Roland's SBX-80 Sync Box and SRV-2000 Digital Reverb jump into action to contribute their part in "Creative mixing with MIDI controlled effects".

In the first part of this series we looked at the introduction of a simple automation facility which enabled a tape recorder, via a MIDI sequencer, to select different effects programs during a multitrack mixdown. This month we look at automation on a higher level, where the use of a realtime control system in the form of the Roland SBX-80 Sync Box allows more precise control of effects at the mixdown stage.

Within the article we'll talk exclusively about the control of the Roland SRV-2000 digital reverb as this is an ideal effect which is not only suitable from the MIDI control point of view, but also because it's a very popular reverb and sounds excellent too.

If you read last month's article you'll be aware that we spoke about a fairly simplistic approach to controlling a MIDI effects device and how that can be achieved with a basic equipment set-up of MIDI sequencer and drum machine. This approach represents what could be seen as the second of three levels of possible operation, the third being the one we shall discuss here.

Not mentioned so far is level one, the manual level, where you are mixing down a multitrack tape to master, adjusting reverb or echo effect settings by hand as and when they arise within the mix. This is clearly not a satisfactory approach as your mind is split between the task of listening creatively to what you are supposed to be mixing, and the mechanics of actually controlling the mixing desk and effects by hand. Screams of 'Damn it - I missed that echo change on the solo again' often being heard...

Effect automation allows you greater involvement in the production at the time when it's most necessary - the mixdown. So, the whole approach to the mix can be divided into two distinct parts: the programming of the effects prior to the mix and the listening to the music during the mix.

Take away the need to be constantly aware of where you are in a mix when the next change of effect comes up, and you can start to think more about how it's all sounding.

One of the problems encountered in last month's article was that when using a drum machine that generates and reads a sync pulse code, every time you stop the tape you have to return to the beginning of the track and reset the drum machine and sequencer before playing the tape again. If the part you're interested in lies near the end, you have to sit and wait for the tape to get to that point.

The act of moving up and down the length of a song recorded on tape and yet still have all the equipment which is being driven off a code remain absolutely in sync has, in the last couple of years, become a reality.

The launch of the Roland SBX-80 Sync Box heralded the first of a new generation of tape-to-musical instrument real-time controllers. Why real-time? Because it brought together the professional standard time-keeping technology of the television industry, SMPTE timecode, and the internationally agreed MIDI system. The result was a box that performs two roles.

Firstly, it acts as a master clock and can output timing information as MIDI, Roland DIN Sync or variable Pulses Per Quarter Note to synchronise various types of equipment. That's often a single piece of equipment in itself!

Secondly, the incorporation of SMPTE means that you can record timecode onto tape and then run the whole show in sync, off tape, with the SBX-80 acting as the master clock rather than the more usual way that deems the drum machine to be the master. Now, because SMPTE is a real-time code ie. hours, minutes etc, you can move the tape forwards or backwards and the SBX-80 will always know where it is. The benefits of this will become apparent later.

Technically, the inability of a sync pulse code to tell you where it is on tape means you're always going to be involved in the tedious and time wasting operations of resetting equipment.

One of the most important and useful aspects of MIDI is that of Song Position Pointers (MIDI jargon that tells you which bar is playing). Now, because the SBX-80 can read code off tape as real time and this can be related to tempo, ie. beats per minute, knowing the beat means you can display the bar number - and hey-presto, you've a means of knowing where you are in the song!

As the SBX-80 converts timecode into MIDI timing information, any sequencer or drum machine can be automatically set to the current bar number as the SBX-80 will convert the real-time code into a bar number. Since rewinding or forwarding the tape will always display a unique time, the unit will always transmit the right song position pointer... Wait until you find out what that means!

CODE OF PRACTICE

Before proceeding any further, a practical word or two about SMPTE code is in order. Many of you may well be familiar with the notion of timecode through your own experience or reading about it.

The SBX-80 generates it's own SMPTE timecode and it's this that you record onto the edge (last) track of your tape. When working with SMPTE the usual procedure is to 'stripe the tape' first of all. This term refers to recording the timecode onto the edge track.

Two points here: firstly it's always good practice to stripe the whole tape on one run - through and secondly, you should never edit tape with timecode recorded on it.

Before moving on to discussing the practical applications of the SBX-80, let's take a look at the reverb unit we're controlling.

THE SRV-2000

When Roland introduced their digital reverb they not only offered excellent reverb treatments but they also made it MIDI controllable. As well as the ability to remotely select any one of the 32 program memories via MIDI patch changes, the SRV-2000 also allows MIDI control of almost all of its parameters eg. pre-delay, reverb time, HF damping and also the three band parametric equaliser. These latter parameters are not directly controllable via an external keyboard, and will require a microcomputer MIDI software package to control them. At present, such a program does not, to our knowledge, exist. Food for thought there - software writers take note.

