HK audio DFC DIGITAL FIELD CONTROLLER

The solution for complex sound-reinforcement challenges and permanent installations.

The DFC is a digital 3-way mono controller designed to be used in an HK AUDIO amplifier rack.
With its specially developed software and matching MIDI interface, it offers a comprehensive
means of managing a complex sound reinforcement system via an intuitive analog-style interface.

PA Remote Management
The distributed sound systems used at today?s large venues have become so complex over the
years that they now practically require a full-blown control center just to set up and manage them
efficiently and maintain a clear overview over them. To ensure that each individual acoustic area is
treated by a dedicated part of the PA, the various sections of the overall system must be divided into
sensible groups,such as PA wing left/right, center cluster, long-throw, near-field, sub-low, delay 1,
delay 2, and so on.
Such a division usually leaves you with a large number of different sound coverage zones, which have
to be treated separately but managed centrally.
A system controlled in the traditional manner would normally need at least one EQ, delay, and crossover
channel per coverage zone. Add to that the necessary standard cabling and rack and truck space,
and you end up with a considerable number of racks and, what?s more, a complicated set up. The
Digital Field Controller offers an easier and more cost-effective solution. The word "controller" usually
refers to functions such as crossover and protective circuitry; the DFC expands the meaning of the word to
include a very different meaning: PA-REMOTE-MANAGEMENT.
To simplify the handling of large system configurations featuring several amplifier racks, you can network
up to 32 DFCs via MIDI interface, controlling them remotely with the aid of a PC.
Using the control program that was developed especially for this very application, you can manage even
extremely large PA systems very conveniently, accessing all installed DFCs individually, if you wish, equalizing
and correcting delay values for each single device separately.
At the same time, you can choose to group several DFCs together in order to control an entire group of
speakers (PA wing, delay tower, subs) that are powered by several amp racks as one. All settings that you
enter for a given group are automatically transmitted to the appropriate controllers. This option for example lets
you effortlessly implement a delay station: All you have to do is assign all of the DFCs that control the speakers
of the delay station to one group, and set one single delay value, which is then automatically transmitted to all
DFCs in that group.
This feature considerably reduces the amount of cables you have to connect and simplifies the entire signal-processing
operation considerably. The group control function lets you comfortably handle PA systems of any size,
from club gigs to major open-air festivals.
The extensive control functions of the DFC system can be operated from the graphic user interface of the
PC software as conveniently and intuitively as you are accustomed to with individual analog equipment.
The graphic user interface of the PC software makes using the extensive control functions of the DFC system
as intuitive as using familiar analog equipment. In fact, you can manage your entire system from just three
screens.
The first screen displays the status of the peak and temperature limiters in the three frequency bands of every
attached DFC. So, the operational status of the complete system can be checked easily from either the FOH
position or the control room.
You can also create groups, and the zones they are intended to cover, in this window.
By double-clicking on the Group, you arrive at a second screen. Here you can assign a name to the group (e.g.
“Long-throw Left“). Additionally you can set basic functions here, such as Mute, Level, Phase Reverse and Delay,
for every one of the three frequency bands, as well as for the Group Master.
From the third screen you can access, for each connected controller and for each created group, a 28-band equalizer
with 15dB of cut or boost, Set-Flat and Bypass functions, and gain control.
Dynamics
The dynamic range of the input section plays a crucial role in a digital audio controller because
* the greater the dynamics of the input section, the better the headroom.
* the greater the dynamic range, the lower the audible noise.
* dynamic reserves in the input stage are the basis of excellent dynamics at the output stage

Through the innovative use of Split-Stack Technology, in which two 20-bit AD converters are stacked together, the
DFC achieves a dynamic range of 117 dB at the input! That exceeds what a high-quality 24-bit converter can do by
4 dB!
Absolute Correction of Frequency and Phase
In contrast to standard digital controllers, the DFC does not use IIR (Infinite Impulse Response) filters that are adjustable
at the unit itself. Instead, at each output it uses one FIR (Finite Impulse Response) filter, which accomplishes both
the dividing and equalizing functions in one.
The difference between the two types of controllers is essentially how the signal is processed in the controller. Most
other digital controllers have a fixed number of filter components which allow you to implement a low-pass filter with a
slope of 12 decibels, or a fully parametric filter. The desired type of signal processing operation is made possible by
a combination of these components. The processed signal is routed to the device's output.
For example, to separate the signal for a woofer with a slope of 48 dB, the device requires eight filter components (four
low and high-pass filters each). Optionally, you also can assign additional parametric filters to equalize the system.
The FIR filters of the DFC, on the other hand, work with a sample of the desired filter impulse response. The sample is
uploaded to the filter using Fourier transformation. It shapes the frequency and phase response of the filter. The sample
is downloaded via the same process. As a result, FIR filters can execute detailed equalization operations with extremely
steep slopes and freely assignable amounts and phases. This type of signal processing operation requires a PC. It
computes the required impulse response for the desired signal processing operation via an inverse Fourier transformation.
Once calculated, the filter can no longer be varied. If you want to change a parameter or value, the entire filter has to be
 recomputed. On the other hand, you no longer have to execute a number of tasks manually. For example, you do not
have to adjust the delay and phase corrections for the split signals, since these operations are carried out automatically.
The DFC is not a universal controller, but is set up for a specific system and it knows its specific characteristics. This is
the only way a sound reinforcement system can really be equalized effectively.
Together with frequency response, the phase response of a system plays a very large role in how that loudspeaker
system reproduces sound. Phase errors are rooted in three main causes:
1. Each loudspeaker itself produces phase errors because different frequencies require different travel times
on the membrane.
2. Loudspeaker enclosures always function as high bandpass filters of the second order in the case of sealed
enclosures, and of the fourth order in the case of bass-reflex cabinets. All filters have the effect of making the
phase response less linear. This includes the filters of a passive crossover network.
3. In most systems, the voice coils of individual loudspeaker components are not lined up on one axis. As a
result, sound waves generated from these components are not in sync but out of phase, yielding distortion in
the phase response.

