Hi,
Just a courtesy email to let you know that a small run of the Pixie PCB is now being done and should be available in the next 4-6 weeks.
I have put pricing on my website for the PCB (complete with the M16C microcontroller), a PCB Component Kit and a suggested Front Panel Component Kit. I will shortly post a copy of the BOM for those interested in sourcing your own components.
As stated on the web, the Pixie is a clone of the EDP WASP. When considering the Pixie readers should be aware of the following deviations from the EDP WASP:-
The WASP Keyboard scanning circuitry (and keyboard) has been completely removed and replaced with an M16C-based MIDI Interface affording more flexibility in the choice and size on controller. This change should have no affect on the audible qualities of the Pixie
The dual 555-based oscillators have been replaced by a dual-DCO design utilising the M16C. This change also includes removal of the Octave and Note Decoding circuitry and also the dual Glide circuits. As all of these stages are simply squarewave generators and dividers I see no reason why this change should have any bearing on the overall audible characteristics of the Pixie and firmly believe that the end result is still a machine that can faithfully reproduce the WASP qualities.
The use of the DCOs has facilitated an increased range for the keyboard controller
Two extra filter circuits have been added to the Pixie. One is a duplicate of the original WASP filter and can be switched in series or in parallel with the original WASP Filter to extend and enhance the filter characteristics. The 3rd filter is a diode-ladder design and uses the same mixed input signal that is applied to the 1st filter, offering additional filtering characteristics which can be mixed in addition to or instead of the filter 1/2 combination.
A Ring Modulator has been added to the design to add further sound manipulation capabilities.
The Noise Generator has been slight redesigned to address the demise of the original chip. The new design offers a similar sound profile to that of the original WASP.
The EG stage used for the EDP WASP has been replaced with a copy of the EG stage used for the WASP VCA. This EG offers more control capabilities over the original design
Two dedicated mixers have been added to the design. The first mixes the various sound sources (VCO1, VCO2, NOISE, RINGMOD, VCA feedback and External Input) which is fed to the 2/3 filter sections whilst the 2nd mixer combines the outputs from Mixer 1 (dry signal) with the outputs from VCF1/VCF2 and VCF3.
Switchable Distortion circuit added to VCF1 and VCF2 (borrowed from an idea by J. Haible)
Expanded Filter Controller to cater for the additional filters
Power supply modified to provide a 5V section for powering the front-end MIDI Interface and DCO sections, with the remaining analogue section running from a separate 9V section. This means that as designed the unit requires a 12VDC power source. However, the 9V can be changes to a 5V supply (change one voltage regulator) and the synth can be operated from a 9V battery making it suitable as a portable synth - NB in this mode of operation that Filter 3 will probably not function properly and may need to be either disabled or modified for this mode of operation - I will be investigating this operational mode in the near future)
There will also be posted shortly, a suggested design and panel layout for the Pixie suiting a small attaché case (as shown in the prototype sample picture on my website). If there is enough interest then I will be getting panels manufactured to suit this case
I would appreciate any comments you may have on this product and whether you are still interested in the Pixie
Best Regards
(Mr) Laurie Biddulph
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