L'Fake has sound! Next is some sort of packaging, though if I really wanted to be in the seat-of-the-pants spirit of Burning Amp, I'd just bring the heat sink w/modules and my bench supply - the connectors are all where they should be, so it would play...
The L'Fake/L'Fake Lite ugly chimera will shamble up to Burning Amp this weekend. It really does look like some sort of garage Rube Goldberg invention from someone with an overheated imagination - bulbs on top...
wrenchone: please update your experience and performance of L'Fake at BAF2012. Is SemiSouth R100 fakeable too? Its demise took the wind from under diy F6 and other worthy Pass projects.
I couldn't always tell which amp was connected at any given time, but what I heard sounded nice.
So am I, but I usually reserve that enthusiasm for tubes. The L'Fake (non-incandescent) was the best working option at the late date I got everything working the afternoon before. The supply toroid I chose (out of a limited selection - some provided by you at the first BA) was a little voltage-shy for the L'Fake Lite. I should have followed my initial inclination, which was to leave off working on the power supply and tuck my bench supply into the chassis, which would have had enough capability to power either amp at its preferred rail voltage (enough room inside, too).
Thanks wrenchone. SIT appears to be scarce. Q3, Q4, Q5 and the associated passives in your schematic are the Triode Characteristic Generator [TCG]. Integrate them on a 2-sided PCB the size of a TO-247 package [4 leads] and sell them as L'Fake SIT. Clones of it will no doubt be made; but your original has an intrinsic power and prestige to be coveted and sought after by DIYers.
it's not that simple
R11, R6 must be in game ....... and they're not so un-correlated to rest of circuit
R11, R6 must be in game ....... and they're not so un-correlated to rest of circuit
Thanks Zen Mod. The challenge and objective continue to convert a cheap MOSFET [voltage controlled current source] to a voltage controlled resistor like a SIT. I am not skilled to determine whether an ideal voltage source power amplifier is a voltage controlled current source or a voltage controlled resistor? There are two R6s in the schematic of wrenchone.
Here's a corrected schematic, so there's less confusion.
If you want to discuss the true kernel of fake-SITness. The simpler light bulb-loaded schematic posted earlier in this thread would be a better start. The circuit currently under discussion has a modulated current source load and a global feedback loop among other complicating factors. It's playing right now, driving a pair of so-so Alesis monitors (4 ohms, no less) and doing a good job of it - Beethoven's Violin concerto with Anne-Sophie Mutter in the lead...
Note - the simpler circuit is shown in post #14.
If you want to discuss the true kernel of fake-SITness. The simpler light bulb-loaded schematic posted earlier in this thread would be a better start. The circuit currently under discussion has a modulated current source load and a global feedback loop among other complicating factors. It's playing right now, driving a pair of so-so Alesis monitors (4 ohms, no less) and doing a good job of it - Beethoven's Violin concerto with Anne-Sophie Mutter in the lead...
Note - the simpler circuit is shown in post #14.
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Thank you wrenchone. Will a circuit of the schematic of post#14 generate the triode-like characteristic curves; for example by using the setup of Rothacher in his first article on SIT? Is it appropriate to refer to your amplifier as " A Solid State Triode"?
I'm irreverent at best - I prefer to call it "L'Fake"...
The idea of Schade feedback to impart triode-like characteristics to pentode-ish devices like power mosfets is not new, and has been discussed at length elsewhere on this site. My added twist was to put a follower inside the feedback loop to allow use of a high value feedback network and still be able to decently drive the mosfet gate capacitance. This makes the whole setup easier to dive with normal sources. I did this all unawares back in '07 with my "Half-Nelson" amp, not knowing anything about this "Schade" business then. I'm still sussing out the implications...
The basic circuit should give triode-like characteristics with a curve tracer setup. Perhaps the best way to try this would be to unhook the lower resistor of the feedback voltage divider and apply the variable bias there. It might be a useful exercise to try. Let me ponder that for a bit.
The idea of Schade feedback to impart triode-like characteristics to pentode-ish devices like power mosfets is not new, and has been discussed at length elsewhere on this site. My added twist was to put a follower inside the feedback loop to allow use of a high value feedback network and still be able to decently drive the mosfet gate capacitance. This makes the whole setup easier to dive with normal sources. I did this all unawares back in '07 with my "Half-Nelson" amp, not knowing anything about this "Schade" business then. I'm still sussing out the implications...
The basic circuit should give triode-like characteristics with a curve tracer setup. Perhaps the best way to try this would be to unhook the lower resistor of the feedback voltage divider and apply the variable bias there. It might be a useful exercise to try. Let me ponder that for a bit.
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