Introduction
7Hz is a relatively new Chinese company that opened for business in 2018, and the flagship i99 is currently one of four models it manufacturers. The 7Hz branding refers to the frequency of theta waves in the brain which foster a meditative state, and 7Hz's goal is to produce product that mimic this state of mind when listening to one of its creations.
When I first found out about the 7Hz i99, I was entranced with the idea of a bass dominate IEM to add to my collection since I typically prefer clarity oriented IEMs like the final A8000 and MOONDROP S8 which are favorites that I own.
Performance
I purchased the i99 ($480) from Linsoul in late April of this year, and received it about two weeks later. The i99 itself is beautifully built using a stainless steel casing with a mirror like finish. It comes in either silver or black, and because the Linsoul picture of the black version revealed a textured finish (unlike the mirror finish of the silver), I opted for black. I was surprised on receiving it there was no texture at all and it looked more like the silver on the front with a darker tone on the rear. I contacted Linsoul, and after sending pictures of my i99 and waiting for them to contact 7Hz, I received a message that indeed I received the correct version, that the picture on its site was an early depiction so those interested in acquiring a black i99 should be aware of this discrepancy (Linsoul as of now has not updated its site with a new picture).
For this review my primary source was the HiBy R5 loaded with hi-res files. I didn't use any equalization during my critical listening sessions. One thing of note, the i99 requires extended burn-in before it sounds its best, the midrange/trebles out of the box coming through with a grainy signature. After about 300 hours of play, the bass was somewhat tighter and the graininess had mostly disappeared. I would also suggest a large bore tip design such as the JVC Spiral Dots since this is a warm sounding design.
Once fully cooked, the dominate tonal character is the elevated mid-bass that also reaches into the sub-bass area, but with less force. Graphs reveal a 10dB bass elevation from 1kHz thus epitomizing a classic V-shaped character due to a similar 10dB rise at ~3kHz.
When I listened to Boston's seminal first album (DSD), the heightened bass added a layer of warmth to the lower mids that also reached into the midrange, a coloration that is easy to listen to, but takes away from any sense of overall clarity. The i99 will likely require EQ for many listeners to even out this tuning.
The trebles have a further little bump at ~5kHz to add presence to the overall warm sound. Bob Marley's album, Exodus (24/96), includes one of my favorite songs of his, "Waiting in Vain," and the added presence brings his voice to the fore. I believe reggae is a good genre for the i99.
I like the soundstage the i99 puts out, very wide with good depth creating a cavernous sound. Due to the bass presence, however, imaging is somewhat congealed, the i99 doesn't pretend to be an articulate reproducer, yet with Massive Attack's album, Blue Lines (24/96), the overall presentation has a huge sound that really gets me swinging my head to the music.
Summary
My belief is the i99 will only appeal to those who like a bassy tone to their music, so as a stand alone IEM, its tonal balance is somewhat limited. Since many of us, however, like to have different earphones in our collection for different types of music and moods, the i99 fits well with these expectations. It is a very well made IEM with a nice SPC cable included that isn't the typical Linsoul design due to its custom fittings and cabling. The wood storage box is a pleasant addition (I use it for my IEM collection), and the faux leather zippered case is really nice. Finally, the diamond like carbon, 13.8" driver further improved with a beryllium coating on each side brings modern day tech to a relatively affordable level. I'm quite happy with my purchase!