TC Electronic Reverb 4000

Photos: Mark Ewing

Digital reverberation is a key component of almost every recording or post-production equipment list, and has been for at least twenty years. One of the leading manufacturers of sophisticated digital reverberation is the Danish company TC Electronic, and their flagship reverb processor — the multi­channel Reverb 6000 — has acquired a phenomenal reputation for the quality of its reverberation algorithms. However, the Reverb 6000 is an expensive processor by anyone's standards, and the demand for true multi-channel units is still far smaller than for stereo effects processors. TC Electronic have recognised this point and have consequently developed a stereo-only version of the Reverb 6000 with a single DSP Engine instead of the Reverb 6000's four. This new machine has been christened the Reverb 4000, and essentially represents the new stereo flagship.

The Reverb 4000 is less than half the cost of the Reverb 6000, and in terms of its market position it has been priced to sit alongside admirable outboard reverb units like Eventide's almost identically-priced Eclipse multi-effects processor, and the industry-standard (but slightly cheaper) Lexicon PCM91. So although the Reverb 4000 is a top-notch reverb processor, it is not beyond the financial means of a serious home studio setup. However, for those environments that can afford its UK asking price, the bigger Reverb 6000 represents better value for money, since it can be used as four stereo reverbs simultaneously — a point worth bearing in mind for anyone considering the purchase of multiple reverb units.

The Reverb 4000 essentially contains the most sophisticated and popular stereo reverb algorithms and presets found in the Reverb 6000. While many of these were previously unique to the Reverb 6000 (including some excellent emulations of several other manufacturers' classic reverb algorithms), many others have been borrowed from TC's earlier M5000 and M3000 processors. So we are talking about a collection of the best of the best reverb algorithms available here.

The unit is housed in a self-contained compact 1U rackmounting case, measuring only 190mm from front to back, and boasts a set of remarkably simple front-panel controls — a key element of the Reverb 4000 is the provision of instant, real-time control through three dedicated rotary controllers. In addition, the unit can be controlled via a USB interface from a computer running supplied TC Icon software.

The rear panel carries an IEC socket and mains power switch, and the machine accepts any mains voltage between 100V and 240V. The balanced analogue I/Os are handled by a quartet of XLR sockets connected to 24-bit/96kHz converters, with menu-adjustable input and output levels to conform with any common house standard. The digital I/O is provided by a pair of optical ports configurable for either ADAT or Toslink interfacing, a pair of RCA sockets for S/PDIF, and a pair of XLRs for AES-EBU. When inputting or outputting ADAT signals, the I/O menu allows selection of any of the four pairs of tracks. The familiar trio of MIDI sockets is also provided, along with a lone USB port for remote control from a computer.

The internal structure of the Reverb 4000 is simple enough. The input source can be selected from either or both of the selected inputs — balanced analogue or any of the four digital input formats — and the LED bar-graph metering on the front panel shows the input level. The reverb processor output is sent to the analogue and all digital output ports simultaneously, and a portion of the dry signal can be mixed with the reverb signal if required (the default is for no dry signal at all).

