LP8 – A TALE OF TWO NOISES: EASY EQ FOR TAPE HISS REDUCTION
October 28, 2022 § Leave a comment
A technical post to celebrate the fact that last Sunday I was finally able to approve all masters for my 8th album Le jour et la nuit du réel, which will be released next year by Thrill Jockey! I hope this info can be of use to those of you who are self-taught like me, or who have not yet taken the first (or second ) step towards this approach, but are tempted: it is soooo satisfying when you manage to solve a problem in your own studio with your own tools!
Let me start with an analogy. If you live in an environment that’s relatively noisy with traffic, passers-by, your neighbours’ lives, your own doings in your house, all noises become blurred in a sort of noise fog, with nothing grabbing your attention in particular. In contrast, if you live in a very quiet environment, the hum of your fridge or a dog barking in the distance will probably drive you (me) nuts. With music, the same phenomenon happens: with a recording of a full band, almost no one’s going to actively register tape hiss or amp hum on a guitar part, because they are buried amid all the musical sounds. If they do come through slightly, the ear will interpret them as “warmth”/“authenticity”. However, if a record consists of just sparse guitar played through an amp and a Space Echo, the same hiss or hum will be so much louder in the mix – since there is nothing else to “cover” them – that they may start to distract from the music and just sound like a bad engineering job or faulty setup.
As you can see from this screen grab from my DAW Reaper showing the MIDI file created as I played the song live, the Grandmother and the 100% Wet Space Echo soundwaves, the songs where I had to do this EQ job all had in common that they were played by hand at a slow pace, with silence between notes. They also don’t have synthesis action going on: they are made up of very pure tones that stay even during the song. It is during those Grandmother silences that a kind of swishing, ebb-and-flow effect happens with the tape hiss, since the Echo produces a more constant sound that appears louder when the Grandmother is not playing.
Luckily, the solution is very easy. I had to tailor the approach to each song, but the principle is the same: on a band equalizer (ReaEQ here), choose a notch setting, take that notch to the top of the dB range and sweep the entire frequency spectrum until the noise you wish to remove is the loudest, then take that notch down until you are satisfied with the noise removal. It is then best to replace the notch by a band so that you have a shallower scoop, to avoid phase issues.
I had to do the EQ job on 3 other Movements of the same cycle + another one – all of which required adjustments (see pics):
– Mvt III is the only song on the album that uses 2 Grandmother parts, which means double the amount of hiss… The second part is played about 2 octaves higher than the first and for some reason, on top of the hiss, I also had a slight hum. This time I kept the notch and I managed to get rid of both hiss and hum in one go.
– Mvt II mimics a celesta, and here the best result was obtained by applying both the shallow scoop EQ of Movement I *and* the notch EQ of Movement III’s high-pitched part.
– Mvt IV has lots of dramatic Lowpass Filter Cutoff sweeps, changes of Oscillator octave, etc. Because of this constantly-changing wide spectrum of frequencies, the tape hiss is imperceptible, but I did have to do something about the beginning, in which I slowly open the Filter Cutoff to let the sequence appear: here the tape hiss was extremely perceptible since there is almost no input going to the Echo. The previous EQ settings did not work for the whole song as they “disfigured” it by taking away too many musically useful frequencies, plus it just didn’t make sense to apply EQ where there was no problem. A simple solution was to use the EQ’s Wet parameter envelope, starting with maximum wet then taking it down as the song grows in volume.
– For Mvt I of “Be without being seen”, I had to add an extra band to the shallower scoop to make it even wider.
Huge thanks to my mastering engineer Antony Ryan / RedRedPaw Mastering for all his help on this subject and so many other technical matters.