It’s kind of appropriate to be returning to review a new Fiio amplifier given that my very first portable amplifier was the Fiio E11. The E11 was a great starting amp for me, but the E12DIY is in a whole different league!

Overview

The E12DIY is a special project from Fiio and is a limited editing offering for audio enthusiasts and tinkerers. The DIY is designed to let enthusiasts tweak the amp by changing op amps (more on that later), capacitors and resistors, but it begins life as a very capable portable amp even if you do nothing to modify it.

Because of the modifiable nature of the DIY, the specs provided (other than dimensions) are indicative and by no means fixed:

• Dimensions:  124 x 65.5 x 14.5mm
• Weight:  163g
• Signal-to-Noise: 110dB
• THD: 0.005%
• Power: 600mW to 16 ohms

Inside the DIY’s box you’ll find a soft carry pouch, a hex key for opening the case, a tool for removing the op amps, a USB charging cable, 3.5mm to 3.5mm interconnect, rubber bands to attach the amp to your player, and a tin containing a variety of op amps, buffers, capacitors, resistors, and adapters.

Design & Features

The E12DIY is a relatively large amplifier, but it’s slim so total volume is similar to other portables like the Tralucent T1 – it’s just packed in a different shaped box. Personally, I figure that the moment you add an amp to a portable rig you’re choosing to sacrifice “pocketability” so they’re all going to be much the same overall once total size and weight are considered. Sure, there are tiny offerings out there like the Shozy Magic and Ray Samuels Mustang, but the majority of amps are similar in overall size and weight.

The E12DIY is a little heavier than other amps I’ve tried, partly due to its solid aluminium shell and partly due to its large battery. I imagine that the battery also partly defines the DIY’s form factor too, but the battery is a key part to the E12DIY’s performance so no complaints here.

The E12DIY is sold (if you can still find one) in either natural aluminium silver or in a gold finish that I haven’t seen “in the flesh”. Both colours differentiate the DIY from the standard E12 models which are black.

Connectivity & Controls

The E12DIY is nice and simple – 3.5mm input and output jacks (1 of each), a micro USB power socket, 2-position gain switch (high / low), and a volume knob that doubles as a power switch (zero volume = amplifier off). Unlike the standard E12 model, there is no bass boost switch or crossfeed circuit. According to comments I read somewhere from Fiio, the E12DIY was deliberately kept simple to allow more space for the best (simplest?) possible audio and power circuit designs and I believe it was a great choice.

Power

Fiio struck a perfect balance with the design of the E12DIY by making it low-powered enough to drive sensitive OEMs, while also providing a high gain mode and plenty of power to drive much more challenging headphones.

The DIY pairs spectacularly with my Unique Melody Miracles, but is equally adept at powering my beyerdynamic T1s and Fischer Audio FA-011 LEs. That’s excellent versatility and means that the E12DIY could easily be the only portable amplifier you ever need to own. Of course, being a portable amp, it doesn’t quite replace a quality desktop, mains-powered amplifier, but is excellent for portable listening.

Something I really liked about Fiio’s provided set of buffers and op amps is that one of them (the LMH6321) is more focussed on high impedance loads (that’s Sennheisers and beyerdynamics mostly), while the other 2 are more general in operation. This means you can focus your amp to drive your exact headphone if you have a higher impedance model or you can keep it more versatile with the other buffer options. I should probably clarify though, that the other buffers still do a great job of driving high impedance ‘phones, it’s just that the LMH6321 is able to produce a little more oomph into higher impedance loads.

Sound Quality

Knowing that you can change the op amps and buffers in this amp, you’ve probably also surmised that the sound quality is variable as a result. Correct!

Because of the completely variable nature of the DIY’s staging and signature, I’m going to restrict this section to discussing the elements that remain consistent regardless of the chips used.

Noise Levels

In short? None!

The E12DIY provides a completely black background with no noise or hash through any earphone or headphone I’ve tried with it. I did notice that using the BUF634 buffer introduced a potential for some noise to be picked up when I moved the interconnect and earphone plugs around inside the sockets (i.e. if I had the amp in my pocket and was walking), but I think this might have been a sign that I needed to re-seat the buffer by removing it and plugging it back in to ensure full contact in the socket. In any case, this was a situational issue while 95% of the time the amp was dead silent with this buffer and is 100% silent with my preferred LME49600 buffer, bur more on that later.

Back to discussing noise levels, the most noticeable benefit of a black background is that it allows every nuance, detail and texture of your music to be heard easily and clearly, but without having to over-emphasise anything. The E12DIY is able to deliver incredible clarity and detail while never sounding like it colours or enhances anything.

Channel Separation

Some years back I worked in car audio, designing and installing stereo systems. My focus was always sound quality and imaging, not necessarily sound pressure levels (i.e. ear-drum-rupturing volume). One of the tricks I often employed to create epic sound quality without spending too much money was to have separate amplifiers for each channel. For example, we’d use a 2 channel amp for the left side of the car (1 channel for the front and 1 channel for the rear) and a second 2 channel amp for the right side of the car. This kept each half of the stereo signal completely isolated so there was nearly zero crosstalk (only what occurred inside the car’s head unit). The term crosstalk refers to the sound from one channel bleeding slightly into the other channel and it has the ability to compress or completely kill the stereo image.

