The Mpressor By Elysia Keeps Even Most Vehe

Transcript

TEST COMPRESSOR elysia mpressor The mpressor by elysia keeps even most vehement signals in check. But who will tame this extroverted sound monster once it starts to surpass all expectations again? By Michael Nötges D ominik Klaßen and Ruben Tilgner are out on business a lot. The reason: Their pro audio company with the epic name elysia demands full activity. In 2005, Tilgner who is responsible for the development of 32 the almost legendary Transient Designer or the Gain Station (review 6/2006) at SPL, and Klaßen whose expertise covers especially the marketing, communication and design sectors, had gotten up the nerve to go their own way. The starting point is the city of Nettetal which is situated closely to the Dutch border. The first project was the design and production of the alpha compressor, a very transparent sounding unit which mainly aims at mastering applications. Since the product launch in 2006, the two young entrepreneurs have been touring half the world untiringly in Professional audio Magazin 11/2007 elysia mpressor Huge, transparent sound Inspiring design and entire musical concept Build quality and construction Analog-dynamic LED display Negative ratios possible Semi-automation for the attack time Antilogarithmic release characteristic possible External sidechains Gain Reduction Limiter Effective Niveau Filters Common mode rejection Summary The mpressor is a creative instrument for extravagant dynamics processing: analog, up to date and technical state of the art. order to present their debut feature to the interested professional audience. Just when the hype around the alpha abated a little, the next and already very promising elysia prototype was presented at this year’s Prolight & Sound show – the mpressor, a two channel compressor focused on sophisticated Professional audio Magazin 11/2007 sound design. It is equipped with discrete current feedback amplifier stages in class A design, features a classic linear power supply with transformer and also the thermal control of critical components like the temperature compensated transconductance amplifiers (see tech box). It addresses cre- ative dynamic pros who are looking to use the numerous special innovative features in order to achieve punchy and crazy sounds as well as sound colorations full of character and lively compression results in general. elysia’s ultimate goal for this unit was to create a modern instrument that meets the 33 TEST COMPRESSOR elysia mpressor On top of the standard features of a compressor, the mpressor offers effective Niveau Filters, Gain Reduction Limiters, negative ratios as well as the innovative Anti Log and Auto Fast functions. the highest sonic demands for inspiring as well as real-world dynamics processing. The mpressor sells for a net price of 3,490 Euro [Germany] and makes the creative sound freak’s mouth water at first sight already. The paint has only just dried as Klaßen hands over one of the first series production units to us personally – half a year after the exhibition of the prototype at the Musikmesse in Frankfurt. “The actual development took about one year”, the elysian explains, “and this splits into six months of developing the prototype and further six months for the following fine tuning.” In order to bring the circuitry to perfection in terms of sound, Tilgner states he had to keep exchanging certain components. “Time and again, it was really astounding how much influence single resistors or capacitors can have on the sound”. Klaßen adds: “We’re all about ears. Even the final inspection does not only rely on measurement equipment, but on our ears, too”. But it is quite obvious that the elysians also know how to use their eyes, as the modern design of the eight kilo sound hunk is very appealing. The looks are precious, have a true style of their own and are not based on trends of days long gone in order to evoke that nostalgic vintage feeling at all costs, like many of the new analog devices do. “We are 2007”, Klaßen says, “not 1960. We like to consider this when we design our products”. The nice powder coating of the housing directly catches the eye and is concurrently more rugged than anodized or painted surfaces. The specific name of this scratch-resistant coating is Sparkling Iron, which is a kind of twinkling grey. The front panel has a strictly symmetrical appearance, and its two channels which are accented in blue color bring the radiator grill design of classic sports cars to mind. The middle is dominated by a background-lit disk of frosted glass that shows the company logo and two accompanying LED chains. The well thought position of the eight aluminum knobs permit comfortable operation. Tilgner assures that the capsuled conductive plastic potentiometers are longer lasting than the conventional