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EMES Owl System

Stereo Monitor & Violett HR Nearfield Monitor By Hugh Robjohns
Published October 2001

OWL ROUND

EMES have developed the first studio monitor to use a patented new single‑point stereo speaker technology. Hugh Robjohns tests the Owl System and compares it with the conventional Violett HR on which it is based.

EMES Studio Monitor Systems is a small company in southern Germany specialising in the manufacture of professional‑quality studio monitor loudspeakers. The three‑man enterprise currently produces twelve monitors and subwoofers covering all applications, from nearfields to soffit‑mounted monsters, most of which are active. The entire range is colour‑coded in a seemingly haphazard manner, with the Pink nearfield being the smallest two‑way design and the Cyan model being a substantial beast with four eight‑inch bass drivers, two five‑inch mid‑range units and a 28mm soft‑dome tweeter.

One interesting feature of the EMES range is that of upgrading. From a pair of nearfield monitors, the user can obviously add further speakers for centre and surround duties, or introduce a subwoofer to extend the LF response of the system — much in the same way as one can with units from most other speaker manufacturers. However, EMES have taken it a stage further by designing their subwoofers to mate physically with specific two‑way speakers from the line up, allowing a small monitor to be upgraded to a three‑way system. This innovative approach allows a cost‑conscious user to improve a monitoring system in stages without having to sell one system to acquire the next. Not only is this financially advantageous, it also means that the sonic characteristics of the system remain relatively constant as the system is upgraded, and it avoids the need to learn the behaviour of a brand new monitoring system.

A Bunch Of Violetts

The Owl System monitor speaker under review here is a version of the EMES Violett HR active model. The Violett HR is a conventional nearfield design, while the Owl System is in a revised configuration employing the novel ESE single‑point stereo reproduction concept — more of which in a moment. The Violett is an active two‑way reflex design porting through a horizontal slot at the foot of the baffle. Intended for use between 0.6 and 2.5 metres from the listening position, the MDF cabinet measures 210 x 380 x 250mm and weighs nearly 12kg. It is finished in a non‑reflective grey Nextel material with rubber side‑edge protectors top and bottom, the profiles of which are cunningly designed to isolate the monitor from the surface on which it is placed. A 28mm silk‑dome tweeter (with ferrofluid cooling and built in thermal protection) is partnered by a 180mm paper/carbon bass‑mid driver. The crossover operates at 1.4kHz, with 12dB/octave Butterworth filters, to deliver an overall frequency response stretching between 42Hz and 20kHz (±2dB). Full magnetic shielding is standard and both drive units are powered by a pair of identical 120W single‑chip amplifiers. There is no rear‑panel heat sink as such — cooling is mainly provided by the air flow through the reflex port, although the rear metal panel does get quite warm.

The rear panel of the Owl System features a set of DIP switches which can adjust the input sensitivity and which also allow you to tweak the extremes of the monitor's frequency response.The rear panel of the Owl System features a set of DIP switches which can adjust the input sensitivity and which also allow you to tweak the extremes of the monitor's frequency response.The tweeter is recessed into the baffle to provide time alignment with the bass driver, a wave guide aiding its coupling to the outside world and helping to control dispersion. The baffle is completely devoid of any mounting screws or other protrusions which might cause image‑destroying diffractions. Stereo speaker pairs are matched to within ±0.5dB — the on‑axis frequency response plots of each speaker, together with the calculated difference between the pair, is supplied with each set.

The rear panel carries the IEC mains inlet with integral fuseholder, a rocker‑style power switch, and an XLR for the monitoring signal input. The mains switch is placed immediately below the XLR and I found that it was both difficult to see and easy to switch accidentally when plugging or unplugging the XLR. An LED mounted just below the tweeter illuminates green when the unit is switched on, changing to orange when the bass amplifier is approaching full output and red when overload is reached. The output power is reduced temporarily if the speaker is driven too hard for too long.

