something so cheap, and which is better, on the Sound On Sound mastering forums and elsewhere.

Regardless of which compressor you decide to use though, they all share similar controls and concepts, and at the end of the day it comes down to whether you're happy with the result you get. With that in mind, lets dive in:

Exploring Compressor Controls

Try this experiment - we're going to overdo everything to begin with, so you get a feeling of what the different parameters do:
  • Choose an instrument to compress and solo it (We'll move on to compressing a whole mix later)
  • Patch a compressor across the stereo master output channel of your system
  • Start with a ratio of 2:1.
  • Set attack and release times of 100ms, if possible. You may have to disable "automatic" options first.
  • Gradually reduce the threshold until the meters show you 4 or 5 dB of gain reduction
One of two things will have happened. Either:
  • The sound will have got quieter, because the compressor is holding back the louder peaks. In this case you need to add some make-up gain, sometimes called output gain. Adjust it until the sound is a similar volume to when you hit the bypass or disable switch
  • The sound will already be at a similar level, in which case your compressor automatically boost the output (make-up) gain
Now toggle bypass on and off and listen to the difference. Depending on your material, you will hear more or less difference. If you can't pick anything out initially, increase the ratio to 4:1 or reduce the threshold until more gain reduction is happening. (If you can't hear 6dB gain reduction with a ratio of 4:1 you should probably get your mastering - and probably mixing too - done by someone else !)

If your compressor has automatic attack and release times, it will probably sound OK (but a bit squashed). Even with manual controls, it shouldn't sound too bad. Once you can clearly hear the difference between the bypassed and compressed signals, you can try and figure out what it is you're hearing.

All the controls interact to give different effects, but before we get to that lets look at each in turn. First, ratio and threshold.


Try increasing and decreasing the ratio. Higher values (4:1 etc) cause a more exaggerated effect - the compression "hits harder". Lower values are more subtle. If your compressor doesn't have auto make-up gain, you'll need to adjust it to match the bypassed version for a clear comparison. As a rule of thumb, use a high threshold and high ratio for a hard-hitting sound, but watch out for unnatural results. Lower ratios give a softer, "warming" or "thickening" effect. I rarely use higher than a 2:1 ratio.


The threshold control determines when the compressor starts working. Lower values will give more compression, higher values give less. A low threshold with a high ratio will give lots of hard compression and probably sound very squashed and lifeless, whereas a higher threshold and low ratio will be a much more subtle. Whatever values you decide on, there is one rule of thumb worth remembering:

If the gain reduction meter doesn't return to zero several times a bar, you're almost certainly using too much compression

- because this means that the signal is being compressed all the time, and will probably sound flattened as a result. Try a higher threshold, and then higher ratio if it's not doing enough.

Attack & Release Time

Since I specified long attack and release times, you will probably hear the sound being "snatched" away right after a new note comes in, and perhaps "pumping" back up afterwards. Sustained notes are a good way to hear this. If you increase the attack and release times you'll certainly hear these effects. (For a deliberate example of this classic "thump-suck-relax" pumping listen to "One More Time" by Daft Punk). Automatic or "intelligent" settings reduce this effect, but increase the risk of using too much compression without realising it.

Now try reducing the attack time to it's minimum value. The sound will probably duck very quickly away to begin with - perhaps too fast to hear it happen, followed by the longer release back up to full volume. The chances are it will have lost any impact it used to have, especially with a higher ratio, and sound quite unnatural. Reducing the release time decreases the "pumping" effect, but as you get too short will start to sound "crunchy" or distorted.

Now your ears are focused on what the settings are actually doing, where should you set them ?

Answers in the next post.

40 comments: said...

nice tips for newbies well done

Ricardo Fernandez said...


Ganesan S said...

Nice tips thanks

Ipan Ho said...


Menuzzy Emmanuel said...

Thanks, its realy

Mickey James said...

Great blog post! I don’t understand how long it will require me to obtain through all of them!like us on our Facebook page

Timon berg said...

I am confident you've got a great enthusiast following there.
best cheap air compressor

francis beth said...

The written piece is truly fruitful for me personally; continue posting these types of articles.
Chauncey Colaiacovo

Annair Controls said...

Very efficiently written information. It will be beneficial to anybody who utilizes it, including me. Keep up the good work. For sure i will check out more posts. This site seems to get a good amount of visitors. Auto Drain Valve || Water Chiller India || Water Chiller Manufacturers

Annair Controls said...

Eminent post with effective and useful information.its really nice post include a lot of resource.keep posting this kinds of blog. thanks for share with us.good bye. Heatless Air dryer || Micro filters || Moisture Separator

Annair Controls said...

This is the first time i am reading your post and admire that you posted blog which gives users lot of information regarding particular topic thanks for this share. Refrigerated Air Dryer || Gold star series || Refrigerated Air Dryer in Thane

Annair Controls said...

