There are very few articles on classical music recording, editing and mastering. However, there are many different techniques to produce professional quality recordings.
We will present here some working guidelines to help you understand the different steps of a classical piano recording.
The audio excerpt that illustrates this article was made with a simulation of the Mozarteum’s great hall in Vienna on a Bluethner Model One grand piano.
Sound recording step
The sound recording is the very first step, but also the most important. The microphones must be placed so as to get the best sound possible taking into account any acoustic problems of the hall. For example, some concert halls will have unpleasant resonances in some places, so they should be avoided. Conversely, other places will enhance the sound of the piano and allow a good balance of frequencies and stereo image.
If you only use two microphones, you only need to find the location that offers the best balance between the direct sound and the reverberation of the hall.
On the other hand, things can become more complicated when using four microphones or more. You will then have to solve delay and phase relationship problems, but you will also have to find a perfect balance between the mics.
In this recording, we used two pairs of microphones, DPA 4006 and 4011. The first pair was placed at a relatively long distance from the piano to capture the ambience of the hall, and the second pair was relatively close to adjust the level of direct sound as we wanted. The acoustics of the concert hall being excellent, we mixed the volume of each pair of microphones so as to obtain this balance, then calculated the delays very precisely.
The editing (or mixing) step usually consists in correcting the defects of the sound recording and improving the sound of the raw tracks. It is not uncommon to use an equalizer to cut or boost certain frequencies, or even a compressor to control the dynamics in a very gentle and subtle way.
For this step (as for the previous one), the quality of the equipments used is very important, because they always leave an imprint on your recording. A high end equalizer will always give you better results than your DAW, if you know how to use it.
Depending on the sound you’re looking for, you can opt for digital or analog equipment to color your recordings or not.
Although a classical piano recording requires above all a transparent sound, many well-known productions and labels use modern and vintage analog equipments to give more warmth or roundness. Digital tools, such as parametric equalizers, can however give more precision in the frequencies treatment, ‘‘without’’ coloring the sound.
Here, the edited version of our recording excerpt:
Nocturne in C minor No. 13, Op. 48 No. 1: Lento – poco piu lento (Chopin, F.) – EDITED
This step – sometimes overlooked in many classical piano recordings – is the recording final touch. EQs or compressors used for mastering must necessarily be very high-end equipment in order to improve the sound without distorting the original mix. In most cases, if the sound recording and the editing work were done correctly, you will never need to cut or boost the frequencies by more than 2 or 3 dB. Of course, it is not forbidden to go further, but in most cases it will be better to go back to see what doesn’t work in the mix. And if it’s not too late, in the sound recording.
Mastering requires very expensive equipments and good experience in sound processing. Also, it is sometimes better to leave this step to a professional.
Beyond these multiple audio treatments that can be done during the mastering step, one of the most important points is the final volume normalization of your recording. This is not so easy, contrary to what many people think, because you just have to increase the gain by only 2 decibels to realize that there may be a problem in the bass, or elsewhere in the mix. The goal here is to make sure your recording has a volume (often measured in LUFS) comparable to your favorite recordings, while maintaining the quality of your editing work.
In the example below, we made the mastering step with the SPL Passeq stereo equalizer to refine the sound and give more presence to the piano. Then we used a complex high-pass filter configuration to better control the low frequencies and give more clarity.
The recordings we used as an informal reference for mastering were the Chopin’s Nocturnes album by Nelson Freire (Decca, 2010) and Maurizio Pollini (Deutsche Grammophon, 2005).
Nocturne in C minor No. 13, Op. 48 No. 1: Lento – poco piu lento (Chopin, F.) – MASTERED