A Portable Headphones Amplifier: Introducing Pocket Amp 2 - Version 2 (PA2V2)                 A Wonderful Sounding, Hi-Fidelity Pocket Headphone Amp

By plugging your headphones into this amp instead of directly into your music player, you will help your headphones to reach their full potential. The amp should improve the overall sound quality of your listening experience. In many cases it makes quite a noticeable difference. Not only does it make the music louder, but more importantly the amp creates deeper, more powerful bass and clearer high frequencies. This is the type of sound you might hear after plugging your headphones into a powerful, full sized home stereo. It is my hope that you will hear and experience your favorite songs in a new and exciting way after adding the amp to your system - that it will really bring your headphones to life! It is interesting to listen to your favorite songs all over again and hear some of the things that have been missing.

A couple years ago while still an electrical engineering student at university, I built Pocket Amp 1 [PA1] to help pass the long bus rides to and from school each day. A few months later PA1 was offered to share with, and help serve the needs of the audio community. Since then over 2800 amps have been ordered and they have found owners in 45 different countries around the world.

The PA2V2 circuit is based on the evolution of its predecessor that won the award Best Design Project at the International Conference for Upcoming Engineers in 2004. The PA2V2 received a review in the WholeNote, Toronto’s leading Opera and Classical magazine. Recently, the amp was featured in a small section of the Absolute Sound magazine which was quite an honor. You may click on any of the three previous links to read more. You may also look at my eBay feedback record to read what many kind people have written about their amplifiers.

As a labor of love, a lot of hard work and careful thought has gone into this amplifier because it is very special. The amp has been improving nicely over the past two years. Now over 100 people order a PA2V2 each month. This increased demand means I can buy the parts in larger quantities to get lower prices at the electronics store. Instead of keeping the savings, I just put the money back into the amp and upgraded some parts.

For example, every single capacitor in the PA2V2 is now from Panasonic’s high end series. Two upgraded 2200 uF output capacitors replace the previous 1000 uFs models and two 470 uF input capacitors replace the previous 220 uF models. The result is very solid bass, even at high volumes, and crystal clear high frequencies. To pick these capacitors I built a test circuit and tried a large number of different models and sizes on the market to find the best sounding combination. There is a higher quality Bourns potentiometer, stronger input and output jacks, and a comfortable new soft-touch, Swiss made control knob. All these parts populate a professionally built circuit board and together, create an improved build quality. Each amp is hand built and tested by myself, a recent electrical engineering graduate.

Most portable devices have an output power under 20 mW (milliwatts). This often isn't enough to enable a decent pair of headphones to reach their full potential. The PA2V2 has an output power of up to 200 mW RMS and makes the music louder by a factor of 610%. The amp can power speakers too, not only headphones. For a small device it can output a lot of power. The frequency response goes from 5Hz to well beyond 40KHz. Critical components are joined with thick, point to point traces for maximum conductivity. The signal to noise ratio (SNR) is 100 dB. Actually, with the volume turned on maximum, and no music playing, there is no static sound or hiss, which is something desirable. Building an extremely quiet, low distortion amplifier was a high priority. An improved power supply filter circuit almost eliminates the 50/60 Hz humming sounds some owners reported when listening with the AC adapter plugged in.

The amplifier is quite small and built to last inside of a strong Hammond ABS enclosure. The amp measures 2.6" by 2.6" and 1.1" thick. You could actually walk on the amp and not break it. A beautiful ruby-red tinted window is used for the faceplate and provides a glimpse into the amp’s circuit. Shining through is a super bright red LED on/off indicator. This light creates a nice effect in the dark and helps you to find the volume knob. This is great if you enjoy spending time at night with your thoughts and favorite music.

Along with the PA2V2 you will receive an AC adapter. You can plug this in to recharge the two AA batteries while still inside the amp, or simply for when you are using the amp at home. The nice thing is that after you install a pair of AA rechargeable batteries, they wouldn't have to be taken back out for a few years. The adapter could be plugged in to charge the batteries over and over again. The amp is quite efficient so a fully charged pair of batteries can last over 100 hours. I know how it feels, to run out of batteries in the middle of a long trip so I made sure the amp would last a very long time and be dependable. This feature saves you the money, time, and trouble of changing the batteries every time they run out. A 3-foot cable is also included for connecting the amp to your source device.

Examples of the many devices that can be used with this amplifier are portable MP3, CD, DVD, Mini Disc (MD), and Cassette players. You can basically use the amp anywhere there is a line-out or headphone jack, such as with your home computer, laptop, television, Am/Fm radio, or portable gaming system. This amplifier works great with all types of headphones including those made by AKG, Audio Technica, Beyerdynamic, Etymotic, Grado, Koss, Sennheiser, Shure, Sony, Ultimate Ears, Westone, and many more. Using a nice pair of headphones with this amp will help do it justice.

The picture below presents some more information about the amp's features.

Ever since the first amplifier was built I have been keeping an online pictographic archive of the name and location of each amp's new owner. Some owners even shared their own pictures, which is very kind. Each amplifier has a unique serial number printed inside.

I will stand behind this product and be happy to service any amp (at no charge) should anything ever go wrong, and this offer extends for the rest of my life. I’ll admit, a few amplifiers have come back for repair and they were fixed, then returned by the next day. Even if the amp breaks and it’s your fault, it doesn’t matter, I will still fix it.

A lot of care is taken when mailing the amplifiers. The amps are surrounded with bubble wrap, then wrapped inside a plastic bag, just in case it rains on the day a person receives their amp. Everything then goes inside a padded envelope and the amp is ready for the journey to it's new home. Each  amp is mailed as a "Gift" and no one has ever reported having to pay a Customs or Duty fee upon arrival.