by Fritz Fey
Studio Magazin (Germany) – November 2012
One of the passions of every audio engineer is to play with sound colors and forms: We want to have a strong influence and control over this. Given today's equalizers and filters, we have a lot of powerful tools to change sonic structures, or even put them completely upside down. A dynamics processor, on the other hand, changes dynamic progresses, but the detailed signal form remains more or less unchanged in most cases. However, looking at this more closely, one could use “wrong” time constants to have a direct influence on the attack and sustain structure of a signal. When the attack time for a percussive signal is too long (on a snare drum, for example), our ear is fooled by interpreting this as an accelerated rising edge.
What is really happening is that the compressor reacts a little bit too late and just does not catch the first milliseconds of the attack phase, and this makes their level more dominant. Very fast release times, on the other hand, counteract the natural sustain phase of a signal by rising the output level faster than the corresponding input level. You could achieve similar results with an upwards expander, but only with quite some effort on corresponding settings. But there have also been specialist forms of hardware and software processors in the market for quite some time now that are aimed at controlling the amplitude of signals during their attack and sustain phase. The German manufacturer now completes its product portfolio by offering a witty contribution to this genre – in form of an quite simple set of parameters, allowing a quick and intuitive workflow while still offering some interesting features we have not seen with similar units before.
Although the nvelope basically belongs to the group of dynamics tools, its processing is based on the difference between two control voltages which can change the amplitude of a signal both in the positive and negative direction. This way, the attack and sustain of a signal can be “accelerated” or “slowed down”. Please check the measuring section of this review to find a diagram showing these effects nicely. The really special thing about this new device from elysia is the dual band splitting which enables frequency-dependent changes of attack and sustain.
The nvelope is a two channel unit that can work in stereo and independent dual mono mode as well. elysia's first approach at envelope shaping had been done in form of a 500 series module, to be followed by this stand-alone rack version with its own power supply, just as they did with their xpressor compressor.
The search for a classic threshold controller on the front panel is in vain, as the unit operates completely independent from the input level. As a side effect of the dual band topology, the unit can also be set into EQ mode with high and low shelf filters. In this case, the Attack controller boosts or cuts the high frequencies, while the Sustain controller does the same for the low frequencies. In Full Range impulse shaping mode, the Freq A controller can be used to dial low frequencies out of the sidechain, similar to a compressor. Accenting the attack phase in full range mode can result in strong peaks, and this is why the developer, Ruben Tilgner, has also included an Auto Gain function to automatically compensate. In all three modes (Full Range, Dual Band, EQ) the left side becomes the master for both channels when the unit is operated in stereo link mode.
In order to get started as quick as possible, let's first have a short look at the control panel. The Attack controller raises or reduces the attack phase of a signal both in Full Range or Dual Band mode. In EQ mode, it boosts or cuts the high frequencies. Right next comes the Freq A controller that sets the starting frequency for attack processing in Dual Band mode, which means that it takes all frequencies below the one set with it out of the control voltage generation for attack processing. In EQ mode, it sets the frequency of the high shelf filter. The frequency range covers 20Hz to 8kHz, so it reaches down to really deep frequencies.
Next is the Sustain controller for stretching or contracting the sustain phase. In EQ mode, this controller boosts or cuts the low frequencies. Then follows the Freq S controller which sets the stop frequency for sustain processing in Dual Band mode, while it remains without function in Full Range mode. In EQ mode, it sets the frequency for low shelf filter with a very broad range from 50Hz to 15kHz. In the middle of the unit there is a row of several push buttons: Separate bypass, EQ and Full Range mode buttons for each channel, plus the stereo link and Auto Gain button for automatically adapting the output level in Full Range mode.
Like we always do, we have measured the nvelope with our Audio Precision System Two, this time with kind support from our friend Uli Apel. Diagram 1 shows the effects on the envelope on a signal. We have used a square wave impulse with a length of 300 ms (blue). The green curve shows the result with both the Attack and Sustain turned completely to the right. You can see how the processor raises the level during the attack phase by 12 to 13 dB, compared to the average level. The sustain phase shows a continuously rising boost by roughly the same amount. The red curve shows the result with both controllers in their fully left position. The attack flank is slowed down quite strongly, dropping quite drastically towards the end of the test signal. Diagram 2 shows two exemplary curves in EQ mode. Freq A had been set to 1.2kHz, Freq B to 1.3kHz.
You can see the maximum boost of 15dB and also the steepness of 6dB per octave, which allows conclusions about the frequency-dependent behavior of the unit while processing impulses in Dual Band mode. Diagram 3 shows the completely clean FFT noise spectrum of the output, and diagram 4 the ruler-flat level and phase frequency response (even with a very fine scale like this one): Up to 100kHz there is only a minimal drop of -0.2dB (blue curve). The output noise in relation to unity gain showed a good value of 87.4dB RMS effective unweighted (22Hz to 22kHz), resulting at a total dynamics of 109.4dB at an output level of +22dB. The quasi-peak measurement with CCIR filter resulted in an expected value of -80,3dBu. Diagram 5 shows the inconspicuous harmonic distortion throughout the complete frequency range. Diagram 6 shows the very good unbalance absorption of the input.
It is not the first time I am reviewing a device that is made for processing the attack and sustain characteristics of audio signals, so I directly knew which kind of sounds I had to use for this test. It's in the nature of its topology that the nvelope performs best when treating signals with a distinctive transient structure, because this is exactly what is needed for a successful tracking and good processing results. This makes it only natural to concentrate on drums and percussion first. The first thing you notice is the the ranges for attack and especially sustain settings are very generous, so you can generate everything from normal to absurd. “Realistic” results for more complex signals or mixes can be found between the 9 and 3 o'clock settings.
