We have reviewed many brands of professional headphones here at Compudio. However, German-based Ultrasone seems to be a brand we have neglected to investigate in. Thanks to the support of Ultrasone’s Canadian distributor, ADI, we managed to acquire the HFI-2400 to sample Ultrasone’s high fidelity series. As the flagship of Ultrasone’s hi-fi lineup, let’s see what the designers and engineers at the company were able to achieve on a price tag of $329.


Specifications
■ S-Logic™ Natural Surround Sound
■ Dynamic principle, open-back
■ Frequency range 10-25.000 Hz
■ Impedance 70 Ohm
■ Sound pressure level 94 dB
■ MU Metal bufferboard, reduced field emissions in accordance with ULE (=Ultra Low Emission) standard
■ Driver 40 mm gold-plated
■ Weight 292 g (without cord)
■ Detachable straight cord (length: 3m)
■ 6.3 mm gold-plated plug
■ Velvet transportation bag
■ Demo CD
■ Long-term availability of spare parts
■ MSRP: $329


Design and Fit (8/10)



Out of the box, the first thing that catches your eyes will be the shiny brushed metallic (aluminum) plates that cover the ear cups. The grey and black color scheme won’t make the phones stand out too much, but the velour pads will guarantee comfort during prolonged listening session. The HFI-2400 utilize a single cord that is detachable from the left ear cup. While the basis of connecting the cord to the cup is rather straight forward, which involves twisting and pushing the cord in, our first attempt failed. No sound was coming out from the speaker drivers. After contacting ADI, it appears that this is a common mistake, and that all we had to do is to push the cord in a lot harder so the seal of the connector would be air tight.

The ear cups of the HFI-2400 can be turned 90 degree inward so they can be made compact for travelling with the supplied black velvet pouch. With a stock 1/4" terminated cord, we were disappointed that Ultrasone did not include an 1/8” (3.5mm) adapter. At this price point, we expected the phones to comply with both home and portable uses without third-party accessories.



The HFI-2400 is comfortable with soft velour pads completely enveloping your ears. The velour and open design also eliminate any ear sweating during prolonged usage. However, these phones can be a bit tight when newly purchased, and would perhaps clamp a little too hard on your head. Give it a few weeks, and the tension of the headband should loosen up significantly.


Sound (8.5/10)

Amplifier: BursonAudio HA160
Burn-in: 100 hrs
The sound of the HFI-2400 is extremely enjoyable. In terms of signature, the phones carry a warm sound with emphasis on lower and mid bass. The frequency starts to recess towards the upper mid-range and shows some small spikes in the upper treble. Right off the bat, it appears that these phones will be fantastic for hip hop. Nonetheless, let us scrutinize these headphones and examine closely on the strengths and weaknesses of the HFI-2400.



Bass:

First, let us talk about one of the strengths of the HFI-2400. The pronounced emphasis on low notes makes the sound appear extremely rich and dark. Using one of my food analogies, listening to the 2400s is like taking a bite into a piece of dark chocolate from Godiva. The smooth, sweet, and dark taste immediately sensationalizes your body, leaving a tiny bit of bitterness in your mouth. Okay, maybe that analogy isn’t the best comparison, but the truth is the large quantity of bass of the 2400s truly gives you an indulging music experience. Although the low notes are pronounced, they are in no way muffled. The bass extensions of the 2400s are deep and they resonate like a $700+ subwoofer. Impact and decay of bass notes may not be the best I’ve heard, but are ranked top among competitors at its price point.


Mids:

The mid-range of the HFI-2400 gave me a bag of mixed feelings. Across the spectrum, the recessed upper-mids are the most obvious. Female mezzo-sopranos like Kelly Clarkson, Beyonce, and Celine Dion seem to have lost some of their upper resonance. While warmth is added as a result of pronounced lower notes and recessed upper-mids, the full range of their vocals and the clarity of their diction are unable to shine through. Given sultry vocalists, such as Diana Krall and Niki Yanofsky may benefit from this added warmth, this thickened, artificial lushness hinders the transparency of female vocals.

