Recording Secrets For The Small Studio - Additional Resources

Chapter 9: Dominant‑array Ensemble Recording

Audio Files

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  • Coincident Versus Non-coincident Imaging Character: The following audio files compare the imaging qualities of coincident XY and non-coincident AB stereo rigs with similar acceptance angles (around 110 degrees). A loudspeaker was used to play back a snippet of the BBC shipping forecast from different soundstage positions in the following sequence: 0 degrees (centre); 20 degrees right; 50 degrees right (close to the right-hand edge of the acceptance region); 0 degrees (centre) again; 20 degrees left; and 50 degrees left (close to the left-hand edge of the acceptance region). This was recorded through two different mic setups: an XY pair of Avantone CK1 small-diaphragm condenser microphones (mutual angle 90 degrees) using their hypercardioid capsules ( Ex09.001: WAV/MP3 play_arrow ); and an AB pair of Avantone CK1s (spacing 30cm) using their omnidirectional capsules ( Ex09.002: WAV/MP3 play_arrow ). Notice in particular the sharper imaging and drier pickup of the XY array, and the greater spaciousness and more naturally extended low end of the AB pair.

  • [Balance, Tone & Depth Across The Acceptance Region:]{#BalanceToneDepthAcrossAcceptance} These audio files are designed to demonstrate how the choice of an XY array’s mutual angle affects not only its acceptance angle, but also the balance, tone, and depth of sources within the acceptance zone. Again, a loudspeaker was used to play back a snippet of the BBC shipping forecast from different soundstage positions, and the result was captured with a coicident crossed pair of Avantone CK1 small-diaphragm condenser microphones (with their cardioid capsules fitted) using three different mutual angles: 90 degrees ( Ex09.003: WAV/MP3 play_arrow ); 110 degrees ( Ex09.004: WAV/MP3 play_arrow ); and 150 degrees ( Ex09.005: WAV/MP3 play_arrow ). In each case the loudspeaker was placed in relation to the array’s acceptance angle (see Table 8.1 in the book) as follows: at the centre; at the right-hand edge; at the centre again; at the left-hand edge. Notice how the narrower mutual angle makes sources at the centre of the image louder, closer, and brighter than those at the edges; whereas the wider mutual angle makes sources at the edges of the image louder, closer, and brighter than those at the centre. By comparison, the 110-degree mutual angle maintains a more even sense of balance, tone, and depth across the whole width of the acceptance zone.

  • [Frequent Problems With Simple Dominant Arrays:]{#ProblemsSimpleDominantArrays} Because many ensembles are captured from a frontal position, it’s very common for a single dominant array to make the rear rows of players appear both too quiet and too far away, as you can hear in this example ( Ex09.006: WAV/MP3 play_arrow ), where a big-band’s room microphones were unavoidably placed closer to the front-row saxophones than to the trumpets, trombones, and rhythm instruments – a situation that was addressed in this case using additional spot microphones. Another increasingly common problem I encounter is people placing figure-eight XY pairs (such as the classic 90-degree Blumlein setup) too close to an ensemble so that some sources fall well outside the array’s acceptance zone into the out-of-phase pickup region, as you can hear with the cymbals in this Blumlein-array drum overheads recording ( Ex09.007: WAV/MP3 play_arrow ). Not only does this make the out-of-phase instruments unnaturally wide-spaced in the stereo image, but also results in poor mono compatibility.

  • Dual Dominant Arrays For A Fuller Sound: When recording single instruments, it’s not uncommon to use two stereo arrays which capture different perspectives of that instrument’s frequency dispersion to create a more appealing composite sound. For example, with piano you might combine an internal close pair ( Ex09.011: WAV/MP3 play_arrow ) with a further pair up by the edge of the lid ( Ex09.012: WAV/MP3 play_arrow ) to get a better blend of definition and natural overtones ( Ex09.013: WAV/MP3 play_arrow ). This same principle can also apply with ensembles, as in this instance where two sets of overhead microphones were used to mic up a drum kit from different angles within a highly damped acoustic: a spaced pair behind the drummer ( Ex09.008: WAV/MP3 play_arrow ) and a coicident pair at the front of the kit ( Ex09.009: WAV/MP3 play_arrow ). Although neither of these pairs present the cymbals particularly well on its own, together they create a much more representative tone within the context of the full-kit drum submix ( Ex09.010: WAV/MP3 play_arrow ).

