Getting a reverb to sound natural and clear can be one of the hardest things to tackle in mixing a track. The hardest part about working with wet, long decay reverbs is getting them to not mud up the original source sound that is being run through it. Unless you want this muddy sound (in which case you would want to use an insert) your best bet is to send your track audio to run through an auxiliary track rather than use an insert. An aux track is a track that does not and cannot actually contain any audio files, but it is a channel to run audio through rather than actually hold audio tracks itself. This makes aux tracks very useful for reverbs, delays, and parallel compression. Aux tracks are very useful because they let us not only send multiple things to the same reverb but they also let us process the audio coming into the aux track separately. This technique works exactly the same for delays but for the purpose of illustrating this technique we will use just a reverb.
Here are the steps to creating a clear vocal/synth reverb:
1). To give a lead or vocal line some reverb first we must send it to an aux track. To send any track through one of the aux channels turn the knobs in the box labeled “sends” above the meters in session view.
2) The next step is to low pass filter or low shelf the highs of this reverb aux track. This low pass filtering is important because it makes the reverb more realistic. The high end is, in most cases, unnecessary for reverbs because its not only unnatural sounding, but it also clutters up the high end, which makes your lead line or vocal melody compete with its reverb for the high end of the spectrum. In most cases its best to have darker, warmer reverbs. A good rule of thumb to find where to shelf or cutout high frequencies in the reverb is to find the highest note this lead plays or vocalist sings, take a look at an EQ on the main track signal and find where it reaches its highest point in the EQ. Then low shelf or filter out the high frequencies that are found above ½ the highest frequency of this highest note. So if your highest note of your melody creates a signal that comes into the reverb at 5K, most of the frequencies above 2.5K in the reverb should be either lowered with an EQ, or completely filtered out with a low pass filter, depending on your personal preference. This is a short, slipshod way to get a more organic and warmer reverbs. Using low pass filters or EQs to cut out the high end makes it possible to make your reverbs wetter and deeper without compromising the high end.
So if this is my EQ on the vocal/synth track, we can see that the highest frequency of the highest pitch in the vocal/synth line is around 11-12K.
So when we EQ or low pass filter our reverb, we should be lowering or cutting out frequencies above 5.5K – 6K.
3) Once you have low pass filtered or lowered some of the high end in your reverb with an EQ, the third step is to use side chain compression on the aux send. If you don’t know what sidechain compression is check out this article here:
If “lead 1” is being sent to “reverb 1” then set a compressor on “reverb 1” and set the side chain to “lead 1”. For this one the EQ input is unnecessary because we aren’t looking to find only the transient of the lead as we do when we high pass filter our sidechain input of kick drums. When we throw a compressor on the reverb/aux track and set the sidechain input to the lead or vocal line we have sending to it, this forms a loop where the signal that is being sent to the reverb is also the same signal compressing that reverb. The track is being sent to the reverb but every time the track passes the threshold it compresses the reverb, which reduces the gain on the reverb. With this technique it is possible to have super clean sounding reverbs that are very lush and thick but won’t be muddy when the vocals need to be clear.
This view gives us a very clear view of what is going on all at once. On the left we have a vocal/synth track, which we can see is being sent to the Send A. Suppose we have a signal coming into the reverb aux channel around 7K. This would mean that we cut out or lower all frequencies above 3.5 K. Keep in mind, this formula is not a rule, but instead its a tool and is not meant to be followed exactly, it is just a general guideline. In this screenshot, we can see Aux/Send track A is highlighted, and in the built in EQ of the Max convolution reverb, we can see all frequencies have been cut out above 3.5 K. This can be accomplished with Ableton’s stock EQ as well, or the EQ built into the stock reverb as well as illustrated here:
These three steps are very essential to creating a realistic but well mixed and clear sounding reverb. The low pass filtering makes it more realistic and the side chain mixes it to keep the reverb from muddying up the clarity of the vocal line.
Want to learn more? Come in for a studio tour!