Some arcane audio gadgets aren’t really necessary to have, but they can make listening to music more enjoyable. Portable headphone amplifiers to go with MP3 players definitely fall in that category. The bad thing is that not all of those portable amps are actually good, and with some it’s not clear if they even do anything (depending on the MP3 player or headphones they’re paired with).
Quite a few manufacturers are trying to make a living in that rather specific niche market – yet many actually fail to deliver products that really improve either sound quality or a player’s usability. Be it by fixing flaws that are found in an MP3 player’s amp circuitry, by giving better volume controls than the usual +/- buttons, by bypassing arbitrary volume restrictions which make some players unusable with certain headphones, and so on. Many amps out there of course make sound louder, but that’s about it. Only a few of the amps I’ve tested so far actually make the sound – as well as the overall listening experience – better.
Robert Gehrke, the man behind the German Headstage company (also of Penguin Amp fame), makes good amps. There’s no big advertising-speak around his products and he doesn’t put some mere basic CMOY-style circuitry in an overly fancy enclosure and calls it a day. Well, besides the venerable Penguin Amp, which is clearly labeled as an advanced CMOY – and Altoids tins might be considered fancy by some. That being said, Robert’s current amplifier, the Arrow 12HE, is definitely among the best products to hit the portable amp market so far – read on to find out why.
- Automatic Power Adaptation with up to 12V Internal Voltage
- 36 Hours Play Time in Lowest Power Mode (5V)
- 15 Hours Play Time in Highest Power Mode (12V)
- Analog AD8397 Opamp in Output Stage
- Three Selectable Gain Settings (1.2dB, 10.5dB, 20.9dB)
- Two-Step Bass Boost (Off, Low, High)
- Two-Step Öhman Crossfeed (Off, Low, High)
- Two-Step Impedance Setting (10/70/120 Ohm)
- Automatic Power Switch (OFF/ON/AUTO)
- High-Capacity 1200mAh/4.2V Lithium-Ion Battery
- High Efficiency Battery Charging from USB Port
- Easy Battery Replacement without Soldering
- Symmetric & Short Audio Paths with Low Noise
- Two Audio Jacks on Top and Bottom Side
- ALPS Analog Volume Potentiometer (Not Digital!)
- Illuminated Bi-Color Power Switch
- Low-Battery Blink Indication
- 4-Layer Circuit Board with two Ground Planes for Low Noise
- Black Anodized Aluminium Case with Laser Engraving
- ABS End Panels with White Silk Print
- Size: 8.4mm x 56mm x 98mm (0.33” x 2.20” x 3.86”)
- Weight: 75g
Photos by Headstage show the final product – my own photos show a prototype enclosure that doesn’t have laser engravings.
The Arrow 12HE and its accessories arrived in a cardboard box, in some bubble wrap – nothing else. This is a very positive first impression for my taste. I don’t like ostentatious, useless packaging – every time I get some gadget packed in pseudo-fancy wooden, metal, leather or otherwise glossy/shiny boxes, I cringe a little due to wasted resources, wasted material, and due to the fact that over-the-top packaging increases a product’s price, even if its box is never to be used again. For a first impression I rather have the product’s quality speak for itself than being distracted by some blingy packaging decoy. Sennheiser IE 8, I’m particularly looking at your box…
First thing one notices is how incredibly flat the amp is. It’s actually so flat that some standard 3.5mm plugs protrude on the top and bottom of it. It’s also rather lightweight, and easy to pair with any audio/video player (the Arrow comes with four Velcro dots and some double-stick tape to non-permanently attach it to any surface of your choice). Everything about the amp is functional, there’s no superfluous design cues to be found. A lot of amps look more blingy, and some appear to be built like a tank. While the Arrow doesn’t look as macho as a Humvee-equivalent of a portable amp, its anodized aluminum shell sure is sturdy enough to withstand any abuse – and it’s way easier to put in your pocket than aforementioned bulky, over-designed amps.
On the front side of the amp sits the power switch, made of transparent plastic. It sticks out a bit and on first impression it doesn’t appear to be overly solid. Looks however can be deceiving, and it sure feels sturdy enough. The switch is illuminated by two LEDs inside the amp. It glows red during operation, green during charge, and mixes both LEDs orange when the amp is turned on while it’s hooked up to charge. It would be more logical that the amp indicates green during operation and red during charge, at least according to a ‘traffic light logic’ (like most other chargeable electronics out there) – but since I like a menacing red HAL9000 light more than a green one, and I only look at the amp when I’m using it anyways, I’m happy with the way it is.
Next to the power switch is the headphone-output jack, the volume potentiometer, and one of the two input jacks. First I thought the placement of the volume control between the two jacks is a bit narrow, and the volume dial is hard to reach. I’ve got used to that however in no time, and actually appreciate now that it’s not too easy to change the volume by accident.
