DIY Class A Headphone Amplifier

The computer sound card just didn't cut it when it came to driving my 32 ohm Grado SR80 headphones, so the need arose for a decent desktop headphone amplifier. Lately I have been reading a lot about Class A amplifiers and have been eager to try one, so a small and simple Class A headamp seemed like a logical first step in this direction.


The circuit is a simple single-ended amplifier with an active load. An inexpensive IRF610 MOSFET is used as the output device and a LM317 voltage regulator is configured as a constant current source (CCS). The power supply is a regulated wall wart which works very well and there is no hum. For the enclosure I used a dead external CD-ROM. This worked out very well as it will reside on my desk at work. I'm sure everyone will be wondering why I have an old external CD-ROM hooked up to a new laptop!


The results were very good. Despite the simplicity of the amplifier circuit it sounds surprisingly good. For more details, photos and a schematic, see the DIY IRF610 MOSFET Class A Headphone Amplifier Project page.

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DIY 8W Class A Amplifier

Dan in Australia has put together a great looking Class A amplifier. The circuitry of the amplifier is based on the popular article "Le Monstre" by Jean Hiraga which appeared in Issues 27, 29 and 31 of the French Magazine l'Audiophile.

Dan used the board layout, transistors and JFETs documented in the articles. However, instead of using a capacitor bank and battery setup, this amplifier uses regulated power supply.

The photograph below shows an early version of the amplifier.


Dan later added additional capacitance and rearanged the wiring as shown in the photo below.


Dan reports that he is very pleased with the sonic performance from this amplifier. For additional information about this amplifier project, see Jean Hiraga's Le Monstre - DIY Class A Amplifier Project.

Related DIY Solid State Audio Projects:

• Mark's DIY Class A 2SK1058 Mosfet Amplifier Project
  
• Jochem's DIY Class A 2SK2221 Mosfet Amplifier Project

DIY Class A Mosfet Amp

Shown below is Jochem's first DIY Audio Project, a build of Mark's DIY Class A 2SK1058 Mosfet Amplfier project.


Jochem's build of this very simple Class A Mosfet amplifier uses the 2SK2221 Mosfet instead of the 2SK1058 that Mark used. The power supply has been modified slightly and uses two large toroid chokes for good filtering. The photographs below show the finished amplifier.



Jochem is very pleased with the results of his first audio project and is looking forward to completing more DIY Audio Projects in the future.

For additional information, pictures and schematics, see the complete project writeup of Jochem's DIY Class A 2SK2221 Mosfet Amplifier Project.

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Class A MOSFET Amplifier

Another one of Mark's projects has been added to the DIY Audio Projects web site. This time, Mark has put together a very simple MOSFET amplifier that he has fashioned after a single-ended (SE) tube amplifier.


The amplifier uses a single MOSFET and the results are a very simple Class A SE amplifier with a low parts count. As with all of Mark's projects, the enclosure work is top notch.


For more information and photographs about this project, see Mark's DIY 2SK1058 Single Ended MOSFET Amplifier Project page.

Related Projects:

• Jochem's DIY 2SK2221 Class A MOSFET Amplifier Project
• Pictures of Michael Edwards DIY Class A Amplifier Project
  
• Pictures of John's DIY Class A Mosfet Amplifier Project
  

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