elysia mpressor Single Channel 500 Series Compressor Module
Manufacturer's DescriptionFuture Dynamics
The mpressor 500 brings the heritage of our extremely powerful rack mount mpressor into the 500 series format. Like its bigger brother, the mpressor 500 combines serious punch with a full and detailed class-A sound. Its great tone and flexibility make it an excellent choice for recording and mixing, while its remarkable special features take it far beyond the borders of what normal compressors can do.
Its massive sound, next generation features and its creative approach make the mpressor 500 a truly outstanding tool in the world of dynamics processing – the compressor from the future.Build Quality
elysia quality is all about details.
Every single of its many aspects – sound, features, circuitry, components, design, materials, manufacturing – has been thought over and over until there was just nothing left to improve. Basically, every single part of our products is custom, and most of these are made according to our own designs and specs.
Only the best components the market has to offer are good enough for our products, and it shows. Each of our product is manually built to order and tested by ourselves, here at our headquarters in Germany.
The benefits sum up in an audio quality that is beyond all doubt. Even when extreme settings are used, the sound always stays clean and powerful.Control Freak
Extreme time constants, negative ratios, antilog release and elysia’s innovative gain reduction limiter provide a whole spectrum of unique dynamics shaping options. A new feature of the 500 series module is its switchable THD boost allowing on-the-fly signal coloration and saturation effects capable of delivering a grittier flavor.THD Boost
Activating the THD Boost function raises the level in front of the gain control element. This generates additional harmonics inside the input stage of this amplifier, which has a significant influence on the sonic structure of a signal.
The mpressor 500 is a pure feed forward compressor, and the gain potentiometer is placed before the control element. This means that the intensity of the saturation can be raised or lowered by different settings of the gain controller.
What’s special: The detector in the sidechain of the compressor runs in parallel and is therefore not influenced by the THD Boost at all. The actual compression does not change, it is only the sound which is being influenced.
You generate a saturated signal which as a result is also reduced in dynamics, but the actual control of the compressor itself is always based on the original dynamics including all transients, impulses and so on.Auto Fast
The attack parameter is a very crucial factor for the operations of a compressor. Choosing the right time settings is very important, but depending on the dynamic progress of the source material this can be a difficult task – no matter if single tracks or complete mixes are processed.
If a very short attack time is chosen, the compressor is able to catch the short peaks, but on the other hand the sustaining signal will also be processed, which might result in audible distortion. Longer settings reduce distortion significantly, but then the compressor is too slow for catching fast impulses.
This is where the Auto Fast function comes into play. For example, if you set the attack to 80 ms and then engage the Auto Fast mode, the attack time will be shortened automatically on fast and loud signal impulses. The compressor reduces the signal quickly and prevents it from slipping through.
Then the attack time directly and automatically returns to its original setting. In Auto Fast mode the compressor can be very fast, but only when it is really needed. This function influences the attack parameter on short and loud impulses only; in all other cases the original setting of the controller has priority.Anti Log
It is the time constants and especially the release parameter that decide if the processing of a compressor is obvious or unobtrusive to the ear. Mastering applications, for instance, require a discreet performance as a general rule. Here you will find mostly logarithmic or linear release curves.
It is characteristic of a logarithmic release that the time constant shortens when the amount of gain reduction increases. The advantage of this behavior is that short and loud peaks (e.g. drums) have a fast release time, while the remaining material is processed with a slower release time.
But if intentionally striking and creative compression is the goal, it definitely makes sense to turn things upside down. In the Anti Log mode of the mpressor 500 the curve behaves just the other way round: If the threshold value is passed and compression starts, the release time will be longer at the beginning. If the input signal starts to decline, however, the release time will become faster as a result.
A special circuitry makes this behavior independent from the absolute amount of gain reduction. No matter if the compressor reduces 10, 15 or 20 dB, the curve will always stay the same at the beginning and it will only become faster at the end. With this feature you can create many exceptional compression effects just by the push of a button!Negative Ratios
Negative ratios – what exactly does this mean? To get a better understanding of this function, it makes sense to realize what the ratio control of a ‘normal’ compressor does:
1:1 The signal remains linear, there is no compression going on.
1:2 After crossing the threshold, an increase of 2 dB at the input will be compressed to an increase of 1 dB at the output.
1:∞ After crossing the threshold, the output signal is constantly held at the threshold level without reacting to further increases at the input (limiter).
At a negative ratio, the characteristic curve bends and returns back down after crossing the threshold. The louder the input signal, the lower the output signal – perfect for groovy compression effects. To get a grip on the extreme ‘destruction’ this can cause, engaging the Gain Reduction Limiter is just the right idea.
Beyond infinity – made possible by the mpressor 500.Gain Reduction Limiter
A specialty of the mpressor 500 is the Gain Reduction Limiter for the control voltage. This limiter is not placed in the audio path where you would usually find it, but in the control path of the compressor. When it is activated, it limits the control voltage according to the setting of the GR Limit controller. This means: No matter how high the input level might become – the amount of gain reduction will never exceed the value which you have set.
