Fit and Comfort

Seen above is the right channel of the Raptgo Hook-X installed into an artificial ear mold, and I am using the size-M black bore silicone ear tips included with the IEMs. It looks and feels exactly the same with the white and cyan bore tips too, so take that for what you will. This was my typical combination for personal use too, and illustrates the nature of the achievable fit with these IEMs. I do have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. The semi-custom design of the shells shaped for the ear concha with ergonomics in mind works out fairly well for most ear types, and the Hook-X is about average in size to where it fits into my concha well. The shorter nozzle coupled with the pivoting ear tips means you need to push in further than you'd think, which will provide a good fit and seal. If not, it will be a loose fit with the IEMs potentially working themselves out over time. The IEMs weigh ~6.5 g each, and the cable with the pre-formed ear hooks further adds support, making physical fatigue minimal. Passive isolation is slightly worse than with the average IEM courtesy the open-back design, with some audio leaking out more so than external stimuli affecting your listening experience, although it's really not as bad as I thought it would be. The open-back design mostly results in no pressure build-up and hours of comfortable listening, which is always a good thing. The neon green can catch incident light and other people's eyes if outdoors, making these potential attention-grabbers if used in public.

Audio Performance

Audio Hardware

The Raptgo Hook-X is to the best of my knowledge and that of Raptgo the world's first and only implementation of a planar magnetic driver paired with a piezoelectric (PZT) driver. The former has been well documented, and you can read more about how planar drivers work on this page. There have been multiple attempts at using full-range planar magnetic drivers in IEMs to varying degrees of success, and it was the Audeze Euclid as well as 7Hz Timeless that heralded the use of larger-sized planar drivers in closed-back IEMs. The Timeless in particular was the first to really use a set of well-tuned 14.x mm planar drivers, and then came the LETSHUOER S12 which also lowered the price entry barrier. There are a couple of others out there or in the works, including the TinHiFi P1 Max, and the Raptgo Hook-X also uses a 14.2 mm planar driver coupled with powerful neodymium N52 magnets for the entire frequency range. Raptgo also claims the acoustic chamber has a deliberately designed damping system to make the most of this driver.

What makes the Hook-X unique among all of these is the use of a PZT driver to add bone conduction in the treble response, with the aim of increasing contrast and improving resolution in the higher frequencies. A piezoelectric driver in IEMs works one of two ways, with the bone conduction implementation complementing another driver as opposed to the more typical method of drivers directly vibrating and producing sound. Here, 18 ceramic piezo elements, 9 per side of the voice coil, vibrate precisely to match the planar driver's treble response. This novel hybrid driver setup is still fairly easy to drive all things said, with the Hook-X having an average rated impedance of 15 Ω, which may not be true throughout the entire marketed 20–40 kHz frequency range owing to the different drivers and likely non-linear impedance response. The sensitivity is also about average at 105 dB/mW, so purely by numbers, it is easily handled by even a basic USB Type-C dongle. The Raptgo Hook-X is just fine with mobile devices thus, and going with one of the portable Bluetooth options we have covered before also makes this a wireless solution. The lack of a 3.5 mm audio jack for most phones these days is another reason to consider a DAC/amp for portable use. If not on the go, space is less of an issue, but the relatively short cable might still be a potential handicap if connecting to a PC as the audio source.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm-neutral signature emphasizing a slightly elevated bass and smooth treble range with detailed mids and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through the sound card. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/12th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the appropriate ear mold fitted to the audio coupler for a separate test to compare how the IEMs fare when installed in a pinna geometry and not just the audio coupler. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the rated frequency response in the Raptgo Hook-X, or at least the useful part of it. The left channel was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two channels are near-identical throughout the lows and most of the mids. There is channel imbalance from 1 kHz onward as we get to the pinna gain region, however, and it's somewhat noticeable in the ears once you pick it up. The right channel seems to be what Raptgo is aiming for based on the factory frequency response curve, and this discrepancy between the channels continues to a lower extent to where I wanted to see better. Measurements taken after 30 hours of testing, including with these playing a mix of various songs as well as white or pink noise and sine sweeps showed no differences. There was no perceived burn-in effect thus, and none was measurable either. The response with the anthropomorphic pinna in place matches the ideal scenario in the coupler very well, which is also an indicator of how good the fit and seal was in the artificial pinna.


Here is the average frequency response for both channels of the Raptgo Hook-X plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. But then you might ask what the deep fit curve is for, and it is what you will actually experience with the ear tips in properly. The orange line is my keeping the coupler resonance at 8 kHz to better match the other IEMs in the database; however, I this shows that the treble response is a touch spicier in practice.