ones and – besides sounding better – should have a better resistance against scratching and other noise artifacts; even after years of use. The black push buttons have a preci- The pin assignment illustration for the connectors in balanced and unbalanced operation is easy to read. 34 se pressure point and are back-lit in active mode, reminding of a solar eclipse with a small corona around the button. This ensures the easy control of all functions even in darker surroundings. Also in this regards the manufacturer has done an uncompromising job: All switching functions of the mpressor are coupled via capsuled relays, which have been placed at the best positions to keep the audio path as short as possible. “We even did not use any internal audio cables”, Klaßen promises. “If you want to make it right, make it discrete.” That is something we want to see with our own eyes, and so we confront the designer piece with a screwdriver. Not often has opening a pro audio bolide been so worthwhile like in this case. The consequent symmetry is conspicuous. Even the ribbon cable for the LED display runs exactly through the middle of the unit. The audio and sidechain PCBs are stacked on top of each other in the front part of the housing. A cross brace shields them from the discrete power supply which occupies almost half of the housing. The oversized toroidal power transformer, Wima capacitors and the coppery T12 (see tech box) are evidences of the high grade and well thought out construction. The PCBs are connected by the means of dedicated multi pin slots. “This also makes service very easy”, explains Tilgner, Professional audio Magazin 11/2007 “because the modules can be exchanged in no time at all”. And indeed: the only existing cables are the ones for the power supply. The back panel features six XLR connectors: two balanced inputs, two outputs plus a separate sidechain input per channel. The pin assignment for balanced as well as unbalanced operation is printed legibly above the specific connectors, which is good help in practical use. If the external sidechain is activated, compression is no longer controlled by the input signals, but by the signals fed into the additional sidechain connectors. This allows frequency dependent compression (e.g. de-essing) as well as triggering the compressor with any audio signal, so that compression follows a dedicated bass drum signal only, for example. The sidechain path is equipped with a high pass filter (80 Hz with 6 dB per octave) in order to prevent the low frequencies from having too much influence on the overall compression process. The link button couples both channels for stereo processing. The left channel becomes the master for the right channel and specifies the compressor and limiter settings for both sides. Equalizer and gain settings, however, still stay independent. For this reason, the stageless potentiometers for these two functions should be set at the same values when working in stereo mode. The mpressor has a hardwire bypass for each channel, meaning that the input signal is directly routed to the output when the unit is in bypass mode. This enables the user to perform direct A/B comparisons to control the applied settings and their effects. In a hectic studio situation, this is a useful and almost compulsory feature. Just as useful are the two LED chains for comfortably controlling the amount of gain reduction. A special circuit layout makes it possible to show indefinite interim values by modulating the brightness of the single LEDs. In doing so, elysia combines the advantage of analog VU meters (stepless display) with the benefits of fast and These two characteristic curves of the compression show both the hard knee characteristic of the mpressor at a ratio of 1:10 (red) and the effect of negative ratios (blue). Because of the Gain Reduction Limiter, loud parts keep their dynamics, as the control voltage of the compression module is limited to a specified amount (blue). The red curve shows the effect of negative ratios. Professional audio Magazin 11/2007 TEST COMPRESSOR elysia mpressor Harmonic distortion is around 0.25 percent and is part of the intended basic sound. The harmonics k2 and k3 earmark the sound of the mpressor and move forward into audible regions with increasing gain. Common mode rejection could be better: at a frequency of 18 kHz it extends the -40 dB mark. The frequency response is reduced smoothly beyond 10 kHz for sonic reasons. The Niveau Filters do a fantastic job in customizing the sound. precise LED meters. The result is: you actually see what you hear. A nice-to-have addition would have been a switching option to also control the input and output level in order to avoid unwanted distortion. The compression stage works with a permanent hard knee characteristic (see curve) and furthermore in the so-called