I’ve written up one hell of a Task Report for the Multi-Bus Compression stage of Brauerizing ITB. Felt rude not to share. Media files and images would share for some reason… but hope use is found in the text. It’s a bloody long read and covers all the aspects, as well as my little critique of the process ITB.
Appendix 5 – Multi-Bus Compression Task Report
In order to successfully realise Multi-Bus Compression ITB, it was important to first understand the methodology of Multi-Bus Compression OTB with hardware equipment. Appendix 3 shows the routing and equipment utilised by Brauer for his Multi-Bus Compression set-up (Brauer, Undated).
The A Bus consists of the Neve 33609 VCA compressor and a Pultec equaliser. McDSP’s 6030 Ultimate Compressor offers 10 different compressors within one plug-in, in which their Brit-C module is modelled after the Neve 33609 compressor and was therefore utilised as a plug-in emulation of Brauer’s set-up (Shilling, 2011). Waves have a modelling series of a number of Jack Joseph Puig’s compressors and equalisers, which include the Pultec EQ and therefore opted to utilise Waves Puigtech as the Pultec’s emulation.
As stated in 2.3, Brauer believes that the reason Brauerizing will not work ITB is due to plug-ins being “clean” and not adding harmonic content, though figure 1 shows a 1 kHz Sine Wave routed through the 6030 compressor and Puigtech EQ, clearly showing that harmonic content has been added to the Sine Wave, as well as the 60Hz electronic hum being emulated in the lower frequencies.
If Brauer’s reason for Multi-Bus Compression not working ITB is due to plug-ins not adding harmonic content to the input signal, figure 1 shows that this is not the case and is only the first step in proving the possibility of Brauerizing ITB.
As shown in Appendix 3, Brauer routes keyboards, pianos, strings and synthesisers to the A Bus. The Compressor and EQ patched across the input of the Bus compliment the input material and are discussed in terms of their impact on the input material within the mix further down in this task report.
The B Bus consists of an Empirical Labs EL-8 Distressor and Brauer discusses that the B bus can either utilise an Equaliser or not. For the purpose of this project, a 3 band Equaliser has been utilised on the B bus. The Distressor is a compressor that has been modelled once again by McDSP, though this time with their Compressor Bank CB303 under the preset “Harmonic Distortion”. Brauer suggests utilising a three band EQ with fixed bands at Low End around 100 Hz, Mid Range around 3 kHz and Hi End around 10 kHz and therefore decided to utilise the Waves emulation of the API 550A 3-band equaliser.
Alike the A Bus, in order to test whether the plug-in processors were adding harmonic content to the signal, a 1 kHz test tone was routed through the compressor and equaliser, with a frequency analyser inserted after the equaliser. The results can be seen in figure 2 and show once more that plug-ins do add harmonic content, furthermore proving the validity of Brauerizing ITB.
As shown in Appendix 3, Brauer routes drums and bass to the B Bus. The Compressor and EQ patched across the input of the Bus compliment the input material and are discussed in terms of their impact on the input material within the mix further down in this task report.
During Brauer’s 2007 AES seminar, he discusses at length the techniques involved in Brauerizing and discusses how his assistant had been experimenting with the technique ITB, and although it was close, it was not quite there yet. During this seminar, Brauer’s assistant discusses how the ABCD configuration included a mono distortion send/return for the B bus to add more harmonics; which I have assumed to be replicating the distortion artefacts that the Distressor is known for, and have therefore utilises a mono distortion send/return (Brauer, 2007). The distortion adds a great deal of harmonic content to the input signal and can be seen in figure 3.
The B Bus combined with the mono distortion adds a great deal of harmonic content to the mix and was able to identify the Brauerized mix in the Blind Listening Test as the mix with the obvious audibly pleasing distortion. The impact that the parallel distortion auxiliary has within the context of the mix is discussed further down in this task report.
The C Bus utilises compression only, and OTB has a Pendulum ES-8 Compressor, a Vari-Mu compressor similar to the famous Fairchild compressor. As the replication of the outboard equipment has been with the most appropriate emulations, it was deemed appropriate that the Slate Digital FG-Vari-Mu compressor should be utilised as they are frequently heralded at their accuracy for modelling analogue equipment. Figure 4 will once more demonstrate how these plug-in processors are adding harmonic content to the input material.
