Usage of the old computer LPT switch, as a box for 5W fet power amplifier.
There are many such boxes in offices left unused because most of new printers are USB or Ethernet.
Before:

After repainting it, adding the front and rear plates and installng PA inside:

2x400W monitor in old (dead) ocilloscope case.
10 band EQ, active crossover, 8x bridge/paralleled LM3886`s in each channel

QuoteSorry, joining this discussion late. Why the OT in the MOSFET PA? Gilding the lilly or does the bandpass like response and non-linear transfer function of the OT add to the "tube sound"?

Some answers to your question you can find there.
http://www.ssguitar.com/index.php?topic=1981.msg12953#msg12953

Small test "Who is who". Reamp samples of the tube "Bogner Ecstasy" (plexi mode) and the FET Superlead.
http://milas.spb.ru/~kmg/files/projects/slp/reamp/Classic%20T.zip

It's not yet my friend, reamp of DI samples downloaded from several Internet sites.
http://milas.spb.ru/~kmg/files/distr/DI%20Samles/
Additional 3 samples:
http://milas.spb.ru/~kmg/files/projects/slp/reamp/fp/Country%20Esque.mp3
http://milas.spb.ru/~kmg/files/projects/slp/reamp/fp/Kid%20Paul.mp3
http://milas.spb.ru/~kmg/files/projects/slp/reamp/fp/LP%20Delay.mp3

The only processing is volume normalization for all samples.

Very good for use with LME49830
http://www.national.com/pf/LM/LME49830.html#Overview

Several additional reamp samples at full power (PA overdrive).
http://milas.spb.ru/~kmg/files/projects/slp/reamp/fp/

QuoteI feel that some/most of the folk would be detered from building some of your circuits as it's Suface mount Double sided stuff.
Not something that the average hobby type is likely to have access to.

Double sided assembly, not PCB.
All of my designs use single-sided PCB (no problems to make them DIY).
About SMD, in Russia, it is often easier to find SMD than through hole components. Except maybe the high-voltage electrolytic and film capacitors and some semicinductors that has only one package version.
For example Mouser offers wide range of SMD compoents.
http://www2.mouser.com/Passive-Components/Resistors/Surface-Mount-Resistors/Thick-Film-Resistors/_/N-7h7yz?P=1z0x6frZ1yzvlks
http://www2.mouser.com/Passive-Components/Capacitors/Tantalum-Capacitors/Tantalum-Capacitors-Solid-SMD/_/N-75hr4?P=1yztnms
Otherwise you can take my schematic and make your own layout for components you can buy.
I just wanted to give my version of the tube emulation using semiconductors.

Be patient, guys. All ideas have a right to live.
IMHO, one important thought:
Tuning the stage for different FET  parameters by changing the resistor at the drain will also affect stage gain and its output impedance (which affects the frequency response of schematic).
It impairs the schematic repeatability.
In my version, of course more complex, adjusting does not affect gain and frequency response of the stage.

"Nothing is perfect" (C) Saint-Exupéry.

If you have a problems with the definition of the parameters of the transformer core ("Bm"), you can use the following trick. Not exact, but good enough.
If you use a power transformer as the "donor" for the output transformer, count winding turns while unwinding primary coil. So you will know the ratio of turns per volt for the lower frequency equal to the mains.
Voltage on output winding equals U = sqr(Pout * Rload)
Using turns per volt ratio you can calculate turns in the output coil.
Now start PP calculator, enter parameters (lower frequency = mains frequency of the transformer). Change "Bm" untill you`ll get calculated output coil turns.

QuotePlease tell us something about that.

Did you see that?
http://www.ssguitar.com/index.php?topic=2020.msg13351#msg13351

Quotefeel free to post some links

Article in Russian from one of the authors of GTLab forum.
http://milas.spb.ru/~kmg/files/literature/%d0%a1%d1%87%d0%b8%d1%82%d0%b0%d0%b5%d0%bc_%d0%b3%d0%b8%d1%82%d0%b0%d1%80%d0%bd%d1%8b%d0%b9_%d0%b2%d1%8b%d1%85%d0%be%d0%b4%d0%bd%d0%be%d0%b9_%d1%82%d1%80%d0%b0%d0%bd%d1%81.pdf
Spreadsheet based calculator form the same author.
http://milas.spb.ru/~kmg/files/distr/PPtrans_1.01.xls
Article in English.
http://milas.spb.ru/~kmg/files/literature/transformers.pdf
Executable PP calculators.
http://milas.spb.ru/~kmg/files/distr/PPCalc/PPCalc.exe
http://milas.spb.ru/~kmg/files/distr/PP-%d1%80%d0%b0%d1%81%d1%87%d0%b5%d1%82.exe

Scalable down 40W version (Primary coil impedance Ra-a = 200 ohms)

If you wish to design your own fet PA, you can use my program to select primary impedance for desired power and supply voltage.


Ra - impedance of half primary winding (1/4 Ra-a)
Vsupply - power supply voltage
Sig Max % - signal amplitude (100% is maximum signal without distortion)
Vsat - fet saturation voltage at peak current
Id0 - idle current
Average Pd - Average drain power (for one side of PP, halfwave)
Average Pl - Average load power (fullwave, but without taking into account efficiency of the transformer)
Average Id - Average drain current (for one side of PP, halfwave)
Peak Pd - Peak drain power (instantaneous)
Peak Id - Peak drain current (instantaneous)

The story at freestompboxes begins from this topic:
http://freestompboxes.org/viewtopic.php?f=28&t=8037&p=90747
On ssguitar I come after this discussion:
http://www.ssguitar.com/index.php?topic=1981.0

It's very simple, I was looking for links to my site, found at this site discuss one of my projects and decided to join the discussion.