Recording Secrets For The Small Studio - Additional Resources
(To download all WAV examples at once: 85MB ZIP)
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/MP3play_arrow; and an AB pair of Avantone CK1s (spacing 30cm) using their omnidirectional capsules Ex09.002: WAV/MP3play_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: 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/MP3play_arrow; 110 degrees Ex09.004: WAV/MP3play_arrow; and 150 degrees Ex09.005: WAV/MP3play_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: 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/MP3play_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/MP3play_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/MP3play_arrow with a further pair up by the edge of the lid Ex09.012: WAV/MP3play_arrow to get a better blend of definition and natural overtones Ex09.013: WAV/MP3play_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/MP3play_arrow and a coicident pair at the front of the kit Ex09.009: WAV/MP3play_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/MP3play_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/MP3play_arrow. The room mics in this case sounded like this Ex09.015: WAV/MP3play_arrow. This technique is extremely popular for drum-kit recordings as well, with comparatively dry, close-placed overheads Ex09.016: WAV/MP3play_arrow being supplemented by more distant room mics Ex09.017: WAV/MP3play_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/MP3play_arrow, figure eight Ex09.021: WAV/MP3play_arrow, and omnidirectional Ex09.022: WAV/MP3play_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.
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.
Ambisonic Microphone Systems: It’s also possible to design even more flexible multi-pattern Ambisonic mics, the output signals from which can be post-processed to emulate any other coincident multimiking rig. Although these were once prohibitively expensive for most small-studio users, in recent years some more affordable products have begun to appear, such as MiniDSP’s AmbiMIK1, Rode’s NT-SF1, and Voyage Audio’s Spatial Mic.