When you go further than that, the results can become quite extreme – but if you like to experiment, maybe that is exactly what you are looking for. For example, my drum set went into heavy pumping with the sustain controller at its maximum position. Keep in mind this is especially the case in Full Range mode. With more careful accents on the attack, the drum set could be shifted to the front effectively, which could be nicely supported by taking just a little bit of sustain away. All this really works nicely, and you can create great effects with it, which create similar impressions that changing microphone distances would. Sometimes you really have to go back to bypass in order to believe that what you are listening to is based on some very different source material.
Shaping single signals like snare and bass drum is a pure pleasure, as almost everything you could dream about in terms of shaping transients becomes possible indeed: starting from ambient, blown-up pumping of compressed room mics, that you can mix to your original signal to create extreme density, ending at unnaturally dry signals that sounds as if it had been recorded in a room without reflections at very close mic distance. Working on drum subgroups can also demonstrate the technical limits of this kinds of processing. Hi-hats and cymbals start to become evil and unnaturally peak or break in unfavorable ways. But exactly this circumstance is the reason why the nvelope offers frequency-selective processing in Dual Band as well.
Once you start taking critical frequency areas out of the way, in this case the treble, the Hi-hats remain completely untouched, while the snare, tom and bass drum can be tailored harder or softer at the same time. The sonic footprint shifts, for example, when the drums are inflated by a good amount of sustain accenting the low mid range. If you wanted to, you could use the EQ mode for further fine tuning, but what remains is a very noticeable accent on the drums that does sound very natural indeed. Of course, this is also a question of personal taste, based on the sound you have in your head in combination with the source material you have – long story short, you need to do all this with your ears open. There are just no recipes or presets for this kind of signal processing.
If you want to go for a massive drum overkill sound, you can get there by boosting the transients while heavily extending the sustain at the same time. Now, your drums not only sound precise, close and tight, but also powerful, voluminous and three-dimensional. By the way, it is absolutely worth mentioning that the stereo link function which enables you to control both channels with just one set of controllers is a true blessing, making your work easy and comfortable. If you don't want to push the lows any further because they come with enough punch already, you have two different options: In Full Range mode, you can use the Freq A controller to reduce the influence of low frequencies on processing (just like with the sidechain filter of a compressor), so the attack times will only be accelerated in the frequency areas above the value you have set.
You will notice that the nvelope will work with a more subtle hand then. When the controller is moved closer to its extreme position, up to 4 or even 8kHz, you will notice a little sparkle or glitter which sounds very interesting. It is not really comparable to what an EQ does, as we are talking about a dynamic process in this case. The second option is the Dual Band mode, offering further possibilities. Not only can you get the lows out of the way, but you can also tailor the high frequencies in a second step, resulting in much more naturally sounding processing results. In other words: It's an incredible fun to dive into the magic world of impulse shaping when you are given such potential tools. You do not even get close to this with any compressor in the world.
Just not to lose the opportunity, I also gave the EQ mode a try. I was truly amazed to realize what an excellent sounding high/low shelf filter can do... The highs sound very airy and silky, the lows very tight and precise. So when you have an nvelope in your arsenal, you will also benefit from a beautiful shelving filter.
Under the influence of being inspired by such positive results from shaping percussive instruments, I also wanted to spend some time with less typical instruments like an acoustic guitar. This time, the results were quite mixed, and in the end it all depended on how the guitar had been played. I would definitively recommend using the Dual Band mode in difficult cases like this. If everything fits, you get interesting results, but you also have a good chance of reaching the technical limits of detecting transients when the impulsive and the tonal part are quite similar. This is also true for the sustain, where the processing results were useable within a certain range, but turned into sounding unnatural quite easily.
I also made a test with a complete mix. Here, too, the results depend on the structure of the audio material you send into the machine, and one more time it becomes obvious that the Dual Band mode is the key to success. The true strength of this unit is processing percussive signals, however. Fantastic possibilities get into reach in this field, possibilities that have never been available before. Attention, this is really addictive and one has to take care not to overdo things from time to time, as you can travel lightyears away from your original source. The processed version often sounds completely different to what you originally had – and still it sounds so good, as if your instrument had originally been recorded just like this. In a way, we can understand the nvelope as a “front/back pan controller” as pushing or taming the attack of a signal has a lot of influence on how close we perceive it in the mix.
elysia has obviously cultivated and extended the possibilities of impulse shaping. Now it is possible to process signals that would not have had the slightest chance for a good result with a standard full range treatment. The build quality of the unit is top notch, and not only in its price price class. Everything is solid, of great workmanship and nice to look at. The controllers have a good feel, and the center detents for attack and sustain help to set the unit to a neutral position quickly. The wide parameter ranges give enough space for even very experimental settings, but the scale of more realistic settings is still sufficient for fine-tuned results. The EQ mode is a useful addition for polishing finished mixes, subgroups or single tracks.
The Dual Band mode makes the nvelope extremely flexible, and the stereo link function is a great convenience when processing stereo material with this exciting tool. With a price like this, the manufacturer certainly went to the limits of what is possible, taking the complexity of the development, the professional technical data and the rules of the market into consideration. The nvelope leaves a very positive impression, and I would not hesitate a second to give it a strong recommendation. If you are into popular music and interested in the idea behind this unit (which you then should by all means), you will find that the nvelope is the perfect solution, combining advanced possibilities and easy operation in a powerful package. Again, we have another really good solution from the elysia guys...