@jimk04 and others,
Back in 2020 Hugh explained it rather well in another thread (reference the schematic below):
It’s important to understand this as it is very similar to the way the Aleph J (and all other precursors to the Aleph J, such as Aleph 30, 60, 2, etc…) works. The big difference is in the DESIGN of the output stage current source in the Alpha Nirvana. It’s even more efficient and is based on a P-Mosfet that is controlled by a PNP transistor. You will realize that this amp really should be called the Aksa Lender Nirvana. Moreover, the damping factor of this amp is much much higher than any “low wattage” SE Class A design (whether tube or solid state I’ve heard). Sonically it isn’t as syrupy sounding in the midrange but does provide enough of that ‘magic’ without losing midbass and bass control. I hope someday(!) to return to this design and change the active N-channel MOSFET to a JFET SemiSouth!
Have fun building it!
Best,
Anand.
Back in 2020 Hugh explained it rather well in another thread (reference the schematic below):
It’s important to understand this as it is very similar to the way the Aleph J (and all other precursors to the Aleph J, such as Aleph 30, 60, 2, etc…) works. The big difference is in the DESIGN of the output stage current source in the Alpha Nirvana. It’s even more efficient and is based on a P-Mosfet that is controlled by a PNP transistor. You will realize that this amp really should be called the Aksa Lender Nirvana. Moreover, the damping factor of this amp is much much higher than any “low wattage” SE Class A design (whether tube or solid state I’ve heard). Sonically it isn’t as syrupy sounding in the midrange but does provide enough of that ‘magic’ without losing midbass and bass control. I hope someday(!) to return to this design and change the active N-channel MOSFET to a JFET SemiSouth!
Have fun building it!
Best,
Anand.
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@bigaudioscotto
Read posts 2363-2370.
I imagine the amp will become even more detailed and that may/may not be what you want.
Best,
Anand.
Read posts 2363-2370.
I imagine the amp will become even more detailed and that may/may not be what you want.
Best,
Anand.
Hello,
Just type the part number and mouser will show you the desired result.
Cheers
Spiros
So Hugh, would this work even though the Exicons are lateral mosfets, instead of a vertical mosfet? Moreover, one needs to be careful about properly connecting the gate, drain and source pins since it is switched on lateral mosfets vs vertical mosfets. The Exicons are certainly very durable devices. More H2 typically means more midrange presence in my experience.
Please share the fruits of your knowledge!
Best,
Anand.
Just remember:
Drain is the center pin on a Vertical Mosfet. Source is the center pin on the lateral mosfet. They have to correspond when you fly wire back to the main Alpha Nirvana PCB.
The snubber boards however were designed for vertical mosfets. It might be a messy modification since C102 and R102 (on the snubber board) connect between the drain and gate and the 15V zener is connected between the gate and source (Cathode towards the gate in an N channel). I’ll need to have X and Hugh weigh in on the options and their opinions.
Best,
Anand.
Drain is the center pin on a Vertical Mosfet. Source is the center pin on the lateral mosfet. They have to correspond when you fly wire back to the main Alpha Nirvana PCB.
The snubber boards however were designed for vertical mosfets. It might be a messy modification since C102 and R102 (on the snubber board) connect between the drain and gate and the 15V zener is connected between the gate and source (Cathode towards the gate in an N channel). I’ll need to have X and Hugh weigh in on the options and their opinions.
Best,
Anand.
I can tell you that C124 is directly in the feedback circuit and will definitely affect the sound. Both in value and in quality of that capacitor. Many will use a non polar capacitor type for best sound, but in this case a minimum value of 100uf is recommended as seen in the schematic. I think it has to do with achieving a low ESR value which larger capacitors such as the 470uf do have compared to 100uf. You can experiment and let us know. My thoughts and experiments are on post 2140.
Best,
Anand.
Best,
Anand.
25V is fine. This is a low voltage node in the circuit from what I can see.
Best,
Anand.
