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TC Electronic Reverb 6000

Reverb Processor
Published April 2003
By Hugh Robjohns

TC's flagship reverb processor, based on the System 6000 hardware, combines 16 channels of world-beating processing with flexible and lightning-fast operation.

In recent years TC Electronic have produced some stunningly good reverb machines, with products spanning all budget levels, from the simple-to-use M300 right up to the new flagship Reverb 6000. The company's approach to reverb algorithms is a little different to that of many of its competitors, with extensive use made of 'ray tracing' to define accurate early-reflection patterns, for example. Over thirty man-years of development time has been put into creating the latest-generation VSS reverb algorithms, but the results speak for themselves with remarkably realistic acoustic environments which incorporate accurate positional information in the reflections, ideal for naturalistic music and post-production applications.

Functional Overview

TC Electronic Reverb 6000The Reverb 6000 is based upon the System 6000 hardware, which provides four separate extraordinarily powerful processing Engines, each able to handle up to eight audio channels. These Engines can be used independently (subject to the machine's maximum of 16 physical inputs and outputs) or they can be interconnected to provide almost unparalleled processing power, working at standard or elevated sample rates. Whereas the Reverb 6000 software is restricted mainly to reverberation algorithms, the full System 6000 package includes a comprehensive array of equalisers, dynamics processors, up- and down-mixing routines, noise-removal algorithms and much more, including some third-party programs such as Massenburg high-resolution equalisers. The System 6000 can be updated to include all the latest Reverb 6000 programs (software version 3.2), and a Reverb 6000 can be expanded to provide full System 6000 functionality, if required.

 

TC Reverb 6000
pros
  • The flexibility of four independent processing engines.
  • Up to 16 channels of I/O.
  • Huge and versatile range of top-quality reverb algorithms.
  • Superbly intuitive Icon graphical controller.
  • Expandability to full System 6000 status.
cons
  • Having to send it back after using it for a month!
summary
The flagship product from the Danish master of reverb. Incredibly powerful, wonderfully intuitive to use, and with stunningly realistic reverb simulations — the latest multi-channel VSS algorithms are truly amazing. Those with the budget are very fortunate indeed; the rest of us will have to wait for the technology to migrate to more affordable products.

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The Reverb 6000 contains a range of familiar time-domain effects — chorus, phasing, flanging and delays (see box for details) — but majors on its 'generic' and 'source-based' reverb algorithms. The former use conventional reverberation algorithms to generate a generic set of early reflections and reverberant tails for a mono, stereo or surround input. The source-based algorithms, on the other hand, generate specific reflections for each separate mono sound source within an overall acoustic environment, with an increase in spatial accuracy and realism. There are also many of the reverbs from existing TC Electronic products including the M3000 and M5000.

To maximise sound quality, all DSP reverb calculations are performed with double resolution, and a 24-bit signal path is maintained throughout. Output resolution can be set anywhere between eight and 24 bits, and state-of-the-art up- and down-sampling is provided to enable standard-rate signals to be processed at elevated rates if required. The machine can also be set up to work with any combination of six-channel, five-channel, matrix surround, stereo, or mono input and output formats, subject to the I/O available.

The machine comes with over 600 factory reverb presets, about half of which are optimised for music mixing applications, while the other half mainly comprise room simulations intended for film and post-production duties. Within the factory presets is a dedicated bank called the Halls Of Fame collection, containing programs contributed by respected post-production, recording and mastering engineers such as Michael Bishop, Chris Boyes, Akira Fukada, Bob Katz, Steve Kempster, George Massenburg, Al Schmidt, Peter Sullivan, Bill Smith and many others. Also included is the first installment of the Skywalker Sound collection (more specialised reverbs and room simulations) and a Best Of TC collection (familiar programs borrowed from the company's other reverb processors).

With four processing Engines and a full complement of I/O installed, the Reverb 6000 can run up to 16 mono-in, mono-out effects, or two 6.1 surround programs, or a variety of mono, stereo and multi-channel combinations in between. Such flexibility should be enough for even the most complex of mixes! Using the VSS source-based algorithms, multiple inputs can be used to provide individual mono sound sources, placed as required, within the virtual rooms created by these sophisticated algorithms. The reverb output can be stereo or multi-channel, with subtly different early reflections created for each independent source, the aim being to provide a realistic impression of a real acoustic space. Such is the power of these algorithms that the first 24 reflections can be controlled individually, various parameters enabling precise control of the sound character.

