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Audio amplifier

Discussion in 'Electronic Design' started by Himlam8484, Mar 2, 2007.

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  1. Himlam8484

    Himlam8484 Guest

    Hi people,

    I intend to make a amplifier circuit for a loudspeaker.
    With the high tone and mid tone, i will use a opamp and a darlington
    With the bass tone, a IRF and a Pi-filter will be applied.

    can anybody support me some idea. I think my plan lacks many things,
    please help me

    i am looking forward hearing from you soon

    Him Lam
  2. Rich Grise

    Rich Grise Guest

    Do you mean your amp will have three outputs, for the woofer, mid-range,
    and tweeter?

    Is this homework? Most people just use a plain amplifier, and a passive
    crossover right at the speaker cabinet.

    If it _is_ homework, then go back and reread the textbook. If that doesn't
    answer your question, ask the teacher. If he or she can't answer your
    question, then I'll take the course for you and spoon-feed you the answers
    for US$165.00/hr.

    Good Luck!
  3. joseph2k

    joseph2k Guest

    Damn, Rich you work cheap. I am already US$250/hr with 8 hour minimum.
  4. Himlam8484

    Himlam8484 Guest

    Hi Rich and joseph2k,

    I made a mistake when i posted my discussion,
    I will make three amplifier, each for one
    I think that this forum is a place which everyone can discuss together
    to improve his knowledge, but you use this forum to advertise. I think
    you should not do that. Do you agree with me???

    I hope i will receive some ideas from some body,

    have a nice day,

    Him Lam
  5. Rich Grise

    Rich Grise Guest

    Well, considering you haven't bothered to answer any of my questions, I
    was only informing what it would cost to have me do your work for you,
    which you seem to be unwilling to do for yourself, and want it done for
    free at that!

    Good Luck!
  6. Himlam8484

    Himlam8484 Guest


    All of things, I thank for you. I wil not argue with you more. I also
    get what things i need.

    Have a nice day,

    Him Lam
  7. Eeyore

    Eeyore Guest

    Yes, you don't need any transistors at all for the 'tone' stages.

    How about explaining exactly what it is you want to do ?

  8. joseph2k

    joseph2k Guest

    You should be posting to sci.electronics.basics That group is more tolerant
    of the ignorant. Plus, you are arrogant for demanding that others do for
    free what you are too ignorant to do for yourself.

    My sig says it clearly. Google if you do not understand it.
  9. Himlam8484

    Himlam8484 Guest

    Hi Garham,

    I intend to make a plan following:
    - a amplifier stage for high tone
    - a amplifier stage for mid tone
    - pwm for bass

    the audio source come from DAC. A amplifier stage to amplify the
    voltage and a transistor to amplify the current. If we don not use a
    trans how we can get high current. Do you any idea?

    I am looking forward hearing from you

    Him Lam
  10. Eeyore

    Eeyore Guest

    I agree 100%.

    Is .vn Vietnam btw ? Looks like it, it goes via Hong Kong. I didn't realise they
    were as arrogant as the Indians !

  11. Eeyore

    Eeyore Guest

    OK. You can happily combine all your tone controls around one or two stages with
    op-amps. One op-amp is acceptable but two gives less control 'interaction' which
    is a 'good thing' !

    Just a pwm (class D) for the bass ? You also want a linear class AB amplifier
    for the mid and highs I expect ?

    From a PC perhaps ? What signal voltage level ?

    You need more than just 'a transistor' to do that !

    Why don't you explain what ideas you have been looking at so far ?

    The choice of parts to use will be heavily influenced by the power levels you
    want to achieve.

  12. Himlam8484

    Himlam8484 Guest


    First of all things, i do not know how people can use the language of
    not_educated person on this forum. I post my idea to ask everyone, but
    i do not ask anyone do it for me freely. All of your ideas are only
    preferent for me. I am not an ignorant. Maybe you do not know, I am a
    Physics professor. I only want to find some thing about electronic
    field. You should know, every one on the world have equal rights.

    Hi, Graham

    the audio comes from FPGA kit. First i intend to use an opamp to
    amplify voltage then use a darlington to go current output high.
    Input voltage is about 3.3V, I would like an output power about 10w
    for high tone, 20w for midtone. And Pwm to output bass, power is about
    70w. here is my idea.

    I know, I need many components to complete my design, but all
    mentinoned above is the main parts.

    Have a nice day!

    Him Lam
  13. Guest

  14. Mr Himlam, best would be if you first just tried to design a simple class
    AB audio amp.
    Indeed ...basics is then a good group.

    'a darlington' sucks, as you need a push pull design, so make that 2, and
    perhaps do not use darlingtons... there are better designs.

    If you never made a class D amp, try to make one from some existing design,
    see if it stays in one piece.....

    Or if you know all these things already, then show us the diagram so we can
    throw mud at it, or hang a gold medal on it.

    Else it is all too vague.
    Speaker impedance, frequency ranges, supply volatge, efficiency required,
    space available, thermal properties of speaker case, heatsinks,
    all these things you should know before you start.
    For class D RFI may be a problem too.
  15. MassiveProng

    MassiveProng Guest

    Said the idiot that has already declared himself as only being a

    Did you spam this guy for a consulting fee, tech boy? I didn't read
    the thread, but it looks like I don't need to.

    What a joke you are.
  16. Rich Grise

    Rich Grise Guest

    Yes, everyone has equal rights to post here, but that goes hand in
    hand with everyone else's right to express their opinion, as well.
    OK, it depends on what the final outcome - what's the purpose of doing
    this? If it is to learn how to build the thing on your own, then the
    clear course of action is to take some classes or at least get some
    basic electronics books.

    If the intent is to just get the thing going, for example if it's
    just a way to make these waveforms, then you'd be better off to buy
    something off-the-shelf, or have it done by a professional.

    Good Luck!
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