Audio Engineering Society UK

Title: Mixing Out of the Box… The New Way?
Location: Leeds University, School of Music, Leeds, LS2 9JT
Description: Lecture by Simon Humphrey, The ChairWorks Studio
Start Time: 18:30
Date: Tuesday 17th May 2011

Abstract

Simon Humphrey is a recording engineer and producer based at the ChairWorks, a thriving independent recording facility in Castleford, near Leeds.

Simon will discuss the burning questions that ‘float’ around today when it comes to the role of the engineer, producer and recording studio. He will tackle that all-too-often-questioned subject of recording studios and their validity in a modern recording industry – ‘why do studios matter?’

Using the ChairWorks Studio as a blueprint, Simon will discuss ‘how they do it’.  While some may think studios are the ‘kiss of death’, we will hear, perhaps most importantly, ‘why do they do it?’

Moving on to studio equipment, Simon puts forward the question, ‘Mixing out of the box, the New way?’  Computers could have consigned analogue mixers and the outboard rack to history, but they haven’t. Simon will discuss Rack V’s plug-ins and explain how they work together with outboard on a mix.

Simon’s experience working in education has allowed students a privileged door to the inner workings of the music Industry and it seems students everywhere ask the same three ‘golden questions’. Simon will discuss and give his answers to these.

Throughout, Simon will be talking about his career over the past almost 40 years. It is a invaluable look into the life of a seasoned engineer’s career through the decades, whose work many see as the benchmark of engineering today.

Title: Music, Movement and Magic [Cambridge]
Location: Anglia Ruskin University, Room 201, Helmore Building, Cambridge, CB1 1PT
Description: Lecture by Dr Richard Hoadley and Sam Aaron
Start Time: 19:00 for 19:15
Date: Thursday 31st March 2011

[Lecture is Thursday 31st, not Wednesday 31st as incorrectly stated in March newsletter.]

Abstract

Transducers for converting physical data into digital data and algorithmic procedures for generating and controlling audio have existed for many years, but it has been only recently that affordable systems and products able to unite the two have become widely accessible. This paper examines the development of hardware and software systems designed to explore the nature of movement and gesture in musical creation, performance and expression.

Our experience suggests that when we move, any resulting actions will reflect that behaviour. In digital systems that can detect these actions there is no direct causal link between event and action: any mapping has to be specifically implemented and might therefore be referred to as Œmetaphorical. Such implementations can include desirable features that would be difficult or impossible to implement in reality. Such features have been described as Œmagical.

This paper describes and analyses work seeking to investigate the amalgamation of these two areas in practice-led activities, where ‘magic’ and ‘delight’ equate with musical qualities usual considered to be aesthetic rather than technical. Music performance in particular uses unique methods of articulating and implementing expressive gesture through physical interaction with objects. Similar undertakings by other performers (such as dancers) and fine artists are also considered.

Richard Hoadley is a composer affiliated to the Digital Performance Laboratory at Anglia Ruskin University.

Sam Aaron leads Improcess, a collaborative research project exploring the combination of powerful sound synthesis techniques with tactile and linguistic user interfaces to build new forms of musical device with a high capacity for improvisation. His current main avenue of exploration is through the use of the monome, a grid of backlit buttons capable of bi-directional communication and Overtone, a novel Clojure front-end to SuperCollider server.

Title: Point One Pitfalls – Monitoring For Surround Mixing Explained
Location: Leeds University, School of Music, Leeds, LS2 9JT
Description: Lecture by Roger Quested
Start Time: 18:30
Date: Tuesday 19th April 2011

**Free shuttle bus from PLASA Focus. Contact north@aes-uk.org to book your place.**

Abstract

Roger Quested will use his knowledge of the world’s top studios and recordings to explain how to make a studio monitoring system produce the best possible surround mixes.  Demonstrating on his company’s own Quested 5.1 V3110 System, he will discuss i) positioning of speakers and subwoofers, ii) the LFE channel and how best to integrate subwoofers into the system and environment, and iii) common mistakes to be avoided. 

