The Primo 8 are a surprising joy to listen to. To be honest, I had not put much stock into Nuforce coming out with a great higher-end product from the get-go, but then I took one listen and could immediately tell they put significant effort into this earphone.
No, it doesn’t have mind-blowing clarity, or velvet richness. I found that the Primo 8 is neither diamond nor cowhide, but definitely also neither pleather nor zirconium. What it is, is a near ideal mix of audiophile inspiration and Joe Blow sensibility.
More surprising was the fact that while total development for this product took only about a year (sound development was pegged to be between six to eight months long), as the Primo 8 feels more like the careful result of lots of beta testing and feedback. For a company completely new to balanced armature drivers, that’s a remarkably quick turnaround. Luckily, BA producers, whether it be Knowles or Sonion, have been providing clients increasingly better applications support over the years, so in the hands of an experienced speaker designer with a good understanding of acoustics, a good product is much easier to roll-out now than it would have been five years ago.
So what is ‘great‘ about the Primo 8?
Without question, it is center image and up-front transparency of the midrange and vocals:
I listened to an old Ella Fitzgerald track of her scat singing ‘One Note Samba‘, and Ella came through true. Her presence bathed my ears, wrapping them with a blanket of warmth but was simultaneously accompanied by a swath of definition.
From my experience with other “phase-coherent” earphones such as the JH Audio FreqPhase demos and CustomArt’s Harmony 8, the large and transparent center image is most certainly assisted by the technical achievement that Nuforce have been able to attain with the Primo 8. Nuforce has been pretty obvious about letting enthusiasts know that they’ve put a lot of work into the crossover arrangement of the Primo 8, and that they’ve achieved flat phase coherence with their Butterworth filter design.
To test out Nuforce‘s claims of phase coherence, I tried numerous tracks with multiple voices and exaggerated stereo panning. In all tracks, the Primo 8 managed to define the stereo image very linearly, allowing for easy directional tracking of instruments and vocalists swaying around on their mics.
For all intents and purposes, the Primo 8 is a “neutral” strung earphone with respect to the bass. To me, it still provides a litle bit of elevation over dead neutral, but the bass doesn’t occlude anything at all, and that’s why the bass response is one of the best that I’ve heard out of a premium universal in-ear in quite some time.
The discerning head-fier will find that the bass response of the Primo 8 hits a near sweet spot. It’s impactful enough not to prompt complaints of not being able to hear a certain bass sound, but it doesn’t really accentuate any part of the bassline either. Earphones with a distinct mid-bass hump like the Westone W50 will give listeners a greater sense of thump and circumstance, but prevent them from hearing the evolution and decay of the various vibrational nodes in a drum instrument. Sub-bass registers still render perfectly, as while there’s subtle roll-off, the dual woofers don’t stop vibrating until below 20 Hz.
The transient speed of the woofer also shines through well, allowing the Primo 8 to stay light on its feet, going from one drum hit to the next with no trouble at all.
As mentioned before, the Primo 8 is one of the most transparent earphones in its price class, and despite a forward midrange, the sound field is rendered realistically.
My singular complaint would be a recessed upper midrange compared to its lower midrange, which gives off the psychoacoustic effect of very forward vocals. While raising the upper midrange response of an earphone will allow for a more even sounding and neutral presentation to the vocal range, my gut feeling is that Nuforce purposely colored their earphone this way to give off the feel of more intimate vocals.
The best way to characterize the Primo 8‘s treble response is that it attempts to present a relaxed milieu without having it sound dark. I’m perhaps compartmentalizing too much by segregating the treble from the midrange, so I’ll say that the treble is a continuation of Nuforce‘s midrange philosophy. They’re attempting to achieve a more intimate feel with the Primo 8, and so, the upper treble will be relaxed. At the same time, the lower treble still contains harmonic information of the vocals, and needs to remain present.
Thus, coming from the relatively bright, but spacious and open-sounding Ultimate Ear Reference Monitor, I felt the upper registers of music are a fair bit relaxed with the Primo 8, especially with the upper treble, and I had to use various methods to try and wring out more upper treble from the Primo 8 (see the later section on Tips, Tricks, Tweaks & Source Matching for useful suggestions). Otherwise, the soundstage of the Primo 8 would’ve felt pretty average. It’s a good thing the center image presentation remains large, circular, and linear — or else the relaxed upper treble of the Primo 8 would’ve made it sound even more intimate.
In general, the Primo 8 is not a sibilant earphone. It is very smooth in the lower treble band, and does not possess any strange strident behavior.
Volume & Sensitivity
Like nearly all balanced armature-based earphones, the Primo 8 is a very sensitive earphone. With the Sony NWZ-F886 (thoughts here), a device with a maximum power delivery of 15 mW per channel, I max out at around 36% on the volume rocker, even in public areas. Most of the time, I listen at 18-30% volume.
Volume may vary according to individual preferences, however — I’m primarily a low-volume listener, as I often listen for hours on end, so during long sessions, my volume goes all the way down to 6% or less, turning music into a whisper.
Impact of Cable on Sound
As mentioned in a previous section, the stock cable on the Primo 8 is a unique, proprietary silver/copper hybrid Litz design. I actually found that when I swapped it out for a regular twisted cable like those found on the current Shure and Westone models, the sound quality of the Primo 8 actually faltered. The sound was less clear and more “fuzzy”. This was a surprising finding, as I tend to believe manufacturers don’t put a lot of stock in the impact of cables on sound, and usually opt to use a “standard spec” cable to minimize BOM costs. Nuforce mentioned trying out various different iterations of the cable before reaching the final design, pointing to a lengthy trial-and-error process.
Tips, Tricks, Tweaks & Source Matching
In general, a listener that craves the most neutral sound out of the Primo 8 will want to boost high frequencies, especially above 10 kHz.
Thus, in order to rescue high-frequency bandwidth, I recommend improvising a stepped acoustic horn by using longer, wide-bore (4-5mm wide) ear tips. The stem diameter of the Primo 8 is only about 2.5 mm wide, so you’ll need spacers, such as those included with Monster Supertips, or de-foamed Shure “Olive” foam tips. These wide-bore tips should hang over the exit of the stem — but not too long, as, depending on the ear canal shape and insertion depth, the tips can induce some sharp treble resonances. Play with different types of tips to get the optimal sound for your personal preferences.
On the other side of things, listeners who crave a darker, warmer sound out of their earphones can opt to pair the Primo 8 with players and amplifiers with higher output impedance, such as the TPA6120A2-based, 10 Ω OI, Sony PHA-1 or PHA-2. The 22 Ω OI Astell&Kern AK100 will make the Primo 8 sound even darker.