Designing Professional Analogue Audio Recording Equipment in the 21st Century #arp13


The PuigTec EQP-1A – but does it sound like Jack Joseph Puig’s original hand-crafted unit?

GASKELL, ROBERT-ERIC (McGill University)

Designing Professional Analogue Audio Recording Equipment in the 21st Century

[abstract] This paper looks at the decisions faced by contemporary analogue audio equipment designers when trying to balance sound quality, commercial demand, intuitive user interface, and financial viability in the current professional audio marketplace. Audio signal processor design straddles the line between electrical/computer engineering and music. It is a fundamentally interdisciplinary combination of art and science. While the goal of professional audio equipment design has always been to provide intuitive, innovative, and useful products that solve common problems in music production, designs often suffer from a lack of communication or understanding between the two disciplines.

Sound recordists and music producers have been forced to learn to think in the terms of the electrical and computer engineers who design the equipment used in recording studios. The names of parameters and the user interface of equipment have been classically defined by electrical engineers not musicians. The paradigms of the past, however, have been persevered and today designs of new equipment maintain many of the controls and even aesthetics that were defined sixty or seventy years ago.

Users have come to expect certain styles and types of interface and control parameters whether or not they are truly the most musical or intuitive.

There is currently an apparent resistance to innovative new designs within the professional audio marketplace. Commercial designers must always keep an eye on the marketability of their products and consider restrictions of cost, convention, and perception. The current production studio market can be defined by the desire of consumers to have access to the tried and true tools used to make classic albums. This desire is related to the rapidly changing production paradigms brought on by smaller budgets and new digital tools. Digital platforms provide relatively inexpensive solutions as well as many modern conveniences, however other factors such as workflow, ergonomics, sound quality, and visual feedback are yet to be fully addressed.

The history and development of some of some common recording studio equipment is overviewed in terms of the human-user interface, control parameters, and control terminology. The contemporary climate for manufacturers and consumers of professional audio signal processors is discussed. Successful future designs must exhibit a firm understanding of the perspectives and workflow of the contemporary music production studio as well as a familiarity with the paradigms of the past. The perspectives of large- scale manufacturers as well as boutique companies and DIYers are considered and examples of specific makes and models of audio signal processors are provided in terms of their innovation and their commercial reception.

The approach Eric takes is to base the research initially on (analogue) electronic components – capacitors, resistors etc. He is asking what contemporary users are looking for, the distinction between analogue and plug-in emulation, and how designers of equipment can embrace the fundamental differences between analogue and digital to keep analogue technologies competitive and relevant. His primary concern is to inform designers. He is looking today and mic preamps, EQs and mixers/summing busses. He intends to focus primarily on nonlinearilites in analogue equipment and how it is distinguished from linearities in digital.

End users are looking for vibe/aesthetics/historical relevance; workflow/user interaction; the idea of permanence and tangibility; and the sonic character and quality. Eric discounts the first as it is well covered elsewhere, and states that he will focus on the other three.

We now move into a discussion of workflow, and see Piccolo studios in Montreal and Eric reflects on the visual clarity of an analogue signal chain (or rack units). He then contrasts this with a screenfull of plugin emulation windows. He discusses the RADAR 24’s ‘analogue like’ sound [e.g. Sound On Sound review 2001] and he notes that its sound was not particularly analogue (its converters were not measurably so) but its workflow felt more ‘analogue’ to end users.

A similar example is the PuigTec EQP-1A + MEQ-5 EQ plugin. Eric suggests that the ease with which users can attain the plugin devalues the sonic/cultural value of the real-world hardware on which the plugin is based. He identifies it as being better value (from a consumer’s PoV), not least that the plug can be used in multiple instances simultaneously. He now discusses ‘WUP’ – the ‘Waves upgrade program’, citing the example of the Apple Intel processor driven enforced upgrade for Waves users. The WUP has a fee of $300 per year to guarantee upgrades. Users are unhappy – online forums use the phrase “I got WUPped”! Eric discusses the issues of uniqueness and consumer value that this engenders.

We now get into the detail of the research, focussing on sound quality. This is divided into Noise, Frequency Response/Time Domain Response, and Nonlinearity (distortion). Eric cites Bruce E Hofer ‘Analog Design in the 2010’ which provides practical approaches to analogue [sorry – I’m a Brit, so must add redundant U and E] design. He has interviewed Saul Walker, founder of API, who reflects that low harmonic distortion is easy to achieve technically for all. What we are looking for, Walker says is “not so much the science as the art and using the science to support the art, not the art to support the science…”. So they question is how analogue can provide us with the sonic colouration we are looking for [that is, how the signal can be inaccurate in a musically pleasing way].

The first item of equipment under discussion is the mic pre. In the industry these are usually analogue. We need an ultra-clean low noise floor but we also require colouration. We now see a frequency response graph for preamps from Neve, API, Hardy MI and BBpre. He shows that the BBpre shows substantially characterless THD (Total Harmonic Distortion) compared to the others, all of which give a ‘smiley face’ distortion frequency nonlinearity. The hysteresis or ‘memory effect’ of transformers is charted and discussed, especially given that this is difficult to model digitally with a lookup table. He now discusses transformer-based LFD in detail, and the relationship this has to the listener experience of ‘punchy low end’.

Because we’re short of time, he skips over capacitors [I assume this will be in the final paper] and goes to the Pultec EQP-1A and notes how the digital plugin model “fails to faithfully recreate the nonlinear performance” of the hardware equivalent. Similar graphs are shown for an API 550EQ.

Finally, Eric discusses Complex Studio Signal Paths, noting how THD can multiply in serial or parallel signal paths. He notes that modelling often does not properly reduce frequency response effects, and that analogue behaviour is always in the context of other devices; he gives a compelling example of the impedance matching inherent in chaining an 1176 to a higher or lower impedance device.

He concludes that there is no inherent superiority of analogue or digital, and that analogue hardware designers should work to the advantages of their medium. Integration (with digital) is key, and equipment should be built to last so that even expensive analogue tools can rival the economy of digital over a long time period.

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