This volume dial is of ye olde analog style, not a digital one, as is the current hype with portable audio gear. While a well implemented digital volume potentiometer with enough steps could certainly be nice, it would increase the price of the amp immensely, just for a novel idea with not all that much real improvement. The Arrow’s standard ALPS volume pot works perfectly well, with no crackling and no distracting channel imbalance, even around the quietest settings.
On the back of the amp is the USB charging port and a second input jack. In some setups an input opposite to the output sure might come in handy. That’s another quite unique and ingenious solution of the Arrow: what other amp adjusts itself to your needs – instead of the other way round? Another quite cute thing to mention is that both the front- and back plates can be reversed. They’re also labeled on the inside, up/down reversed – so you never have to be bothered by upside down fonts on your portable rig! That’s almost bordering on being OCD, but it sure shows that the manufacturer really cares about their product.
Between those two aforementioned jacks is where all the tweaking goodness takes place. It reminds me quite a bit of the features found on those obscure Xin Supermacro amps that were around some years ago, but with even more steps to the settings on the Arrow. The four switches aren’t particularly logical in their increments (Bass: 0-2-1, Crossfeed: 1-0-2, Gain: 2-1-3, Impedance: 0-2-1), but one gets used to that in no time and can operate them without looking. I guess it’s just not possible to implement all switches equally.
The Arrow’s bass boost comes in the flavors ‘subtle’ and ‘noticeable’: meaning, a 3.5dB or a 9dB boost. It’s a remarkably punchy and tight bass boost compared to many other amps with a similar feature. Especially the 9dB boost starts rather low: its slope is centered around 100Hz and its peak is at 25Hz, so it doesn’t muddy up the midrange at all. The 3.5dB boost’s slope centers around 250Hz and peaks at 60Hz. All in all, the Arrow’s bass is excellent; it’s the best ‘hardware’ boost I’ve heard so far. The MiniBox-E+’s bass boost sounds muddy in comparison, the FiiO E7 and E5’s isn’t absolutely clear either and rather subtle, and the iBasso T4’s bass boost is completely useless, it’s barely noticeable. [Note: The Arrow’s bass boost might be different in the final product, boosting by 6dB and 12dB, respectively.]
The Arrow’s crossfeed filter is built after a design by Swedish audio engineer Ingvar Öhman. What it does is feeding the sound of one stereo channel delayed and attenuated to the other channel, to imitate how sound waves act in open air, compared to how headphones can feel ‘claustrophobic’ and fatiguing since both ears get only their respective channel of the stereo signal but not a mix of both. In short, with crossfeed engaged your left ear gets fed a little bit of the signal that’s meant for the right ear, and vice versa, resulting in a more “out of the head” experience. The way this works in the Arrow is very natural and smooth to listen to. I haven’t heard any other hardware crossfeed solutions, but many software crossfeeds like the ones in Rockbox or some VST plugins can sound somewhat nasal or muddy. The Arrow sounds crisp and precise on both settings, low and high. Stereo imaging width becomes a bit narrower with crossfeed enabled, rather noticeably on the higher setting, but it makes sound more natural and pleasing when listening to ‘extreme’ audio material, like for example most 1960-70ies recordings. Back then the concept of stereo was new and sound engineers often used to hard-pan instruments 100% to the left or right. This is almost unbearable to listen to with headphones – the crossfeed ‘fixes’ such records very well. Another application for it is watching movies; especially ones with (downmixed) surround sound. Since I’ve gotten used to the Arrow, I can’t even imagine how I used to watch movies on my PMP before, without crossfeed.
Next there’s the gain switch of the amp. On the lowest setting the gain is 1.2dB, which means more or less pass-through of the original signal, useful for very sensitive IEMs to just “fix” MP3 player hiss, crosstalk, and/or bass roll-off, and to use the Arrow’s sound tweaks. The two higher gain settings boost the signal by 10.5 and 20.9dB, respectively. Which one to use is only dependent on how efficient the attached phones are, and how loud one prefers to listen to music. My 300 Ohm Sennheiser HD 650 are already loud enough for my taste on the middle gain setting, and can go to really respectable SPL on the highest one. To my ears the gain settings don’t alter the sound in any way, but it is hard to thoroughly test that, since one has to adjust the volume dial to counteract the gain, making a volume-matched AB-comparison a bit tricky.