  • Dual Dominant Arrays For Dry/Wet Control: A very common reason for supplementing a simple stereo dominant array with an additional mic pair is to allow mixdown control of the recording’s dry/wet ratio after recording. For this to work properly, you typically have to make the main pair a little drier than you might normally, as you can hear in this example ( Ex09.014: WAV/MP3 play_arrow ). The room mics in this case sounded like this ( Ex09.015: WAV/MP3 play_arrow ). This technique is extremely popular for drum-kit recordings as well, with comparatively dry, close-placed overheads ( Ex09.016: WAV/MP3 play_arrow ) being supplemented by more distant room mics ( Ex09.017: WAV/MP3 play_arrow ) so that the levels of these signals can be automated at mixdown to enhance the apparent dynamics of the performance – for example, by riding down in the verses and up for the choruses.

  • Coloration Of Off-axis Spill By Budget Large-diaphragm Condenser Mics: The following files demonstrate how the off-axis response of a fairly budget multi-pattern large-diaphragm condenser mic (a Groove Tubes GT57) colours spill pickup. A singer was set up 20cm away from the microphone roughly 135 degrees off-axis (in other words behind and to the right of it), and was recorded using each of the microphone’s three polar patterns: cardioid ( Ex09.020: WAV/MP3 play_arrow ), figure eight ( Ex09.021: WAV/MP3 play_arrow ), and omnidirectional ( Ex09.022: WAV/MP3 play_arrow ). I’ve evened out the levels between the files to make them easier to compare tonally, and you can easily hear how much more coloured the cardioid mic’s tone is than that of the figure-eight or omni.

  • Spot Mics For Balance Correction: The most common reason for using spot mics within a dominant-array setup is to adjust a balance misrepresentation within the dominant array’s signal. For example, in this dominant array recording, the necessity of locating the singer in the organ loft caused her to be underrepresented in the balance ( Ex09.023: WAV/MP3 play_arrow ), so a spot mic was recorded ( Ex09.024: WAV/MP3 play_arrow ) in order to redress this imbalance in the final mix ( Ex09.025: WAV/MP3 play_arrow ). As is quite common, a little artificial reverb was used to avoid the spot mic’s more direct sound pulling the vocalist too far forward in the depth perspective.

  • Spot Mics For Tonal Adjustment: In this dual-pair dominant-array recording the cembalo felt as if it could benefit from a bit more tonal warmth ( Ex09.026: WAV/MP3 play_arrow ), simply because the instrument itself sounded rather thin acoustically. A smooth-sounding ribbon spot mic for the cembalo helped here, and using it up close also boosted the instrument’s low end on account of the figure-eight polar pattern’s strong proximity effect ( Ex09.027: WAV/MP3 play_arrow ). Mixing this spot-mic signal in with the dominant array lent the instrument’s lower midrange the desired hint of unearnt flattery ( Ex09.028: WAV/MP3 play_arrow ). This kind of tonal use of spot mics has many applications, but it’s important to scrutinise the dominant array’s sound before placing the spot, so that you make sure the close mic delivers the necessary tonal character. For example, this drum overheads recording ( Ex09.029: WAV/MP3 play_arrow ) clearly needs a snare-drum close mic not only to give it more level in the mix, but also to enhance the rather mellow high-frequency content. Sadly, however, the snare close-mic signal on this particular multitrack recording sounded both unnatural and muffled ( Ex09.030: WAV/MP3 play_arrow ), and therefore required serious remedial work in Mix Rescue March 2011!