Raptgo speaks a lot about harmony and balance in the sound signature, and it does look fairly balanced if you ignore the channel imbalance issue on my sample. This is a U-shaped signature, with the dominant profile being bassy and airy. Indeed, there's an 8 dB SPL boost from the lowest point in the mids at 600 Hz and maxing out at ~40-50 Hz followed by a subtle dip all the way down to 20 Hz. The hard-hitting planar driver is an absolute must since the open-back nature of these IEMs otherwise results in a more diffused sound. It's not a set I'd recommend for mind-thumping, head-shaking genres, such as electronic or house music, or even heavy metal. Where I thought this worked best was when you prioritize bass quality coupled with a larger sense of space, and rock music as well as old school funk recorded in a larger hall almost makes you feel you are there. As such, this is a set with a narrow dynamic range inside of which it's quite resolving.

The mids are going to be more divisive depending on your preference, and the Hook-X is going to be a crowd-pleaser for those who prefer vocals over instruments. Male vocals in particular are front and center, and forward-facing would be the least I could say about it compared to instrument fundamentals. It's a careful balance between bass guitars in the lower frequencies giving way to baritones, and while it wasn't my cup of tea, I can see again why this would be appreciated by those who listen to classic rock, disco, country music, and soul music. The technical performance is not lacking either, with a wide and diffused soundstage as expected of this open-back design and imaging quite precise within a wide cone in front that then gets hazy around the sides before improving again. Binaural recordings help identify the shortcomings and strengths here. The upper mids start to rise at ~800 Hz, which will work well with most HRTF profiles, and I did notice it peaks slightly earlier before confirming as much with the measurement. A pinna gain of ~8 dB centered around 2 kHz will work well for most fans of female vocals too, further cementing the Hook-X as a set for vocals. It works fine for general media consumption and is a set you can keep in your ears during all the hours working from home, and the various breaks in between.

It's the instruments where the Hook-X seemingly falters in the mids, some of which continues in the treble frequencies. I generally like the tuning of the Hook-X here, but that resonance peak can get you. In my case, I felt it around 8.5 kHz, which corresponds with the fundamentals for some string instruments and the second-order harmonics for several other piano keys and cymbals. There was enough ringing with orchestral music that it isn't a set for me in that regard, but it is so heavily user-dependent I can't outright dismiss it. Depending on your ear canals and the fit, this may not be an issue at all. That's really the only thing to watch out for as Raptgo has gone with a more aggressive damping system to keep the treble peaks in check. Normally, this would also cut down detail, but this is where the piezoelectric drivers come in. While I can't tell you the bone conduction is strong enough to make a significant difference as I am still trying to understand where it is exactly contributing and where it's just the planar driver—I was pleased with the instrument separation, lack of sibilance, and generally resolving notes that have relatively quick decay, too. If anything, I noticed the PZT driver contributing more in the mids and upper mids with acoustic guitars in particular. However, the vocal-centric nature of these IEMs makes it harder to notice.

Comparisons

The obvious comparison has to be with the other planar driver IEMs in the price range, or those using a similar 14.2–14.5 mm driver anyway. These include the 7Hz Timeless and LETSHUOER S12, both of which are less expensive than the Raptgo Hook-X, closed-back, and only use a full-range planar driver. I also have a prototype of the TinHiFi P1 Max which is in my database and will be replaced by the frequency response measurement of the retail unit that should arrive soon. That too is less expensive, closed-back, and uses a single planar driver. Common to all four is the use of a full-range 14.2–14.5 mm planar magnetic driver that seems to be from the same OEM factory. It's certainly a driver that is a winner simply by its tuning. The planar nature helps with technicalities too, with the others having more slam and being more receptive to music genres the Raptgo Hook-X isn't as good at. By contrast, the strengths of the Hook-X are so different in terms of build quality, excellent cable, comfort, soundstage, and arguably the best overall treble response that it not only makes a strong case for itself among this small bunch that will no doubt grow as the planar wars continue. It is in my opinion the best of the bunch so far, worth the money for those who want the best of the budget planar IEMs.


Plenty of other comparisons are possible on a price-point basis, but I want to compare the Raptgo Hook-X to two sets in particular. The MOONDROP KATO is my go-to recommendation for a single dynamic driver in the ~$200 market and brings with it lower bass quantity by default but better-executed mids and treble. The pinna gain is also more conducive to a neutral-bright response, and bass can be upped via EQ. It can get fatiguing over time though, and isn't a vocal-first set such as the Hook-X. The detail in the higher frequencies also gives an overall edge to the HOOK-X, and the open-back nature and that cable further justify a place for this Raptgo offering. Then there is the HarmonicDyne P.D.1, which is the only other hybrid IEM involving a planar magnetic driver at my disposal. It is an excellent example of what not to do, and you can read the review to figure out why. It also costs more than the Hook-X, and as the Hook-X has nullified its planar hybrid novelty, there is now even less reason to go the HarmonicDyne route.