Feed Forward mode. This fourth coupled circuit analyses the input voltage very precisely in order to generate the optimal value for the control voltage from the result of this measurement. In a manner of speaking, this elaborate circuit kind of predicts what is going to happen next concerning the development of the level. This is also the basis for the optimal implementation of the possibility to set negative ratios and the external sidechain feature. The make up gain of the compressor already happens in the input stage, which is also the reason for the absence of an additional output control36 ler. The threshold covers a range from +16 to -18 dB. The attack time varies between 0.01 and 150 milliseconds and therefore offers very effective compression even of fast transients. The release time can be set between 5 and 1,200 milliseconds, thus it covers a great range that opens the door to extreme effect compression. The ratio controller initially makes it possible to set conventional compression rates (1:1.2 to 1:10). But the extensive range of the mpressor transcends the usual standard functions and additionally offers negative ratios (1:-0.3 to 1:-4). These result in very loud input signals being extremely low at the output. The mpressor hits like a cat of prey This compression effect results in a great amount of reduction for snare drum beats or other very dynamic signals, while weaker impulses stay untouched. In addition to the gain controller that not only raises the level but also adds harmonics to the signal, the Niveau Filters also influence the basic sound of the mpressor. If this equalizer module is active, the special filters affect the frequency response like a pair of scales: One controller determines the center frequency between 26 Hz and 2.2 kHz, and another one controls the change in amplitude. An additional push button shifts the frequency range by factor ten (260 Hz to 22 kHz). Frequencies ‘left’ of the center frequency are boosted up to 6 dB by turning the EQ Gain controller counter clockwise, while the area to the ‘right’ is attenuated correspondingly. If the controller is turned clockwise, though, the changes in amplitude happen just the other way round. In the exact middle position, the scales are even and the frequency range stays untouched. Therefore, a boost of low end frequencies Professional audio Magazin 11/2007 always goes with a simultaneous cut of the treble. But this is not the end of it by far. With its Auto Fast and Anti Log functions as well as the Gain Reduction Limiter, the mpressor has a couple of further interesting special features on board. The semi automation called Auto Fast automatically shortens the attack time on fast and loud signal impulses. With it, the newcomer can cope with sudden changes in dynamics without the constant need to use extremely short attack times which could potentially produce audible distortion. This also ensures that abrupt level peaks will not be able to escape the compression process, because the Auto Fast function reacts as quickly as a flash. After that, the compressor works with the dedicated setting of the attack controller again and is virtually on the qui vive to catch the next peak reliably. The Anti Log function changes the release characteristic of the mpressor. Linear or logarithmic release curves usually build the basis for subtle compression results. Hence it needs an antilogarithmic pendant in order to create striking and creative compression. The return line becomes the exact opposite of a logarithmic curve: the release time is longer at the beginning and then accelerates its speed while the signal level goes down. A special trick in the circuit ensures that this function works independently from the specific gain reduction value. The Anti Log function gives the user completely new sounds at the push of a button; resulting in exceptional reverse effects or vivid breathing of the compressor. Another specialty of the mpressor is the Gain Reduction Limiter which defines the control voltage to a chosen value. As this happens independently from the input level as well as ratio and threshold values, no further compression goes on beyond the limit of the GRL. The result: Loud passages maintain their dynamics, because they will not be compressed any further above the fixed GRL value. The Gain Reduction Limiter makes ducking and upward compression effects possible without changing the proper dynamics. As always, the measurements from the Professional audio Magazin test laboratory are consulted for an objective quality control. Noise floor and external voltage floor are at good 82.6 and 76.7 dB respectively. The harmonic distortion stays under 0.25 percent when no input amplification is used. The FFT analysis shows k2 and k3 that clearly reach the -50 dB mark when +4 dB of amplification are applied. They