Elby Designs Pixie Attache EDP WASP, User Manual

Page 1: ...lby designs bigpond com www elby designs com 1 of 18 Pixie Attaché User Manual Revision 2 0 March 3rd 2018 Please note that this document is still currently under revision and we apologise for any errors or omissions Readers should feel free to e mail any comments to the address given below ...

Page 2: ... play in creating the unique sound of the WASP The Pixie Attaché is a clone of the EDP WASP that includes features that offer several enhancements over the original EDP WASP including a 2nd EDP WASP filter Both the EDP WASP Filters include a distortion circuit courtesy of J Haible a 3rd low pass filter a simple Ring Modulator a mixer providing a mix of signals in to the filter section a mixer prov...

Page 3: ...ent of 300mA or more The Pixie Attaché has a POWER switch and a status LED to indicate when the power is ON We recommend the use of a linear AC DC wall wart although switching supples can be used as well External Amplifier The LINE OUT output 21 on the Pixie Attaché panel is suitable for driving an external amplifier while the HEADPHONES output 20 can drive a pair of high impedance headphones Turn...

Page 4: ... affect the pitch of Oscillator DCO 1 In addition to having variable pitch the actual way in which the oscillator vibrates known as the wave shape or waveform can be modified The five position WAVEFORM selector 6 is used to switch the oscillator to give square sawtooth triangular or sine wave shapes These wave shapes are shown in Figure 2 Figure 2 Oscillator Wave Shapes A fifth waveform provides a...

Page 5: ...oscillators are in tune when a note is played ACTION Turn down the volume 38 for DCO1 Rotate the PITCH OFFSET control 2 and note that Oscillator DCO 2 can go up or down about 5 or 6 semitones Therefore any required interval between the oscillators can be obtained It is normally recommended to make Oscillator DCO 1 the fundamental pitch and to set Oscillator DCO 22 to the required interval above th...

Page 6: ...esn t have a fixed pitch like an oscillator but consists of random frequencies that cover the audio spectrum the range of pitches which the ear can detect ACTION Set all MIXER 1 controls 37 38 39 40 to minimum Turn up the NOISE control 40 and play any note The characteristic hissing can be heard On its own this does not sound very exciting but it is particularly useful especially for percussive so...

Page 7: ...ator in the Pixie is an XOR function fed from the square wave outputs of the two oscillators For the limited case of square or pulse wave signals this is identical to true ring modulation There are no controls for the Ring Modulator other than the mix level control 34 in the MIXER ACTION Set all MIXER 1 controls 37 38 39 40 to minimum Turn up the RING MODULATOR control 39 and play any note Adjust ...

Page 8: ...s to re trigger when a new note is played or a note is released while a 2nd is being held on DUAL MODE When OFF 12 both DCOs track the keyboard on the same note the PITCH control in DCO2 allows DCO2 to be offset from DCO1 When ON only DCO1 plays when only a single note is being played When a 2nd note is received this is assigned to the 2nd DCO While in DUAL MODE the SYNC 3 switch is ignored GLIDE ...

Page 9: ... shapes selected by the SHAPE rotary switch 26 Reading clockwise these are triangle falling sawtooth slope rising sawtooth ramp square wave noise and random ACTION 1 set the controls as in Figure 1 2 set the DCO MODULATION 28 to the mid position 3 hold any note The pitch of DCO1 will smoothly rise and fall as represented by the shape of the triangle wave 4 while still holding a note try the effect...

Page 10: ...pe and speed being determined by controls 17 and 18 Rotating it anti clockwise gives a similar effect but the modulation wave shape is inverted ACTION 1 set up as shown in Figure 1 with DCO 1 and DCO 2 in unison on 0 4 and the DCO 2 control 37 turned up 2 3 Hold middle C and rotate the LFO control 15 clockwise and then anti clockwise When it is clockwise positive modulation the filter will be swep...

Page 11: ...puts from the two oscillators are fed to a mixer along with the Noise output and Ring Modulator outputs The blend of these signals can be set using the relevant level controls 37 38 39 40 The Mixer 1 output is then fed to the filters for processing In addition the Mixer 1 output is also fed directly to the VCA output mixer where it can be mixed in to the final output 24 ...

Page 12: ...s Band stop This basically is the inverse of the Band Pass filter and supresses frequencies within a certain band of frequencies either side of a set frequency It should be noted that there is not a sudden cut off above at or below the set frequency but a gradual decrease in volume of pitches moving away from the set frequency This may become clearer by reference to Figure 2 The set frequency abou...

Page 13: ...se The VCF EG control 13 which is explained fully in Section VIII also introduces modulation of the filters but from the VCF EG Envelope Generator This is the reason why controls 13 and 15 are placed together on the front panel In addition the Filter cut off frequency like the frequencies of DCO 1 and DCO 2 is also determined by the note played on the keyboard ACTION 1 set the Pixie Attaché up as ...

Page 14: ...vel determined by the SUSTAIN control 28 decaying at a rate set by the DECAY control 29 The envelope amplitude will remain unchanged until the note is released after which the envelope will decay to zero at a rate set by the DECAY control 29 Releasing the note before the SUSTAIN section is reached will result in a simple ATTACK DECAY envelope Figure 3 Envelope stages NOTE The DECAY control defines...

Page 15: ...TION 1 Set up the Pixie as in Figure 1 2 Turn up the DCO 2 control 37 3 Adjust PITCH OFFSET 2 so that the oscillators are in unison 4 Play the keyboard The Pixie should now be producing familiar synthesiser like sounds 5 Experiment with the Filter FREQUENCY control 14 6 Experiment with the VCF EG ATTACK 30 DECAY 29 SUSTAIN 28 and VCF EG 13 controls Figure 4 Envelope Generators in REPEAT mode SUSTA...

Page 16: ...er allowing for a mix of signals from VCF1 27 VCF2 26 VCF 3 25 MIXER 24 The LINE OUT output 21 is suitable for driving external equipment such as a mixer or audio amplifier while HEADPHONES output 20 is suitable for driving a pair of high impedances headphones The output level is adjusted using the LEVEL control 22 Inserting a jack in to the LINE OUT output 21 will disable the HEADPHONES output 20...

Page 17: ...ve duty cycle output adjustable from 50 to 90 WAVEFORM Square Sawtooth Triangle Sine Modulated Pulse approximately 4 7Hz modulation Oscillator DCO2 PULSE WIDTH Square wave duty cycle output adjustable from 50 to 90 WAVEFORM Square Sawtooth Triangle Sine Modulated Pulse approximately 5 3Hz modulation PITCH OFFSET Detune from DCO1 by approximately one octave up or down MIXER 1 DCO1 output from DCO1 ...

Page 18: ... Exponential decay rate variable from 3mS to 12 seconds Decay is interrupted by a sustain period while the keyboard is being touched SUSTAIN The sustain signal level is adjustable from 0 to 100 REPEAT The repeat function causes continuous attack decay cycles while a key GATE is ON SUSTAIN must be set to minimum VCF EG VCF1 VCF2 Envelope Generator ATTACK Linear attack rate variable from 3mS to 2 se...