As shown in Appendix 3, Brauer routes Guitars to the C Bus and the slow characteristics of Vari-Mu compression compliment the input material routed, which is discussed in further detail further down in this task report.
The final bus of the Multi-Bus Compression stage utilises compression only; alike the C bus, though with a higher ratio than the other busses; and therefore limiting the audio signal. Brauer suggests utilising a limiter, though as shown in Appendix 3, Brauer utilises Edward the Compressor; a limiting compressor with a stereo width knob cranked fully (Miller, 2013). In order to replicate ITB, the Waves V-Comp plug-in was utilised set in limiter mode with a Stereo Widener patched post compression to emulate Edward the Compressor’s width knob. Figure 5 shows how these plug-in processors are adding harmonic content to the input material, once more.
As shown in Appendix 3 Brauer routes Backing Vocals and spatial effects; reverbs and delays, to the D Bus and believe that the gentle limiting of the input material allows for the elements to remain controlled, while the widening compliments the backing vocals and reverbs as it allows them to appear larger than life and can add further dimension to a mix, this will be discussed in the context of the mix further down.
Throughout the figures in this Appendix, it would be accurate to state that Brauerizing with Multi-Bus Compression as a means to add harmonic content to the input material has been achieved and proved with the frequency analysers. “Counter-Pumping” as defined by Brauer was always possible through configuring the compressors to modulate amplitude at varying rates and believe Multi-Bus Compression has been achieved ITB.
Once the ITB emulations of Brauer’s OTB hardware equivalents had been sourced and configured across the ABCD busses, it was paramount to calibrate the compressors to Brauer’s specifications in order to “drive” the input of the compressors in a comparable way ITB as Brauer would OTB. In order to Calibrate, a Signal Generator was patched across insert A of the ABCD busses, and a VU Meter at the output. In this instance the stock Pro Tools Signal Generator was utilised and plug-in VU Meters by PSP Audio; due to these being available in the AAX 64-bit plug-in format at the time of the project.
The SSL9000J that Brauer utilises equates 0 on the test Oscillators to 0 VU (unknown, 1994), which was emulated ITB by setting the Sine Wave Signal Generator to -12dB which read 0 VU on the PSP VU meters. The SSL9000J allows for the test Oscillators to be routed to any of the centre groups; which Brauer utilises for his Multi-Band Compression ABCD Bus set-up, and the following paragraphs will detail how this calibration process has been emulated ITB.
Bus A has the test Oscillator set to 1 kHz at 0 VU going through the 33609 and Pultec, with the threshold on the 33609 altered so the Gain Reduction on the compressor reads at 1 dB. The Pultec’s Low Frequency is set to 100 Hz and the High Frequency to 8 kHz. The SSL’s Test Oscillator frequency is then changed to 100 Hz and the low frequency band on the Pultec is boosted until the VU meter reads at +1 VU. The SSL’s Test Oscillator frequency is then changed to 10 kHz and the high frequency band on the Pultec is boosted until the VU meter reads +1.5 VU. Upon returning the SSL’s Test Oscillator frequency to 1 kHz the VU meter; where the compressor and equaliser have been calibrated correctly, will read at +1 VU (Brauer, Undated).
In order to replicate ITB, the Signal Generator was set to a 1 kHz Sine Wave and a level of -12dB; to replicate 0 VU. The McDSP 6030 Brit-C module’s threshold was then reduced until the gain reduction reads at 1 dB. The Puigtech’s frequencies are selected at 100 Hz and 8 kHz, with the Signal Generator frequency altered to 100 Hz and the low frequency gain on the Puigtech increased until the PSP VU reads +1VU. The Signal Generator frequency was then changed to 10 kHz and the high frequency gain parameter on the Puigtech was boosted until the PSP VU read +1.5 VU. Upon returning the Signal Generator’s frequency to 1 kHz, the PSP VU read at +1 VU and therefore concluded successful calibration of the A Bus.