contribute to the special sound character. “At first, the mpressor sounded much too neutral and clean”, explains Tilgner, “so that we started to try lots of different options to add that certain dirt with the help of added harmonics.” He also claims that the frequency response was attenuated above 10 kHz for sound reasons. The corresponding diagram confirms this characteristic (see curve). With values better than The two channels can be linked for stereo operation. The analog dynamic LED displays are an exact optical counterpart of what is happening acoustically. -60 dB the channel crosstalk is good as expected. The common mode rejection could be better, though: at 10 kHz it is only -45 dB. This time, the extensive practice and listening test of Professional audio Magazin seems to go on forever with no end in sight. The reason for this lies especially in the great diversity of settings and combination possibilities. The basic sound of the mpressor alone (with the threshold controller fully counter clockwise in order to idle the compression module) has a character of its own. The sound impression appears considerably larger and more direct as the original. The stronger the input amplification gets, the fuller and livelier the signal appears – the additional k2 and k3 contingents (see FFT analysis) certainly have their share in this. But for all that, the TEST COMPRESSOR elysia mpressor A look behind the scenes of the mpressor Ruben Tilgner did not leave any aspect of the construction of the mpressor to chance, and thus it became a rich source of technical innovations and finesse. It starts with the discretely built power supply that, as Tilgner states, fundamentally determines if a unit behaves dynamically and openly or if its sound is more on the calm and reserved side. After all, the developer explains, the power supply feeds all active stages and therefore has a noticeable influence on all parts of the circuitry. Background information: Processing loud and dynamic signal impulses demands great amounts of current for a short time. Therefore the power supply must have a sufficient capacity at all times. In the mpressor, a special placement of the electrolytic capacitors in the circuitry keeps the high charging currents away from the signal ground in order to ensure an optimal voltage supply. Additional MKP capacitors are placed at many positions for the same reason. An improved noise and hum rejection builds the basis for clear and clean sound characteristics. “Even the rectifier diodes have an influence on the sound”, Tilgner explains and proceeds: “They charge the electrolytic capacitors in the power supply for a short moment and then provide electric current for the complete circuitry. For this reason, we use very fast diodes that we chose as a result of listening tests. The class-A output stages are push-pull-amplifier designs, which means that one is handling the positive half cycle and another one the negative half cycle. As both of them are supplied with a quiescent current, they will stay conductive even when there is no signal present. If this was not the case, the amplifier would work in class-B mode which would cause crossover distortion, occurring because of a small glitch at the joins between the two halves of the signal at the zero point. The manufacturer states that the mpressor has a quiescent current of 14 milliampere, which is an unusually high value for an audio device. As a result, the transistors always stay conductive – even when a low resistor load causes a high amount of current. Thus, crossover distortion will not appear in the first place. The amplifier stages of the mpressor are also discrete designs, which means that they are composed of single transistors, resistors, diodes and capacitors. This enables the developer to realize his sound conception in every detail by selectively exchanging components – provided that he has the needed experience. Additionally, elysia runs all amplifier stages in current feedback mode. The reason for this: Conventional amplifiers for audio applications use voltage feedback designs. These op-amps are based on a two transistor differential amplifier concept. Input and output are compared with each other in order to make corrections if necessary, but this also produces a slight delay. This changes the phasing and results in an oscillation at very high frequencies and causes the negative feedback to become positive. Often small capacitors are used to avoid this effect by deliberately reducing the speed of the amplifiers and decreasing high frequency amplification. “These capacitors have a negative influence on the sound quality of a signal”, says Tilgner. His logical consequence was to create an amplifier circuit that would not need any capacitors that interact with the frequency response. In the amplifier stages of