The Oakley Sound SRE330
The Oakley SRE330 is a multi mode stereo ensemble unit designed to mimic the behaviour of
the multichannel chorus and ensemble units of late 1970s and early 1980s. The SRE330 uses
up to four channels of bucket brigade delay (BBD) lines and up to four voltage controlled low
frequency oscillators (LFO) to achieve a sound reminiscent of various types of string
machines, guitar chorus pedals and studio rack effects of yesteryear.
Unlike the original devices the SRE330 allows greater control over the modulation depths,
speeds and waveforms, as well as featuring a wet/dry control. Input and output level control
pots are also provided to allow maximum flexibility in dealing with a variety of input signal
levels. Both the stereo input and output connections are balanced but can be used with
unbalanced connections if desired.
The unit features classic companding noise reduction circuitry which keeps unwanted noise
levels to an acceptable level while also adding a 'vintage' sound of its own. A four LED level
meter helps you keep signal levels at optimum ensuring a good noise to signal ratio without
clipping.
The SRE330 features two basic types of ensemble, three phase and multimode, which are
selected by a front panel switch.
The three phase setting replicates the action of classic string machines originally from Europe
such as the Solina and Logan String Melody. Three BBDs are used in this mode and their
delay times are controlled by two three phase fixed frequency sine wave oscillators. One of the
oscillators, the chorus, runs very slowly. And the other, the vibrato, runs a little faster.
However, unlike the majority of classic string machines, the modulation depths of each
oscillator can be controlled with the appropriate front panel level pot.
The Multimode setting is designed to replicate the actions of various classic synth chorus units
and string machines from Japan. The Multimode setting, as its name implies, has three modes
of operation:
1. Quad ensemble. All four delay lines are operating in this mode – with two BBDs and two
LFOs being used for each stereo channel. This mode is at its most effective when the wet/dry
control is set to around 100% wet.
2. Dual ensemble. In this mode two BBDs are being used, one per stereo channel. Each BBD
can be modulated by its own pair of LFOs. This mode is very effective when the wet/dry
control is set to around 50%.
3. Stereo Chorus. Again, in this mode, two BBDs are being used. But this time both BBDs are
being driven from the same pair of LFOs. However, one of the BBDs will receive the inverted
outputs of the VC-LFO pair. Like mode 2, this mode is very effective when the wet/dry
control is set to around 50%.
The four LFOs used in the Multimode setting are made from four separate circuits. Two of the
LFOs produce sine waves and two of them produce triangle waves. The SRE330 is wired so
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