THE CONTROL ROOM SET-UP
As one or more members of the recording team setup the performance space or live room for a session, someone (commonly the main engineer) should be responsible for the preparing and running of the equipment in the control room, i.e. although on occasion individuals may be required to run sessions on their own, approaching all tasks sequentially, under ideal circumstances at least two people should work simultaneously for the purpose of tracking.
As we have seen, certain procedures can be carried out well in advance to the arrival of the musicians to the studio, e.g. testing, calibration, DAW file creation, etc., so when the performers are ready to play, recordists should be fully prepared for sound check. This should help maintain a creative and energetic atmosphere, commonly referred to as the ‘vibe’, which should be seen as the most important element in any session (it is not possible to overemphasise this last statement). A good production team is able to maintain a positive mood in the studio, through the minimising of the time gap between set-up and recording and through the creation of a psychologically motivating environment for those who are waiting.
Setting DAW Preferences
Most DAWs allow the user to select their desired hardware buffer size. This set-up step is very important, as it may have a significant impact on latency and therefore the success of a session. As a general rule for recording, engineers must aim to keep the buffer size at a low number of samples to ensure that signals can reach the DAW and leave to be subsequently monitored with a minimum of delay. During mixing, buffer sizes should normally be increased in order to allow the DAW to manipulate and sum signals with no insufficient processing power related problems (here latency is not an issue).
Music Playback During Set-Up
Some recordists/producers may find it beneficial to play music during set-up, as this may:
• Help the team tune their ears to the recording environment
• Inspire the artists
• Remind all involved of why they are there.
The selection of tracks to be played during set-up should be influenced by the discussions that took place during pre-production (influences) and it is important to point out that it is not advisable for the team to listen to the demo at this stage, as this may curb creativity or drain the performers’ energy (making the music seem less immediate or ‘fresh’).
GAIN STRUCTURE
Gain structure has an enormous impact on the quality of recordings and it is one of the main aspects separating professional work from amateur attempts. In broad terms, levels should be set so signals conform to the dynamic range of the audio chain and, more specifically, to that of the recording medium, i.e. gain should be set high enough for the material to be well above the chain’s noise floor at quiet passages, while staying below the clipping point during the loudest ones. This appears simple enough until one considers how often levels may be manipulated between the first input stage of a signal path and the output to the recorder. In the case of analogue consoles, this could include the gain of a microphone preamplifier and of an equaliser(s), dynamics processor(s), channel fader, group buss summing amp, etc., therefore it is vital for recordists to understand the role of each of the aforementioned elements in order to optimise (or avoid) their use. As a rule of thumb, signals must be made as robust as possible at the earliest possible stages of a signal chain, as any amplification at later points will not only raise the level of the material, but also that of any noise picked up along the way.
The following is an example of the possible gain stages that a signal may go through before reaching a recorder:
In the previous diagram we see a microphone input signal going through a preamplifier, a possible insert point, a four-band equaliser. a dynamics processing section comprised of a gate and a compressor, a channel fader and a group buss fader before reaching the recording device.
Recordists should only evaluate the suitability of signals after determining their correct gain structure. Please refer to Appendix 5 for an example of gain setting procedure.
Compression During Tracking
It is not uncommon for some sound sources to have a dynamic range that exceeds that of the recording signal chain. As an example, untrained (and in some cases even experienced) singers may have such an enormous dynamic range that if levels are set so they are adequate for the recording of quiet passages, they will lead to clipping during the loudest moments of the same recording. As a solution to such problem, engineers have long been using dynamic range processing (compression) to reduce the gap between level extremes.
Metering
The metering of signals is extremely important for both the calibration and the running of audio systems. A few different standards exist and some of them have been in use for over 70 years. The following is an overview of the more common types of meters:
VU (Volume Units – IEC60268-17)
VU meters work on level averages with a behaviour that approximates (or aims to emulate) that of the human ear. This type of metering commonly spans between – 20 and + 3 VU and presents a rise time of 300 milliseconds (the time taken for the meter to reach full deflection for a steady tone input signal).
Recordists working with VU meters must consider the implications of their slow ballistics and learn to interpret readings. The following are a few observations regarding volume units:
• Transient (short impulse) signals may fail to deflect VU meters
• Peaks for shorter impulse signals may correspond to values that are 6 to 20 decibels over what is displayed on a VU meter, e.g. when recording transient rich instruments such as drums, operators should not let the VU meter deflect much past – 5 VU.
PPM (Peak Program Meter)
Peak program meters aim to provide more instantaneous level readings. Original BBC UK PPM (IEC 268-10 IIA) devices’ readouts span from 1 to 7, where 4 equates to 0 dBu and 5 to + 4 dBu. Another version of PPM meters, the EBU PPM (IEC 268-10 IIB) spans from – 12 to approximately + 14, where a ‘Test’ readout equates to 0 dBu and all other readings correspond their values in dBu, e.g. + 4 EBU PPM = + 4 dBu). It is important to point out that ‘true’ audio waveform peaks may be 6 to 8 decibels higher than what is displayed on PPMs.
EBU Digital (IEC 60268-18)
EBU digital meter readings span from – 40 (negative fourty) to 0 dBFS (the clipping point). In purely digital metering, the establishing of average operating levels is not as important as the detection of peaks.