the mpressor, the Just like its exterior, the inside of the mpressor is a great show: the coppery T12 Heater keeps critical components at a stable operating temperature. the mpressor always stays bright and transparent and seems to further enlarge the sound characteristics. The additional Niveau Filters are an outstanding feature to adapt or bend the basic sound. If the filter is used subtly, the signal appears a little freshened and somehow leaner by boosting the treble and cutting the bass. The other way round, the sound will become fuller and darker with the high frequencies reduced and the lows raised. But extreme high and 38 low pass filter settings are also possible on top of those subtle changes, as well as effective modifications of the mid frequencies. During our next test run, the mpressor has to prove its capabilities on compressing a drum submix. One thing is obvious very fast: the mpressor is no easygoing exponent of its kind, but an agile creative tool that does not want to hide what it is doing, but loves to show it candidly instead – Not least it is the symmetrical consistency of the mpressor that points out the accurate and well thought out concept. negative feedback directly modulates the current and therefore avoids the delay in the differential amplifier. This reduces the delay of the signal significantly and keeps the phasing even of high frequencies stable. The manufacturer states that their amplifiers can process frequencies up to the megahertz range and that they have a fast slew rate as well as a high impulse constancy. On top of that, elysia uses a so called T12 heater in order to make heat sensitive components work constantly. This keeps temperature fluctuations of the integrated components at a minimum degree. Up to twelve discrete transistors are integrated into a massive copper ring which is warmed up to a defined temperature. After a short start up phase, only a small amount of current is needed to keep the working temperature at a stable level. An electronic control circuit ensures that the possible tolerance is only a few degrees. The gain reduction cell of the compression module is not off-the-peg either. The mpressor employs a discrete and temperature compensated Transconductance Amplifier (TCA). The core of this circuit is a difference transistor pair with a modulated current source regulating the amplification. Further transistors reduce noise and the influences of the control voltage to the signal. One advantage of a TCA is that it can react fast to the control voltage – an important condition for fast attack and release times. The make up gain already happens in the input stage and runs in parallel with the sidechain. Thereby it does not influence the compression process, and even strong amounts of compression will not result in an increasing noise floor. and we are talking about great potentials here. Slight compression with a low threshold and small ratios are always possible, but the hard knee characteristic still makes the mpressor to appear effectively and uncompromisingly. This is a major difference to unobtrusive sound refiners like Universal Audio’s 1176LN (Test 4/2007) or Drawmer’s S3 (Test 8/2007) that treat the audio material at hand much more deliberately and gently. The mpressor is like Professional audio Magazin 11/2007 Profile a cat of prey on the qui vive: In the right moment, it hits smoothly yet relentlessly at the same time. The very short attack times will not even let the fastest of transients produced by heavy snare beats escape – even those are reduced mercilessly. As a result, drum signals are very direct and controlled and sound as if they were processed with a brickwall limiter leaving almost no dynamics at all if increased ratios (1:10) and long release times are used. By activating the Auto Fast function the mpressor becomes extra fast just in the right moment without unwanted distortion. The result: Drums sound like far away, the transients are eliminated and the quieter ambience and fading instruments come to the fore noticeably. Without the Auto Fast function and humane attack times and ratio (10 to 20 milliseconds and 1:5), the drums almost seem to attack you, and the room becomes more audible and present in addition. By shortening the release time, the groove appears more and more punchy and aggressive. From a certain point on, the mpressor starts to pump rhythmically. Equipment and signal form a perfect team with the right setting, making the groove much more vivid. Now we activate the Anti Log function: Because of the antilogarithmic characteristic in combination with a short release time, the drums suddenly sound extremely dense, expressive and start gasping for air violently. A longer release, however, results in intense effect compression and generates completely new ideas for interesting drum