The reason I told that little story is because some amps do a better job than others at replicating this type of isolation of the 2 stereo channels. You can always tell when an amp does it well because the auditory image is always deep, beautifully defined, and engaging. The E12DIY does this extremely well! There are no crosstalk measurement published, but to my ears, the stereo channels are beautifully isolated and this is particularly true when using the OPA1611 op amps (2 mono op amps being used much like my 2 separate car amp analogy above).

Overall, the E12DIY’s ability to provide a “blank canvas” for the sound and to keep the stereo channels well isolated results in a wonderfully fun foundation with which to chop and change op amps and buffers to tailor the sound to your tastes and your gear while always maximising the performance of the components you install.

Op Amps and Buffers

I am a complete newbie when it comes to op amps and buffers, or at least I was when I bought the E12DIY. I would suggest that I have progressed from newb to beginner or amateur over the last few months, but am still far from an expert so what follows is a layman’s explanations of what I have discovered and learned with the chips supplied by Fiio and a few others I’ve bought myself.

Op Amps vs Buffers

My layman’s understanding of op amps and buffers is that they are both very similar, but used differently. In my understanding, an op amp processes the incoming signal a bit like a pre-amp. The buffer then provides the gain (or voltage) to drive the signal into the headphones. To put it another way, the signal comes from your device (let’s say an iPod line out) and is first fed to the op amp which outputs an amplified signal. The amplified signal now needs power applied to allow it to effectively drive the headphones you’re using and this is the role of the buffer as I understand it.

As I said, I am still learning this area of audio and electronics, but I think of the op amp as a pre-amp of sorts and the buffer as the interface between the amplifier and headphones – the engine that drives the headphones according to the directions provided by the op amp.

If you know more about this topic and can clarify (or correct) my explanation, please feel free to share your knowledge with me and others via the comments section.

What Fiio Provides

The silver tin that comes with an E12DIY contains a selection of 4 op amps and 3 buffers. The op amps essentially offer different flavours of sound while the buffers offer a combination of flavouring, but also tailoring the power output to suit your chosen ‘phones.

The op amps provided are:

• AD8620
• OPA1611
• OPA604
• AD797

I will hopefully be able to dedicate a whole post to the different sounds and flavours of various op amps in the near future, but my personal preference from these op amps is the OPA1611 which balances near-neutrality with a touch of bass warmth and lots of detail and clarity.

Until I can write in more detail about these op amps, there is some great discussion of different op amps scattered throughout the E12DIY thread over on Head-Fi.

The buffers provided are:

• BUF634 (general)
• LME49600 (general)
• LMH6321 (more focussed towards powering high impedance headphones)

To my ears, the BUF634 and LME49600 provide different presentations of the sound with the BUF634 creating a more intimate, warmer presentation and the LME49600 feeling more spacious and transparent. The BUF634 might have a slight edge in the texture and weight of midrange, but I find myself preferring the LME49600 and the consensus (by a small majority) on Head-Fi points towards the LME49600 being the preferred buffer.

The LMH6321 presents sound quality that, overall, is almost on par with the LME49600, but it is able to provide greater power and therefore may perform even better than the LME49600 when paired with higher impedance headphones. THe LMH6321 is a bit of a specialist in that respect because it is less capable with lower impedance ‘phones than the other buffers. It still sounds great, but just not as great as the other two “generalist” buffers. If I were using the E12DIY solely with a headphone like the Sennheiser HD650 or beyer T1, the LMH6321 would likely get the nod.

Extra Adapters

In addition to the range of supplied chips, Fiio went one step further and provided all manner of adapters so you can try your own selection of op amps. The design of the E12DIY won’t allow for DIP-8 style op amps like the OPA2107, LM4562, or MUSES 01 (to name a few), but you can grind / file the inside of the case slightly to allow sufficient clearance if you’re brave enough. So far I’ve resisted this urge because I’m worried that it would require making the aluminium housing a bit too thin, but maybe I’ll get brave one day…

Back to the supplied adapters though. When you lift out the foam inside the tin full of op amps, there are a myriad of adapters stuck to the bottom of the foam (just using the 8 pin connectors pushed into holes in the foam). These adapters include options for both buffers and op amps including dual and mono varieties. It means you can have plenty of fun trying unusual, cheap, expensive, and exotic op amps to your heart’s content… so long as you’re happy to wield a soldering iron. No soldering is required with the stock provisions, but any op amps or buffers you buy yourself will either require soldering (for surface mount options) or filing / grinding (for DIP-8 options).

So far I have only tried an AD8599 which is the same op amp as used in the Tralucent T1 and while it’s magic in the T1, I preferred the OPA1611 in the DIY.

Summary & Wrap

As I write this summary, there are probably a few new, retail units of the E12DIY in captivity so if you’ve read this far and it’s still close to April / May 2014 then you might want to get hunting for a remaining E12DIY at a dealer. For the price you pay you will not find a comparable package of sound quality, power and bespoke sound. It’s a sleek package of brushed aluminium that happens to perform somewhere in the range of twice it’s price point. In terms of transparency, neutrality and overall quality, the E12DIY will absolutely not disappoint the most demanding users as a portable amplifier and will be equally as much a bargain second hand (if you can find one) as new.

With the E12DIY, Fiio seem to have announced their arrival into making serious, headphone performance gear and have taken a step beyond their previous (excellent) mid-fi offerings. The recently released X5 portable media player is a further step in this direction and I’m looking forward to reviewing it in the coming weeks so stay tuned!