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TPA3122D2 Class D Audio Amplifier TPA3122D2 IC is used as a class D audio amplifier and can deliver up to 15W of power at 10% distortions. The real advantage of using a class D amp, especially TPA3122 is the fact that this IC doesn’t need a heatsink because it has a high efficiency. Another great thing about it is that you can buy a $20 built-it-yourself kit or even cheaper from ebay but you need to be careful not to buy a fake one. TPA3122D2 Class D Audio Amplifier I discovered this IC while searching for an audio amplifier circuit that I need for the 2 x 10W/4Ω speakers received from my brother-in-law. I think that TPA3122 can provide enough power for what I need even though it can output only 8W with 1% distortions on a 4Ω speaker (something that some of you might find too low). The main reason I would choose this instead of a class A or B IC is the fact it doesn’t need a heatsink, so the whole amplifier will be lighter in weight and cheaper.

This is a circuit of SA58672 Small Class-D Audio Amplifier. This circuit is suitable for mobile device. It has maximum output power of 3.0 W for a 4ohm load and 1.7W for 8ohm load with power supply of 5V. If we uses 3.6 V power supply, the maximum output power is 900mW with 8ohm load. Here is the circuit : Using 9-bump Wafer Level Chip Scale Package (WLCSP), the SA58672UK save space in portable designs, because it measures only 1.66 x 1.71 x 0.6 mm. This circuit produces better overall audio performance because it has improved RF rectification and immunity to noise. The SA58672UK is suitable for cellular handsets or wireless and other portable audio application because it has fast start-up time of 7 ms eliminates pop-on sounds. [Source: NXP Application Note]

I have built this amplifier and it does sound good. It requires a preamp as it hasn't got much gain. It requires big heat sinks and a large transformer and a great power supply and careful wiring, but in the end it is xtremely simple and it sounds very good. The zener diode rejects any ripple coming from the power supply, But you still only want a ripple of 10mV max. The ripple reaching the input is amplified, so the zener diode gets rid of that, but whatever ripple there is will still reach the power stage.

This Class one Headphone Amplifier circuit is derived from the Portable Headphone Amplifier featuring an NPN/PNP compound pair emitter follower output stage. An improved output driving capability is gained by making this a push-pull Class-A arrangement. Output power can reach 427mW RMS into a 32 Ohm load at a fixed standing current of 100mA. The single voltage gain stage allows the easy implementation of a shunt-feedback circuitry giving excellent frequency stability. . Class one Headphone Amplifier Circuit Diagram : Class-A Headphone Amplifier Circuit diagram The above mentioned shunt-feedback configuration also allows the easy addition of frequency dependent networks in order to obtain an useful, unobtrusive, switchable Tilt control (optional). When SW1 is set in the first position a gentle, shelving bass lift and treble cut is obtained. The central position of SW1 allows a flat frequency response, whereas the third position of this switch enables a shelving treble lift and bass cu...

This solid-state push-pull single-ended Class A circuit is capable of providing a sound comparable to those valve amplifiers, delivering more output power (6.9W measured across a 8 Ohm loudspeaker cabinet load), less THD, higher input sensitivity and better linearity. Voltage and current required for this circuit are 24V and 700mA respectively, compared to 250V HT rail and 1A @ 6.3V filament heating for valve-operated amplifiers. The only penalty for the transistor operated circuit is the necessity of using a rather large Heatsink for Q2 and Q3 (compared to the maximum power delivered).In any case, the amount of heat generated by this circuit can be comparable to that of a one-valve amplifier. An optional bass-boost facility can be added, by means of R5 and C5. 5 Watt Class-A Audio Amplifier Circuit diagram Parts: P1 = 47K R1 = 100K R2 = 12K R3 = 47K R4 = 8.2K R5 = 1.5K R6 = 2.7K R7 = 100R R8 = 100R R9 = 560R-1/2W R10 = 1R-1/2W Q1 = BC560 Q2 = BD439 Q3 = BD439 C1 = 10uF-63V C2 = 10uF-6...