Oakley SE330 - Four Channel Stereo Ensemble Module

This board has been discontinued. An enhanced version is now available as the SRE330.

A completed SE330 module fitted into a 1U 19" rack alongside the Oakley HVM. The front panel legending is created by using two 1.5mm thick Scheaffer panels attached to the plain front panel of the rack.

The Oakley SE330 is a 'mono in, stereo out' ensemble unit designed to mimic the behaviour of the multichannel chorus and ensemble units of late 1970s and early 1980s. The SE330 uses four channels of bucket brigade delay (BBD) lines and four voltage controlled low frequency oscillators (VC-LFO) to achieve a sound reminiscent of the Japanese string machines, guitar chorus pedals and studio rack effects of yesteryear.

The fully populated issue 1 printed circuit board for the SE330 awaiting housing in a suitable case. Issue 2 boards are similar.

Unlike the original devices the SE330 allows greater control over the modulation depths, speeds and waveforms, as well as featuring a wet/dry control.

A simple render of the suggested front panel layout.

The SE330 features three basic modes:

1. Quad ensemble. All four delay lines are operating in this mode – with two BBDs and two VC-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. Stereo ensemble. In this mode two BBDs are being used, one per stereo channel. Each BBD can be modulated by its own pair of VC-LFOs. This mode is very effective when the wet/dry control is set to around 50%.

3. Dimension. Again, in this mode, two BBDs are being used. But this time both BBDs are being driven from the same pair of VC-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 VC-LFOs are made from four separate circuits. Two of the LFOs produce sine waves and two of them produce triangle waves. The SE330 is wired so that each stereo channel's BBDs are controlled by one set of triangle and sine wave LFOs. Each pair of similar waveform VC-LFOs are controlled by one set of speed and depth pots. So one set of pots controls the two sine wave LFOs and one set controls the two triangle wave LFOs. Each pair of similar waveform LFOs will therefore track each other but one is set to always run 20% slower than the other.

One channel of the analogue delay line showing the 3102 driver and 3207 BBD devices.

An effective compander circuit reduces the inevitable noise created by the analogue delay lines to a respectable level. A peak LED lights when the input signal is getting too big and noticeable distortion would result.

The SE330 uses only currently manufactured parts.

Input and output level control pots are also provided to allow maximum flexibility in dealing with a variety of input signal levels. Both the input and output connections are balanced but can be used with unbalanced connections if desired.

The power to the unit should be a regulated split supply of +/-12V to +/-17V. Power is admitted onto the main circuit board via a four way 0.156” (2.96mm) header of MTA or KK type. The module can be powered by our own Rack Power Supply Unit (RPSU) or any other MOTM compatible supply such as the Oakley PSU.

The board size is 198mm (width) x 234mm (depth). Power consumption is +140mA and -110mA at +/-15V.

Sound Samples

The raw sound is a simple sawtooth waveform from u-he's DIVA soft synth. The output of DIVA is fed out of the DAW and into the SE330. The output is then fed back into the DAW for recording. The file is best listened to by downloading it.

The prototype Oakley HVM and SE330 modules side by side in a 1U 19" rack from Bryant Broadcasting. The power is supplied to a single RPSU module with an external Yamaha PA20 line lump for safety reasons.


SE330 Issue 2 User Manual

SE330 Issue 2 Builder's Guide

Construction Guide Our handy guide to building Oakley DIY projects

Parts Guide Our handy guide to buying parts for Oakley DIY projects.

se330.fpd Frontplatten Designer file of the suggested panel design. You can edit this to suit your own panel design or print it out to use as a drilling template.

Use 'save as...' button to download and view the files.

The schematic is provided only to purchasers of the printed circuit board. This will be sent to you as a PDF file with your shipping confirmation e-mail.

For technical support on all Oakley projects please refer to the knowledgeable and helpful Oakley Sound Forum which is hosted at Muffwiggler.com. Tony Allgood and Paul Darlow do not provide building support for Oakley projects, but both and many others are usually available for help via the forum.

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Copyright: Tony Allgood
Last revised: October 04, 2017.