The Yamaha DMP7 digital mixer was quite a revolutionary product when it was unveiled some two years ago, and Yamaha have no doubt received a great deal of feedback from users and potential users since its introduction. One of the most frequently criticised aspects of the DMPs has been the awkward approach to equalisation. In response to criticisms and suggestions from engineers, Yamaha have developed the RTC1, which provides remote control of up to four DMP7s, DMP7Ds and/or DMP11s from one dedicated piece of hardware. As well as allowing centralised operation of several Yamaha digital mixers, it also offers improved access to certain functions (such as EQ) and creates a few facilities that are not available on the mixers themselves. Before looking at the RTC1 in any detail, a quick recap on what Yamaha's DMPs are all about would seem to be in order.

DMP MIXER OVERVIEW

The initials 'DMP' stand for Digital Mixing Processor, so obviously these units are mixing and processing audio in the digital domain. Each model in the current DMP range is an 8 into 2 digital line-level mixer. (If microphone inputs are to be used, an optional mic amplifier unit is required.) The A/D and D/A convertors are all 16-bit linear operating at 44.1 kHz, while internal processing is 24-bit.

One of the most innovative features of the DMP range is the inclusion of built-in, SPX90 style multi-effect processors. Another unique (at least in this price range) aspect of these mixers is the ability to store every setting on the console into memory for subsequent recall. For one type of automated mixing or for use in live performances, over 90 different setups ('scenes') can be stored and recalled at the appropriate time.

As useful as this capability may be, if you connect the DMPs to a MIDI sequencer things start to get really interesting. Every function and parameter change can be recorded, edited, and replayed in sync with tape by any competent MIDI sequencer. In order to further expand the scope of the mixers, a 'digital cascade' feature allows several DMPs to be connected, one after the other, to create 16, 24, 32 or more inputs while still keeping the audio in the digital domain right up to the stereo outputs (which could also be digital in the case of the DMP7D).

Although the DMPs are not ideally suited for track-laying in a conventional multitrack recording studio, their powerful automation capabilities would seem to make them an obvious choice for MIDI programming suites and for certain applications in concert, theatre, and television sound. But with all the amazing facilities available, there are necessarily some limitations inherent in the system, and recording engineers must abandon many of their traditional methods of console operation.

In order to create such a versatile and fully automated mixing processor, Yamaha has employed an assignable approach for many of the DMP's functions. For example, to adjust an EQ parameter the procedure is as follows: 1) the appropriate channel button must be selected; 2) the desired frequency band button is pressed; 3) EQ is switched on; 4) a cursor is moved around an LCD to locate the right parameter; 5) a pair of buttons or the data entry slider is used to adjust the value.

In reality; with a little practice, this procedure can be carried out rather quickly and many engineers are quite happy to work this way (especially in light of the many advantages offered by the DMPs). But for some people, the equalisation process just does not feel right if they are not able to use traditional rotary knobs. With the exception of the input trim controls on the back panel, the provision of rotary knobs is conspicuously limited on Yamaha's digital mixers. In other words, there aren't any! Having said that, now may be the ideal time to look at the RTC1, because one thing it definitely includes are rotary controls.

THE RETURN OF ROTARY CONTROL

The RTC1 is a solidly built, typically black piece of hardware designed to provide remote control of up to four DMP mixers, while also offering a more conventional approach to functions like equalisation and panning. It includes a few useful features, such as fader grouping and adjustment of several effects parameters simultaneously, that overcome some of the DMP's limitations. It can also function as a general purpose MIDI control change transmission device, which could expand its applications to use with MIDI equipment other than the digital mixing processors.

The RTC1 is designed to be mounted on a table top or similar surface and every control necessary to operate the unit is sensibly laid out across the top panel. It is connected to the DMPs from the rear panel, which contains one MIDI Out and four MIDI In sockets. The MIDI Out can address up to four DMPs, either in series (using MIDI Thru) or in parallel via a MIDI patchbay. The four MIDI Ins are necessary to allow two-way communication between the RTC1 and the mixers, and each DMP is assigned its own MIDI channel, of course.

