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Type: Posts; User: northumber82

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  1. Closed: Re: Voltage error in CFP VAS of audio amplifier

    EDIT: Q6 is KSA1381
  2. Closed: Voltage error in CFP VAS of audio amplifier

    Hello, I have a trouble in the VAS stage of an amplifier.

    156595

    The amplifier is powered by +10V _ GND _ -10V. The voltage at the Q5 base should be about 9.2V as simulator said, but it's only...
  3. Closed: Re: Current and degeneration resistor in input pair

    Yes sorry, should be NPN, error of mine.
  4. Closed: Current and degeneration resistor in input pair

    In analog audio amplifier, what is the calculation to do concerning the degenerative resistances of the differential input emitters?

    156472

    As I understand it, the degeneration resistors R1 and...
  5. Replies
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    298

    [SOLVED]Closed: Resistors in Wilson current mirror

    I have some questions concerning analog audio amplifiers: what is the purpose of resistors R1 and R2 in the Wilson current mirror? With what formula are they calculated? Can they be omitted? If they...
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    536

    [SOLVED]Closed: Re: Ground plane in audio amplifier?

    Thank you for the answer.
  7. Replies
    5
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    536

    [SOLVED]Closed: Ground plane in audio amplifier?

    Hello, a question: can a ground plane, create problems in power audio amplifiers?

    Example: if touching the input with the tip of whatever, the amplifier oscillates, can it be the fault of the...
  8. Closed: [Moved]: ESS Tech DAC libraries? (ES9038/ES9028/ES9018)

    Does anyone know where I can find the ESS Technology DAC libraries?

    I want to produce them and I don't want to buy them from China. But I can't find any libraries (schematic and board layout) of...
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    2,860

    Closed: Re: Measure bode plot in LTspice?

    CTRL+L show the error log.

    I found how to display the magnitude and phase of every run at specific frequency with this command:


    .MEAS ac Vo V(out) at=Freq

    How now to implement the IF (Y)dB...
  10. Replies
    6
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    2,860

    Closed: Re: Measure bode plot in LTspice?

    Yes I know the IF statement but I don't know the syntax for the specific case. How to first of all, (Y)dB at (X)Hz? Then how to save the resistor with MEAS?
  11. Replies
    6
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    2,860

    Closed: Measure bode plot in LTspice?

    Hello, my problem it's a bit complicated.

    I want to measure the magnitude (in dB) of the bode plot of a specific frequency after an AC analysis.

    In my configuration:

    1) I have a circuit (a...
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    [SOLVED]Closed: [SOLVED] How to beta tolerance in LTspice?

    There is a method to set a percent value tolerance of beta of BJTs models in LTspice?

    I used function "Worst Case" and "Monte Carlo" for resistors and capacitors:


    Worst case function:
    .func...
  13. Closed: Re: Auto bias vertical Mosfets in audio power amplifier

    Vertical MOSFET = Hexfet

    The Vbe bias current changes at voltage variating. In many amplifiers this isn't a problem because the voltage swing is little (5V).

    My problem is that I've to use my...
  14. Closed: Re: Auto bias vertical Mosfets in audio power amplifier

    Yes I already saw that, I found nothing of useful for the scope





    Yes, I already use a Vbe multiplier, but it does not adapt to voltage or load change.
  15. Closed: Re: Auto bias vertical Mosfets in audio power amplifier

    No, VAS, in audio amplifier means Voltage Amplifier Stage. In which voltage of the Input Stage is amplified before the Output Stage. The problem is another: my VAS and the gate driver are the same...
  16. Closed: Auto bias vertical Mosfets in audio power amplifier

    As title, I'm searching a simple circuit to biasing vertical mosfets in an audio power amplifier.

    The output stage I'm using, is composed by two simple mosfet IRFP240/9240 in push-pull...
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    1,121

    Closed: Re: Amplifier output mosfet protection

    Ok found the source of distortion: lowing the load crossover distortion seem to be higher. MOSFETs act like a unbiased class B amp. Then mosfet are not the best solution
  18. Replies
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    1,121

    Closed: Re: Amplifier output mosfet protection

    20Hz:

    Large signal: 0.000015% VS 0.000339%
    Small signal: 0.000001% VS 0.05%

    Large signal: 1V input
    Small signal 0.1V input

    I test the protection circuit directly with a voltage source and...
  19. Replies
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    1,121

    Closed: Re: Amplifier output mosfet protection

    Distortion at 20kHz:

    Low signal: 0.0005% VS 0.16%
    Large signal: 0.007% VS 0.007% (no differences)

    "And a side question, how much is the maximum DC voltage which can appear on the speaker? Very...
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    1,121

    Closed: Re: Amplifier output mosfet protection

    Ok then:

    At large signal distortion is ever low, but at small signal the distortion difference is very high 0.000018% vs 0.08%.

    The load is EVER a 8ohm resistor.

    I checked only at 1kHz sine...
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    1,121

    Closed: Re: Amplifier output mosfet protection

    149001

    These are simulation results before and after the mosfet driver, seems the distortion is doubled, but ever low. This because the signal is attenuated by RDSon but second and third harmonic...
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    1,121

    Closed: Amplifier output mosfet protection

    Hi guys, I designed this amplifier output protection for speakers. This circuit blocks DC output from amplifier and is also an antibump.

    148996

    Originally, the circuit was using a relay, I...
  23. [SOLVED]Closed: Vbe multiplier temperature problems in audio amplifier

    Hello, I have an audio amp (of my creation) with mosfets as outputs (precisely IRFP240 and 9240).

    147768

    I used the first configuration of Vbe multiplier as bias regulator (A type), all perfect...
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    Closed: Re: Audio amplifier output problem

    R18-19-20-21
  25. Replies
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    500

    Closed: Re: Audio amplifier output problem

    Dual Power supply +-30V, 5A max. The I have to deacrease the CFP differential resistances?
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