2 channel amplifier

Discussion in 'The Projects Forum' started by awwende, Jun 14, 2009.

  1. awwende

    Thread Starter Active Member

    Feb 17, 2009
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    I'm trying to design a 2 channel amplifier with volume control to drive external speakers. I would like the amp to put out at least 3W per channel.

    My original plan was to use the TDA2822 2006417212313245.gif and then have those outputs feed into the inputs of the TDA1517 TDA1517.jpg .

    The problem that I realize I might run into, is that the smallest adjustment on the pots would increase the gain too quickly.

    So my first question is am I correct with the potential problem? And secondly, what IC should I use that will give me at least 3W per channel and give me enough control of the gain to make small adjustments?

    If you need me to clarify anything, just ask. Thanks
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    The TDA2822 is a power amplifier. It is too noisy to be a preamplifier.
    Use low noise opamps if you need a preamplifier.

    The preamp has a gain of 100 and the power amp has a gain of 10. Then the total gain is 1000. Why do you need such a high amount of gain?

    A logarithmic volume control (audio taper) matches the logarithmic response of our hearing to loudness. Then a small adjustment of the pot will result in a small adjustment of the volume.

    The TDA1517 has an output of more than 3W at clipping into a 4 ohm speaker per channel. Its output into an 8 ohm speaker per channel is less than 3W at clipping.
     
  3. awwende

    Thread Starter Active Member

    Feb 17, 2009
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    the only reason i'm using the 2822 is because i used it in a pocket amp i made. but the output was only going to headphones which only went up to 1W max per channel (even though i never had a need to go full power). any recommendations for a low noise dual op amp?
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    The TL072 is an inexpensive low noise dual opamp. Its minimum supply is 7V.

    The OPA2134 is much better with very low noise and a minimum supply of 5.0V.
     
  5. awwende

    Thread Starter Active Member

    Feb 17, 2009
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    that is great, thanks. I'll be using a 19DCV, 3.5A laptop power supply for the circuit. will i need an inverter like the one I've seen you comment on aaroncake circuits to avoid clipping, or am I fine using a 7805 regulator for v+ and ground for v-?
     
  6. Audioguru

    New Member

    Dec 20, 2007
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    The TDA1517 has a minimum supply voltage of 6V and will not work from only 5V.
    With a 6V supply, its output per channel into 8 ohm speakers at clipping is only about 0.2W.
     
  7. awwende

    Thread Starter Active Member

    Feb 17, 2009
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    0
    can i power the TL072 and OPA2134 from +12V and ground, or do i need to have v- -12V to avoid clipping?

    for the entire circuit I'll be using 4 TL072. will i be able to use the attached circuit to provide the -12V (if needed), or will the op amps draw more current?


    http://www.aaroncake.net/circuits/vinvertr.asp
     
    Last edited: Jun 16, 2009
  8. Audioguru

    New Member

    Dec 20, 2007
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    You do not need a supply as high as plus and minus 12V.
    First you must decide on your load impedance and how much max RMS power you want.
    then you calculate the supply voltage for the power amplifiers.
    Use that supply also for the opamps.
     
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