With experience of surround systems gained from working with such names as Hans Zimmer (Gladiator, Pearl Harbour, The Dark Knight), Hackenbacker Studios (Downton Abbey, Spooks, Shaun Of The Dead) and Trevor Horn, this will be a chance for those hoping to maximise their surround mixes to understand the complex monitoring elements that affect all studio environments.

Title: Active Acoustic Absorbers: Do They Work?
Location: Royal Academy of Engineering, London, SW1Y 5DG
Description: Lecture by John Vanderkooy
Start Time: 18:30 for 19:00
Date: Tuesday 10th May 2011

Lecture Report

Active acoustic absorbers can replace low-frequency ‘passive’ absorption techniques. Passive techniques generally involve solving resonance problems in a room by introducing absorbing materials or resonant structures. General-purpose acoustic absorption, comprising sheets of heavy material attached to rigid frames, are somewhat impractical in many rooms, because the size at which they become effective is between a quarter- and a half-wavelength of the frequency of interest — around six feet when treating a 50Hz resonance. Membrane absorbers and resonators are tuned to move when stimulated by certain frequencies, and hence to terminate standing waves. These can be relatively small in size, but because they can react to only a small range of frequencies, several may be required to treat a room. We can alleviate serious problems in a room by equalising the loudspeakers that excite them, but this addresses only problems of sound pressure level. Equalisation cannot treat the equally insidious phase and reverberation time discontinuities that afflict specific frequencies.

Active absorption is effected by positioning subwoofers or full-range loudspeakers strategically, and driving them with a specially-calculated signal that cancels a large range of frequencies, using less space and treating a greater range of frequencies than a passive absorber could.

A relatively simple and theoretically ideal example of this is the ‘delay and cancel’ scheme. Taking a rectangular room, we can place two loudspeakers 25% and 75% of the distance along a wall, and drive them coherently. The images of these loudspeakers reflected in the other walls are evenly spaced, creating a plane wave along the room. This can be cancelled at the rear of the room using a similar arrangement of loudspeakers, delayed appropriately. The bass then becomes effectively anechoic at low frequencies.

Given a rectangular room of dimensions 8 × 7 × 3.5 metres and a reverberation time of one second, we can use the Sabine formula to calculate that the room contains 31.5 sabins (square metres of ideal absorption). The effective area of an active absorber is equal to:

A_abs = λ² / 4π

This is about 3.7 sabins at 50Hz (an extra 12% of absorption in this room), and 24 sabins at 20Hz (an extra 74%). The theoretical benefits of ideal active absorption are clear, but there are some practical difficulties. Firstly, an ideal loudspeaker is a point source radiator, and the wavefront that we want to treat is generally closer to a plane wave. How do we know that our absorber is not interacting elsewhere with the wave that we are attempting to absorb? Secondly, how does this treatment work in a room where the absorption signal itself is reflected?

John Vanderkooy’s derivation of the driving voltage for an acoustic absorber was performed very rapidly at the lecture, but the brief answer is that both conditions are met without difficulty. The emerging formula for the absorbing signal is:

q(t) = 2πc/ρ × ∫ ∫ p(r,t) dt dt

Where q(t) is the desired volume velocity of the active absorber loudspeaker. Thus, the cone velocity of the absorber is proportional to the double time integral of the pressure at the loudspeaker from the room. To produce this volume velocity we could use a  velocity-sensing coil on the loudspeaker in feedback, for example.  The pressure p(r,t) must not be contaminated by the absorber signal itself, so we must know the absorber response and subtract it from the microphone signal.  Eliminating the self-pressure of the loudspeaker (caused by its provision of the absorbing signal), and shaping the output transfer function to be both stable and correct for the loudspeaker is a significant challenge.

In summary, active absorption is an acoustically valid way of treating low-frequency problems in real rooms, but there are considerable practical difficulties in doing it well. One practical barrier is the necessity for near zero-latency analogue-to-digital conversion and DSP in order to suppress the local absorber signal, read the instantaneous external pressure from the room, react to it, and hence calculate the desired absorption signal.

Report by Ben Supper

Title: 21st Century Mastering Workshop [London]
Location: Royal Academy of Engineering, London, SW1Y 5DG
Description: A group of leading mastering engineers discuss the latest techniques and the challenges they face.
Start Time: 18:30 for 19:00
Date: Tuesday 8th March 2011

A recording of the workshop is available here (66MB mp3)

A report will be avialable shortly.