Gain can be used in combination with the impedance switch. The basic effect of this switch is that attached phones get quieter when it’s engaged. Added impedance also removes hiss from sensitive phones, even on the highest gain level. It can alter the sound character of some phones, attenuating high frequencies a bit. This isn’t apparent with all phones, and depends on the impedance the phone itself has. I generally find multi-armature IEMs with crossovers (like SE530, UE11, or ATH-CK100) to respond the most to added impedance in this aspect, but that could be coincidence. Using both gain and impedance can alter those phones performance in a subtle way. The lowest impedance setting isn’t zero, it’s 10 Ohm – this helps getting rid of hiss from any phone while still being low enough as to not alter the sound. The two higher settings are 70 and 120 Ohm. An additional 70 Ohm is the classical “P-to-S” tweak, named after the fact that one can make a 27 Ohm Etymotic ER-4P phone sound like its (presumably better sounding) 100 Ohm ER-4S sibling.
Besides the switch-activated tweaks, my favorite feature of the Arrow is its ingenious way of automatically powering on and off. In automatic mode, the 12HE powers up as soon as it gets a signal on the input (it takes less than a second to turn on), and it turns itself off after a minute of silence. In normal mode the amp doesn’t automatically power up, but it still shuts down on its own after 20 minutes of silence to conserve the battery. There are some other amps like the FiiO E7 or Practical Devices XM5 that have a sleep timer, but it’s much more comfortable to have the amp turning off on its own without any interaction – and turning on the same way. I actually never use the power switch at all; automatic mode is all I need. Pure ‘set and forget’, never having to worry about a drained battery anymore. Robert Gehrke told me leaving the amp in auto-mode all the time doesn’t deplete the battery any more than when it’s turned off. Battery self-discharge should be higher than what the amp needs for stand-by mode, so it’s negligible.
Let’s take a look at some less obvious features… The battery inside the Arrow has the same dimensions as the 4th generation iPod Video’s battery – so it should be available for the foreseeable future without any problems. Headstage sells matching batteries on their website, fitted with a plug so no soldering is needed for replacing them once their time has come (which usually is about 5 years or so before modern Li-Ion batteries get too short battery life for real usage, give or take a few).
The amp can automatically adapt its power output to match the attached headphones requirements; from its 3.7V battery it can boost as low as 5V for sensitive phones and can deliver up to 12V for demanding high-impedance ones. With efficient IEMs the battery can last up to the claimed 36 hours (verified by me). With less efficient, full-sized phones at 12V it should give about 15 hours (not verified, but I take Mr. Gehrke’s word for it). For my usage patterns, the amp lasts about a week before I need to recharge it. There are certainly amps out there that can get twice the battery life of the Arrow or more, but they’re also more than twice as big usually – yet many of them can’t drive 300 Ohm phones as well as the Arrow does. That’s why the “HE” in the amp’s name stands for “high efficiency”.
Another battery-related feature is that the Arrow sounds good until the battery runs completely dry. Most other amps will start sounding distorted or develop an annoying ticking sound when their battery voltage gets too low. The Arrow’s switching power supply manages to keep the amp sounding as it should until the very end – and low battery is indicated via the power switch’s blinking red LED. That’s quite subtle compared to the aforementioned noisy alternative.
Last but not least: Unlike some overly dramatic manufacturers (you know who you are) Headstage has nothing to hide – the chips used in the amp aren’t filed off or their markings hidden beneath a layer of nail polish. Not that anyone cares, and such operatic secrecy shouldn’t make a product any more desirable to copy anyways (if we lived in a perfect world). The Arrow uses an Analog Devices AD8397 opamp in the output stage, a chip that performs admirably well. It’s very powerful, very fast, very low noise – yet somewhat finicky to properly implement in an amp design. In the Arrow it certainly looks/sounds as if it was used the right way.
Now some audio purists might think that so many features and components in an amp might affect the sound quality in a negative way. That definitely isn’t the case here at all. The Arrow is perfectly linear and transparent sounding, more so than some pricier amps I’ve tried. Sometimes apparently more is more.
Just like any amplifier worth its money, the Arrow has no distinctive ‘sound’ of its own (when one doesn’t engage bass boost, crossfeed, or added impedance). It’s neither ‘cold’ nor ‘warm’ sounding, or similarly vague descriptions one might have read about devices like this. It’s just how an amp should be: it transparently amplifies an input signal and delivers it in the best way possible to a pair of headphones. It fixes the flaws most MP3 players display with certain headphones, be it background hiss or rolled-off bass response with low-impedance IEMs, or lacking dynamics and too quiet sound with high-impedance phones. It can add ‘flavor’ to the sound with its bass booster, crossfeed, and (with some phones) impedance switch, but it doesn’t do so by default.
That’s basically all there is to say about the 12HE’s sound: it’s how an amp should behave. There’s nothing esoteric about it. And that’s more than can be said about the multitude of other portable amps I’ve tried so far.