Bus B has the Distressor’s parameters configured to a 6:1 ratio, attack time of 10 ms and a release time dependant upon how the input material feels; going back to the Multi-Vibe Compression analogy suggested in 2.3. With the SSL’s test Oscillator frequency set at 1 kHz and the level set to 0 VU, the threshold is then configured so that the Gain Reduction reads at 1 dB. When utilising Equalisers; as with this project, frequencies 100 Hz, 3 kHz and 10 kHz are all utilises with a gain increase of 1 dB at each frequency band (Brauer, Undated).
To replicate ITB, the McDSP CB303 preset “harmonic distortion”; modelled after the Distressor’s characterists, was utilised, with the ratio set at 6:1, attack time to 10 ms and the release time configured to compliment the input material; this is one post calibration. The Signal Generator was set to a 1 kHz Sine Wave at -12 dB and the threshold of the compressor was altered until the Gain Reduction read a reduction of 1 dB. The API 550A was then configured so that 100 Hz, 3 kHz and 10 kHz all had a gain increase of 1 dB.
Busses C and D don’t have as strict calibration. Bus C utilises the Pendulum in it’s fastest mode, with the SSL’s Test Oscillator set at 0 VU and 1 kHz for calibration. Input Gain of the compressor is increased until the VU meter reads at +1 VU and the output gain set to 1 o’clock. Threshold is then adjusted until the VU Meter reads 0 VU, which will indicate a reduction in gain of 1dB (Brauer Undated).
In order to replicate ITB, the Slate Digital FG Vari-MU was configured so that the attack time and release time were at their quickest. The Signal Generator Sine Wave was set to 1 kHz and -12 dB, with the input gain of the FG Vari-Mu increased until the PSP VU read +1. The Output gain was set to 1 o’clock and the threshold of the compressor adjusted until the VU meter read 0 VU which equated to 1 dB of gain reduction.
Bus D is calibrated identically to Bus C, with the SSL’s Test Oscillator set to 0 VU and 1 kHz. The input gain of Edward the Compressor is increased until the VU meter reads at +1 VU and the output gain is set to 1 o’clock. The threshold on the compressor; set in limit mode, is adjusted until the VU reads 0 VU indicating a gain reduction of 1 dB. The widener knob on the unit is set to it’s maximum; emulating an increase of 100% in stereo width, (Brauer, undated).
In order to replicate ITB, the Waves V-Comp was configured to limit mode. The Signal Generator Sine Wave frequency was selected at 1 kHz and -12 dB, reading at 0 VU on the PSP VU meters. The input gain on the limiter was increased to read +1 VU on the VU Meters, with the output gain set to 1 o’clock and the threshold adjusted until the VU Meter reads 0 VU, equating to a Gain Reduction value of 1 dB. The Waves S1 stereo widener was set to 200% width, emulating the widener knob on the hardware equivalent.
Once calibrated, it was important route the multi-track accordingly and therefore routed all keyboards, strings, synths and pianos to Bus A, drums and bass to Bus B, guitars to bus C and backing vocals and spatial effects to Bus D. As Brauer utilises the SSL routing matrix buttons to route the audio out of the stereo bus and directly to the groups; in post-fader mode allowing the faders to drive the compressors, it was important to emulate this ITB and was done so by creating a dummy bus in Pro Tools.
The Dummy Bus allows for all of the audio within the multi-track to be routed to a destination that is not being outputted to the main outputs; as Pro Tools disables faders, pan pots and sends when selecting the no output function. In utilising the dummy bus, the ABCD post-fader configuration was emulated using the channel sends in order to route audio to their desired busses. Please see Appendix 4 for the Signal Diagram for Multi-Bus Compression ITB and compare to the OTB Multi-Bus Compression configuration shown in Appendix 3.
It would be fair to state that the Multi-Bus compression aspects of Brauerizing are more than possible ITB, and have been emulated successfully; following specific definitions by Brauer himself. Once calibrated; as defined by Brauer, and routed accordingly, it did not take too long in pushing faders before the plug-in compressors “sweet spots” lay, and found that anywhere between 1 dB and 3 dB of Gain Reduction sounded aurally pleasing, anything over 3 dB sounded over compressed and thin.