The DFC is the first controller which not only uses time alignment to compensate for any time lags between the
individual components, but goes a step further and compensates for the phase distortion arising from the enclosure,
the crossover networks and each individual loudspeaker.
So now, for the first time, a tool is available that uses a comprehensive approach for truly flattening the phase response
of an entire sound reinforcement system.
For the user this means a previously unattainable level of clarity and sonic purity, more effective use of equalization,
a more natural soundstage, and a greater tolerance among listeners for higher volume levels.

Biamped and 3-Way Active: Best of Both Worlds!
Both two-way and three-way systems have specific advantages and disadvantages. In combination with the two-way
systems of the HK AUDIO R-Series and T-Series, the Digital Field Controller enjoys all the typical benefits of both
two-way and three-way systems without having to suffer their disadvantages. As already mentioned, the DFC is dealing
virtually with three separate ways ? low, mid and high ? but recombines the mids and highs before the output stage.
In other words, the DFC produces a two-way signal, and yet each frequency band can be muted separately, and even
its phase can be reversed separately! In a mid/high loudspeaker module such as the RT 112 (12“+2“), you are free to
control the volume of the 12" speaker separately, reverse its phase, or even mute it briefly altogether without affecting
the high frequency driver at all. And that, mind you, although both are connected to the same speaker cable and both
are running over one and the same passive crossover.

* Comprehensive frequency adjustments
* Quick access to speaker components
* Individual speakers can be muted
* Corresponds to traditional international usage
* Easier to wire up
* Less power amplifiers are required
* Less electrical power is needed
* Less weight
* Less warehouse / truck space needed
* Fewer sources of error
* Higher Return on Investment

Perfect Protection for the System: the Limiters of the DFC
The HK AUDIO Digital Field Controller includes two anticipatory limiter sections per frequency band:
a) Thermal Limiter
Since the DFC has data on the entire sound system, power amps included, it can continually monitor the operating
state of its individual components. Taking into consideration how long the system has been running, it compares the
processed signal with the stored maximum system values, and momentarily reduces the output as needed. In this
way, the PA is protected against the dangers of overload.
b) Peak Limiter
The signal which has been processed by the DFC is checked with a peak detector before it reaches the output. If the
signal is too high, the peak limiter section is directly activated; it calculates how much to reduce the signal before the
peak signal reaches the output stage. In contrast to previous analog and digital controllers, the DFC does not use a
feedback circuit of the sort where the limiter only reacts after the first peak has already gone through. Instead, the signal
between the peak detector and the limiter is delayed by two milliseconds, allowing the needed corrections to have
already been made before the peak reaches the outputs of the DFC and, therefore, the P.A.
Delay Functions
The DFC features both a master delay and a frequency-band delay. The master delay serves to compensate for the time
lag between individual coverage zones, for example between the FOH PA and delay towers farther back in the audience.
Up to 2000 milliseconds of delay is available to sync loudspeakers that are up to 680 meters (2230 feet) apart from each
other, and that should be enough for most applications...
The frequency-band delay offers up to 100 milliseconds to align the individual components of a PA stack with each other,
for example if the mid/high cabs are flown but the bass cabs are resting on the floor. Both types of delay can be entered
in time (milliseconds) or distance (feet or meters).

Lab Gruppen NLB 60E
The NomadLink network provides remote monitoring, control and power sequencing functions for multiple C Series or FP+ amplifiers. Indeed up to 16 NLB 60E network bridges, each monitoring up to 60 amplifiers may be accommodated in one system. Easy setup, redundancy, and minimum maintenance were bywords when developing this network format.

NomadLink is a closed-loop, daisy-chained network topology with the NLB 60E providing the bridge to the familiar world of Ethernet/LAN. NomadLink reduces installation time and cost significantly, includes redundancy during operation by design and simplifies the location of faults or system abuse.