loops. Unlimited creativity In search of more crazy effects, we test the negative ratios with a complete house track. The result is a reverse effect: loud signals are suddenly reduced by extreme amounts and then return to their original level slower or faster (depending on the specific release time). Here the Anti Log function has a very interesting effect on the release as well, behaving like a reverb decay played backwards. In order to achieve a preferably fast but still distortion-less control process, experimenting with the Auto Fast function can be of great benefit here as well. After this, we insert the mpressor as an external effect into Cubase 4 and use it on a couple of different single instruments. A slap style electric bass produces gain reProfessional audio Magazin 11/2007 duction values of 15 and 20 dB quickly. The GR Limiter helps to keep the reduction at a fixed value which is completely independent from threshold and ratio settings. Even if a very strong compression is set, the reduction can be limited to e.g. 4 dB. The transients come to the fore very obviously. The electric bass sound has more freshness now; punch and even extreme variations in dynamics cannot irritate the mpressor anymore, because the applied limiter value will not be exceeded at any time. The output stays at an even level. Now the sidechains come into play: We trigger an eighth groove of the electric bass with a corresponding bass drum signal. The compressor works with a ratio of 1:3 and a threshold of about 1 dB. The attack controller is set to 21 and the release time amounts to 150 milliseconds. Instantly, both signals melt into a compact entity and appear to be more powerful. Setting a negative ratio of 1:-1 makes the electric bass pulsate and gives it a vivid groove. Now our pioneering spirit is aroused for good. We copy a snare track in the sequencer, provide it with an eights delay and use the clone as the trigger signal. The effect is set to 100 percent wet so that only the echoes are fed into the sidechain of the mpressor. Applied to a synth pad, this results in a dynamically wafting sound structure that keeps changing its characteristics all the time with new settings of the delay and the mpressor. From extremely cutting to slightly wavy – everything is possible. Feeding the pure effect signal into the inputs of the mpressor and the dry original into the sidechain also produces very interesting results. This time the effect, no matter if it is a chorus, flanger, phaser or reverb, has its compression triggered by the original signal. A phaser which is applied to a snare signal disappears on the actual hit and then starts to increase until it is choked again by the next snare hit. Experimenting with the different parameters and special features opens up new sound worlds and provides unlimited creative fun. RESULT Analog does not necessarily mean vintage, and elysia’s new creative compressor is the best proof for that. Because of its innovative features, the mpressor Model mpressor Manufacturer elysia Distributor elysia GmbH Ringstraße 82 41334 Nettetal Tel: +49 2157 126040 Fax: +49 2157 126312 [email protected] www.elysia.com Type Compressor Price (net, Euro) 3,490 [Germany] Dimensions WxDxH (mm) 483 x 377 x 89 Weight (kg) 8 Features Channels 2 Inputs 2 balanced XLR Outputs 2 balanced XLR Sidechain 2 XLR Meter 13 segment LED for gain reduction, LED for GRL Controls Input controller 0 to 20 dB Threshold 16 to -18 dB Attack time 0.01 to 150 ms Release time 5 to 1,200 ms Ratio 1:1.2 to 1:-4 (negative ratios can be applied) Equalizer gain Up to 6 dB Equalizer On Equalizer frequency 26 Hz to 2.2 kHz Equalizer frequency (x10) 260 Hz to 22 kHz Gain Reduction Limit 0 to 21 dB (control voltage limit) GRL On/Off Sidechain Ext. On/Off Auto Fast Semi automation attack Anti Log Antilogarithmic release curve Bypass compression Separate for left and right channel Stereo link On/Off Accessories Manual Specialties Auto Fast, Anti Log, Gain Reduction Limiter, negative ratios, analog dynamic LED meter, discrete power supply design, Niveau Filters, current feedback amplifiers, thermal control of critical components, transconductance amplifiers (TCA) Measurements Maximum input level (dBu) 13.4 Maximum output level (dBu) 12.3 Noise floor (dB) 82.6 External voltage floor (dB) 76.7 Maximum THD (%) 0.25 Rating Construction very good Features very good / outstanding Usability very good Measurements very good Sound very good / outstanding Final grade Top class very good Value for money Good is as modern as it is state of the art concerning its concept and construction. It sounds excellently and leaves nothing to be desired in terms of flexible dynamics processing and fancy sound design. The designer piece costs 3,490 Euro net, but to the modern sound aficionado, the mpressor is warranted to be worth every Cent. 39