TC Icon Editor Although the advertising blurb suggests the supplied TC Icon editor software is compatible with both PCs (Windows 2000 and XP) and Macs, the version supplied on CD (v3.25) with the machine appears only to support PCs, as does the latest version available on the TC Electronic web site (v3.28) — this being the version I used for the review. Installing the software was a trivial process using the automatic Wizard program. The software discovered the Reverb 4000 as soon as I plugged it into the USB port and loaded the necessary driver without any problems. Two views available within the TC Icon software. Two views available within the TC Icon software. Two views available within the TC Icon software. Two views available within the TC Icon software. The TC Icon editor provides an attractive and configurable means of controlling up to eight compatible machines — currently the list includes the System 6000, Reverb 6000, Reverb 4000, and the DB8 and P2 dynamics processors. Accessing the various functions and menus is a case of pressing on the appropriate tabs, which are pretty logical and understandable for the most part, although familiarity is required to become a speed operator. The remote control is bidirectional, so that changes made on the Reverb 4000 are reflected immediately in the TC Icon software, and vice versa. Across the top of the TC Icon display are four tabs to control the housekeeping functions. The left-most tab features a picture of the currently active machine and enables access to the USB configuration and device selection pages. The remaining three buttons relate to the selected machine — loading and saving of presets (Library), the I/O and utility functions (System), and the actual effects parameters (Engine). Tabs down the left-hand side reflect the various submenus applicable to the current function — I/O, Levels, MIDI, Mapping and so on in the case of the System menus, for example. The normal remote control of a reverb processor requires the Engine screen, and in this operating mode the various sub-pages are accessed through tabs down the left-hand side. The names and functions of these tabs change with the different base algorithms, so in the case of a VSS4 preset, for example, the options are Main (principal early reflection and reverb parameters), Setup (room types and source positioning), Colour (reverb damping and crossover parameters), and Gloss (modulation features). By way of contrast, the Nonlin2 algorithm is provided only with two sub-pages: Main (envelope, reverb and Twist parameters) and Level (levels and filters). I found the continual changing of tab labels and functions confusing at first, but in practice few users will stray from the Main page, which generally carries the most critical parameters of each preset. And of those that do require more sophisticated control, the pragmatic approach of clicking on each menu page until the required parameter is found is probably the easiest technique! Whatever the selected menu page, each parameter is provided with a box detailing its name and value, along with a miniature slider showing the current value within its allotted range. The graphical interface can be configured in various ways, such as its colouring and the presence and configuration of on-screen faders. One mode dispenses with on-screen faders completely, while a second provides just one fader on the right-hand side — the currently selected parameter being controllable from that fader by clicking and dragging the mouse over it. The default mode is with a panel of six faders along the bottom of the interface. The sixth and right-most fader is the assignable one just described, while the other five carry the most important parameters — the three primary parameters shown on the machine's own home screen, plus two others. This arrangement makes it very fast to adjust the key parameters as well as to gain access to any one specific parameter. The Library search Wizard is essentially the same as that in the machine itself, except for the useful addition of a text string search, which is a great help if trying to find a preset by name rather than by family or size. The TC Icon software is a welcome addition to the Reverb 4000 and provides a useful alternative method of controlling it, particular for the 'super user' who requires easier access to a wide variety of parameters or visual confirmation of their settings.

The front panel has a typical TC Electronic look about it and, as usual, is dominated by a large backlit yellow LCD screen on the left of the panel. The main user controls comprise just four rotary encoders and a handful of buttons across the remaining panel area, with the three smaller encoder knobs providing direct, simultaneous, real-time adjustment of three reverb parameters. A simple menu system accesses a wealth of further parameters, and this approach is very simple and intuitive, extremely quick, and works remarkably well in practice.

Looking at the front panel in more detail, there is a power standby button on the left-hand side, with a PCMCIA memory card slot below which can be used both for backing up user presets and for loading future software updates. When in standby mode, the LED in the power button blinks once a second... not that I found that irritating at all!

The display window panel incorporates a stereo bar-graph input meter and eight mode indicator LEDs in a separate area to the left of the main LCD. The meters span a 40dB range, while the LEDs indicate sample rate, input mode, MIDI activity and whether the current settings have been edited. The Edited light also flashes while a new preset is being loaded, the process typically taking about five seconds.

The backlit display screen is clear and uncluttered, with five lines of information. The top line shows the current preset number; the category of the current algorithm — (Hall, Room, Plate, Effects, Wizard, User, and Card); and the current operating mode (Recall, Store and Wizard). The middle section of the screen displays the current preset name and, on the line below, its underlying algorithm type, while the bottom two lines show up to three parameters and their current values, which can be controlled by the three rotary encoder knobs. For most reverb programs the initial parameters are pre-delay time, overall decay time, and high-frequency decay time — in other words, the most critical parameters and those which need to be adjusted frequently.

To the immediate right of the display two buttons are provided to step up and down through the various parameter layers available within the current algorithm. The Hall reverbs incorporate twelve levels, and 35 separate parameters, so there is plenty of scope for twiddling here! The parameters are grouped logically into subsections such as reverb, early reflections, decay, crossover, modulation, space modulation, and levels. By pressing the Home button above the cursor keys, the menu returns directly to the top default level. Although the assignable encoder knobs are adjacent to the menu display, rather than directly below them — which is less than ideal in the ergonomic sense — translating the current three soft functions to the corresponding knobs isn't a problem in practice.