 Test Spec  
 
  • TC Electronic Reverb 6000 OS v3.2
 

With so many physical and DSP engine inputs and outputs, signal routing is inherently complex. However, one of the Icon control screens determines the signal routing structure through a simple graphical patchbay analogy. The 16 inputs and outputs can be hooked up as required to the inputs and outputs on each Engine without restriction — physical inputs can feed more than one Engine, and Engine outputs can be mixed together at the physical outputs. The four Engines can also be interconnected in series or parallel to create some very intricate signal-processing arrangements indeed.

Routing configurations can be saved and recalled easily, either as simple Routing presets or as part of complete reverb programs. While the latter would probably be the norm, the former is useful to accommodate different surround sound track allocations on the inputs and outputs, for example.

Editing effects settings using the Icon remote controller is as easy as touching the desired parameter and adjusting one of the touch-sensitive motorised faders.Editing effects settings using the Icon remote controller is as easy as touching the desired parameter and adjusting one of the touch-sensitive motorised faders.TC Electronic Reverb 6000In addition to the Routing presets, there are also Engine and Scene Presets. Engine presets are used to store the specific programs used in each Engine — VSS reverb, delay, chorus, and so forth. The Scene presets are complete system-wide presets which contain all the necessary Routing and Engine preset data needed to set the machine up as a whole. The internal preset memory in the M6000 is sufficient for the user to store up to 50 Scene, 50 Routing and 100 Engine user presets, in addition to the more than 600 pre-installed factory presets.

System Hardware

The Reverb 6000 hardware comprises three separate units: the M6000 mainframe, which houses the DSP and audio interfaces; the CPU6000, which provides the control processor; and the Icon user interface. The first two units are black, mains-powered rack units, occupying 2U and 1U respectively, and the latter powers the Icon directly. Alternatively, the M6000 can be controlled from a PC or Mac using dedicated software to replicate the Icon remote control functions, if required, although I think most users would prefer the immediacy of the Icon controller.

Hooking the Reverb 6000 system together is simple enough. Audio inputs and outputs (analogue, digital, or both) are connected to the M6000 mainframe, which would typically be installed in a machine room. The mainframe interfaces with the CPU6000 unit (which needs to be in the studio near the Icon) over a 100 Base-T Ethernet interface, and a special crossed Ethernet cable is used to link them together. The final system link is between the CPU6000 and the Icon control surface, which involves a 36-pin multicore cable of up to 7.5m in length. With the whole system hooked up, the M6000 and CPU6000 can be switched on and the system boots fairly quickly.

The front of the M6000 mainframe is equipped with a floppy disk drive (for software updates and preset archiving), and a PCMCIA slot for quick access to additional presets — a 1MB card will store up to 500 Scene, 500 Routing and 1000 Engine presets, all of which can be accessed directly from the appropriate library pages on the Icon controller. The rear panel of the mainframe carries MIDI connectors, the Ethernet port, an unbalanced quarter-inch SMPTE timecode input, a GPI trigger input, and a multi-pin socket used only for servicing. The timecode and GPI inputs can be used to activate program changes stored within an event list, providing a degree of automation, while up to six parameters per Engine can be assigned and controlled in real time over MIDI.

Rear panel of the M6000.Rear panel of the M6000.The rear panel also has four slots, three of which are available for optional interface cards. One slot carries a DSP6000 card, fitted as standard, which provides four AES-EBU interfaces (eight audio channels) plus an external word-clock input on a BNC socket. A breakout cable is supplied to convert from the card's D-Sub port to AES-EBU XLRs. Currently, the available option cards comprise a mastering-grade dual-channel A-D/D-A converter, and an eight-channel AES digital interface. To access all 16 physical inputs and outputs, an AES card must be installed, and the remaining two slots could be filled with a pair of analogue cards. In this case any combination of 16 inputs can be selected from the 20 physical ports available, and all outputs can be driven simultaneously (from the 16 output streams).

The analogue interface supports 24-bit/96kHz working, with user-configurable headroom up to +30dBu and a switchable soft-clip function, while peak output levels can be up to +24dBu. Interestingly, you can select the kind of anti-alias and reconstruction filtering used during conversion: Linear, Natural, and Vintage filter options all obey the Nyquist rules, but with different phase responses and tonality, while the Bright and Standard options deliberately permit some aliasing distortions. This novel facility is one which is apparently popular with mastering houses, and should be considered an important signal processing function in its own right.