Now that digital recording technology has superseded analogue, is it the ‘perfect sound forever’ that we were promised at the launch of the CD back in 1982?

A group of leading mastering engineers discuss a range of topics encompassing:

Synchronisation: How come it’s the sound that is always out of sync? Why is it not the pictures?
Dither: Is it important any more? Can we hear the difference? What changed?
Compression: How loud does it need to be? What is required for the best results when broadcasting or digitally distributing data compressed files?
Creation of a future proof archive: Just which of those 37 files labelled ‘Master – Final Version’ is actually the master, and whose responsibility is it to keep a record of this information?

On the panel are:
Crispin Murray – Metropolis Mastering (Moderator)
Mazen Murad – Metropolis Mastering
Ray Staff – AIR Mastering
David Woolley – Thornquest

They will share some experiences and advice, along with hopefully some amusing anecdotes of what to avoid in order to produce the best results.

 ‘A4V: Audio for Visuals’ is a one-day symposium covering the many aspects of creating sound for pictures.

The symposium will be held on Saturday 5^th February 2011 at the National Film and Television School, Beaconsfield, starting at 9.00am and finishing at 5.30pm. It is aimed at audio engineers seeking to broaden their horizons and students wishing to get a flavour of the wide range of visuals-related disciplines that make up today’s audio industry.

For more information about the event, the provisional programme and details of the various ways to register, please visit the A4V: Audio for Visuals web page.

Title: Restoring the EMI REDD51 mixing console
Location: Royal Academy of Engineering, London
Description: Lecture by Brian Gibson, TG Electronics
Start Time: 18:30 for 19:00
Date: Tuesday 8th February 2011

A recording of the lecture is available here (52MB mp3)

Lecture report

Origins of the REDD51 Development
The Record Engineering Development Department was set up to develop Stereo Recording Technologies in 1955 under Len Page. Up until then the simple 8 i/p Mono Consoles had two sizeable racks of equipment (amps, pre-amp’s, power supplies etc.). Following the developments of EMI in Germany in 1958 the REDD17 console was built with all the electronics integrated, with M+S on both channels 1/2 & 7/8 of the 8 channels – this model was only ever used for mobile recordings, and not in Abbey Road. The console was then expanded to have 4 channel monitoring to work with the EMI 4 track tape machine and became the REDD37. These used the Siemens and Halske cassette 40 dB V72S amplifier. EMI then developed the REDD47 amplifiers to replace the V72S in order to be more self reliant as a company and to reduce production costs – however these used 5 times the power and consequently heat! This combination became the REDD51 console, and was installed from 1963 onwards; two being installed at EMI’s Studios in Abbey Road. Console production numbers are uncertain as a number of consoles were built for other territories.

Amplifiers
The main difference between the Siemens and the EMI REDD47 amplifiers is the requirement for external power supplies (Siemens are self contained with 240 v input); therefore there are six sizeable psu’s, two in each base, and one in each upper unit.

Valve Architecture
EF86 (or CV4085) pentode in an antivibe mount followed by a dual triode E88CC low impedance cathode follower into the transformer.

Operational Signal Path
Very much an ‘old school’ design using a series of three 40 dB amplifiers, with passive sections in between to give attenuation, equalisation and panning – this is a novel configuration in that a mono signal is split in a hybrid transformer and then fed through a pair of faders in a differential arrangement to give panning. There follow 4 group outputs to feed a 4 track tape machine with 4 tape returns for monitoring.

Mechanical Arrangement
The console is arranged as five separate sections that are held in position by locating pins and are clamped together, with a separate distribution for mains power. Signal distribution is by a set of plugs and sockets with a screw clamp to maintain integrity. This was simply so that the console could be broken down and transported easily, and hence could be used for mobile applications. In the left hand side of the console is a test panel and meter to fully test the operation of the REDD47 amplifiers in situ. The centre section of the console is filled with EMI ‘in house’ built transformers to buffer all stages.