In keeping in the “sweet-spot” a thickness and harmonic colour was added to the mix that is found on works by Brauer, and therefore deem that the plug-ins were more than capable of imparting harmonic content to the audio signal. Delay Compensation within the Digital Audio Workstation remained solid and therefore ensured that slight delays didn’t cause the multi-track to phase; another problem Brauer found with Brauerizing ITB.
In referring your attention to the Index of Media files, you will find Soundcloud links to listen to each of the busses in isolation. The following paragraphs reflect an analysis of each of the busses in isolation, discussing how the input material compliments the processors across the auxiliaries, as well as the harmonic content added by the plug-ins.
In isolation, Bus A sounds very controlled in a manner that does not audibly contain the artefacts of heavy compression. In referring your attention to the Pro Tools session found on the Data Disk submitted with the report, you will note that the tracks routed to Bus A; colour co-ordinated light blue, have volume automation at various points within the track. Volume automation is a fantastic method of controlling dynamics, without the audible effects of heavy compression (Gilder, 2011), which when utilised in conjunction with the gentle compression of Bus A, allowed for the input material to sound natural and controlled.
The British C; as mentioned previously, models the VCA based compressor utilised by Brauer on the A Bus. VCA compressors are known for their bright, colourful characteristics and therefore compliment the bright, transient heavy input material (Haas, 2008). The slow attack of the compressor allows for the initial transients to have presence and keep their rhythmic accents, while the medium release allows for the compressors gain reduction to pulsate with the track’s overall feel. It would be accurate to state that the low 2:1 ratio of the compressor; for every 2dB to pass the Threshold one dB of Gain Reduction will occur, allowed for the compression to be even less noticeable, allowing the compressor to add pleasing harmonic qualities, but the compression itself to be relatively transparent. The settings for the compressor can be seen below in figure 6.
The frequency spectrum of Bus A combines low frequency weight, emphasising the fundamental frequencies of the instruments contained within the Bus, as well as high frequency “sparkle” in the top octave of the input material’s frequency content. The utilisation of the Pultec emulation allowed for Bus A to add to the power of the low frequencies within the mix with a 2.5 dB boost at 100 Hz, as well as complimenting the bright characteristics of the compressor with a 4.2 dB boost at 8 kHz. The settings on the EQ were calibrated to the specifications outlined by Brauer and can be found below in figure 7.
The pairing of the 33609 styled compressor with the Pultec styled EQ allowed for Bus A to remain the “Almighty Top”; as named by Brauer himself (Brauer, 2007), gently controlling the output with subtle compression and sculpting the Brauer “colour” with the Equaliser.
In referring your attention again to the Index of Media Files. Bus B; alike Bus A, has a great deal of natural sounding dynamic control and in once more referring your attention to the Pro Tools session included on the Data Disc, you will note subtle volume automation on the individual channels, as well as on the parallel channels in order to bring the average level of the tracks up, increasing overall loudness naturally.
It would be accurate to state that Bus B has a much more coloured sound than Bus A and has intentionally been processed in such a way. Brauer’s B Bus contains the Distressor compressor, a compressor known for it’s distortion artefacts (Unknown, undated) and therefore intended to ensure the B Bus ITB held similar colouration and distortion artefacts. During Brauer’s 2007 AES lecture, his assistant discusses experimentation with the Multi-Bus Compression ITB, where the effects of the Distressor were achieved by utilising a mono send and return auxiliary, with a distortion plug-in inserted. It was therefore of paramount importance to ensure similar processing was utilised when recreating the B Bus ITB.
The utilisation of distortion embellishes the B bus and introduces artefacts similar to limiting, while systematically adding high frequency content to the input signal allowing for the material to cut through the mix furthermore (White, 2000), and believe this to be the conclusion as to why Brauer couples distortion with the Drums and Bass, to allow the lower fundamentals of the bass and kick drum that add power to the mix, to cut through just as much as the crack of a snare drum.
The McDSP CB303; as shown in Figure 8, was utilised to emulate the distressor with a relatively quick attack; 10ms, allowing for the initial percussive transients of the input material to bass the compressor, compressing gently once more and releasing after 40ms. The quick release adds a great deal of punch to the signal with the 6:1 ratio allowing for the harmonic effects of compression to be audible, though in a pleasing, saturated manner.