The rear panel of the CPU6000 not only bears the Ethernet connection for the M6000 and the multi-pin D-Sub for the Icon, but also offers sockets for mouse, keyboard and VGA monitor. The USB connectors are as yet unused.The rear panel of the CPU6000 not only bears the Ethernet connection for the M6000 and the multi-pin D-Sub for the Icon, but also offers sockets for mouse, keyboard and VGA monitor. The USB connectors are as yet unused.The CPU6000 is essentially a rackmount PC. There is only a power switch on the front panel, but a lot of interfacing lurks on the rear. In addition to the Ethernet port and the multi-pin Icon connector already mentioned, there is also a PS2 socket for hooking in a keyboard and mouse, a standard VGA monitor port, and two USB sockets. The USB ports are not used at present, but the monitor socket allows a remote display of the Icon screen graphics at the same 640 x 480-pixel resolution.

The Icon control surface comprises a colour LCD touchscreen in an angled top section, with six motorised touch-sensitive faders in the bottom section. A threaded socket is provided for mounting the panel on a mic stand, and a desk bracket is also provided to increase stability when the Icon is used free-standing.

 The Reverb 6000 Algorithms 
 The list below gives an outline of the core Engine algorithms provided in the Reverb 6000:
  • VSS 5.1 Source: a 5.1 room simulator which generates an accurate array of early reflections for each output channel from up to four independent sound sources placed wherever desired in the virtual acoustic environment. Not only does this approach create more natural-sounding rooms, it also improves the imaging and localisation accuracy. The reverb tails are created by five separate uncorrelated reverb algorithms to ensure compatibility when down-mixing from a surround source.
  • VSS 5.1 Reverb: a similar algorithm which accepts a full 5.1-channel input instead of discrete sources and also enables sources to be panned around within the reverberant space using a remote joystick or by dragging a finger around on the TC Icon screen. A further level of sophistication is that the LFE channel is passed through unaffected, but in correct time-alignment with the other processed channels.
  • VSS SR: produces an 'encoded' reverberation optimised for use within matrix surround applications such as Dolby Pro Logic programmes. Separate parameters are provided for the front and rear sound field characteristics.
  • Spacepan 5.1: provides an eight-source surround panner, outputting to a 5.1 sound field. Both amplitude and time panning coefficients can be used independently or in concert. Once again, the Icon screen or an external remote joystick can be used to determine source positions.
  • VSS 4: a new stereo reverb created from accurate reflections derived from mono or stereo sources positioned within the virtual space. TC Electronic claim this to be the best stereo room simulator they have ever developed, but its DSP and memory requirements make it unsuited to other current TC Electronic hardware or software products.
  • VSS 3: the forerunner of the VSS 4 and VSS 5.1 algorithms. This is a mono-in, stereo-out program, generating accurate room reflections from the positioned source, with facilities to determine the nature of the surfaces, the room furnishings, and so forth. Mono compatibility is also preserved with this program.
  • Reverb 3: derived from the M5000 and provides a 'generic' stereo reverb program with a very dense but natural-sounding decay, the rate of which can be adjusted independently in four separate frequency bands.
  • Reverb 2: also borrowed from the M5000, and provided as a popular selection for percussion. It is also fully uncorrelated, making it a good choice where mono compatibility is important.
  • Phaser 1: another algorithm from the M5000, this time a simple but effective phaser.
  • Chorus 1: you've guessed it, a stereo chorus program, but one which can also produce flanging and chorus-delay effects.
  • Delay 1: a simple stereo delay.
  • Delay 2: a more sophisticated stereo delay program, with cross-channel feedback facilities.
  • Rev Core 2: an algorithm which produces accurate small-room simulations.
 

Using The Reverb 6000

A machine with the huge processing power of the Reverb 6000 is inevitably complex in its detailed operation, but TC Electronic have done an excellent job of making routine tasks surprisingly intuitive and logical. The large, clear screen graphics are easy to navigate and all the functions have obvious names, so finding your way around is very simple. Recalling and loading Scene memories is the easiest way to use the machine, each preset reconfiguring the entire system. Although the title of each preset is reasonably logical, initially I found it necessary to refer to the handbook to check what input configurations each option required, and the nature of the programs loaded into each Engine.

An alternative to using the Scene memories is to configure the machine in a manual way, setting the required Routing through the dedicated Routing page, and then loading required algorithms into each Engine. A selection of standard Routing presets are available, but the on-screen graphics make the whole process of creating a patch so easy that I preferred the hands-on approach!

The Engine presets are gathered into sensible groups and presented as simple lists under factory and user headings. If these are overwhelming (and there are an awful lot of them!) a Wizard option accesses facilities for filtered searches. Preferences can be selected for the required program, such as the type of input source, the style of reverb program, the size and nature of the room, and so on, and then a list of corresponding presets is displayed.