Next along are three Program buttons labelled Recall, Store and Wizard, and these determine the current operating mode of the machine. Recall is the default mode in which presets can be selected and loaded. The Store mode enables the current program to be stored as a user preset in one of 99 internal memories, or in a memory card if fitted. This mode also enables any existing user memories to be deleted, and the titles of presets to be amended as required. The Wizard mode will be familiar to users of other TC Electronic products, providing a search facility with which to locate suitable reverb presets.

The system filters possible presets based on Origin, Source and Size. The first selects the origin of the algorithm, the options being All, S6000 (ie. Reverb 6000), M5000, M3000 and Emulate (ie. emulations based on other manufacturer's processors). The Source filter is used to select the intended application, and the options here are All, Most Wanted, Vocal Lead, Vocal Back, Snare, Kick, Strings, Keys, Brass, and Generic. As you will probably have anticipated, the Size filter is used to select the most appropriate scale of reverb from All, Micro, Small, Medium, Large and X-Large. As the appropriate filter selections are made, the screen updates a tally of how many presets conform to the required list. Pressing the Wizard button again reverts to the Recall operating mode, and by selecting the Wizard category at the top of the display the subset of found presets can be accessed as required.

The next set of three buttons is labelled Control and these are used in conjunction with the fourth and largest encoder wheel to select and activate the required preset. Two buttons provide another up/down pair to scroll through the algorithm categories mentioned earlier. Within each selected category, the rotary encoder steps through the related presets in sequence, moving automatically on to the next category when the end of the current one has been reached. When a required preset has been located, the Enter button is pressed to load the preset, during which time the reverb output is muted until the new algorithm is functional (a pause of about five seconds). Although the operation of the Reverb 4000 is very simple once familiar, I must admit to initially becoming frustrated, as I often found myself pressing the Recall button instead of the Enter button when trying to load a selected preset. I suppose it's my own fault for not reading the manual first...

To the right of the large encoder wheel, three more buttons select the various housekeeping facilities. The bottom is a configurable Bypass button which can be used to mute either the input to the reverb processor or the output from it, as best suits the application. The top button accesses the I/O menu screen, which provides fifteen parameters arranged on eight levels. The list starts with the input selection (analogue or digital), and whether to use a stereo or mono input as the reverb source.

At this point I discovered what appears to be a minor software bug. Selecting the left input as a mono source initially seems to work as expected — the single input channel is routed to both inputs of the reverb processor and also to both main outputs if a portion of dry signal is mixed with the reverb output. However, if the reverb preset is subsequently changed, the mono source selection appears to revert to stereo, such that the dry signal now only appears on the left side. Reselecting the left input channel in the I/O menu immediately clears the problem. The same was true when selecting the right channel as a mono source. Anyone using the Reverb 4000 in a conventional effects loop with a mixing console won't be troubled by this bug, because there will be no need to dial in any dry signal with the reverb effect — which is probably why it has apparently escaped the notice of TC's technical boffins until now.

While I'm wearing my 'complaining hat', I have to say that the menu structure is a little odd in places too. For example, the Clock Select parameter provides the expected options of internal 44.1/48kHz (or 88.2/96kHz if double sample rate mode is selected) and Digital In, but also provides a Word Clock option even though there is no word clock input connector! Something carried over from when the Reverb 6000 operating system was ported to the Reverb 4000 hardware, perhaps. Again, a relatively trivial bug to fix, but it is surprising to find such simple errors in a flagship TC Electronic product. A menu structure issue which seems equally surprising is that, having selected Digital as the input source on level one of the I/O menu, choosing the specific digital input format from the four available requires descending ten further levels! Again, not a really major problem, but one that may cause a certain degree of frustration needlessly.

On a more positive note, the I/O menu does offer a lot of customisation and flexibility. Among the configuration facilities found in this menu, for example, is the ability to set the relationship between the internal digital peak level (0dBFS) and the peak analogue input level. This parameter spans +21dBu to -11dBu, enabling the Reverb 4000 to accommodate all common professional and semi-professional operating-level standards. Further parameters allow the actual analogue input and output levels to be adjusted relative to this nominal operating level to optimise the actual headroom margin — the available range is dependent on the previously determined peak analogue level setting, but can span up to ±20dB.