NomadLink together with the associated DeviceControl software allows the subnets’ architecture to be automatically uploaded even without individual IP addresses in the amplifiers. All in all, it is the fastest and easiest monitoring and control network on the market today.

Specifications:

Network Connectors:
   * Nomadlink Out: EtherCon housed RJ45
   * Nomadlink In: EtherCon housed RJ45
   * Ethernet rear-panel: EtherCon housed RJ45
   * Ethernet front-panel: Standard RJ45
General Purpose Inputs (GPI):
   * One Voltage sensing input: Two pole Phoenix
   * Two contact closure inptus: Two pole Phoenix
Front Panel Indicators:
   * Front operation locked: Yellow LED
   * Fault warning: Red LED
   * Amplifier subnet muted: Red LED
   * NomadLink network connected/activity: Blue LED
   * Ethernet connected: Orange LED
   * Ethernet Activity: Yellow LED
2 x 16 Character display: White text, Blue background
Navigation and Adjust keys: Yes, x 6
Subnet Power on/off keys: Yes, x 2
Power: 100 to 240 VAC, 50 to 60 Hz (auto-select)
Power consumption: Finish: Anodized aluminum front, Plated and painted steel chassis
Approvals: CE, CSA
Dimensions (W x H x D): 19" x 1.73" x 8.2" (483 x 44 x 208 mm), 1 RU
Weight: 5 lbs. (2.25 kg)

• XLR balanced ins and outs
• Mode switch for stereo 2-way or mono 3-way operation
• Low frequency summed (subwoofer) output
• x10 range switch on both channels
• 40Hz high pass (low cut) filter both channels
• Phase reverse switch on all outputs
• Individual level controls on all outputs
• 24dB per octave Linkwitz-Riley filters (the professional standard)
• Stereo/Mono status LEDs indicate the selected mode
• dbx® 2 year parts and labor as standard
• CSA NRTL/C approved
• CE compliant

With 6 inputs and 4 outputs the dbx ZonePro? 640 and 641 provide flexible signal routing,
powerful DSP processing and multiple control interfaces for Commercial Audio applications.
Designed to offer superior system sonic performance and flexibility, the 640/641 deliver the
highest quality tools available. Even the input and outputs connectors were chosen for their
standard usage and reliability. The ZonePro products offer Euroblock connectors for balanced
signals and RCA connectors for interfacing with consumer equipment often used in commercial
applications; there is also a simple analog input buss that allows inputs to be sent from one
unit to the next for unit and job scalability. The 640 and 641 provide every necessary processing
tool, from the input processing like gain control and EQ available on all inputs to highly sophisticated
and specific functions such as selectable paging microphone processing including Gating,
De-Essing, Auto Gain Control, Compression and Feedback Suppression. The heart of the
ZonePro products is the Routing module that provides of course Primary Source Selection
but also Source Ducking for Paging and Priority Override. The outputs also offer a wealth of
processing designed for commercial applications like our patent-pending AutoWarmth? function
that was co-developed with JBL to provide natural low frequency extension at any signal level.
Each output also offers EQ, Bandpass and Crossover filters, Limiting and Delay for system
optimization. With the ZonePro? every tool is at your disposal to maximize the response of
your system.
Beyond processing, the ZonePro? products offer multiple forms of control to further extend the
versatility of your system. From easy-to-use wall panel Zone Controllers for standard end-user
functions like source select and volume control to advanced system control including a built-in
Real Time Clock that can provide programmable system changes throughout the day or week.
For system setup and monitoring the ZonePro Designer software provides an intuitive interface
and a speedy setup Wizard for configuring and editing all system parameters.

The ZonePro? 640 and 641 will take your Commercial Audio system to the next level with advanced
processing, versatility and control.

? Advanced Feedback Suppression (AFS?)
? Autowarmth?
? Auto Gain Control
? Compression
? Limiting
? Noise Gating
? Notch Filtering
? Bandpass and Crossover Filters
? Parametric EQ
? Security Lockout
? Wall Panel Control
? RS-232 Control
? Windows? 2000 and XP GUI
? IEC, UL and CSA Approvals

• Three-input, six-output loudspeaker management system
• Four different mono- and stereo-output operating modes
• Individual crossover filter types including Butterworth, Bessel and Linkwitz-Riley, with selectable roll-off characteristics from 6dB to 48dB per octave
• Choice of high-, band- and low-pass filters for each input and output
• Dynamic EQ for level-dependent equalization and parametric EQ selectable for each channel
• “Zero" attack limiters on all output channels for optimal signal protection
• Automatic or manual-adjustable delays for all inputs and outputs allow for adjustment due to room temperature, phase and arrival time differences
• Link option via RS-485 network interface allows for linking multiple units for larger installation requirements
• Downloadable software enables single- or multiple-unit remote control utilizing a Windows based computer
• Sixty user-defined internal presets can bestored via software or on a PCMCIA card
• Internal universal power supply allows the unit to operate virtually anywhere