After producing a drum and bassline from an original drum pattern last month, Roger 'James' Brown continues to dissect the analogue sequencing mimicry of Cubase's Interactive Phrase Synthesiser. This month, he puts poor old Pachelbel's Canon to 'the acid test'.

In last month's introduction to the Interactive Phrase Synthesiser, we kept things uncomplicated and simply used the IPS to revoice our drum pattern by pitch-shifting and Mute Play, and generated a one-note bassline by using the Repeat function to carry the rhythm of our drum pattern over to the bass. Repeat generates a repeating note, which is the original input note laid over the rhythm of our original phrase. All very well for minimalist basslines, but what do we do if we want to produce a melodic bassline from our source material?

To produce other melodic material from an original pattern, it is necessary to turn to the central set of filters on the IPS page, and do some manipulation from there. We have already looked at simple transposition using the Pitch Filter, but the other two filters can be even more useful in transforming source material. This month, instead of spinning out our drum pattern even more, we'll take a look at producing a new, melodic pattern by taking a slow chord sequence and chopping up the rhythm into something more riff-like.

If you look at figure 1 you'll see that the IPS is set up, as in last month's example, to simply retrigger a chord pattern according to the key we input from the keyboard. Let's just record that as it is, by setting the Output to MROS and record into a track on the Arrange page. Now we'll move to IPS A, and take the same chord sequence and see if we can't make something a little more funky out of it.

The chord sequence is a familiar one, my pastiche of Pachelbel's Canon in C Major. We used the Logical Editor on this to produce a MIDI volume gate in part 3 of this series, and the result was a little more rhythmic than the original two bar chords. Let's see if we can't get something even more riff-like, with the assistance of the IPS.

As a first step, I've set the Pitch Filter to transpose our phrase up an octave, so we can hear our phase over the original, as shown in figure 2. The next step is to introduce some rhythmic variation into the phrasing. We can do this initially, by using one of the Rhythm filter's LFO's to 'play' the phrase, and introduce some variation as the IPS replays the phrase, according to the 'pulse' of its virtual LFO. This introduces a slight variation to the original phrase, but not enough to qualify as a bass or lead line. To do that, we need to break up our pattern into shorter notes.

If you look to the right of the Rhythm filter, you will see we have a few ways of doing this. The frequency filter will increase or decrease the occurrence of the phrase, on a percentage basis from 1-200%. As a setting of 200% here will effectively double the incidence of the notes, producing a jumping bassline, we'll ignore that and the Amplitude filter, which really only determines the attack level.

Let's turn instead to the two settings which directly affect the length of the notes, and their quantisation. Setting the length of the notes to 16T (sixteenth triplets), as in figure 4, turns out short notes, but the original phrase is still based around two-bar quantisation, which is not quite the effect we're after. The Q filter is the one to set to produce a faster or slower rhythm. If we set this to eight, for instance, the musical phrase will be quantised to eight measures, producing a slow, walking bassline effect. Moving the quantisation up to sixteenths (see figure 5) results in a faster, more rhythmic phrasing, and provides us with an ideal pattern for sending out to those acid patches.

We can vary the order of the notes, to give a more random factor to the acidic leadline we've now produced with the LFO in the Pitch filter. In the pitch filter, the LFO simply takes the notes fed to it by the Interpreter list, while the LFO rate (between 0.1 and 30 repetitions per second) controls the speed and order of replay. This is an effect which is open to experimentation, and you can even alter the LFOs in real time whilst recording, which is ideal for turning out evolving leadlines.

If you are too much of a slacker to do that, you can set the IPS to do that for you as well. Go to one of the two Modulation filters at the bottom of the page, and set the filter to control either Pitch:LFO, as shown in figure 5, or Pitch:LFO Frequency. Choosing an LFO for the Modulation Filter will then activate this, and you can watch as the LFOs or the LFO Frequency in the Pitch filter change and affect the notes being played.

That's all for this month folks! Have fun experimenting with the various filters within the IPS, and see if you can come up with some stormin' acid basslines. I have actually chosen to play this pattern on an electric guitar patch, for a bit of rockist riffing as the original chord pattern is still intact. It's just reduced to a bunch of sixteenth notes, but this is ideal for either acid 303 or guitar riffing, lending credence to the view that the 303 is the electric guitar of the '90's.

Roger 'James' Brown gets down, trying to put some gunpowder into Pachelbel's Canon.