I have designed long ago, a type of SRPP MOSFET output amplifier, that has ended after several models to
How it works.
The Q1,Q2,Q4 don't need explanation. Q3 is biased by a voltage across 470uf capacitor Vc subtracted by the voltage across the resistor 0.27 ohms as R(I+i). I being the bias current adjusted by adj bias resistor, making the control voltage of Q3 to be
Vc-R(I+i).
When Q4 pushes more current, the control voltage decreases and the Q3 pulls less current and the reverse with Q4 decreasing the current. Hence it operates self commanded push pull output commonly known as SRPP.
The weighing resistor, R15 adjust the 2 outputs to be perfect complimentary that yields very low THD, hence, the Nmos and the Pmos outputs don't require itself to be complimentary.
The first of this model I started using only the output stage and a step up transformer 600:10k
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With this model, it has very natural high frequencies being single stage but lacks damping factor for good in bass reflex.
The actual 3 stage has a similar high frequencies as JLH1969 but much better pronounced bass. It can output 40w 8 ohm with gigantic heatsinks as each output dissipates 45w biased 1.67A 27v. For 4 ohms a different version, with 19v and 2.35A. These are the maximum but down to 10w is easy to obtain replacing the JLH1969.
I will develope a PCB with a servo if there is a demande for it, myself I prefer the sound of the 3 transistors one
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How it works.
The Q1,Q2,Q4 don't need explanation. Q3 is biased by a voltage across 470uf capacitor Vc subtracted by the voltage across the resistor 0.27 ohms as R(I+i). I being the bias current adjusted by adj bias resistor, making the control voltage of Q3 to be
Vc-R(I+i).
When Q4 pushes more current, the control voltage decreases and the Q3 pulls less current and the reverse with Q4 decreasing the current. Hence it operates self commanded push pull output commonly known as SRPP.
The weighing resistor, R15 adjust the 2 outputs to be perfect complimentary that yields very low THD, hence, the Nmos and the Pmos outputs don't require itself to be complimentary.
The first of this model I started using only the output stage and a step up transformer 600:10k
the Phoenician follower
A Phoenician is a negative impedance load. http://www.diyaudio.com/forums/chip-amps/302190-30watt-class-phoenician-amplifier.html Here ,the Phoenician loads -RL/2 . It measures the output current and provides the same to the load , doubling the output power , decreasing the output impedance and...
The actual 3 stage has a similar high frequencies as JLH1969 but much better pronounced bass. It can output 40w 8 ohm with gigantic heatsinks as each output dissipates 45w biased 1.67A 27v. For 4 ohms a different version, with 19v and 2.35A. These are the maximum but down to 10w is easy to obtain replacing the JLH1969.
I will develope a PCB with a servo if there is a demande for it, myself I prefer the sound of the 3 transistors one
3 transistor classA 50w/25w with variable output impedance as SE triodes.
Function description is here. https://www.eevblog.com/forum/projects/can-this-3-transistor-classa-amp-50w4ohm-with-1-3a-bias-still-be-called-classa/#msg5701985 This amp initially I designed to function with constant current, where the power CCS modulates itself to keep a constant current from...
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