Oakley Sound SE330 User Manual

Oakley Sound Systems
Stereo Ensemble – SE330
PCB Issue 2
User Manual
V2.0.3
Tony Allgood Oakley Sound Systems CARLISLE United Kingdom
Introduction
This is the User Manual for the Stereo Ensemble SE330 module from Oakley Sound. This document contains an overview of the unit and goes into some detail regarding the operation of the module. It also contains the calibration instructions.
For the Builder's Guide, which contains a basic introduction to the circuit board and a full parts list for the components needed to populate the board, please visit the main project webpage at:
http://www.oakleysound.com/se330.htm
For general information regarding where to get parts and suggested part numbers please see our useful Parts Guide at the project webpage or http://www.oakleysound.com/parts.pdf.
For general information on how to build our modules, including circuit board population, mounting front panel components and making up board interconnects please see our generic Construction Guide at the project webpage or http://www.oakleysound.com/construct.pdf.
2
The Oakley Sound SE330
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. Unlike the original devices the SE330 allows greater control over the modulation depths, speeds and waveforms, as well as featuring a wet/dry control.
The SE330 features three basic modes:
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.
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%.
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% faster than the other.
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.
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 . Power consumption is +140mA and
-110mA at +/-15V
The printed circuit board size is 198mm (width) x 234mm (depth).
3
Operating Instructions
INPUT LEVEL
The input level should be set so that the peak LED never lights continuously. The brighter the LED shines the more you are overdriving the unit and this is generally to be avoided. Ideally, the peak LED should never come on in normal operation. Once the input level is set to the correct point then the output level control can be adjusted to suit.
PEAK LED
This gives a visual indication of when the signal being sent to the delay line circuitry exceeds the recommended amount. As soon as the LED starts to glow the delay line circuitry will be close to clipping and distorting. The level required to clip the delay lines varies with frequency and the harmonic content of the signal. Brighter sounds, or ones of very high pitch, are more likely to clip than low frequencies. For example; a static sine wave at 200Hz will clip at 3.6V peak-peak. While at 2kHz clipping will start at 1.2V peak to peak.
TRIANGLE RATE
Controls the rate of the triangle wave low frequency oscillator (LFO). An LFO produces an output signal that changes in voltage with a repeatable and periodic shape. The triangle wave output rises at a constant rate, reaches an apex and then descends at the same rate as it went up. Then at its lowest point it rises again and the process repeats itself. It is called a triangle wave because when viewed on an oscilloscope the trace is made from a series of triangles.
TRIANGLE DEPTH
Controls the depth of the triangle wave modulation. The deeper the modulation the greater the change in delay times the BBD lines exhibit. Quick changes in delay are heard as a change in pitch by the listener. With a triangle wave the pitch changes can be quite severe as the waveform changes direction.
4
Loading...
+ 7 hidden pages