Male vocals, however, pair very well with the HFI-2400. The emphasis on warm notes boosts the lower registry of the male voice, giving male vocalists, whether it be baritone or tenor like Pavarotti, an added passion. Even though it may not be the most accurate representation, the added passion and virile quality leave the listener a satisfying impression.


Treble:

In the past, Ultrasone headphones have been known to have trebly highs. The company seems to have listened to their customers’ displeasure with an overly bright sound and has modified their products to tailor to a larger group of potential buyers. Indeed, while a brighter or darker sound may be just a matter of personal taste, sound with an overly harsh treble will undoubtedly fatigue listener in a short period of time. The HFI-2400 exemplifies Ultrasone’s move towards a darker house signature. While empowering the lower notes, the highs are well controlled. Maintaining the obvious presence of treble, the highs are presented in a fun and slightly metallic way. The slightly metallic quality may be attributed to the sudden peak in the upper-high frequency, causing rougher edges to high notes from bells and strings. The treble of the HFI-2400 undoubtedly gives the phones many details, making them excellent for orchestral and string-based music. However, there is definitely room for improvement to making the highs more crystal-like. To me, the highs are still a little bit too hard when listening to percussions-packed music at higher volume levels.


Soundstage:

The highlight of the HFI-2400 is the soundstage. The headphones are badged with S-Logic technology, which is a patented design from Ultrasone that claims to make the sound more natural and three dimensional without any artificial/digital modification. Whatever they did, they did it right. As a result of this design, the soundstage is incredibly large and shockingly surrounding. Since the HFI-2400 do not utilize any drivers to recreate 5.1/7.1 surround sound, activating multi channels on a DVD movie is not possible. However, any virtual surround sound generated from stereo speakers, such as the binaural recording of Virtual Hair Cut will sound exceptionally accurate and real. In fact, any stereo source, including MP3s, movies, and games will come alive without any additional digital processing. Ultrasone’s S-Logic surround sound technology definitely deserves two thumbs up.



Specifically to music, the HFI-2400 give the performance an incredible space with fantastic depth and width. Combined with their open-ended design, the HFI-2400 possess one of the biggest overall soundstages I’ve come across in years. In addition, instrument placement is extremely accurate. At times, bass appears to be shaking independently at the back of my head, which made me think someone was approaching me from behind. With the Ultrasone HFI-2400, you are pushed within the music as it envelops your senses.


Score Breakdown

Treble (8/10)
Mids (7/10)
Bass (9/10)
Soundstage (9.5/10)
Details (8.5/10)





The Ultrasone HFI-2400 receives a 5/5 for our safe hearing rating. The HFI-2400 is able to produce clear notes across the spectrum at minimal volume level. In addition, the headphones’ S-Logic technology redirects the sound across the ear cup instead targeting volume directly into your ear canal. The result is a more three dimensional sound as well as a safer listening environment for prolonged audio sessions.


Conclusion ( 8.5 /10)


Is the sound of Ultrasone’s HFI-2400 completely neutral? Certainly not. Is the sound magically enjoyable? Absolutely. Coupled with a good amplifier, these phones can do wonders. With pronounced bass hits and small spikes in the upper-treble, the HFI-2400 are perfect for hip hop and classical. Although not the best in the class, they also do very well in vocals. Nonetheless, what makes listeners pick up their HFI-2400 time and again is the soundstage of the headphones. The incredible spatial dimensions and directional accuracy are simply incredible. As a result of the fantastic soundstage, even though the mids are not perfect, listening to choir-incorporated pieces, such as Josh Groban’s “You Raise Me Up” and Michael Jackson’s “Will You Be There” is simply amazing. The Ultrasone HFI-2400 is an exceptionally sounding headphones that excel across genres and uses, which makes it a perfect all-arounder for music, games, and movies.


We'd like to thank Richard Lasnier over at ADI for making this review possible.