Simple Phono Preamplifier

Simple circuitry suitable for moving-magnet cartridges Passive high-frequency equalization. This simple but efficient circuit devised for cheap moving-magnet cartridges, can be used in connection with the audio power amplifiers shown in these webpages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency transients behavior due to passive equalization in the 1 to 20KHz range. Transistors and associated components provide ±18V supply to the op-amp, improving headroom and maximum output voltage.

Source:http://www.redcircuits.com//Page10.htm

Soundblaster Preamp

The Sound Blaster 16 PCI and Sound Blaster 16 ISA do not have a very sensitive microphone input. This little one transistor amplifier is powered directly from the microphone jack on the sound card and has LOTS of gain. Just put a 100uF bypass capacitor in parallel with the diode to increase gain even more.

Source: http://members.shaw.ca/novotill/SoundBlasterPreamp/index.htm

Subminiature 40W Stereo Audio Amplifier Module Kit

The UAM4 is the big brother to Ramsey's extremely popular UAM2. It uses the latest spread spectrum amplifier technology to bring you clear, crisp, high-power audio without any of the heat which is normally associated with such an amplifier.

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10-14W Class A amplifier by TIP3055

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 extremely simple and it sounds very good.
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Power Amplifier Class A 25W

Musical Fidelity would let you believe that this is a Class A design. However, in common with most commercial amplifiers, it is a class AB amplifier - it simply has a rather high standing current in the output stage, which results in the first 8 watts or so being class A.
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Power Amplifier Class A 25W

Musical Fidelity would let you believe that this is a Class A design. However, in common with most commercial amplifiers, it is a class AB amplifier - it simply has a rather high standing current in the output stage, which results in the first 8 watts or so being class A.
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200W MOSFET Amplifier Hifi audio powerhouse

A compact audio powerhouse ideal for guitar or PA work or for use as a general-purpose subwoofer or hifi amplifier. Many people prefer Mosfets because of their legendary ruggedness. Altronics had a Mosfet amplifier module which produced 200W into a 4 Ohm load and so we decided to take a look it.

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Power Amplifier MOSFET HI-FI 300W by 2SK1058, 2SJ162

The amplifier consists of two completely separate monaural amplifiers each channel has its own power supply, resulting in zero inter-channel cross talk, a common phenomenon in amplifiers sharing the same power supply. In order to obtain the full output power each supply transformer should be rated at 40VAC - 0 - 40VAC at 640VA.

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50 Watt Amplifier with ICL8063 and 2N3055

This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source.

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Power Amplifier with STK40xx Series Module

The series STK40xx is power amplifiers in completed form in a nutshell. They are characterized by the very good quality of sound and their low price. It is easy we make a power amplifier using only few external components.

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