Low frequency content can often be problematic when configuring a compressor due to the energy low frequencies consume, and therefore utilised the Pre-Filter stage of the compressor to ensure that frequencies below 55 Hz did not trigger the threshold of the compressor, allowing the plug-in to add character to the fast transient attack of the input material. This can be heard within the isolated Bus B media file, as the bass guitar’s fundamentals still sound round and open, unaffected by the compressor, which in conjunction to the low frequency boosts on Bus A embellishes the low frequency content of the mix, creating a rounded bottom end.
Similar to Bus A, Bus B utilises an Equalisation stage too, utilising the Waves API 550A 3 band EQ to add more colour to the input signal. As shown in Figure 9, the EQ has been set at 100 Hz, 3 kHz and 10 kHz respectively. The low frequency and high frequency bands of the EQ are set to shelving filters and therefore gently boost frequencies below and including 100Hz; to furthermore round the low frequencies of Bus B, and gently boost frequencies above and including 10 kHz; adding presence and air to the input material. The mid frequency selection of 3 kHz compliments the attack of the kick, snare and bass, furthermore adding colour to Bus B and shaping the frequency content around Bus A, allowing the two to cohere.
The pairing of the Distressor styled compressor with the 3 band Equaliser, paralleled to a mono distortion, allowed for the compressors character to remain punchy and aggressive; complimentary of drums and bass, with the 3 EQ boosts complimenting the input material by boosting the power of the fundamental frequencies, allowing the input material to cut through with the mid frequency boost and adding clarity with the high frequency boost. Coupled with the parallel distortion, the colouration of the B Bus allowed for the input material to remain present within the track, both dynamically and sonically.
In referring your attention to the Index of Media Files. Bus C; alike previous busses, has a great deal of natural sounding dynamic control and again referring your attention to the Pro Tools session included on the Data Disc, you will note a great deal of volume automation on the individual channels, controlling the dynamics naturally as well as accentuating the rhythm of the parts being played, as well as on the parallel channels in order to bring the average level of the tracks up, increasing overall loudness naturally. In isolation; particularly around 3:25, richness in the 3 – 5 kHz range can be heard, which is due to the utilisation of the valve compressor emulation on the C Bus.
Valve compression tends to have a slower attack and release time than the other types of compressors, and therefore compliments it’s application on the Guitar Bus, as this allows for the initial attack of the guitar to pass the compressor, with the compression smoothing out the sustain of the guitar. The emulation of the tubes allows for non-linear distortion artefacts to be introduced to the frequency spectrum, adding the richness discussed above (Haas, 2000).
The plug-in emulation utilised was that of the Slate Digital VBC FG-MU compressor, based on the classic designs of the Manley Vari-Mu and Fairchild 670 tube compressors (Slate, 2013), mimicking Brauer’s utilisation of Tube/Mu compression on Bus C with the Pendulum. The parameters set; as shown below in Figure 10, shows a medium/fast attack time that was set to allow the initial transients of the guitars through, and the quickest attack time. The quickest attack time was found to pulse with the rhythm played by the electric guitars and therefore found it most appropriate. Note that the “Stereo Link” is switched off, this is a key feature of Brauerizing; with all other plug-in compressors working in unlinked Multi-Mono to emulate unlinked Stereo compressors.
Through unlinking a stereo compressor, each side works independently and therefore modulates amplitude dependant upon the placement within the stereo field; as stereo field placement will cause the signal amplitude to be stronger for one side of the compressor when panned. Traditional stereo compressors take the loudest signal and compress the whole stereo spectrum according to the signal, though where unlinked, the left could compress 3 dB while the right side remains untouched, causing a difference in amplitude between the left and right of that particular auxiliary and therefore adding width.
With the A Bus sculpting the sonic spectrum of the input material to carve space for the middle frequencies, the harmonic imparting of the B Bus compression and parallel distortion adding an overall clarity to the input material, as well as the Equalisation allowing for the presence of the Kick, Snare and Bass Guitar to sit in the space left by Bus A, Bus C; consisting of hard panned guitars, wraps itself around Bus A and B in terms of stereo field, while the harmonic impact of the tube compression furthermore fills the frequency gap left by A.