Plug In Equalisers
‘Pop’ and ‘Classic’ units, as removable or exchangeable modules. All are capacitor and inductor circuits, for their phase characteristics, and are consequently quite lossy (hence the gain structure of the console) but great sounding. The Pop equaliser is a peaking eq based on 5k centre frequency, whereas Classic equaliser is a shelf based on a centre frequency of 10k, with up to 10 dB cut or gain in 2 dB steps.

Faders
There are fourteen faders arranged across the centre section, 1-4 input faders, aux channel (originally echo return), the 4 track sends, another aux channel, 5-8 inputs.

Overall Layout
Below meters are the routing switches, beneath that are the ‘spreaders’ for the MS channels that are selectable via plug in modules on the rear panel, and panpots for the others channels. Lower down are the echo sends (two switchable) and the returns. Above the four track sends in the centre are the track routing switches, generally left 1, 2, 3, 4. The quadrant faders are Painton stud faders, and the majority of the controllers are also from the same source, with each stud connected to a separate precision resistor: quality first, cost second!

Amplifiers
The main difference between the Siemens and the EMI REDD47 amplifiers is the requirement for external power supplies (Siemens are self contained with 240 v input); therefore there are six sizeable power supplies, two in each base, and one in each upper unit. Valve Architecture EF86 (or CV4085) pentode in an antivibe mount followed by a dual triode E88CC low impedance cathode follower into the transformer.

Limiting and Outboard
There was no limiting built into the console however operationally there tended to be a pair of Altec limiters on Tape Channels 1 & 2 for the rhythm tracks, and a pair of mono Fairchild 660’s on 3 & 4 for the vocals.

Metering
Although originally supplied with PPM metering, EMI replaced these with the VU Meters that are still installed. The meter drive amp is self powered from 240 v, and is of a transistor design. It features a +10, 0, -10, -20 control that can also be remote controlled via a relay array, with push buttons on the top panel to allow for auxiliary meter gain during quiet sections of classical music. 4 VU meters are set in a bridge or penthouse with a phase correlation meter in the centre.

No One Needs More Than 8 Microphones
Len Page had decided that 8 microphones would be sufficient, however quite a number of engineers started to require more, so a 4 channel sub mixer was created that was often routed into one of the Echo Faders (by now Aux Faders). An original unit was sourced from a former Abbey Road engineer and has been restored to original condition and is used regularly.

The British Grove Console
This console came to light at a brokerage in Italy as “The Beatles Console”…. British Grove Studios sent Dave Harries (legendary Abbey Road and Beatles and Air Studios boffin) to verify the provenance and he confirmed it was both complete and genuine. It was possible to determine that it had been installed in the Milan Studios of EMI, however it had languished unpowered for the last 30 years. Following negotiations it was purchased and brought back to England into the care of Brian Gibson to restore.

Cleaning
40 years of dust had to be cleaned out and it was very sticky! For the most part the console was completely dismantled and was entirely cleaned with a small brush and soapy water – a very patient operation.

Component Replacement
Where for the most part the old components were just cleaned, the electrolytic capacitors were all replaced for both sonic and safety reasons; there is a multi stage capacitor that has in most cases been retained, however it was found that there was a company in the USA that was remaking this particular model with identical values, so any suspect ones were replaced as a matter of course.

And So to British Grove
The console has pride of place in the main studio alongside a later EMI TG Console and a modern Neve 88R, it is used regularly on most recording sessions in the studios, often as an insert into the Neve console, its younger sibling the TG console is also used regularly in this fashion to much acclaim, giving artists, engineers and producers probably the best of all worlds.

Report by Crispin Murray

Title: Technical Visit – FULL
Location: Royal Opera House
Start Time: 10:45am for a 11:00 start
Date: Wednesday 19th January 2011

Read a report on the visit.

A rare opportunity to see behind the scenes at this historic venue.

The ROH has scheduled a rehearsal of Swan Lake for the 19th, which has required some changes to the start time and running order of the tour.

The tour will start with a short overview of the ROH’s history followed by a look at the auditorium, the layout of the orchestra pit and the microphones used for recording and foldback to the stage.

There will then be the opportunity to see and hear some recent productions in the audio suite. This is equipped with a Studer Vista console, Pyramix editing system and B&W 5.1 monitoring, and is used in conjunction with the in-house HD video facilities for a variety of applications such as recordings for the ROH’s Opus Arte video label, live events to cinemas and Radio 3 broadcasts.