Three sets of DIP switches at the top of the rear panel allow system tuning, providing adjustments for input sensitivity, bass and treble response. The four‑element input sensitivity switch provides up to 20dB of attenuation over sixteen steps, accommodating both professional‑level balanced, and domestic‑level unbalanced connections. Both bass and treble adjusters use similar four‑element DIP switches, the bass section principally affecting the 45‑125Hz region with 16 possible equalisations spanning the range ‑6dB to +8dB. These are intended to compensate for placements near walls or to improve the subjective bass response in over‑damped rooms. The treble section offers equalisation between +5dB and ‑4dB in sixteen steps.

Listening To The Violett HR Monitors

The Violett HR speakers initially sounded hard and forward in my listening room, particularly when compared to my reference PMC IB1s. However, after a few minutes of experimentation, I found a combination of LF and HF equalisation which allowed the speakers to sound better balanced and more natural within my listening environment. These adjustments were pretty gentle: 2dB off the extreme top and 1.25dB up at the bottom.

Having fine‑tuned the EQ and physical positions of the speakers I found they were able to deliver an extended frequency response without any significant resonances, exhibiting a tight but powerful bass with clear, detailed treble. The all‑important mid‑range was impressively neutral and both singing and speaking voices were presented with precision and naturalness. Sound stages had good width and stability with accurate and well‑focused imaging, although the overall impression seemed a little two‑dimensional, with depth information being less obvious when compared with my references. The built‑in amplifiers can certainly deliver substantial volume when called upon to do so, and the portrayal of dynamics was excellent, without any hint of strain. The bottom line is that the Violett HRs provide good monitoring quality with typical Germanic engineering at a reasonable price.

Single‑point Stereo

The Owl System can be simplistically described as a pair of slightly modified Violett HRs bolted side by side. This peculiar arrangement has been designed to generate a stereo sound image from — as near as is claimed to make no difference — a single point.

The idea is a corollary of the M&S stereo microphone arrangement where, instead of capturing the left and right hemispheres of the sound stage directly, the spatial information is gathered in terms of the centre and side sounds. A similar, albeit reversed, concept is employed by the Owl System, based on patents held by a Swedish company, Embracing Sound Experience (ESE). Sound is reproduced as centre and side signals, with their in‑room interaction reconstituting left and right information.

The review system appeared to comprise a pair of conventional loudspeakers mounted side‑by‑side, with a common baffle. The two tweeters are placed as close to the inside edges of their respective cabinets as possible and a removable vertical fin has been attached between the two bass‑mid drivers. The overall appearance is vaguely reminiscent of an owl, surprisingly enough...

A simple sum‑and‑difference matrix is integrated with the line‑level inputs, summing the left and right inputs to produce the centre 'M' signal, the difference being the 'S' signal. The 'M' signal is reproduced by all four drive units (over their appropriate frequency ranges), while the 'S' component is reproduced by the right set of speakers in the same polarity, and by the left set of speakers in the reversed polarity. I am told there are no deliberate delays or any phase tweaking involved in the signal processing.

However, I find it hard to accept this description of the system's workings as the complete explanation, as a little rudimentary maths quickly reveals that, in combining the M&S signals to drive the two sets of speaker cones, the left signal is reconstructed on the left‑hand pair and the right signal on the right‑hand pair. (The relevant equations are: L+R=M and L‑R=S, therefore M+S=2L on the left‑hand side and M‑S=2R on the right.) This would imply that simply pushing a pair of conventional speakers next to each other would produce similar results... which wasn't that far from the truth! Placing the standard Violett HRs next to each other on top of the Owl System, with a magazine trapped between them to replicate the fin, did seem to produce a stereo effect. Although this didn't quite match the performance of the genuine Owl, this might be because it wasn't possible to space the two sets of drive units identically.

This M&S style of stereo reproduction is claimed to have a number of benefits, most of which are to do with overcoming the inherent shortcomings of the conventional spaced loudspeaker arrangement we have all come to know and accept. The fundamental argument is that, in the conventional setup, both ears of a listener can hear both loudspeakers, this inevitable crosstalk resulting in comb filtering of the intended audio signals, confused imaging information, and a very small sweet spot. Guilty as charged... although this flawed system can obviously be made to work tolerably well, as it has been used universally for 70 years! The ESE approach, since it is generating sound from close to a single point, is claimed to obviate this crosstalk problem, and a white paper produced by ESE goes to some lengths to try to substantiate this — although I have to say that I was not entirely swayed by some of the technical arguments presented in it.