Within the SRV-2000 are 16 factory preset reverb programs, so for those of you who have an SRV we'll use three of these reverb settings as a point of reference. And for those who don't have an SRV, let's briefly describe each one so you can imagine the different effect they'll have on a sound.

The beauty of this particular Roland unit is that the reverb parameter display is very detailed and allows you to see clearly and quickly the current status of any factor which contributes to the reverb eg. the predelay time in milliseconds, the room or hall size in cubic metres etc.

The three programs used in this article are: number four - Medium Room which has a pre-delay of 19ms and a reverb decay time of 1.7 sec in a 22m³ room; number eight - Small Room with a pre-delay of 7ms, a decay time of 1.3 sec in a 7m³ room. And finally, number sixteen - Non Linear Inverse with a pre-delay of 10ms, a reverb time of minus 0.9 sec (which means that it gets louder), and a 223ms gate time, which tells you the duration of the sound before it's cut off.

LINKING UP

As MIDI increases its presence amongst equipment of all types, both synthesizers and effects, so the need for some sort of MIDI routing box is rapidly becoming a daily necessity rather than a luxury. It avoids continually re-plugging the system which, with the complexity of some configurations, can become very time-consuming, so they're certainly worth a thought.

PROGRAM CHANGE

Let's consider the programming of the sequencer with the correct reverb program numbers.

As you can see in the diagram, both the output from the keyboard and the SBX-80 want to control the sequencer via MIDI In, though obviously not both at the same time. When you intend to use the keyboard it must be connected to MIDI In ready to send program change data to the sequencer. For the sequencer's part, the correct tempo, bar length and internal clock should be selected.

Having patched all the equipment together as shown, and programmed each of the reverb characteristics into the SRV-2000 memories, you can start to programme the sequencer with the actual changes. It must be pointed out that what you are doing is programming the points at which the reverb effect will change. This presumes, therefore, that you have already recorded the majority of the music as you do of course need something to play through the reverb unit if you're considering where to use different types of effect.

By selecting the drum pattern already used when recording the music, you can control its tempo from the sequencer. Therefore the approach to programming reverb changes on the drum track, say, would be as follows.

Start the sequencer off with the first reverb program selected. As you approach a section where a program change is required, ie. a gated reverb (SRV preset 16, Non Linear Inverse) for the middle eight, you can do one of two things: if you're working in real-time sequence mode you have to listen and hit the desired program button on the synthesizer at the precise point, but working in step-time you can slow down the tempo of the sequencer and listen through as each drum beat passes slowly and then hit the button precisely on time.

To get the reverb effect to start on the right beat, it's necessary to change the reverb program one beat before, so that any muting of the reverb's output as it changes memory program, takes place between beats. You have to experiment in this area as tempo has a bearing on its success. As you move through the song you can programme in the reverb changes as you want them to occur during the final mix. You may decide, for example, that all the verses use SRV-2000 preset 4 (Medium Hall), the chorus could use preset 8 (Small Room) and a middle eight something different like preset 16 for a gated reverb effect.

Once programmed, you can then reset the sequencer to the start, switch over to external clock control and connect the SBX-80 into the sequencer's MIDI In. You should have already striped a tape with SMPTE timecode prior to recording the music, as described earlier, so that all you have to do is switch the SBX-80 to read timecode off tape and set the tempo to be the same as that used for the sequencer.

At this point you should have the SRV-2000 reverb patched into the auxiliary send and returns of your mixer and so by playing the tape the timecode will now drive the sequencer and hence switch the program changes on the SRV, all perfectly in time. You can run through the whole tape from start to finish or you can play a section over and over again with all the program changes resetting themselves to the current tape location courtesy of the MIDI song position pointers mentioned earlier. It's only fair to point out though that the SBX-80 can only store one cue point and in this respect it shouldn't be viewed as an autolocator because it isn't intended to be.

However, the ability to move anywhere along the tape and almost instantly have all the right effects selected automatically is indeed a very powerful mixing aid in its own right. It's pretty exciting to listen to as well!

EXPANDING IDEAS

As the creative use of a MIDI controllable effect such as the SRV-2000 reverb offers immense scope, you could be forgiven for thinking that you only ever need the one device as you can change its settings so quickly during a mix. But this is not true, for you may well require the reverb on a sound to remain constant throughout the mix. Here again, the application of MIDI controlled effects wins the day, as you could quite easily add further units to the mix, the limitations being those imposed by the number of auxiliary sends available on your mixer and the amount of sequencer tracks.

The Roland MSQ-700, for example, is an eight-track unit which should cope with most needs unless you're into driving every conceivable synth and drum machine combination plus all the effects simultaneously from the sequencer.

Ultimately, of course, even MIDI is limited to driving sixteen different effects devices, each one programmed to be on a different MIDI channel. Or is it? Access Page M next month and find out.

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