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Tension Labs EAP03 Earphone Audio Processor review



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Tension Labs EAP03 Earphone Audio Processor
  • Tension Labs EAP03 Earphone Audio Processor
  • Tension Labs EAP03 Earphone Audio Processor
  • Tension Labs EAP03 Earphone Audio Processor
  • Tension Labs EAP03 Earphone Audio Processor
  • Tension Labs EAP03 Earphone Audio Processor
  • Tension Labs EAP03 Earphone Audio Processor


Our Score:


I'm not usually one to ignore the chance to ridicule grandiose nomenclature, so when I was first introduced to the Tension Labs EAP03 by our resident newshound, Mr Kelly, my first temptation was to mock the name. After all, it's really just another portable headphone amp, isn't it? For once, no. The EAP03 is both much more and just a little less than that.

Released some time ago in the US, but now being introduced to the UK by the guys at Advanced Communications Solutions, the EAP03 is designed to accompany your MP3 player and earphones - more specifically in ear monitors - both on and off the road. The point about IEMs is important. While other portable headphone amps, like the iBasso Boa D2, are aimed more at larger, over the ear headphones - though they also work wonders with demanding IEMs like the Klipsch Image X10s or Shure SE530s (aka the E500PTH) - the EAP03 is focused squarely on the type of thing you wedge into your ear canals. You can use it with full-sized headphones, but that's not really where its strength lies. You see, on top of basic amplification, the EAP03 also provides a range of features aimed at optimising and enhancing the output from IEMs, and making using them a little more practical while on the move.

Measuring 82mm x 53mm x 13mm, the EAP03 has a similar profile to an old iPod mini, and at 55g it's both smaller and lighter than competitor products like the aforementioned D2 or the Graham Slee Voyager Amp (though of course not the miniature E5 and E3). The design is fairly simple, with a 3.5mm input, a 3.5mm output and a mini USB connector, a jog dial on the side and two buttons, a two-line monochrome LCD screen and a microphone on the front. Despite the plastic construction build quality is generally sturdy, and a number of stick-on Velcro patches are provided so you can affix your player to the EAP03 for easy transport. The only other accessories provided are the USB cable (for charging) and a short but chunky 3.5mm to 3.5mm interconnect, for hooking up the input on the unit to the output from your player of choice.

For power, the EAP03 uses a built-in lithium polymer battery, which takes two to three hours to charge and lasts for seven to eight hours at a time. That doesn't compare brilliantly with the iBasso D2, but it's enough for everyday use, if not a weekend trip or long-haul flight.

The EAP03 takes a little more setting up than your regular headphone amp. First of all, you need to know the sensitivity rating of your IEMs in dB/V at 1KHz. Some common Shure, Ultimate Ears and Etymotic models are listed in the manual and you can find more detailed on the Tension Labs website (http://www.tensionlabs.com/support.htm), but you can easily find the information yourself if you need to with a visit to Google.

Once you have this info, you can set up the EAP03 by using the jog dial to flick through the settings and the Audio and Mic buttons to make adjustments. First you set the Earphone Sensitivity, then you set the Amp Gain accordingly - without these two steps, you won't get a great result from the unit. In fact, you'll probably make the sound worse than it is through your player's regular headphone output.


June 28, 2009, 3:02 pm

I'm confused by your comment: "Secondly, the EAP03 isn't designed to power demanding, low impedance, full-sized headphones.". I thought that high impedance phones were harder to drive? Or rather for a fixed current, voltage is directly proportional to impedance.


June 28, 2009, 3:59 pm

The only reason I'd buy this is to see the increasingly incredulous looks from friends and family when I explain its function and its price -- on top of headphones 10x as expensive as they have ever bought. I'll maybe -- maybe -- go for a simple headphone amp (with long battery life) at some point, but the extra features this offers seem like gimmicks, to me, anyway.

The nanny feature is sensible, but if you're sensible enough to use it, you can just as well check up on yourself and regularly ask yourself: "Do I need to listen at this volume?" I try to do this, and my volume level varies a lot along with what I'm doing and my mood. (But I'm sure it's still bad for my hearing.) I also wonder how accurate their calculations are -- for instance, at least my perception of volume varies a lot when I just reposition my IEMs. And can you really accurately calculate the db produced using those response figures? If so -- neat.

As for the microphone feature, I guess some people do need this, and Etymotic (I think) has a cable in-line adapter that does the same thing. Personally, I don't think any of the (many) IEMs I had really had such an effective seal that I flat out could not understand people talking in a normal voice when the music was paused. I can (and do...) go about most things with my IEMs in place. On the other hand, I often remove them because it's simply impolite to leave them in -- for instance, at the checkout in a shop, I remove them because it's just rude otherwise, even though I can understand the cashier just fine.

The sound expansion features, finally, seem like something the player should do, really, and I'd think most of them do have these features (equalizer etc.).


June 29, 2009, 2:47 pm


You're quite right. I meant high impedance but for some reason typed low. Will get this fixed asap.


June 29, 2009, 2:55 pm


Fair enough - this product isn't for you. I think it does have a niche with people who own and love high-end IEMs, and for them it's a decent choice. As I said in the body of the review, if you just want a simple, basic and very affordable amp, you can't go far wrong with the FiiO E3 and E5 (£10 to £20), but even then you're better off splashing out on the headphones first, and the amplification second.


July 25, 2009, 4:21 pm


GoVibe Martini for you, then. 400hrs of battery life purportedly and small and relatively cheap, but much more of an investment than a FiiO.

fix a fix

July 31, 2009, 9:43 pm

I bought this product and was so disappointed by the amount of hiss I was experiencing with my custom IEMs (ACS T2) that I returned it for a refund. What with shipping and exchange rate differences, it turned out to be an expensive trial. :-(

Tension Labs' Steve Iseberg seemed surprised that I should be able to hear the hiss as he later tested the unit with his most sensitive headphones. I, however, found the hiss present at all gain settings and regardless of whether plugged into my source (ipod on or off) or not. (And obviously with the ambiance mic off!).

Steve promised to let me know the results once he had run it through his production test system which was being upgraded so was unavailable. That was April and I still haven't heard back from him :-(

I have been keeping an eye on the Tension labs site in case a better product emerged but this doesn't seem to have happened yet. My father has some hearing loss in one ear and I was hoping to find a product that would have at the very least: a balance control, and ideally a parametric EQ which could be configured differently in each channel.

In response to Morsch's comment about still hearing what people say with the IEMs in place, I find the soft silicone used to make the ACS T2s make them particularly effective at blocking out external sounds so I really have to remove them to hear someone talking to me - the EAP 03 ambiance mic would have been helpful if the sound quality issue hadn't forced me to return it.

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