I have to say that the information here was the most complete that I found anywhere. I am definitely bookmarking this to come back and read later. Air Dryer Manufacturer || Air Dryer || Air Compressor Manufacturers

Lisa Martinez said...

A great tutorial you share here. It is such a unique and informative information. Best article. +1 from my side.
Airtool Direct

Anna Wilson said...

Thanks guys for sharing such brilliant post with all of us, surely nobody can defeat this.

Air Dryer | Air Compressor Manufacturers | Refrigerated Air Dryer | Heatless Air dryer | Micro filters

kayblowers said...

Hello! I simply wish to give you a big thumbs up for the excellent info you have here on this post. I will be coming back to your website for more soon.

Mechanical boosters
Industrial blowers

Vigrx Plus said...


Jasmin said...


Jasmin said...
This comment has been removed by the author.
Compressor Part said...

Great article with excellent idea! I appreciate your post.

Compressor Part

jorn karl said...

Perfectly fitted filter elements for air compressor specially Atlas Copco, Ingersoll Rand, SullAir, CompAir, Hitachi, Boge etc. Order your element today from

jorn karl said...

Perfectly fitted filter elements for air compressor specially Atlas Copco, Ingersoll Rand, SullAir, CompAir, Hitachi, Boge etc. Order your element today from

Compressor Part said...

Very Good Post, Gives very brief information thank u!

Compressor Part

Compressor Part said...

Your website is very good, I liked....

compressor parts

kayblowers said...

Thank you for sharing this post and shining a light on what
can be a confusing subject. With so much information out there it’s
nice to have the material narrowed down to a simple presentation
of the facts.

Monower hossain said...

Thanks for sharing such a useful information with us …. I like the way you describe the post with us. Many thanksthanks for share

Alisha Anderson said...

Thanks for Posting keep it up

Air Dryer | Refrigerated Air Dryer | Heatless Air Dryer

Armando Iswahyudi said...

Hi there,I enjoy reading through your article post, I wanted to write a little comment to support you and wish you a good continuationAll the best for all your blogging efforts.

Katalog Gambar Mebel Set Meja Makan Model Minimalis
Lemari Pakaian
Kursi Makan
Kursi Tamu
Kursi Tamu Jati Murah
Tempat Tidur minimalis
Mebel Murah
Sofa Minimalis
Kursi Tamu Minimalis Modern Murah
Kursi Teras Minimalis
katalog gambar mebel buffet rak tv jati model minimalis
katalog gambar mebel set meja makan model minimalis
mebel jepara

alfred said...

When not in use, the air compressor must be stored in a cool, dry place. The tank must be drained of all moisture. Disconnect all the pipes and hang them with the open ends down to drain any moisture that could still be present in them.

Aero Blasts

etsakronjati minimalis said...

Meja Antique

Kursi Klasik Set

Sofa Modern Romawi

Toko Mebel

Gazebo Sirap

James Gerber said...

Thanks for your sharing! This useful for me.
Choosing the best portable air compressor
Read the best air compressor reviews

Jepara Furnistore said...

set meja makan

Focus Engineerrs said...

Thanks you vary much for your valuable post.
metering dosing pump manufacturer in india

Focus Engineerrs said...

I would like to do all the information .
chemical dosing system

Mahaveer cooling towers said...

I just want to say that all the information you have given here is awesome. Thank you
clean fruits and veggies

fruit and vegetable cleaner

fruits purifier

vegetable wash

vegetable washer

vegetable washer liquid

veggie wash

fruit and vegetable washer

fruit and vegetable sanitizer

Focus Engineerrs said...

Thank you so much for your post.

dosing metering pump manufacturer in india | pump manufacturer in india | chemical dosing system | water treatment equipments | chemical dosing system

Green Wash said...

I just want to say that all the information you have given here is awesome. Thank you
clean fruits and veggies

fruit and vegetable cleaner

fruits purifier

vegetable wash

vegetable washer

vegetable washer liquid

veggie wash

fruit and vegetable washer

fruit and vegetable sanitizer

Focus Engineerrs said...

Thanks for sharing the information.

metering dosing pump manufacturer in india | chemical dosing system | water treatment equipments | dosing pump manufacturer in india | chemical dosing system | electromagnetic & motorised dosing pumps

suchit trident said...

I found your website perfect for my needs nice post and lots of information about the industrial roads
solid tires Manufacturer

Vellore Information said...

Now they will be benefited when they will arrive on this blog post,

dosing pump manufacturer in india | metering pump manufacturer in india | chemical dosing system | water treatment equipments | chemical dosing system | electromagnetic & motorised dosing pumps

Deba Sheesh said...

Great blog and I love what you have to say and I think I will tweet this out to my friends so they can check it out as well. I like what you have to say.
Paddle Wheel Flow Meter