30W Hi-Fi Class A Mosfet Amplifier

446

06:14:19

Some of the specs:
- Output Power - 30W/4ohm
- Drawn Power - 132W (avg.)
- Efficiency - 23%
- THD - >0.001% at 1Khz/30W. Worst case scenario THD is 0.01% in reality, which is also not bad at 30W easy listening is guaranteed at these levels.
- Frequency response - 7Hz - 25Khz at -3dB
- Ripple response - Very good at -93dB which is partially the reason for the low THD. 

published 9 years ago

GBleezy

9 years ago

Well, I can at least say this circuit looks really 😳 😨 😬 but in a kinda 😗😎👏🏾way that seems like lots of ⚡🔋️💥🚀⤴️ to look forward to 🔎📝📚📓 and to have this 🎓💡📚 be on a particular topic of interest 🎼🎤🎧📣 for ♍️ is all that cooler

hurz

9 years ago

Its an Class Ab for me with an Iq=4.14A and 175Watt idle power. An big A and little b (b also from push pull topology). I ask you and myself if power in idle is already that high, how can it be draw less power in action? One note to ripple rejection, its missing for which frequency you have measured that 100Hz 120Hz? And the power on behavior is quite slow because of 10k to 220uF tau. It take more than 10-20s to settle. Keep it up!

thebugger

9 years ago

At 10k and 220uF the charge time ia 2s not 20s. I agree on the AB thing since this is a modified class B amp but it sorta works in class A mode. It all depends on the idle current.

hurz

9 years ago

Tau=R×C but this is for 1 tau!! To almost fully charge it take 4 or even 5 tau! Not taken into account some current goes to the base and not to the cap.

thebugger

9 years ago

Despite the mode of operation what's your opinion on the THD. I surprisingly found it very low.

hurz

9 years ago

Yes, its extremly low.

Farmie

9 years ago

How do you set the MOSFET parameters? Eg. Vds, Vgs & Id

thebugger

9 years ago

Trial and error my friend. MOSFETS I have not dabbled with much

Phildela

9 years ago

Correct me if Im wrong but if you alter the 33pF cap to 10pF in the feedback loop it improves the high end frequency response

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