Afterwards, members of the ROH’s sound and broadcast facility team will be happy to answer questions. The tour is expected to take about two and a half hours.

The tour is now fully subscribed but we are hoping to arrange another one later in the year.

Those attending should aim to be at the Stage Door in Floral Street by 10.45 to allow time to pass through security and obtain badges. Please be advised that the ROH is an old building with several staircases backstage which will have to be negotiated in order to participate in the whole tour.

Title: Cutting Edge Research – From The University of Surrey
Location: Royal Academy of Engineering, London
Description: An introduction to our research will be given by the Director of research, Dr.Tim Brookes, followed by demonstrations and posters from our postgraduate researchers
Start Time: 18:30 for 19:00
Date: Tuesday 16th November 2010

Abstract:

‘Psychoacoustic Engineering at the Institute of Sound Recording (IoSR)’

The IoSR is responsible for world-class research in audio-related subject areas, and offers postgraduate research-based MPhil and PhD programmes, as well as being home to the world-famous Tonmeister™ BMus undergraduate degree course in Music & Sound Recording.

Since the creation of the Institute of Sound Recording (IoSR) in 1998 it has become known internationally as a leading centre for research in psychoacoustic engineering, with world-class facilities and with significant funding from research councils (in particular EPSRC) and from industry (we have successfully completed projects in collaboration with Adrian James Acoustics, Bang & Olufsen, BBC R&D, Genelec, Harman-Becker, Institut für Rundfunktechnik, Meridian Audio, Nokia, Pharos Communications and Sony BPE).  Additionally, the IoSR was a founding partner in the EPSRC-funded Digital Music Research Network (DMRN <http://www.elec.qmul.ac.uk/dmrn/> ) and Spatial Audio Creative Engineering Network (SpACE-Net <http://http://SpACE-Net.org.uk/> ).

We are interested in human perception of audio quality, primarily of high-fidelity music signals. Our work combines elements of acoustics, digital signal processing, psychoacoustics (theoretical and experimental), psychology, sound synthesis, software engineering, statistical analysis and user-interface design, with an understanding of the aesthetics of sound and music.

One particular focus of our work is the development of tools to predict the perceived audio quality of a given soundfield or audio signal.  If, for example, a new concert hall, hi-fi or audio codec is being designed, it is important to know how each candidate prototype would be rated by human listeners and how it would compare to other products which may be in competition.  Traditional acoustic and electronic measurements (e.g. RT60, SNR, THD) can give some indication but a truly representative assessment requires lengthy listening tests with a panel of skilled human listeners.  Such tests are time-consuming, costly and often logistically difficult.  The tools that we are developing will describe the quality of the prototype without the need for human listeners.

An introduction to our research will be given by the Director of research, Dr.Tim Brookes, followed by demonstrations and posters from our postgraduate researchers. We welcome those working in industry and academia to attend the presentation and to discuss our recent findings and overall research goals.

For additional information please visit:

http://www.surrey.ac.uk/soundrec/

Title: Technical Visit to ATC Loudspeakers
Location: ATC Loudspeakers, Stroud, Gloucestershire
Description: Technical Visit to ATC Loudspeakers (members only) – just a few places remaining.
Start Time: 11:00
Date: Friday 16th July 2010
End Time: 16:15

This technical visit is now full!

A technical visit has been arranged to ATC Loudspeaker Technology in Stroud, Gloucestershire on Friday 16th July, offering AES members a rare opportunity to see first-hand how these very highly regarded speakers are designed and built right here in the UK .

The visit will start at 11:00 and finish around 16:15. ATC are also very kindly providing refreshments and lunch.

ATC is a specialist British manufacturer of loudspeaker drive units and complete sound reproduction systems. They design and manufacture loudspeaker drive units and systems to achieve levels of performance far in excess of the industry norm which is achieved by adopting a thoroughly professional engineering approach to the issue of basic design, materials science and production technology.

The visit will include a tour of the design and production facilities and demonstrations of their products.

The number of places is strictly limited, so book your place early to avoid disappointment.

To reserve your place, please ring Heather on 01628 663725 or email uk@aes.org.