The speakers on many smartphones can be painfully lacking in detail and bottom end, and really start to distort when the volume is pushed to levels guaranteed to annoy fellow commuters. Listening to music with the help of the built-in headphone jack will almost certainly offer an improved sonic experience, but high quality? Probably not. External headphone amps can help to increase the quality of mobile music devices, but (with some notable exceptions) these can add significant bulk to your pocket. A tiny new headphone amp named Uamp is making a bid for production on Kickstarter and, though small in size, its makers reckon that portable music lovers are in for a clearer, louder and richer listening experience.
The pre-production prototype of the Uamp measures 1.69 x 1.69 x 0.36 in (43 x 43 x 9 mm) and tips the scales at less than an ounce (26 g). If you wear jeans with one of those handy coin pockets to the right, then the tiny headphone amp has been designed small enough to fit in there while the cabled smartphone slots into the pocket proper.
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It's said to offer five times the power of the amp found in an iPhone, and is capable of increasing the volume by up to two and a half times without any harshness or distortion creeping in. All of which means that you can turn down the volume level of the source device so that its own amp doesn't have to work so hard, and rely on the Uamp to deliver improved audio quality at the same comfortable listening level.
"With this project our aim was to get the high quality headphone amplifier experience to as many people as we could, and we found that the convenience factor was the biggest barrier, most people did not want to carry a device that was essentially the size of another phone," Uamp's Joe Chehade told us. "There are not very many options for headphone amplifiers that are truly convenient, so we thought we could innovate by having a better design inside an out. The Uamp is an analog design, a headphone amplifier with no DAC or DSP included, we wanted to focus on what we thought was the weakest link in most portable music players which is the headphone amplifier."
Within its cool aluminum housing, the Uamp uses precision low noise op-amps from Texas Instruments with three stages: EQ, volume and output buffer. There's a dual rail power supply with low noise voltage regulators and plenty of filtering (so that it can be used with USB power). The electronics also allow for inline controls and microphones on headphone cables to be used for controlling source playback or taking calls.
Its rechargeable battery is claimed good for up to 10 hours and is charged via micro-USB (though we have no info on how long it takes to charge). When the battery's juice does run out, the audio signal will not pass through the unpowered Uamp – so users will need to unplug the middle man and connect headphone directly to the source device until the Uamp's battery gets topped up.
The pint-sized headphone amp is said to be compatible with most consumer headphones and earphones (with a 3.5 mm jack) thanks to a high input impedance. Chehade told us that "the current prototype can do 100 mW into a 16 Ohm load, and 10 mW into 300 Ohms which should drive a pair of HD600s to a decent volume. Current tests show around 0.01 percent THD but we believe with the next iteration of design we can get that number down further, and hence we haven't yet published the full measurement test results."
The Uamp's five EQ presets are selected using a button on the side. There are two bass-boosting settings, one that gives the treble end a kick, another that's been specifically developed for listening to streaming audio from services like Pandora, YouTube and Deezer, and one with a flat response. Users can also create a custom EQ setting to match personal tastes. LED status lights act as visual EQ and status indicators.
The crowdfunding campaign has already blown through its modest AUD15,000 target and, unsurprisingly, all of the early bird units have been snapped up. The lowest pledge level remaining is AUD65 (about US$50), and if all goes to plan, the first units will start shipping this coming July.
Have a look at the pitch video below for more on the Uamp.