Bus D from the Index of Media Files is perhaps the most difficult of the busses to comprehend in isolation, due to the lack of input material, but is where spatial effects such as reverbs and delays are routed to, as well as Backing Vocals, with the plug-in processers utilised on the D Bus add width and saturation similar to that of Bus C. OTB Brauer utilises “Edward the Compressor” in Limit, with the width knob cranked to full (Brauer, Undated) and have therefore utilised the Waves V-Comp in Limit and the Waves S1 Stereo Imager plug-in cranked to fully wide in order to emulate the hardware utilised by Brauer.
The parameters set on the V-Comp; as shown below in figure 11, are set so that the plug-in is working in Limit mode only; ratio higher than 10:1, with the attack set to fast; 1 micro second, to ensure the limiting is crushing the signal when reducing the gain, adding the distortion artefacts of the limiter, and the release set to auto; ensuring that the gain reduction works rhythmically with the input signal (Unknown, Undated). In setting the release time once more to a musical value, all four busses will modulate gain rhythmically, allowing for Brauer’s “Counter-Pumping” technique to take place (Brauer, 2005).
In referring your attention specifically to 3:00 into Bus D’s media file, the saturation qualities of V-Comp can be heard on the reverse reverb tail leading up to the initial delivery of the vocals, with the hard limiting and rhythmic “pumping” of the limiters release time obvious on the word “me” each time, with the delay also rhythmically “pumping” as opposed to naturally decaying as a delay typically does, with the widener qualities most audible at 3:26 on the line “life” as the delay sounds as though it is panned outside of the stereo spectrum.
With the above discussed regarding the Multi-Bus set-up, the calibration, configuration and routing has been a success, with the harmonic coupling of plug-in processers complimenting the input material also being successful. The most critical aspects of Brauerizing that have been achieved through this task has been the confirmation that plug-ins do have the ability to saturate and add harmonic content to the input signal, and have also managed to cause “Counter-Pumping” between the four busses, with each compressor on each bus releasing rhythmically.
Though Brauer himself uses the term “Counter-Pumping”, it would be useful to consider the term “Sonic Weaving” as a substitute. “Counter-Pumping” would suggest that as one compressor is modulating gain, another remains unaffected, though this is not the case and at any point during a mix all four compressors may be reducing gain. “Sonic Weaving” is a more visual metaphor for the audible phenomena, as all four busses “intertwine” through the gain reduction rates rhythmically differing at any one time within the mix. This “dynamic weaving” of the four busses allows the vast array of input material to cohere and glue the mix together, while still remaining dynamic due to the rhythmical relationship with the track itself.
With each of the busses averaging a gain reduction rate of around 1.5 dB, the accumulative gain reduction is around 6 dB. Due to the multi-bus compression stage occurring pre-stereo bus, the issues Brauer found with Stereo Bus compression; as discussed in the Introduction of the report, can easily be avoided, with each bus reducing the gain subtly prior to reaching the Stereo Bus. Although each of the four busses that make up the Multi-Bus Compression Stage remain loud, dynamic and punchy, they do not affect the Stereo Bus in an audible manner, and the averaging 6 dB of Gain Reduction across the four busses in conjunction with the 2 dB averaging gain reduction on the Stereo Bus Compressor allow the mix to be loud, yet dynamic, where 8 dB of Gain Reduction alone on the Stereo Bus would cause unpleasant compression artefacts and make a mix sound flat. Please refer your attention to the ABCD Excerpt found in the Index of Media Files to hear the ABCD busses introduced gradually, along with the vocals. Note how as each one is introduced, the punch of the track is unaffected thanks to the utilisation of the Multi-Bus Compression stage, as well as how all four busses subtly pulsate, rhythmically.
Despite all of the advantages discussed, it should however be considered that the routing process is a long, technical and meticulous one and the importance of saving session templates to allow ITB Brauerizing to be imported to other sessions must be stressed. It must also be stated that Multi-Bus Compression is not a guaranteed method of adding a professional sheen and loudness to a mix, and that the mix itself must be performed well in order to furthermore embellish with the Multi-Bus configuration. Whether or not Brauerizing as a finalising technique holds any more weight than Stereo Bus, Multi-Band or Parallel Compression is something that will be concluded later in the report.