Simulations of - and a copy of the EasyEDA LM386EE spice model used in - each of the major stages used in the EasyEDA Tesseract DIY Guitar Practice Amplifier: > which includes a complete PCB design and Bill of Materials. The EasyEDA "Tesseract" Guitar Practice Amplifier is an LM386 based low power amplifier designed to deliver up to about 500mW into an 8 Ohm speaker when run from a 9V battery. The design given here is highly flexible and allows the several options in both the build and use of the amplifier. As well as a clipping circuit that some other designs - such as the more well known Smokey, Little Gem, Ruby and Noisy Cricket - have incorporated, Tesseract has several unique effects features designed into it: * Selectable Bipolar or Junction FET input stage for different input overload effects; * Adjustable gain and clipping 'hardness' in the Distortion stage; * An adjustable fullwave rectifier stage, driven by the distortion output, that generates a type of fuzz and frequency doubling effect called 'Wreckage'; * An optional low frequency oscillator stage to sweep the `Wreckage` effect; * A simple mixer to blend the 'Wrecked' and the 'Distortion' outputs; * Selectable, adjustable low or high frequency boost (a type of tone control); * An important aspect of the design is that all the features and FX can be tweaked for your delight and delectation. * Most features are also optional and can be wire linked out if not required without affecting the other functions. * The design could easily be modified to suit the LM380 2.5W or LM384 5W amplifier chips (although the Boost function would have to be omitted) or a range of other devices. * The design also includes a headphone output jack. * The PCB includes dual footprinting to simplify the choice of some of the components. To obtain a copy of the LM386 subckt model simply download a copy of the LM386EE.sub.txt attachment. The model runs in ngspice (which is what EasyEDA uses anyway) and LTspice. It'll run in SIMetrix and probably run in PSpice.