Tuesday, November 20th, 2018

Event Electronics : an insight into professional monitor loudspeaker design

By editorApril 30, 2012

TECHNOLOGY

Marcelo Vercelli, Event's Director of Engineering

The Event story starts almost twenty years ago alongside the ‘project studio’ boom of the late 1980s and into the early 1990s. Russell Palmer, a former executive at Alesis, who’s ADAT system was an instrumental factor in the empowering of artists at that time, identified the market need for a relatively low cost, high performance studio monitoring system and thus Event Electronics was born. Russell worked closely with Event’s engineering team with the singular focus of identifying the deficiencies present in the smaller reference monitors that were the only affordable option for most audio engineers at the time. After extensive research and development, coupled with hours upon hours of critical listening, Event finally realised its vision: The 20/20 nearfield studio monitor.

In 2006 RØDE Microphones’ parent company Freedman Electronics acquired Event and immediately recruited a new engineering team comprised of some of the world’s best speaker designers, with the aim of once again redefining how artists and engineers heard their mixes, just as the 20/20 had over ten years earlier.

Marcelo Vercelli (formerly of Mackie, RCF, KV2) joined the new Event team as Director of Engineering, and established Event’s R&D labs in Woodinville, USA where he was soon joined by analogue amplifier guru Anibal Yusem (formerly of QSC). Event’s manufacturing and production was relocated to Freedman Electronics’ 75,000 sq. ft state-of-the-art manufacturing plant just outside of Sydney, Australia.

Marcelo very kindly agreed to give Audio Times his insights into the design of high quality Monitor Loudspeakers.

Many of our readers will be familiar with the common audio performance parameters such as frequency response, distortion and colouration but there’s quite a bit of confusion about what are the really important performance issues with regard to monitor loudspeaker performance. What do you consider these to be, and how have they influenced your design philosophy?

“The listening experience of a loudspeaker system is the result of how the components within that system work together to deliver the highest audio performance. Over the years we have been able to determine what we believe is a fundamental set of criteria that allows us to determine the performance and quality of individual components on factual data gathered with state of the art equipment.

“Ultimately, the nature or character of the speaker system is a summation of signal processing, amplification, acoustic design (the box) and transducer technology. Performance and character depends on how you set up your system. Ultimately however, the quality of the system depends largely on the ability of the system to keep the noise floor of the speaker as low as possible. This means that the distortion behaviour of the transducer and the electronics must be looked at from a perspective of how they perform at and near clipping levels, and what kind of audible distortion by products they introduce into the signal chain. This is important because studio monitors should be able to reproduce audio signals that have very high dynamics, (snare, rim shot etc) which require predictable, controlled behaviour from the speaker system. Good ones sound very open, almost as if there is no output level ceiling and this is always what we shoot for.”Do you favour designing professional monitoring speakers for a listening environment which is fairly dead or for a more ‘natural’ listening environment?

“The listening environment will always dominate the behaviour and performance of the speaker system especially with respect to the low frequency performance of the system. I believe that users need to develop a much better understanding of speaker placement, room treatment and how it affects the listening experience at the mix position. We never take the listening environment into consideration because it will always be different from user to user. If the speaker performs up to our criteria and is manufactured consistently, it becomes a reference tool for engineers moving from one environment to another where the listening position remains in the near field (1-1.5m). Having the room treated for standing waves is great – if this is done you increase the chances that bass response can be better defined.”

Event 20/20BAS Studio Monitors

Is there a significant difference in design approaches for nearfield loudspeakers as opposed to for ‘whole room’ monitoring.

“Not really. The most notable issues you will run into as you step farther away from the speaker are twofold. First is the power required to achieve the higher output levels that are experienced in the near field. These can be substantial as you get three, four, five meters away. You start hearing the “limits” of the speaker very quickly. Second is the influence that secondary reflections have on the speaker’s critical listening frequencies (800-8kHz). If the speaker has phase response issues, the problem becomes more audible as distance increases, and when blended with the secondary reflections, you start hearing a harshness or a discernible nasal or honk quality. Overall, you start noticing that the speaker sounds different at different output levels. That is to say that it sounds one way at low volume levels, another at higher volume levels, and finally falls apart when you push. A good speaker should always sound the same no matter what the output level.”

How important are the frequency sensitive directional properties of speaker systems and are there other important issues to consider when designing monitor speakers to offer a stable stereo image?

“The most sensitive part of the speaker system is the crossover region of a two way speaker. it usually occurs in the 1.5 to 2.2 kHz region where the human ear is most sensitive. what is also important is the off axis dispersion of the woofer and the tweeter at the crossover frequency. The total amount of energy delivered by each device, should be the same in order to ensure that the total amount of acoustic power being delivered during the crossover transition is equivalent and therefore inaudible. This is referred to as the power response of the woofer and tweeter and greatly influences imaging and the speakers ‘openness’.”Coming back to listening environments, a reality seems to be that many people are trying to monitor in less than ideal acoustic environments. They may make an attempt to deal with the worst of the room’s standing waves and may sometimes over deaden the listening environment. Is there anything which can be done within the monitor speaker design to lessen the effects of poorer listen environments? Can DSP processing play a useful part?

“Let’s assume that the speakers are in a small, less the ideal room. The room itself will dominate the speaker’s low frequency performance relative to the listening position. You can attempt to adjust low frequency performance (below 250Hz) mostly through the process of notching. I never recommend adding EQ. If the room is killing the bottom end, I would try and treat the room or change the speaker position. I also do not believe in adding auralization through DSP to try and fix poor listening environments as you ultimately end up listening to the DSP itself and not the mix.”

Event 2030 Studio Monitor

Are there significant advantages in designing monitor speakers and their power amplifiers as a ‘matching pair’?

“I think that the correct way of looking at this is a little different. It is more important to design an amplifier for a specific application. In the case of a high frequency amplifier, you need a reasonable amount of power, say 100 watts. It is more important to design something with ultra low distortion characteristics (say below .003% at 100 watts) which behaves consistently no matter what the input frequency and whose clipping behaviour is predictable and soft. A low frequency amplifier has a different set of requirements. You need lots more power delivered to the voice coil. You may need to consider its behaviour relative to the phase shift conditions presented by the low frequency speaker. You may need to consider the heat that needs to be dissipated by the amplifier losses (heat sink cooling) and you need to get the same low distortion behaviour and clipping characteristics as the high frequency amplifier. Totally different set of requirements.

“Once you have the speakers and amplifiers designed, how they work together is defined by your pre amp and control electronics preferences. Controlling how the system behaves when pushed to the limits is extremely important in assuring safe, long term usage of the system.”

What advice would you give to readers in respect of selecting and installing monitor speakers (and power amps) for their studios?

“I would start with developing good evaluation techniques. Make a listening CD with tracks you know inside out, choose a variety of music. Use a CD player and pre amp that you know sound good. Always try and separate the speakers by a consistent length (say 1.5-1.8m). Use a laser pointer to make sure you point them to the listening position accurately. Buy an inexpensive sound level meter and make sure your left/right levels are even and consistent. Keep your average listening levels between 84-86 dB and take breaks during the day.

“Ultimately, humans are designed to listen to one thing, sounds that occur naturally in nature. Speakers, electronics and recordings are easily capable of introducing anomalies that distort audio making it easy for humans to discern between speakers that sound open and real and speakers that don’t. This is why speaker evaluation by musicians and engineers is so important, they have held the guitar, stood in front of the bass stack, and heard the snap of the snare. They have the clearest idea of what music should sound like.”

Many thanks to Marcelo.

You can review the entire Event Professional Monitor Loudspeaker range at http://www.eventelectronics.com

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