When you are looking for tools that will enhance and improve your audio recordings in your home studio there are a vast range of both digital and hardware based effects available. One of the best but often overlooked tools is compression. A little goes a long way and the proper amount can make the difference between a recording that is too low or is hopelessly distorted from being too high.
There are several different versions of compression but this article will focus on the dynamic compression that is often used by professionals in a single track or channel and on final mixes where compression is used on the main bus. Compression in a dynamic context is used to keep the highest level of audio transients from clipping or exceeding the 0 db mark on an audio metering system. In the days of old there was only so much headroom available to audio engineers because the two main mediums for audio were vinyl or electromagnetic tape. Most consumers would purchase a vinyl recording of their favorite audio in the form of records. Because of the limitations of a vinyl record and the way that they were manufactured there were limits on how loud a record could become before the needle skipped or vibrated off of the vinyl medium. This presented a problem because the best selling records were the ones that were perceived as louder than others.
Compression was introduced as a tool to be used by audio engineers in an effort to create the loudest recording possible without crossing the “too loud” threshold. A standard was set that all audio engineers had to adhere to and a new form of audio engineering techniques were established.
The introduction of cassette tapes and 8-track tapes raised the bar slightly but not much was changed. Once the digital age was ushered in the standards of loudness were once again raised and in digital formats audio engineers discovered that even more headroom could be found in higher resolution recordings. The additional headroom or loudness factor started a loudness war among audio engineers that were competing for the best jobs and highest pay. Most audio engineers will tell you that pushing the loudness barrier is bad because it decreases the amount of dynamics in a recording but they do so intentionally because that is the standard and in order to compete with other audio engineers they must also push the limits as far as possible without inducing the distortion that is associated with going too far with compression and other dynamic tools that are used in the audio industry.
If it sounds good then why bother with additional tweaking? The answer is the Red Book CD standard. In 1980 a set of standards were established for audio recordings and this standard was adopted by the Digital Audio Disc Committee as the standard that all professional audio engineers should use when mixing and mastering audio works by artists and musicians. This standard was replaced with updated information in 1987 and 1999 as changes in the amount of data and the resolution of digital recordings changed. What you hear on a CD is considerably lower quality than what is heard at the time of recording in a professional studio and now home computers with slightly better sound cards can match very closely what a room full of equipment could achieve years ago.
Now days a savvy home audio engineer can produce results that the average listener would believe came from a high-end professional studio. If the home engineer plays his cards right and uses the best tools available he can even fool some professionals into thinking that his work came from an established high-end studio. The trick is to get the recording as loud as possible without causing the transients to clip or distort and by keeping the lower level transients high enough to be heard over the noise floor. Most of the currently available Digital Audio Work stations (DAW) can do this by inserting silence where there is no signal and by using just the right amount of compression where there is an audible signal. Finding the sweet spot between these two extremes is essential in creating the loudest and most natural sounding program material.
The spaces between these limits should be allowed to “breathe” and should have a slight bit of ambiance before and after the signal trails off into silence . This is where attack, hold and release settings for compression plug-ins and hardware come into play. There are no set rules for adjusting these settings because each application will be different. If you do not want to hear the initial pick of a guitar string then set the attack rate higher, just beyond the sound of the pick, and then only the note itself will sound without the initial pick strike. Set a lower release for the compression control if you want a choppy, short tone. The best thing to do is to experiment with what you are working on and try to get the most natural sound. Try to go for what you would hear in a live environment in most cases, unless you are intentionally working towards an un-natural effect.
Compression comes in different flavors and is useful for adding “color” or being completely transparent. Many debates have been started over the difference between completely transparent compression and the warm color that tube compression can achieve. Still, to this day, some engineers prefer the warm sound of vinyl and tube based electronics to the cold and precise digital based effects. Even some digital based effects companies have gone so far as to model their plug-ins on real world hardware such as tube pre-amps and tube based rack mounted audio systems that were used years ago. Be your own judge in this case as some things you record will require a surgically clean sound treatment while other program material will be best suited for old world electronic styles and configurations.
The absolute best tool you have will be your ears. Season each recording to taste and include the best possible solutions that pertain to the program material you are working on. When using compression the best rule of thumb to remember is that less is best. You will want to use compression in a way that seems transparent in most applications, meaning that the effect is slightly less than audible to the trained ear. The higher the resolution and the better the quality of the recording is will also help determine how well the recording will transfer into lower resolutions such as MP3’s and CD standard recordings. Also consider how good your analogue to digital and digital to analogue converters are and if they can translate your material effectively into the final product that will be distributed. The best AD/DA converters will also improve the performance of your compression tools and other audio effects you may be using.
What compressor should you use? Excellent question. There are so many companies manufacturing audio tools today that they can’t even be listed here. Most of them do the same job but may have a more pleasing interface than others. The best thing to do in this case is to listen to your favorite artists and then research what they used to record their material. If you are going for a certain sound, whether it be classic or contemporary, there will be a multitude of tools available for the task at hand. Listen and then research. As a hint there is a standard that most old school audio engineers will use when setting up their live sound and calibrating their equipment. The artist Steely Dan went to great lengths to perfect their sound after it was recorded and used some of the best tools available at the time to mix and master their material that was later released. Out of all the sound checks I have attended where other engineers were setting up the equipment Steely Dan CD’s were played to set the EQ’s, compression and levels for the show. I asked one day why so many engineers used Steely Dan’s material to set up with and the answer was “It is as close to a perfect and flat audio response that anyone has heard so far without over compressing the transients”.
If you have any tips, tricks or techniques you use in your work then leave me a comment below. Also if you would like to recommend the best compression hardware or software and why you use it exclusively then let everyone know in the comment section.