  • Delaying Spot Mics At The Mix: Here’s a baroque ensemble concert recorded through an ORTF dominant array ( Ex09.033: WAV/MP3 play_arrow ). Because the extremely shallow stage required the singer to be well off-axis to the main pair, she was given a separate small-diaphragm condenser spot mic ( Ex09.034: WAV/MP3 play_arrow ), and here’s the mix with that faded in ( Ex09.035: WAV/MP3 play_arrow ). However, this made the singer feel a little too close to the listener, so the spot mic was delayed 20ms at mixdown (based on measurements of the recording setup taken on the day) to roughly time-align it with the dominant array ( Ex09.036: WAV/MP3 play_arrow ). A touch of artificial reverb was also applied to it for similar reasons ( Ex09.037: WAV/MP3 play_arrow ).

  • Equalising Spot Mics At The Mix: Here’s a gospel-choir recorded through a three-mic ‘curtain’ dominant array, supplemented with a direct feed from the accompanying keyboard ( Ex09.038: WAV/MP3 play_arrow ). The vocal soloist was also given a close-placed large-diaphragm condenser spot mic ( Ex09.039: WAV/MP3 play_arrow ) to try to give her more presence in the upper half of the frequency spectrum. However, the mic’s proximity effect also boosted the vocal’s low midrange, making the singer’s tone indistinct and woolly when the spot mic was mixed in with the rest of the ensemble ( Ex09.040: WAV/MP3 play_arrow ). Cutting these unwanted lower frequencies with an EQ on the spot mic dealt with this problem ( Ex09.041: WAV/MP3 play_arrow ), and a splash of reverb then helped place the singer a little further back in the mix ( Ex09.042: WAV/MP3 play_arrow ).


  • Correction: On page 308, line 31, the UK pricing for the C414B-XLS should be around £650, not £1600 as printed.

  • Spot-array Delays & The Precedence Effect: While discussing the practicalities of delaying spot arrays (pages 303-305) I forgot to mention that doing this reduces the spot array’s influence on the stereo positioning of its Focus instrument(s) – particularly if the spot array is delayed beyond the point of phase-match with the dominant array. The reason for this is something called the Precedence Effect (or the ‘Law Of The First Wavefront’): by nature, we humans normally determine the location of any sound source based on the perceived direction of the first sound wave that reaches our ears, the underlying assumption being that this first sound wave will have come directly from the sound source, rather than being a sonic reflection. The upshot of this is that if you want a given spot array to adjust the stereo positioning of its Focus instrument(s), then it’ll be more effective at doing that if you don’t try to phase-match it with the dominant array using delay. In practice, though, for a lot of dominant-array acoustic-ensemble sessions you’ll probably want to match the stereo positioning of each spot array to the dominant array anyway, so this isn’t really an issue. However, for something like a dominant-array drum-kit recording it becomes more of a concern, because music-genre conventions for stereo positioning of different kit elements (for example the pop/rock norm of placing the snare-drum centrally, but the toms evenly spread across the image) may not tally with the pickup of any real-world dominant-array setup, in which case undelayed spots may be a more appropriate choice. (Besides, undelayed spots will also pull the spot-miked instruments more upfront in the depth perspective, of course, which many engineers consider desirable as well.)

  • Schoeps Polarflex System: This clever system uses Schoeps’s Polarflex dual-mic coincident array in conjunction with a special cross-platform Polarflex DAW plug-in to generate a wide variety of different frequency-selective polar patterns.

  • Rode NT-SF1: Another very flexible multi-pattern mic system is Rode’s NT-SF1 soundfield mic, a mic design based around a tetrahedral array off four cardioid capsules. The Ambisonic signal this mic outputs can be converted to act like the signal from any coincident stereo/surround mic array, using a special free cross-platform DAW plug-in.

  • Rycote Microphone Data Site: For detailed information about all the microphones mentioned in Chapter 9’s two hypothetical case-studies, get yourself registered (for free!) at the fantastic Microphone Data web site.

Further Reading