The LIMIT.ONE grew out of a need to address the demands of preparing audio for today’s evolving digital distribution channels. The way that people obtain music—from free streaming services to high-resolution downloads to YouTube and all the rest—has transformed the way we must prepare audio, yet so many of our tools were developed in the analog era, which had vastly different requirements and expectations.
Specifically, today’s engineers are expected to bring volume levels up to within just a few samples of digital clipping (0dBFS) while still providing clean, professional results. Precision analog devices developed specifically for this purpose are rare, and in their absence a number of questionable practices have emerged: clipping converters, intentionally distorting and clipping the digital waveform, using excessive compression and/or limiting, and—most commonly— relying on digital processing to generate an audio file that approximates the original while peaking dangerously close to clipping. We often call these various methods “brickwall limiting.”
The LIMIT.ONE is among a very few all-analog limiters designed specifically to accomplish brickwall limiting while offering ultra-clean, audiophile sound quality before you hit your A-D converter. Achieving your maximum volume before converting to digital is one of the most overlooked and misunderstood aspects of creating truly professional digital masters. By avoiding digital overs in the converter and using the full bit-depth available—rather than “making up” empty bits in the digital realm—your final digital audio file will be both clean and truly full volume. These are the marks of a processional master.
Unlike most digital brickwall limiters, the LIMIT.ONE’s unique circuit maintains the shape of the original waveform as much as possible. The processed waveform is not identical, of course, but rather than being flattened at the peaks, the waveform processed by the LIMIT.ONE can maintain the original (typically rounded) shape. We might say that the LIMIT.ONE can be more faithful to the original signal while still providing brickwall limiting.
These unique abilities of the LIMIT.ONE are accomplished by employing a current controlled attenuator between two Pikatron transformers. We’ve taken this core design from the renown broadcast limiters developed in the 1960s by TAB Funkenwerk, specifically the later models which were solid state designs utilizing dual transformers. However, we have added significant updates and features that make the LIMIT.ONE as powerful and effective in the digital era as the U73s were at the height of the analog era.
Of course, clean brickwall limiting is not the only use of the LIMIT.ONE’s unique circuits, and we encourage creative uses for it that go beyond the original intentions. You’ll soon find that there are many unique ways to use the LIMIT.ONE whether you’re mastering, mixing, tracking or even working in a live concert setting. Some of those other uses will be explored after we take a closer look at the unit’s unique controls and features.
LIMIT
This unique multi-knob is used to set the threshold of the limiter. The multi-knob subdivides itself upon rotation so that you can achieve, and easily recall, exact settings. Because the goal of the LIMIT.ONE is often ultra-precise limiting, we felt it was necessary to develop this unique control.
The LIMIT.ONE can handle very loud input signals (as high as +26dBu), but has a wide range on the threshold to accommodate much quieter signals as well. Note that the 0 setting on the multi-knob (fully counter-clockwise) turns the limiting function off, but this position is not a true bypass (use BYPASS switch for that).
OUTPUT
All the way counter-clockwise, there is no make-up gain. Each click gives exactly +.5db of gain and the total make-up gain available is +5dB. These stepped attenuators are from Elma. They provide perfectly matched gain settings between channels, as well as effortless recall.
The OUTPUT gain circuit comes after the detector circuit, such that changing the OUTPUT level will not affect the behavior of the limiter.
For those using the LIMIT.ONE as the final unit in their chain—especially if you’re setting exact levels to be sent to your converter—you will want to leave the OUTPUT fully counter-clockwise.
In other applications where the LIMIT.ONE comes before other processing units, the added gain available through the OUTPUT knob will allow you to drive or “hit” other units more aggressively as desired.
SPEED
These four settings adjust the release time of the limiter. The four different SPEED knob settings provide a wide variety of tone qualities and dynamic behaviors. As you get to know the LIMIT.ONE, you will find different uses for each of these release times.
• S — SLOW — More bass will pass on this setting, making it more neutral tonally, but limiting artifacts become audible when pushing beyond threshold more aggressively. This setting is the most faithful to the original Telefunken U73 broadcast settings (which were fixed).
• M — MEDIUM — This is what we consider the “normal” release time for the LIMIT.ONE, and is our recommended starting point for using the unit in most cases. We feel it offers the best balance between maintaining transients while maximizing transparent limiting.
• F — FAST — Very useful for controlling lowend with fewer limiting artifacts. As you push past the threshold, you’ll notice the low-end tightening up.
• E — EXTREME — The fastest setting that will attenuate bass but will have less audible limiting artifacts. There may be some distortion on this setting when pushing beyond the threshold more aggressively. This distortion is intentional and very useful for parallel compression configurations (see below for more). Used more subtly, this setting can be very effective at tightening up the low-end.
BYPASS
Individual hard bypass switches for each channel.
LINK
The LIMIT.ONE’s channels can operate independently, or they can be linked. When you link the channels, the unit will attenuate both channels identically based on whichever channel is limiting the most at any given moment. For this reason, it is typically a good idea to set the two channels identically when operating with the channels linked. However, there may be instances when allowing one channel to dominate the other is desired (such as when using the limiting artifacts as a rhythmic effect).
HAMMER LIGHTS
These are highly accurate indicators of when the limiting circuit is being activated. When setting the threshold using the LIMIT knob, these lights are your window into the behavior of the circuit. When you’re aiming to transparently control “overs” before your A/D converter, for example, you will want to set the LIMIT multi-knobs such that the HAMMER LIGHTS only come on briefly at the very loudest transient moments in the program material.
USE OF EXTERNAL METERS
For mastering, we encourage the use of very accurate external RMS/Peak meters with the LIMIT.ONE. These may be free-standing units or they may be incorporated into your converter or console. Alternative balanced XLR outputs are provided on each channel for easy connection to external meters.
INPUT XLR
Individual inputs for each channel.
OUTPUT XLR
Individual outputs for each channel.
ALT OUTPUT
An exact mirror of the output, this is provided primarily to allow the use of external Peak/RMS meters, but can also be used for various other purposes, such as feeding a headphone system during mixing, more elaborate parallel processing configurations, and so on.
IEC PLUG AND FUSES
A standard IEC power cord is used. Fuses are on a spring loaded panel next to the IEC socket.
Frequency Response
• 40Hz – 15 kHz ± 0,35 dB
• 20Hz – 20 kHz ± 0,73 dB
• Amplification 0 to +5 dB
• Max Output level ( 40Hz k3 -50dB ) +24dBu
• Voltage 115/230V AC
• Power usage 5W
• Dimensions B/H/T 483 mm (19“) 44,2 mm (1HE) 27,5mm
• Weight 3,95 kg
Input symmetric, isolated ground
• Input resistance ⪴ 30kOhm
• Input damping at 15KHz ⪴ -60dB
Output symmetric
• Output resistance ⪴ 80Ohm
• Output damping at 15KHz ⪴ -42dB
• Harmonics k3: at +4dBu
Noise floor
(at + 4dBu Output at 5)
• pGer ⪴ -75 dBqs ( CCIR 486 )
• pFr ⪴ -85 dBq ( Bandwidth 10Hz – 30 kHz)
