Boss have excelled themselves by producing what is probably the cheapest pitch tracking sampler currently available with automatic sound triggered loading — the RSD-10

It seems that the Boss Micro Rack system is growing weekly and if they carry on at this rate, there will soon be a Boss ladder on sale to enable you to reach the controls of the top unit.

The RSD-10 is the same physical size as the other Micro Rack modules in that it is 1U deep but only around half the width of the more familiar 19" rack effects units. It derives its power from an external Boss 9v power supply and one such supply can run several modules, a daisy chain linking system being built in to facilitate this.

The circuitry is based around a digital delay which offers up to two seconds of delay with a 7kHz frequency response. Whilst this is not going to sound as bright as a more sophisticated DDL, it does sound much better than any analogue delay in the semi-pro price range and it gives around six times the delay time. Delay mode is quite straightforward, so I'll deal with that first.

Digital Delay

The delay time is set using the first five-positions of the Range/Mode switch and, by using the adjacent Fine control, it is possible to set the delay anywhere between 2mS and 2 seconds. Feedback is provided for creating repeat echoes and this also works in the sampler mode to control the overdub level, but more of that later. The Effect Level control acts as a balance between the input signal and the delayed output and there's an Effect On/Off switch located to the extreme left of the panel with a square red status LED just above it.

The Trim control has no relevance in the delay mode but one omission that you might have noticed is the lack of an input level control. Because this is supposed to be used as part of a system, it's expected that you will have some means of controlling the line level into the machine, but you can manage without at a pinch. This is because there's a dual position sensitivity switch on the rear panel offering the choice of -20dB into 1 MΩ or -10dBm into 47kΩ matching. The high impedance on the most sensitive setting gives the user the capability to plug a guitar or bass directly into the unit and I also used a high impedance mic without any problem. The input level can than be controlled by the instrument volume control or by altering the mic position. A red overload LED flashes to warn you when the input signal is too high and in practice I got the best results when this came on dimly on peaks.

By way of connections for this section, there's a choice of jack or phono connectors for both input and output and these are to be found on the rear panel as is a jack for a remote bypass switch.

Sampling

This sampler operates in a slightly unconventional way in that it does not require a CV input but actually tracks the pitch of the controlling keyboard's audio output. The keyboard gate output is then connected to the sampler's Trig In and that's all there is to it. However, the circuitry does require a clean waveform to work on so it is best to set up your synth to give a square wave output with a fast attack and a couple of seconds of release time. The low pass filter should be set to the highest cut-off frequency and no resonance should be applied.

There are two ways of loading a sound and these are selected using the Mode switch in its A or B positions. Switching from B to A arms the unit. In this mode, a signal at the input starts the record process whereupon the Rec LED flashes until the sample has been taken. The sampling duration depends on what note was last played on the keyboard as does the replay pitch so it makes sense to select a note on the keyboard that corresponds to the pitch of the sound you are about to sample. Of course if it's a percussive sound, then this doesn't matter.

Mode B works in much the same way but here the sampling process is initiated by pressing a key on the synth.

"Whilst this is not going to sound as bright as a more sophisticated DDL, it does sound much better than any analogue delay in the semi-pro price range and it gives around six times the delay time."

As any sampled data is lost when the unit is switched off, Boss have fitted an extra socket labelled Tape on the rear panel so that you can in effect record your sounds onto tape and resample them later. Using a stereo recorder, you can also record the keyboard pitch at which the note was sampled and you can use this to re-record the sample at the correct pitch.

Once you've sampled a sound that you're happy with, pressing a key on the synth will cause it to replay all the way through unless another keystroke is initiated before the sound ends in which case it will start again from the beginning. If your sampled sound is too long for your liking, you can use the Trim control to shorten it and this has the effect of rapidly fading the sound rather than just cutting it off so there is no click at the end of the note. There is however no facility for trimming the beginning of the sample, but at this price that comes as no surprise.

Should you want to layer a sound, (for example to produce a choral effect using several vocal parts) simply advance the Feedback control to around the nine o'clock position and record your second part. If you want more parts, repeat this procedure. The setting of the Feedback control for best results does require a bit of experimentation.

In Use

Although this unit has no inbuilt modulation facilities for producing chorus or flanger effects, it's very simple to use. You can produce delay, repeat echo and ADT treatments quite easily and the sound quality is very good, though a little lacking in brightness due to the limited bandwidth.

As a sampler things are also pretty straightforward, but you have to be careful in the sound triggered mode that you don't accidentally trigger the thing before you're ready; a bit of practice is all it takes.

When used as a sampler, the note length will vary depending on the pitch at which it is replayed, because this sampler changes the pitch of a stored sound by speeding it up or slowing it down. The maximum length of sample occurs at the middle of the pitch range and is two seconds. Although the manual claims that the machine tracks over only two octaves, (C5 to C7) I found it to be usable over a range of almost four. You may have to switch octaves on your synth until you find the sampler's operating range, but that takes no more than a few moments.

One advantage of the pitch tracking system is that it will work on synths that don't conform to the one volt per octave standard and you can even use a digital polysynth provided that it has a gate or trigger output and that you play it monophonically (preferably in mono mode). This means that you can at last find a use for those old Yamaha and Korg synths with linear oscillators but, if it's a Korg or a Moog, you'll need to buy an S to V trigger converter before you can use it. If you are handy with a soldering iron, send me a SAE and I'll send you a diagram for a one transistor converter that you can build for around 50 pence. In addition, any portamento or pitch bend applied to the controlling synth will translate accurately to the sampled sound.

"I like this product; it is a worthwhile addition to the Micro Rack and for what is really a very modest outlay."

In terms of sound quality this is no Synclavier but it is certainly usable and I sampled bass guitars, voices and percussive sounds with ease. Once a signal is replayed at more than a few semitones below its original pitch, it does start to show signs of quantisation and aliasing but for some people, that is all part of the charm of sampling and it certainly doesn't make the sounds useless. Conversely, increasing the pitch causes no problems although the sound does get shorter.

Because this is a pitch following system, I assume that it uses a phase locked loop or something very similar to multiply up the control frequency which means that there must be a slight slurring between notes as the pitch follower lags behind. In practice this was not audible, even on two octave jumps, so someone in the design department has done his homework well.

Finally, one unusual side effect of this tracking system means that in the delay mode, the delay time can still be controlled by the synth pitch so you can create some interesting quasi-flanging effects from the keyboard and, though the manual doesn't suggest it, you could use the LFO on your synth as a modulation oscillator in this mode to produce chorus and flanging in a more or less conventional manner.

Conclusions

This is a very useful piece of all round outboard gear and, though I wouldn't recommend it purely as a DDL because of its limited bandwidth, it's certainly very flexible when used as a sampler and gives the budget user something that's more than an interesting toy (which is all you usually get for this price in the sampler department). The background noise in both the sampler and delay modes is surprisingly low, but this should not be confused with quantisation noise which only manifests itself when a signal is present. Soft sounds such as bass guitar demonstrate this effect most clearly, but if you sample at as high an input level as you can get away with, any noise will lose itself in the mix. Getting more range than specified is certainly a bonus and the tracking accuracy is quite adequate. I like this product; it is a worthwhile addition to the Micro Rack and for what is really a very modest outlay.

The RSD-10 costs £200 including VAT.

Further details are obtainable from Roland UK, (Contact Details).