I tried adding 100nF and 10 Ohm resistors, but it still doesn't solve the problem.100nF is plenty
I later removed it.The inductor (air-cored, several µH) is to avoid the amp seeing an overly capacitive load from long cables, which can oscillate the GNFB loop by adding more phase shift. This is not needed if there is no global feedback loop.
My idea is to let the OPA output a small current through the transistor to output a large current to reduce the power consumption of the LM1875.What's the reason for the TIP transistor output stage when the LM1875 can drive a 4 Ω speaker directly?
tried adding 100nF and 10 Ohm resistors, but it still doesn't solve the problem.Use the Zobel values 0.1µ/10R as recommended above.
I have found this problem, the output sound is "mixed sound",so I remove the inductor.The 1875 has better transistors already in it for that speaker. Also if you try to pick off the feedback After that inductor you certainly Will get "mixed sound", maybe even a little smoke.
I am a student, I want to use the AB class to eliminate the problem of crossover distortion, I have tried physical wiring, there is no burning problem, I want to try to design a circuit by myself.R u trying to boost wattage from lm1875 by adding another output transistor, if yes then shearch for propper schematic , don't play with this beautiful ic otherwise that gonna fry 😉 search , search, search until u get the proper one or two some expert, who makes amp like this, circuit is basic opamp direct coupled amp but I thing there will be more circuitry
If there is something wrong with the design, please let me know, thank you very much.
I just tried it and it worked!!Ad bootstrap like this
May I ask your academic principle?
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Deleted member 550749
For more power u can easily bridge 2x lm1875 ic and if u r trying to make that more efficient, then best of luck , 😉
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Deleted member 550749
When I first made an amp , used only resistor like you to the base of the transistor, amp was working but the problem with constant current solution, capasitor charge or backup the current feed during input voltage swing, and it's works, without that bootstrap cap distorted sound, and clicking sound happens, or u can ad any other current source,
Sometimes just wound around the resistor.The inductor (air-cored, several µH)
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Deleted member 550749
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