The top control panel is divided into five blocks, associated with different aspects of the RTC1's operation. At the top is a 16-character by 4-line backlit LCD (twice the size of a DMP display), which does a reasonable job of conveying information about four DMPs at the same time. Next to this are a couple more LCDs providing details about channel and program selection as well as the currently selected control assignment set (more about this later). Below these LCDs are the channel and bank select buttons, which allow any one of the possible 32 different channels to be assigned for control by the RTC1.

The equaliser/pan block is centrally located on the RTC1 and is an area that seems to be mainly devoted to allowing more conventional and immediate access to commonly used mixing console functions. As opposed to the DMP's multiple button-pressing procedure, the RTC1 provides individual rotary knobs and switches to control every parameter available in the very versatile digital EQ system. Provided the EQ for the currently selected channel is switched on, the main LCD will automatically display all the EQ parameter values as soon as any EQ control is operated. Obviously equalisation is always performed by ear, but it is often very useful to be able to see just what adjustments have been made in each frequency band, and the visual display here is excellent. This block also includes a rotary knob for panning the selected channel, and a phase reverse button.

Although one of the most seductive features on the DMP7 is the motorised faders, none of the controls on the RTC1 physically move without human assistance. As a result of this, every rotary knob and fader on the RTC1 is associated with its own null indicator. Whenever a new channel is selected for adjustment, the position of most of the controls will not match the actual parameter values. The null indicators show the engineer (by displaying arrow-shaped LEDs) in which direction the rotary knobs and faders must be moved in order to match the memorised data. Parameter values can only be altered after the null position has been matched. In practice, this system works reasonably well, although it is easy to overshoot the null point unless the control is moved slowly. This is one area where the visual display of the EQ values is quite useful, as it gives the engineer a clear indication of just where the rotary knob should be positioned.

Located below the EQ/pan section is the input block. In this area we find one of only two faders on the RTC1. This fader will control either the channel level or the effects send level from the selected channel to any of the three DMP effects programs in use. This brings up one of the apparent limitations of the RTC1 when used in place of hands-on control of the DMP7s, for instance. Whereas the DMP7s require an assignable approach for most parameter controls, they do at least provide an individual fader for every channel. The single channel fader on the RTC1 could be a real disadvantage, particularly in a live mixing situation. Yamaha have included a couple of features (soon to be explained) in an attempt to overcome this potential shortcoming, but they are no real substitute for immediate access to a complete set of channel faders.

One of the very useful features on the RTC1 is the solo mode, also found in the input block. Normally, when operating more than one DMP unit using digital cascade, a solo on one DMP will have no effect on the signals passing through the other mixers. However, a solo implemented on the RTC1 will mute all other signals.

The RTC1's other fader resides in the master block and controls the main stereo level as well as the effects return levels from each DMP. When assigned as the stereo master, the fader always controls the level of the last DMP in the chain. The stereo level of the other DMPs can be controlled elsewhere, if necessary.

FADER GROUPS

The last block - the program change and control section - is where most of the RTC1's unique features are to be found. Four more rotary 'control' knobs are located in this section, and these can be assigned to several different functions which can expand upon the capabilities of the DMP mixers. As mentioned earlier the RTC1 can create fader groups, allowing simultaneous control of up to eight channel or effect send levels. Once a fader group has been created, its level can be altered by one of the control knobs. One essential limitation of this feature is that the group level can actually only be lowered. This would appear to be the result of a fundamental design restriction, but with adequate pre-planning (in other words, setting each channel artificially high before the group is formed) it can still be a useful facility. Four separate fader groups can be assigned to the different control knobs, although only one can be active at a time.

A crossfade function is also available in this block, again utilising the control knobs. Several channels can be faded up while several others are faded down, although no channel can actually be faded to higher than its original level. Also, it is important to keep in mind that a channel cannot be assigned to a fader group and a crossfade group at the same time.