Once a suitable program is running on an Engine, its parameters can be adjusted. The key parameters are listed across the bottom of the screen, aligned to the six faders below. The selection of parameters allocated to the faders can be customised by the user and stored with the preset. At the same time, program parameters are displayed in pages of 16 values in the main part of the Icon's display screen.

By pressing the screen on a parameter box, its function is assigned directly to the right hand fader, so accessing parameters not already assigned to a fader is quick and easy. The key parameters already assigned to a fader — pre-delay time or overall decay time, for example — can be tweaked immediately by simply nudging the appropriate fader. If a different Engine is selected then the parameter displays, fader assignments and fader positions all change immediately to reflect their new roles. Input and output metering is always shown to the right of the program parameters, and a bypass button is always available on the left-hand side.

And that's pretty much all there is to it. Anyone with any experience of digital reverb machines will find their way around the Reverb 6000 in minutes — all thanks to the superbly designed graphical interface on the Icon controller. Even the initial configuration and housekeeping functions (which are inherently very complex) are trivially simple to navigate.

 Pricing & Options 
 
  • M6000 mainframe with editing software for Mac and PC and DSP6000 eight-channel AES-EBU digital interface, £5052.50.
  • M6000 mainframe, CPU6000, Icon controller, and DSP6000 eight-channel AES-EBU digital interface, £6403.75.
  • AES8 eight-channel AES-EBU digital interface option, £1323
  • ADA24/96 two-channel analogue interface option, £1010.50.
  • Bundle of three ADA24/96 two-channel analogue interface cards, £2021.
 

Premium Sound

In terms of sound quality, this is about as good as it gets. The analogue interfaces sound superb, and the filtering options allow subtle but significant tweaking to remove (or maintain) the digital sound character and replace it with a slightly more natural analogue quality, if required. I was surprised and impressed by how effective these options were.

The reverb programs are quite simply stunning. The overall quality is superb, with lovely dense tails and precisely controlled early reflections. The acid test of a good reverb is how it sits in a mix. Most reverbs sound fine in isolation, but some seem to clutter a mix while others just fill the empty spaces — not a scientific description, I know, but compare a cheap and an expensive reverb and you'll hear exactly what I mean! Needless to say, the Reverb 6000 always delivered the goods, adding subtle reverb which enhanced and never smothered the source instrumentation.

The program parameters associated with each program preset allow very precise shaping of the reverb, with simple rapid-access tweaking through the faders, and detailed polishing through the parameter menus. This user interface is without doubt the fastest and most intuitive for controlling digital reverbs I have ever come across, and going back to operating TC Electronic's M*One XL in my studio rack seemed like going back to the Stone Age by comparison!

Anyone familiar with the high-end TC processors will already know the impressive qualities of the newest VSS programs, but these multi-channel versions are mind-blowingly good. Being able to place individual mono sources within a defined acoustic space, each generating its own distinct reflection pattern, really does enhance the whole effect quite dramatically. I found the results comparable with coincident mic arrays and Soundfield mic recordings in reverberant acoustics, in terms of the imaging accuracy and realism. The individual sources really did sound as if they were positioned in a genuine space, and a very natural sense of position and depth was maintained over a wide listening area, in both stereo and surround monitoring arrangements.

Small room algorithms — often the area where lesser reverb units disappoint — were well up to the expected standard. The film and post-production presets were universally good, and only minor parameter tweaks were needed to fine-tune the artificial acoustics to almost any desired room character. These facilities alone should make the Reverb 6000 a must-have tool in any dubbing theatre.

I could find nothing to fault with this machine. It is stunningly simple to use, incredibly versatile, and sounds absolutely superb. It may seem expensive in the UK if you think of it as a simple reverb, but aside from the fact that the quality, capability and flexibility of the reverb algorithms goes way beyond almost any other digital reverb machine currently on the market, this can actually offer four top-quality stereo digital reverbs, and in that context it is a real bargain. Furthermore, the machine can be upgraded to include other processing software such as the specialist mastering tools, increasing its capabilities and usefulness even more. To say I was impressed is an understatement — reviewing a tool like this is what makes this job so enjoyable!

information
infop.gif See 'Pricing & Options' box.
infot.gif TC Electronic UK +44 (0)800 917 8926.
infoe.gif tcuk@tcelectronic.com
infow.gif www.tcelectronic.com
Published April 2003