Picture of How to make a pocket headphone amp!
In this instructable, I will be showing you how to make a  headphone amp. If you have some big headphones such as Sennheiser, beats by dre or some other big headphones (in my case, some sony MDR-XD100) an or an MP3 player isn't enough, especially if they have a high impedance. This circuit was originally  developed by a man by the name of and it has been extremely popular. There is only one difference with mine (and most others) and that is the fact that he used two single op-amps and we will be using a dual op amp.
So lets get started!

Please don't be too critical, I'm only 14!
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Step 1: Parts

Picture of Parts
Here are the parts you will need:
OPA2134PA op-amp. There are alternatives but I have had most success with this one. The only other one that I would recommend is  OPA2132
1x IC socket
2X 470uf or higher 10V capacitors
2x stereo audio jacks
2x 0.2uf MKT or pollyester capacitors
2X Pannel mount LEDs
1X NPN transistor
1 or 2 9V battery clips
male header pins
1X stereo 10k potentiometer
10k, 100k, 1k, 4.7k, 47ohm resistors (I got packs of 8)
2x SPDT micro switches
3v button cell and holder


Step 2: The POWER section

Picture of The POWER section
Follow the schematic for the power section if you can. 
1. mark a line with a width of 2 holes right down the PCB board. This will be the ground.
2. Solder in the male header pins for + and -
3. Now solder in the Two 4.7k  resistors. 
4. Solder in the 470uf capacitors
5. Look at the diagram (pic 5) and look closely at the "stray" resistor. this is 1k and it's for the power LED
6. try and solder it so it's as compact as possible
In the diagram, the green lines represent the under-board connections. They are usually made with jumpers or solder. In the last picture, I have an example of the under-board connections or "green lines"
Don't worry about the other parts in the last picture, they are for later.
chillrov10 months ago

sir can i have a clear schematic please?

dog digger (author)  chillrov8 months ago

Schematics are available from tangentsoft and here's a link from their site:

rotem1 year ago
how do i make the left channel and the right channel to one 3.5 mm connector

i mean how do i connect it to 3.5 mm jack and make it stereo
dog digger (author)  rotem1 year ago
On the stereo connector, you should have 3 pins. Left, Right and ground. If yours only has 2, then you have a mono connector
nkhoo1 year ago
Can you explain what the header pins are for? I apologise for my inexperience but i am very blur. Any explanation would be greatly welcome. Thank you in advance
dog digger (author)  nkhoo1 year ago
Sorry for the very late reply but I used them because they make it easier to solder wire to the PCB so if something goes wrong, it's easier to troubleshoot
can you draw up a diagram of the circuit and send it to me
mdog932 years ago
Will ANY NPN transistor work? What criteria does it need?
agm88 mdog932 years ago
oh and an s9014c transister is pre amp low noise and low level transister
but i would rather use a bc548 for the LED synce
agm88 mdog932 years ago
any NPN general purpose transister will work like for example
2n4401 works quite well
and bc548 which is eqivalent to a 2n3904
Knerps2 years ago
This looks great, +1 EET1982, can you provide a single schematic?
EET19822 years ago
Very cool instructable. I will be building it soon. Would you happen to have a full schematic of the circuit?
jeddlestone2 years ago
will 2 470uF 16V Radial Electrolytic Capacitors work instead of 10V rated?
antmanadam3 years ago
Can you tell me what exactly what pot you have an where you got it
dog digger (author)  antmanadam3 years ago
It's a 10kohm dual log potentiometer (generic) found at my local electronics store.
Would a BC548 work for this application?
The only other ones I have are S9014C.

Are either of these ok for this purpose?
dog digger (author)  mdog932 years ago
Any general purpose transistor will work so yes, they will work
toj cookies3 years ago
nice job
lewster3 years ago
nice instructable, dog digger!
jman 313 years ago
Nice job! It's great to see young people like yourself getting interested in electronics!