How can I calculate low and high frequency in my circuit? I have used an 8-ohm speaker.
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\$\begingroup\$ my spekaer is 10watt 8 ohm \$\endgroup\$ – REDi Jun 7 '20 at 17:20
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\$\begingroup\$ 6V supply is not enough for 741 to work reliably: electronics.stackexchange.com/questions/304521/… \$\endgroup\$ – MarkU Jun 7 '20 at 21:32
The low frequency will be limited by the three high-pass filters of C1, C2 and C3. The most limiting filter is the one at the output (C3), resulting in a cutoff frequency of about 200Hz.
The high frequency will be limited by the gain-bandwidth product and the slew rate of the operational amplifier. The renowned 741 is not optimal in this respect with a gain-bandwidth product of only 1MHz. A TL071, an LF356 or a MCP6293 would probably be a better choice.
With an power suply voltage, the amplifier can only produce an output voltage with an amplitude of much less than 3V. At a frequency of 20kHz, the slew rate will only be \$0.37 \frac{V}{\mu s}\$. However the sine power will be less than 0.5W.