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• SONAR Professional or SONAR Platinum is required to use the ProChannel Module Channel Compressor

Maximize Your Mix

It’s more important than ever to deliver mixes that stand out from the crowd. And it’s not just about being “loud”. It’s about maintaining punch, clarity, and good dynamics while achieving the levels necessary for a particular sound or an entire mix to stand up and get noticed.

The Concrete Limiter uses clever look-ahead and oversampling techniques, smooth gain curves, and frequency-dependant limiting to intelligently limit peaks without ever sounding “harsh” or “squashed”. And it does this while introducing only 1.5ms of latency, so you can use it in a mix and still maintain responsive playback and recording of audio tracks and softsynths.

• Efficient CPU Usage
  
• Low Latency
  
• Optimized look-ahead
  
• Native x64 Operation
  
• Frequency Dependent Limiting
  
• Smooth Gain Curves
  
• Inter-sample Peak Limiting

Solidify Your Sound

The Concrete Limiter not only offers precise, transparent, peak-limiting, but also features Bass Lift Technology designed to deal with problems sometimes associated with limiting and to enhance low frequencies in a way that is musically pleasing.

While desirable in many cases, limiters that strive to achieve total transparency can often lack character. Due to its dominance, bass is often the first thing limited, and this can have negative effects when limiting certain kinds of material, like drums or bass heavy synths.

The Concrete Limiter’s “Bass” switch deals with this in a musical way by processing low-frequency material through a specialized circuit designed to gently soft-clip while limiting. This innovative design maintains a clear and natural tone while increasing perceived level and imparting the fat, punchy, sound associated with tube-type soft-clipping. It does wonders for bass, kick drums, drum buses, and final mixes.

Music Concrete

The Concrete Limiter’s informative, space-efficient interface and simple controls ensure ease of use and excellent results while native x64 operation and 64-bit double-precision ensure solid performance and the highest fidelity. It’s fast, dependable, and most importantly, it sounds great.

And the fact that the Concrete Limiter is optimized for ProChannel means it’s highly-ergonomic, drag and drop routable, and instantly available on any track or bus. No plugins to manage and no additional floating windows - just efficient, transparent limiting right at your fingertips.

A flexible and transparent limiter is an indispensible tool for any engineer mixing today’s music. Whether peak limiting percussion tracks, slamming a drum bus, or carefully adding a few needed dB to a final mix, the Concrete Limiter is sure to become a favored, “go-to”, processor with a wide variety of practical uses.

Bass Lift Technology

Since bass material often dominates the peaks of source material (bass drum, etc), it is often the first thing to be limited, and this doesn’t always produce desirable results. In the case of a drum kit, for example, the bass drum will be limited quickly, leaving the hi-hat to grow disproportionately as the threshold level is reduced. Additionally, it is often desirable to make the bass sound "fatter", thus adding “character” to the source material.
Bass Lift Technology image

The Concrete Limiter's "Bass" switch allows low-frequency material to slightly soft-clip while limiting. This offers an increase in RMS and perceived level while imparting the “fat” sound associated with tube-type soft-clipping. The perceived level increase can be +6dB for low-level signals (well below the threshold value) and about +1.5dB for signals that are being actively limited with gain-reduction.

Frequency Dependent Limiting

An important feature of high-end limiters is that they engage the gain-reduction in a frequency-dependent way.

Consider the test audio clip below:

This is a 100Hz test tone at -6dB peak that has two "pulses" riding atop the base wave. The first pulse is a single-sample, high-frequency spike that peaks at 0dB; the second is a wider pulse of 100Hz tone that also peaks at 0dB. If this sample is processed through a limiter with a threshold setting of -6dB (or +6dB on some limiters), it will attempt to bring all material up to 0dB. In order to give both pulses “breathing room” and to avoid clipping, the area surrounding the pulse must be lowered in level. This can be done quickly on the leading edge (attack), but should be done more slowly on the trailing edge (release).

Here is the result of processing the sample through an arguably inferior Limiter:

The majority of the sample is now peaking at 0dB. The holes, or dents, in the waveform are the result of gain-reduction intended to make room for the two pulses. Note that the high-frequency spike and the bass pulse have created the same pattern of gain-reduction or denting. Cheaper limiters often exhibit this behavior. In the majority of cases where the source material has a mix of high and low frequencies, the bass is unnecessarily reduced by the gain-reduction, because to the algorithm, "a peak is a peak". On the other hand, if the release time is set too short, bass material will distort as though it were run through a vacuum tube. The solution is a type of program-dependent release that uses frequency-dependent gain-reduction.

Now take a look at the Concrete Limiter output:

Concrete Limiter

In the diagram above it is evident that the high-frequency spike hasn't imposed much on the 100Hz base tone; however the release time on the low-frequency pulse is appropriately longer. This preserves the integrity of the bass signal. In the Concrete Limiter, the amount of auto-release, for frequencies between the two extremes, is continuously variable making it a much more sophisticated design overall.

Smooth Gain Curves

The Concrete Limiter uses smooth, 4th-order, gain curves for all applied gain-reduction. The diagram below shows a close-up of the "dent" imposed by a high-frequency pulse on some DC-biased material, after limiting has been applied:

The same type of curve will be applied for mid-range and bass material, the only difference being that the release times will be longer.

Inter Sample Peak Limiting

The Concrete Limiter employs an advanced, 16x Oversampled, 6th-order Windowed-Sinc, Interpolation mechanism that detects peaks in-between samples. The problem with sampling, in-general, is that even though individual samples may all fit under the 0dB-full-scale clipping level, the waveform can still clip in the analog domain:

The problem occurs when the DAC (digital-to-analog converter) output needs to reconstruct a smooth curve from a digitally sampled one (see graph). Many DACs are equipped to handle any analog overages, but some are not. Studio engineers often set the Output Ceiling level to -0.1dB, or similar, because of this frequent issue. A better solution is for the limiter to model (oversample) the DAC's output, and limit to the modeled, analog peak. The Concrete Limiter works this way.

Inter-sample Peak Limiting vs. True-Peak Limiting

True-peak Limiting is a form of Inter-sample Peak Limiting, and it simply means that method used to calculate the analog output is mathematically perfect. In theory, attaining perfection is impossible - because it requires a infinite amount of both look-ahead, and history, of the input signal. In practice, True Peak Limiters can earn their title with a few milliseconds (or more) of look-ahead. At that level of processing, the error becomes manageable, and falls below the threshold of hearing. True Peak Mastering Limiters are becoming commonplace, but with the true-peak accuracy, there also comes a heavier CPU-load, as well a higher plug-in latency associated with the extra look-ahead.

It should be noted that the ProChannel Concrete Limiter is not considered to be a "True-peak Limiter". While it calculates inter-sample peaks and limits to them, its low-latency model may still allow analog- overages on very high-frequencies when they are driven hard (i.e. with low limiter threshold levels). The Concrete Limiter represents what we believe to be an excellent compromise between low-latency, low CPU-loading and output quality. With its smooth, frequency-dependent gain-reduction algorithm, it produces very transparent, level-limited output - with a minimum of audio artifacts.