The Owl System In Practice

The real test of a radically different approach such as this is in listening to it: is the Owl System a critical monitoring tool, as opposed to simply a 'spacious experience'? I found that the performance of the Owl was heavily dependent on the material being auditioned — different recording techniques produced radically different results. Of course, you can say the same of stereo portrayed over conventional stereo speakers — a spaced‑pair recording has utterly different spatial characteristics to a coincident‑pair recording, for example.

The Owl's image width appeared to be strongly related to frequency — the higher the frequency, the stronger the stereo effect. Rock music with dual, panned kick drums was portrayed with obvious spatial separation over the conventional speakers whereas the Owl produced overlayed central drums. However, a strong stereo effect was obtained with any material which was strongly phase‑incoherent — both natural and artificial reverberation was portrayed with generous width, often seeming to curve around the side walls, for example.

Obviously, centre‑stage sounds were presented with an absolute rigidity of positioning which normal stereo speakers can never equal — and given that a huge proportion of music has dominant central sounds, this is an appealing feature. It is possible to move well off the centre axis of the Owl System and still have the image located around the same fixed center spot, with the image width remaining fairly consistent around that point. This is clearly an advantage if you want to be able to move around a wide area without the image collapsing.

In comparison with my reference monitoring system, the Owl seemed narrow and constrained. The stereo image extended outwards from the box to between a half and three‑quarters of the width of my normal speakers. Although reverbs and room acoustics seemed much wider, individual instruments and voices always remained relatively close to the centre, and where signals were hard left or right the imaging was very confused indeed. I found it hard to locate the intended sound source in recordings of stereo mic 'walk‑arounds', and time‑difference panning was no better. I also found trying to position instruments within a mix using ordinary pan pots very difficult — trying to pan an instrument's spot mic from an eight‑track orchestral recording to match its location as portrayed through the main stereo microphone pair was virtually impossible! However, EMES mention that it can take a long time to learn to use the Owl System, and to 'unlearn' the characteristics of normal stereo speakers. EMES have supplied Owl Systems to several well‑known engineer/producers who find the system useful.

Interestingly, Ambisonic recordings and binaural recordings both worked surprisingly well over the Owl System, producing some of the widest and most spacious impressions. These two recording techniques are almost diametrically opposed, one being entirely coincident and the other being spaced, yet they produced similar impressions of scale. Binaural recordings worked remarkably well over the Owl speaker, with spatial positions reproduced in a similar way to when heard over headphones. In contrast, these same tracks replayed over conventional loudspeakers were very disappointing, with narrow diffuse images and the ever‑present feeling of out‑of‑phase material.

The Owl System and the ESE concept are certainly alternatives to conventional stereo monitoring and have some advantages, notably the stable centre and the ability to portray binaural recordings very well. It does take a while to get used to the stereo imagery, and I suspect some people's ears will find the Owl System easier to work with than others. As a one‑box system I think it will appeal more strongly in consumer applications than in professional ones, as it provides a pleasant spacious sound and is almost immune to being set up incorrectly, unlike normal stereo pairs of speakers or the six elements of a 5.1 surround system! The L+R centre also reveals mono incompatibilities directly (ie. phase or timing errors) which would only be discovered in a conventional situation by listening in mono via a single speaker (and few stereo consoles allow that easily!).

The Owl is an interesting design, and is worth investigating if the opportunity arises. However, that said, I won't be throwing any pairs of speakers out of my studio just yet.

Pros

  • Compact one‑box solution.
  • Relative immunity from room location problems.
  • Reveals audio problems undetectable over normal speakers.
  • Solid centre image and extremely wide listening area.

Cons

  • Imaging heavily dependent on recording technique.
  • Panning sources seemed vague.
  • You need to learn to listen differently.

Summary

The components of the Violett HRs reconstructed to generate a stereo sound stage from a centrally placed loudspeaker. This innovative approach is not without merit and provides an interesting alternative to the more traditional stereo monitoring arrangement.

Published October 2001