Fostex's TE-04

After the TH-900 Mk II and the TH-610, Fostex sent me two of their IEMs to try out. I've had them for about a week and a half at the time of writing this. The review for their higher end IEM, the TE-05 should be released next Friday, if all goes according to plan. The subject of this review, the TE-04, however, runs for around $80, and features a single dynamic driver in a very unique enclosure.

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Fit and Form

The headphones arrived to me in their retail packaging: an attractive box, which slips apart to present the headphones and all of their accessories, aside from the faux leather carrying bag, which resides in the back of the packaging.

Speaking of accessories, included are the headphones, a cable without a microphone that has a cinch to stay the wires underneath the user's chin, a cable with a microphone and a single button controller, but no cinch, a bag containing 3 extra sizes of silicon eartips, and the aforementioned carrying bag, which cinches closed with a retained cord.

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The headphones themselves feature a very unique design. Near as I can tell, the dynamic drivers themselves reside close to the insertion point of the MMCX connectors which hold on the cables, while the nozzle sits further down on the shell. I can't imagine the acoustic design work that was required to make something with this system of reflections inherent in its design sound good, but they have, in some ways, done that, as we'll get to later in this review.

I'd like to take this section, after discussing the design, to talk about fit. I was shocked at how well this design fit in the ear - they hold on and don't come loose at all, which is rare for me. I have particularly small ear canals, and that often means that I am fighting with most IEMs, but I was not with these. They were comfortable physically, and sat flush in my concha.

The included cables are of good quality, seemingly plastic over kevlar over the actual wire itself, although they do hold kinks a little bit more than I'd like, which I noticed when wrapping and unwrapping them for storage. However, a run down them with my fingers removed those kinks, so it was functionally a non-issue. They are both lightly microphonic, but that was never noticeable once music began playing through them. As mentioned above, they insert at the earphone with MMCX connectors that are of good quality, and that are marked left and right, thankfully. The microphone cable terminates in an 1/8" TRRS auxiliary connector (the "S" being for controls and microphone use, not balanced operation), while the cinch-able cable terminates in a regular 1/8" TRS auxiliary connector - no frills. Both source-end terminations are right angle plugs, with good stress relief and a small, raised "Fostex" branding.


These headphones are surprisingly competent for their price point. They lack a little bit of bass detail and mid-range reality, but we'll get to the details later. They are slightly V-shaped, but with more of a bass emphasis than treble. The mids are, thankfully, not very noticeably recessed. Vocals of both genders still present very well, without seeming distant or foggy. Regrettably though, the treble is noticeably peaky, and that did come across as somewhat grating in long listening sessions.

Soundstage is about exactly average for closed-back IEMs, with a fairly intimate overall presentation. The imaging is slightly above par though; the headphones offer a very good sense for positioning and separation within the track, which I noticed both in supposedly casual listening sessions and in analytical sessions. Props to Fostex for not ignoring this aspect of technical performance in their development of what is, admittedly, a lower-end (in terms of price) product.


Songs used: Feels by Calvin Harris feat. Pharrell Williams, Katy Perry, & Big Sean, Smoke Again by Chance the Rapper, and Show Me Love by Hundred Waters feat. Chance The Rapper, Moses Sumney, & Robin Hannibal

Although it is undoubtedly the emphasis of this headphone, I wouldn't necessarily call the bass the highlight. It isn't bad by any means, but I found it a tad slow for my tastes. I have just come off of a number of texture and speed kings across price-ranges (see Periodic Audio's Magnesium to Noble Audio's Kaiser Encore), and they have tailored my tastes towards those features. The bass is certainly involving and engaging, in a very similar way to Advanced Sound's Model 3. It is full and has good bloom, but does (as a result) miss some of the faster transients and decay sequences of more fast-paced, electronic music. Thankfully though, there isn't much bleed into the mid-range by the mid-bass, which I have often seen in headphones with the aforementioned characteristics.

Key descriptors: ensconcing, full-bodied, and slow


Songs used: Fortunate Son by Creedence Clearwater Revival, Mama's Gun by Glass Animals, and The Way You Used to Do by Queens of the Stone Age

Where I mentioned above that I wouldn't call the bass the highlight, I was reserving that for this range. The mids are surprisingly engaging, and don't recede to the point of annoyance as I have come to expect with this tuning in IEMs. Although they aren't the most natural that I've heard, they are fairly lush and cohesive. This isn't my personal taste in mids, but I understand that this hobby is inherently subjective, and that this may be the preference of other people reading this review. Even with their lushness, there is fairly good detail retrieval and poignancy of instruments, even in more dense tracks, although some of those details can be lost in more bass-heavy songs, sheerly as a result of volume. This is a very comfortable range, which is the way I think I can best put it. Although it isn't the most detailed or the most detailed, it does yield a very pleasant portrayal of the music put through them.

Key descriptors: lush, engaging, and pleasant


Songs used: Ageispolis by Aphex Twin, Grebfruit by Benny Greb, and Morphogene by Machinedrum

This was the problem range for me - there is some noticeable peakiness in the mid-treble that made sessions of around 2+ hours somewhat unpleasant. This didn't ruin the headphones for me, and I don't want to imply that, but it was something that was off-putting and did put a damper on my enjoyment of these headphones. It was particularly noticeable with vocal overtones and higher-pitched electronic passages. Otherwise though, the treble does add some sense of air and space to the sound signature, which I feel was much needed given the bass emphasis, generally speaking. Aside from the peakiness, there was very little sibilance that I noticed, which was a positive - I encountered the odd case in tracks that I know can bring it out of all but the best headphones, but nothing more than that, to my memory.

Key descriptors: peaky, grating, and extensive

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In sum, I feel that this review has read somewhat negatively. I will admit that some of my critique is colored by my recent exposure to a lot of very, very competent headphones. But, even considering that, I feel that Fostex missed the ball here - there are many headphones out there in this same price bracket that don't suffer the same problems that these do (see: Zero Audio's Carbo Tenore (even cheaper, at just over $40) and Advanced Sound's Model 3 ($80, with wireless and wired capabilities)). Neither of the parenthetically referenced headphones suffer the same treble peakiness (or to the same degree and intensity) as these do and make for much more pleasurable long-term listens. None of this is to say that the TE-04 were abhorrent or irredeemable, I just feel that they are not a good purchase at this price point, especially not for those that are particularly sensitive to treble.


These headphones were provided to me by Fostex. I am not being paid by anyone to write this review, to endorse the product reviewed, or for the content that I put in the review.

These headphones were powered by an Astell&Kern AK Junior, a Google Pixel, a Neurochrome HP-1, and by whatever soundcard is in the motherboard of my computer.

I have had these headphones for about a week and a half, and I have put about 20 hours of analytical listening through them during that period.

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