There is also a digital input level trim facility, which enables the input signal to be attenuated in 0.2dB steps to -24dB. The last two menu parameters set the output word length between 24, 20, 16, and eight bits, with or without dither; and determine the format of the status bits sent via the S/PDIF and AES-EBU outputs. The Utility menu comprises eleven levels, with eighteen separate parameters. Facilities here include adjustment of the LCD contrast/viewing angle, MIDI channel, SysEx ID, and MIDI Program/Control Change message receive options. There are also facilities to dump SysEx information to an external sequencer, to configure mapping of MIDI Program Change message numbers to preset numbers, and various memory-card management functions such as copying data between user and card memories and formatting memory cards.

The reverb algorithms are all derived from other TC products, mainly the Reverb 6000, so rather than cover old ground here, further detailed information can be found in my previous review back in SOS April 2003. The majority of presets in the Reverb 4000 are derived using the source-based VSS4 and VSS4 TS (True Stereo) algorithms first seen in the Reverb 6000. However, other programs provided include the VSS3, Ambiator, DVR2, Rev4, and Nonlin2 algorithms.

The VSS4 algorithm generates accurate early reflections based on complex ray-tracing of various generic room types. These include an oval room, cinema, church, theatre, living room, Vienna concert hall, garage, bathroom, hall, and jazz club. Furthermore, up to two input signals can be positioned independently within this modelled acoustic environment to generate credible true stereophonic early reflections and reverberation, the options varying with the selected environment, but typically spanning ±30 degrees with near and distant perspectives. TC Electronic claim this is the best stereo room simulator they have ever developed, but it is very heavy on DSP and memory resources, and so is only available in the new Reverb 4000 and its bigger Reverb 6000 sibling.

The VSS3 algorithm will be familiar to generations of TC Electronic reverb users, as a generic reverb program designed essentially to add a flattering sustain effect with minimal early reflections, and is therefore suitable for use on complete mixes where strong room-localisation effects are not required. DVR2 is another generic reverb, but one which has more of a vintage character. It was apparently developed specifically to replicate the EMT250 reverb processor, which it does extremely well.

Nonlin2 provides more vintage reverb effects — specifically all those ambience, reversed and gated reverb effects which became so popular in the 1980s. However, in this incarnation the program also adds a new twist with a parameter called, er... Twist! The function extends the versatility of the algorithm considerably, enabling all sorts of innovative reverb sounds to be created. Twist appears to control the nature of feedback within the reverb algorithm, such that the processed sound becomes coloured in various weird, comb-filtered ways. There is a Ratio parameter to determine the amount of the effect, and a Type control to select the form, with options such as Aircon, Chicken, Guts, Hotair, Kazzoo, Moony, Muffled, and many more.

The Ambiator algorithm is designed to replicate the acoustics of natural environments. The user is presented with options to select the room size, type and surface material, plus a nominal position within that room. It is therefore a useful tool for helping to add a credible acoustic environment on individual close-miked sources. Finally, the Rev4 algorithm is a development of the Rev3 program found in the M5000, providing a relatively simple but dense generic reverb best suited to spring and plate simulations.

The word which immediately springs to mind after using the Reverb 4000 for a short time is 'fabulous'! Apart from a couple of very minor software gremlins mentioned earlier, this machine is about as good as it gets when it comes to generating workable stereo reverbs — and at a surprisingly attractive UK price given the quality of the algorithms presented here. Whether you want believable rooms, generic reverb washes, or identifiable reverb effects, this machine does it all with immense clarity and superb resolution.

The user interface is sublime, and enables both superficial tweaking of the key parameters and detailed editing of in-depth parameters with equal aplomb and ease of access. Inveterate programmers can access and fiddle with all the reverb algorithm parameters they desire, while those more interested in obtaining an effect that works quickly and without fuss will also find this a great machine to use. The display is clear and informative, and the control-panel facilities nicely laid out and intuitive to use. The audio interconnectivity is also very comprehensive and flexible, and it can be switched to operate at elevated sample rates with no apparent penalty in terms of reverb algorithm options, maximum decay times or pre-delays. In other words, this machine does exactly what you expect of it in all operating modes.

I was bowled over with the Reverb 6000, and to find that machine's fantastic characteristics in this new Reverb 4000 — at least as far as the stereo environment is concerned — is a real pleasure. In terms of the sonic quality of the VSS4 reverbs, the user interface, and the connectivity, the Reverb 4000 really must be considered the new class leader in stereo reverb processors, taking the trophy which has long been held in America.