Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

DoZ Headphone Amp

DoZ Headphone Amp

You really need to see the original article – Project 36 – to see all the design details for this project. The project presented here is simply a modification of the original design, with much lower power dissipation and adapted specifically as a headphone amplifier.
Class-A is ideal for this application, since headphones are such an intimate way of listening. An amplifier for ‘phones should be as clean and free from crossover distortion as possible, and must also be quiet. A background of hiss and hum does nothing to enhance the listening experience.

Headphone amps are somewhat misunderstood, but in reality there are few points that need to be made. Most ‘phones are designed to be operated with a source resistance of 120 ohms, and damping factor (as applied to conventional loudspeakers) is largely irrelevant. The actual source impedance should have very little (if any) effect on the frequency response or dynamic behaviour, since there is no cavernous enclosure and no heavy cones to try to control.

The IEC 61938 international standard recommends that headphones should expect a 120 ohm source (5V RMS maximum) – regardless of the headphone’s own impedance. If the manufacturer followed this standard, the 120 ohm resistor used in this circuit will not affect sound.

Power requirements are usually in the 10 to 100mW range, and this is quite sufficient to cause permanent hearing damage. With the current set for 330 mA as suggested, this amp will be able to drive a minimum of 2 (but probably 3) sets of headphones at once. With 40 Ohm ‘phones, it can give a maximum power of over 150 mW, so caution is needed to prevent hearing (and headphone) damage. Even with 8 ohm ‘phones, power will be about 110mW – more than enough to have you asking people to repeat everything they say.

Description

The final circuit for the DoZ headphone amp is shown in Figure 1. It is almost identical to the original (well, apart from the output transistors and size of C3, it is identical), and there is no longer the need for massive heatsinks and TO-3 output transistors. As shown, there are outputs for 2 sets of headphones. Needless to say, only one channel is shown – the other is identical.

For final testing you will need a multimeter. As shown in the power supply circuit below, use a 10 Ohm resistor in series with the power supply positive lead. When you measure 1 volt across this resistor, this means that the amplifier is drawing 100 mA. The resistor remains in circuit, providing a useful reduction in supply ripple. You will lose about 3.3 V at operating current, and a 5W resistor is sufficient – it will get slightly warm. The output resistors (120 Ohm) should be rated at at least 2 Watts – a pair of 220 ohm 1W resistors in parallel will do just fine (the absolute value is not critical).

Visit Here for more.







 

More Articles to Read

Gesture Controlled Smart Home
Gesture Controlled Smart Home
Design for a Wideband, Differential Transimpedance DAC Output
Design for a Wideband, Differential Transimpedance DAC Output
Wrist thrusters let you fly through the water effortlessly
Wrist thrusters let you fly through the water effortlessly
Bertan/Spellman 225-20R HV power supply teardown
Bertan/Spellman 225-20R HV power supply teardown
Blinking Christmas Lights
Blinking Christmas Lights
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adding an “extra sense” with rangefinders
Adding an “extra sense” with rangefinders
This wireless game controller looks like a rug
This wireless game controller looks like a rug
How to run your ESP8266 for years on a battery
How to run your ESP8266 for years on a battery
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Making beats on a tiny Arduino DJ controller
Making beats on a tiny Arduino DJ controller
Qinsi-QS5100 Sn63Pb37 solder profile
Qinsi-QS5100 Sn63Pb37 solder profile
Water Detection System
Water Detection System
Professional Hi-Fi 15W Tube Amplifier circuit
Professional Hi-Fi 15W Tube Amplifier circuit
This Arduino machine will judge how sick your ollies are
This Arduino machine will judge how sick your ollies are
Turn an old payphone into a boombox for ’90s hits
Turn an old payphone into a boombox for ’90s hits
Big F’n 3D printer build
Big F’n 3D printer build
Temperature alarm for boiling milk
Temperature alarm for boiling milk
QuadBot is a 3D-printable walking robot for everyone
QuadBot is a 3D-printable walking robot for everyone
MicroConverter I2C Compatible Interface
MicroConverter I2C Compatible Interface

Top


Shares