For comparison, imagine a fader on a mixing console with your hand moving the fader to ‘play compressor’. If now the fader was limited by a piece of duct tape at -10 dB, for example, it could only reduce the signal up to this value. If the input level dropped below this limit, the fader would be moved up correspondingly.
However, if the input signal got even louder, the fader could not be moved down any further because of the duct tape limit, and then the output signal would become louder again in correspondence with the input signal.
Loud parts in an arrangement can keep their dynamics, as they will not be compressed beyond the limit of the Gain Reduction Limiter. Some very nice special effects like ducking or upward compression can be achieved with this easily by only reducing the quieter parts without changing the original dynamics at the same time.Analog Dynamic LED Meter
The gain reduction meter is a very important visual tool for evaluating the operation of the compressor in addition to what your ears tell you. A lot of devices make use of sometimes more, sometimes less precise VU meters. But because of the inertia of the needle these meters are only useful with moderate time parameters.
Another popular form of meter is the LED chain. Unfortunately it has a disadvantage, too: When the standard driver units are used, the change between two values always happens abruptly. A single LED in the chain can therefore only show an imprecise value in a defined interval. Hectic flicker indicates that the actual value must be somewhere in between.
The mpressor 500 solves these problems by using an analog dynamic variant that combines the benefits of both VU meters and LED chains. This meter is based on LEDs, too, but a special circuit design makes it possible to show intermediate values by modulating the brightness of the LEDs.
This means a true analog way of showing the operation of the compressor: Very fast, but with smooth transitions. The user gets an important tool for precise gain reduction monitoring – finally the relationship between acoustic and visual perception feels just right.Transconductance Amplifier
A crucial part in the development process of a compressor is to design its control element that reduces the audio signal controlled by voltage. This is also where the main technological concepts show the most obvious differences.
The mpressor 500 uses elysia’s special Transconductance Amplifier (TCA). A differential pair of transistors that uses a modulated current source to affect the amount of amplification builds the core of this module. A few extra transistors were added in order to further decrease noise and unwanted influences of the control voltage.
Another advantage of the TCA topology is the very fast response to the control voltage. This is the basis for a compressor that can even handle rapid changes in dynamics and which provides extremely fast time constants.
Also remarkable is the fact that the make up gain was designed as an amplification of the input signal. This is running parallel to the sidechain path and therefore does not have any unwanted influence on the processing itself. The essential advantage of this arrangement is that the background noise always stays at the same level, no matter how much amplification is applied.Stepped Controllers
The mpressor 500 features stepped potentiometers for all its parameters throughout. The 41 steps make a precise recall very easy, and they provide a useful range of possible settings at the same time. And you will just love the feel of them, too ;-)
Stepped controllers are something you will usually only find on much more expensive gear, special mastering editions, or in most of the cases – not at all. The mpressor 500 establishes this very handy feature in the regular serial version without any luxury up-charge.Ground Layer Shield
The PCB of the mpressor 500 has a total of none less than six layers: While the first five are used for separately routing audio and power supply, the sixth one is a dedicated ground shield layer. But what’s the idea behind this?
As the additional ground layer is placed extremely close beneath the traces which carry audio, it is very efficient as a shield against unwanted noise interferences caused by electric fields.Discrete Class-A Topology
To explain the advantages of discrete circuitry we’d like to present a comparison that might seem a little odd at first: Audio technology vs. cooking! If somebody uses instant meals exclusively, he will have to accept whatever comes out of the box. A creative cook, however, focuses on his own special recipes and ingredients.
In this respect, integrated circuits (ICs) are often similar to packet soups: They are cheap, mainstream and they simply do not match haute cuisine. So if you want to design an analog audio device 100 % according to your own demands and ideas without any compromise, there will be no way around a discrete design.
The mpressor 500 follows this philosophy consequently. Its complete audio path is a new design which is based on high grade discrete components. A truly unique recipe!
In addition, our creative compressor operates in permanent class-A mode. This means that the transistors are always conductive, resulting in the absence of crossover distortion and providing a pristine sonic base: The general sound character is always wide, open and punchy.
- <10 Hz - 390 kHz (-3 dB) THD+N
- @ 0 dBu, 20 Hz – 22 kHz: 0.04 %
- @ 10 dBu, 20 Hz – 22 kHz: 0.19 %
- @ 0 dBu, 20 Hz – 22 kHz, THD Boost: 0.24 %
- @ 10 dBu, 20 Hz – 22 kHz, THD Boost: 2.20 %
- 20 Hz – 20 kHz (A-weighted): -79 dBu
- 20 Hz – 20 kHz (A-weighted), THD Boost: -87 dBu
- 20 Hz – 22 kHz: 99 dB
- Input: 21 dBu
- Output: 22 dBu
- Input: 10 kOhm
- Output: 68 Ohm
- Total: 75 mA