One very interesting application of the control knobs is in what Yamaha call, appropriately enough, control mode. In this mode, the knobs can be used to alter effects parameters, as well as for general MIDI control change transmission. Unlike when being used as group faders, in this mode all four knobs can be utilised simultaneously. This means, for example, that reverb time on one effect can be increased while initial delay is decreased and, perhaps, feedback gain on another effect is altered at the same time (provided the engineer has three hands!). Of course, when using the DMPs in conjunction with a sequencer, effects like this can easily be created through overdubbing. But this feature could be very handy for live mixing applications, and 50 different control assignment sets can be created and called up when needed. By the way, a numeric keypad would have been a helpful inclusion on the RTC1 for recalling control sets and program changes, as well as for entering digital delay times.

While still on the subject of effects parameters, quite a nice touch on the RTC1 is a button simply called 'Help'. In order to squeeze as much information onto the LCD as possible, some mysteriously short abbreviations are employed (would you have guessed that 'MY' represented 'modulation delay'?). Pressing the Help button while the cursor is on an unintelligible abbreviation solves the mystery. Another thoughtful inclusion is the Fader Status button, which produces a display of all 32 fader levels potentially under the RTC1's control. Some way of numbering the channels in the display would have been helpful here, but this would probably have required a larger LCD.

Also within this final block is a button labelled 'Request', which initiates a bulk dump from each connected DMP unit. This is necessary when a fader or parameter setting has been altered on a DMP itself. In this case, RTC1 data would not match that of the DMP unit on which the changes were made. Unfortunately, whenever the Request function is used, all fader group and crossfade group data is erased. This was not just a fault in the review unit; it is clearly stated in the manual that this will happen. This is a real limitation against using both the RTC1 and the DMP control panels together. However, if each unit is used exclusively for what it does best (ie. the DMPs for adjusting fader levels and the RTC1 for EQ, fader grouping, effects parameter changes, etc), then the units can complement each other quite well and the Request function is not needed.

The Program Change mode, of course, causes programs to be changed simultaneously on each DMP (very useful for 'scene' change automation, particularly in live mixing situations). The Name function allows fader groups, crossfade groups, and programs to be named using the same sort of parameter key approach found on the DMPs, REV 5 etc.

Lastly, we find the Utility mode, which accesses eight additional functions in the following sequence: parameter range selection, compression on/off, effect send pre/post, stereo input enable, dynamic filter enable, fade time, MIDI channel, and battery check. Most of these will be self-explanatory to anyone familiar with a DMP mixer (dynamic filter applies to DMP11s only). Parameter range selection allows currently assigned effect parameters to be adjusted with either coarse or fine control.

Stereo input enable provides for control of a stereo input signal by the one channel fader on the RTC1, as well as applying the same EQ settings and effects sends to both channels in the pair. If independent EQ's are set up and then a stereo pair is created, the EQ's will revert to the initialised state. A fader group would need to be used in order to have separate EQ but combined level control.

RTC1 SUMMARY

To summarise, I think the RTC1 definitely has some very worthwhile features to offer and very little in the way of shortcomings.

Strengths:
- More conventional and immediate access to equalisation and panning.

- Fader grouping and crossfade groups (although a bit of advance planning is necessary to get the most out of these features).

- Convenient access to four effects parameters simultaneously.

Weaknesses:
- Only one channel fader actually available at any given time (fader grouping overcomes this limitation to some extent).

- Erasing of fader groups and crossfade groups whenever the Dump Request function is implemented.

Personally, I found the RTC1 most useful alongside the DMPs, using each control panel for what it does best. The RTC1 offers improved control over many of the mixing functions, but I would prefer to have the DMP mixers themselves within reach for more immediate access to channel and effect send faders.

CONCLUSION

The RTC1 basically delivers what it promises, and whether or not that is enough to justify the cost is, of course, up to the potential buyer to decide. I think the RTC1 will have its greatest appeal to engineers who love the fully automated capabilities of the DMPs but cannot stand the multiple button pressing/data entry slider approach to equalisation. If that sort of approach to EQ does not bother you, then the RTC1 is not likely to be of great interest. I am inclined to feel that most DMP owners will be able to think of more exciting ways to spend £629. However, the availability of the RTC1 may attract more engineers to the Yamaha system of digital mixing, and it is always encouraging to see a major manufacturer responding to feedback from the people who actually operate the equipment.

FURTHER INFORMATION

£629 Inc VAT.

Yamaha-Kemble (UK) Ltd, (Contact Details).