Stereo image fix after applying analogue processing

Running stereo buses or full mixes through analogue devices like compressors, equalizers, summing boxes etc. is fun. They can add that magical touch to your track – a bit of stardust, the so-called 3D effect, punch, fullness and all sorts of adorable favours. But many times you face a problem even with high-end devices: the stereo image shifts…

I was mastering a track recently which has been run through a very expensive channel strip unit to add some shine to the mix. Sounded gorgeous except for that the mix – most noticeably the bass and the vocals – slightly shifted to the left, which was kind of annoying.

I asked my client to send me the mix without the channel strip processor applied on it. Then I measured the RMS levels for the left and right channels on both versions of the song (you can use Voxengo SPAN for such tasks). It looked like this:

Original (in the box) mix: Left: -18.2 dB, Right: -18.3 dB
Mix run through the channel strip: Left: -19.4 dB, Right: -20.4

You can see that the right channel has become 0.9 dB quieter compared to the relative levels of the original mix. To compensate for this I used the free Stereo Tool VST plugin from Flux where you can adjust the levels of the left and right channels independently (besides many other options). I increased the level of the right channel by 0.9 dB: now the vocals and the bass came back to the center. Problem solved!

Just a final note. Always check the mix with your ears too because RMS values are sometimes misleading. So don’t compensate for the stereo image shift in the mix blindly.

Stereo image fix after applying analogue processing

Free VST plugins for professional use

Well, not a mixing technique this time but a very useful entry for many of you I’m sure!

I’ve always been very critical about selecting the best tools for my studio which ensure a seamless mixing and mastering workflow. Through the years I’ve came across several freeware VST plugins and other free audio software too. Here’s a list of the free software I use regularly and which are on par with the most expensive ones:

A very musical sounding HP/LP filter, great for mastering as well:

One of the best software audio analyzers:

A general purpose mid-side plugin:

My go-to stereo tool and analyzer:

A great tool for widening the stereo image:

A utility for delaying left/right or mid/side channels:

A neat autopanner:

Delay effect with a very good sound:

And finally one of the best sample rate converters available (not a plugin and runs from command line; a short tutorial will follow this entry soon):

Free VST plugins for professional use

Mixing with headphones

Although mixing with headphones is something I wouldn’t recommend to do there are situations when you’ve got to go for it. So let’s see what’s wrong with it and how you can compensate for the disadvantages.

When you listen to music through headphones you experience a quite unnatural ‘in your head’ sound. First, room acoustics is totally excluded which results in a dull and fully dry sound. Second, the sound doesn’t come from the front but goes directly into your ears which causes total stereo separation. Also, your ears respond to sound pressure coming from speakers differently then when coming from headphones. That’s quite bad so far… But here comes the good news!

To compensate for the undesired side effects of listening to music through headphones you can use virtual speaker simulation tools. Most of them operate with head-related transfer functions (HRTF) under the hood to simulate acoustical transfer from loudspeakers to ears and reflections from the human body, and binaural room transfer functions (BRTF) to simulate room reflections. For me the most convincing results were produced by the now discontinued Focusrite VRM box. My second choice would be TB Isone by Toneboosters which is a binaural room simulator in VST plugin format. Other options cover (not exclusively) 112 dB’s Redline Monitor, G-Sonique’s Monitor MSX5 or Beyerdynamic’s Virtual Studio. For best results you should use high quality headphones with a full band flat frequency response especially designed for pro audio applications.

Still, I wouldn’t solely rely on such a tool during a mixing session. However, I would recommend using it to double check your mixes to hear how they would sound in various listening environments. Also, if you don’t have a decent loudspeaker based monitoring environment you’ll most probably produce better-translating mixes by using a speaker simulator when monitoring through headphones.

Mixing with headphones