So what does it actually do? My real-world example: I’ve been using my Arrow mostly with a Cowon O2 audio/video player and a pair of Sennheiser IE 8 phones. First, the IE 8 are a bit hissy and difficult to drive, the Arrow fixes that for good. It also improves on other aforementioned flaws, like channel crosstalk or bass roll-off (which really isn’t an overly audible issue in this case). Next, the O2 doesn’t have any sound enhancements in video mode, which of course is rather pathetic for a full-fledged video player. The Arrow adds all the needed bass that is lacking from the player’s flat output, and with crossfeed enabled it also makes surround-downmixed audio tracks much more pleasing for headphone listening. Should I ever fall asleep to one of Hollywood’s action-romance-drama masterpieces, the Arrow will turn itself automatically off a minute after the player does. Another huge flaw of the O2 is the lack of tactile buttons, so I mapped the volume buttons – the only two buttons it has – to act as FFWD/REW, and use the Arrow to control the volume in a much more comfortable manner. All these points considered is what makes the Arrow more than worth it for my needs.
How about a few comparisons? Compared to the MiniBox-E+ the Arrow is a much more refined, much better performing amp in about every aspect – and it doesn’t pop/click at turning on as insanely as the MiniBox does, possibly damaging one’s phones. The Minibox is impossible to use with low impedance phones since it hisses so much (and its impedance switch makes the sound quality much worse) – in comparison, the Arrow works with any phone. The Minibox delivers constantly 18V output power and can go even a bit louder with the HD 650 than the Arrow, but the Arrow can go more than loud enough with these 300 Ohm phones already. Also, ‘louder’ doesn’t necessarily mean ‘better’.
The Corda Headsix is a huge bulky monster in comparison – yet it’s actually the smallest Corda amp available (not to mention some ‘portable’ products made by other companies). Due to its size it does have better battery life than the Arrow. It also uses standard 9V batteries, which might be more comfortable than an internal Li-Ion battery in some aspects (long travels without recharging possibilities, etc). Then again, despite its weaker 3.7V battery (but thanks to its switching amplifier), the Arrow can drive high impedance phones better than the Headsix, with low impedance phones they’re both about the same, both don’t hiss. The only feature the Headsix has is an internal gain switch – which isn’t very useful since low gain sounds not so great on it, due to rolled off treble. The volume pot on the Headsix is the worst I’ve ever used – it crackles like a campfire and is extremely unbalanced at low volume levels. The Arrow’s volume pot is perfectly well behaved.
Compared to the Fiio E5, E7, iBasso T4, GoVibe Derringer, and all the other amps I have… well, let’s just stop here. Those would be quite unfair comparisons in most aspects.
Nothing to say in conclusion except that this is the best portable amp I’ve tried so far and that I can’t think of any real improvements it could benefit from – neither sound-wise nor feature-wise. That sounds like an advertisement, but it is my honest opinion. People who read my other reviews know that I’m usually the first one to complain about every tiny detail – writing up a review without at least some nagging is a particularly hard task for me.
Poor Robert Gehrke, he might have a hard time designing a successor to the Arrow. The 12HE makes many of the amps the competition has to offer look a bit sad, dated, and/or overpriced in comparison, since hardly any other one is as well designed and versatile as the Arrow 12HE. It’s not just about the obvious features like bass boost, crossfeed, and so on – and I guess some people wouldn’t make use of them, or some ‘audiophiles’ might even be offended by their presence – but it’s also about the less obvious ingenuities that make this amp so much more practical than others, like the excellent auto-on/off feature, the switching power supply that makes the amp sound good at any battery level, the second input jack on the back, and so on.
Of course it also helps that the Arrow can drive any pair of headphones without problems, from the most over-efficient IEMs to demanding full-sized phones. I can’t say I know of any other amp that would drive my UE11 as well as my HD650, and anything in between. There’s also no need to question the amp’s ‘synergy’ with different audio players, as some people like to do (even if it’s silly) – it of course works the same with any brand player you throw at it, be it a Cowon, Sansa, Iriver, or what-have-you.
If you’re in the market for a portable amp, I strongly recommend taking a good long look at the Headstage Arrow 12HE. Of course everyone’s requirements are different, but the Arrow might very likely meet most people’s needs. Sure, in the grand scheme of things 200 Euro aren’t exactly cheap, but the Arrow just does its job right – very, very right. The amp is made in Germany, which makes its price appear even more adequate – especially considering what some eg. Chinese manufacturers ask for their not-so-great amps in comparison. One won’t get ‘better’ sound quality by spending more money on another portable amp, let alone even remotely comparable features. So I guess that makes the Arrow almost a bit of a bargain…
Thank you, Mr. Gehrke, for thoroughly thinking this one through. I wish there were more products and more manufacturers like this.