@▷ Hybrid Headphone Amplifier | Diagram for Schematic

Hybrid Headphone Amplifier

Hybrid Headphone Amplifier



 

Hybrid Headphone Amplifier

 


Simple Hybrid Headphone Amplifier DIY Audio Project. Rogers has put together a very simple hybrid headphone amplifier. The head amp uses a 12AU7/ECC82 vacuum tube for voltage gain stage and a IRF612 MOSFET follower biased in Class A with a passive CCS. What is nice about the project is that both the tube and MOSFET operate off of a 24V external switch mode power supply. Read on for more details about 12AU7 Tube / IRF610 MOSFET Hybrid Headphone Amplifier.


Hybrid Headphone Amplifier

I have always been intrigued by tube amplifiers, but most DIY kits are very expensive and use very high voltage. So I decided to build an amplifier that would be inexpensive and had the least amount of parts necessary to drive a pair of 32 ohm Grado headphones.
Having built several YAHA amps based on the fa-schmidt design, and a Szekeres Mosfet follower I wondered how the two would sound together. So I built the schematic into TINA-TI, a free spice based program to test circuits before the build, and the results were remarkable. Nearly 20dB of gain across 20Hz-100kHz from a 24VDC power supply.

As you see in the schematic and parts list, there are less than 30 discrete components and most DIY'ers will have them as spares from other builds. I chose the 12AU7 / ECC82 vacuum tube because it can be driven with low voltage and the filament voltage is 12.6 volts, so there is no need to regulate the voltage much further. I used 1/4W resistors in the first stage and 2W in the second. The 2W resistors may be overkill but I did not want to change them later. The 20ohm resistor must be a minimum of 5W and do not use wire wound, as the inductive characteristics will distort the response curve.


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