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Ultrasone HFi 2400

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MSRP $399.00
This product is no longer available at HeadRoom.

The masterful Ultrasone HFi-2400 open-back headphone delivers serious German-built audio engineering and uber-stringent build quality. Proprietary 'S-Logic' surround sound technology takes the music 'out of your head' for the most expansive, airy soundstage dimension and spatiality. The proprietary Ultrasone MU-metal ULE (Ultra Low Emmissions) electrical radiation shielding complies with new European health guidelines ensuring the safest long-term listening, even if you use your headphones all day long. This is the only Ultrasone HFi model with detachable cord!


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Product Features:

  • Large-front 40mm drivers with huge frequency range 10Hz~25,000kHz
  • Foldable, full-size circumaural design
  • Proprietary S-Logic surround sound and ULE features
  • Detachable cord
  • 100% manufactured in Germany

What's In The Box:

  • Ultrasone logo padded carrying bag
  • Extra set of earpad cushions
  • Ultrasone owner's manual and CD


The Ultrasone HFi 2400 are the only open-back 'HFi' model and it also handily provides a user-detachable cord that is not found on the other HFi series. The full-size circumaural earcups fit all the way around the ear and feature the unique Ultrasone Ultra Low Emission (ULE) technology for maximum listener safety, an especially welcome feature for studios, producers and music addicts using their headphones constantly. Large-wave, gold-plated 40mm drivers deliver airy, accurate and finely nuanced 3-dimensional sound reproduction with excellent instrumental definition and separation with an intensely rich bass response also extending into the low mids. Specifically designed and uber-durable detachable / replaceable velvet earpads will comfort your extensive listening hours. The aforementioned high-definition 40mm gold-plated drivers are placed slightly off-axis per Ultrasone's proprietary principle of the 'S-Logic' soundstage dimensionality, and provide great sound quality with a cleanly punchy and musical tone that should likely please detail-loving listeners not wanting to skimp on impact. 100% manufactured exclusively in Germany.

The Ultrasone HFi 2400 come in a stylish black frame headband assembly with dark grey/silver matte earcups, a very cool and appealing look for pro and studio headphones. The earcups are hinged and fold up into the headband for ease of transit or storage. The easily detachable headphone cord on the HFi-2400 exits from the left earcup, extends almost to 10ft and is terminated to a full-size 1/4" stereo plug. An Ultrasone logo carry bag is included in the box along with an extra set of velour 'speed-switch' earpad replacements. The manufacturer's warranty remains in effect only when proof-purchased from true verified/authorized Ultrasone headphone dealers, like us here at HeadRoom!


Ultrasone ULE and 'S-Logic' Natural Surround Sound Design

To understand what ULE-technology does, you need to know that most headphone drivers produce low-frequency magnetic fields as they convert an electric signal into an acoustical signal you hear as music. In response, Ultrasone developed a special MU Metal shielding (ULE-technology) to reduce the radiation by up to 98% compared to current headphones. The ULE-technology has stood the test of international review and is recommended by technical surveillance organisations. Ultrasone originally developed the ULE-technology for professionals as they do spend half of their lives in headphones. But due to intense industry and consumer demand, ULE-technology has now been integrated into other Ultrasone headphone lines.

Through S-Logic Natural Surround, the sound is said to move out of your head and into the room around you. Consequently, the music appears no longer confined, but 'breathes' once again, spacious and organic as live music should be. Direction and distance are more easily perceived and no additional equipment is necessary. S-Logic does not only create a Surround Sound experience but also allows for a reduction of sound pressure levels by up to 40% (3-4 dB) for the same loudness ''sensation'' and musical impact. This may reduce the risk of long-term hearing damage while ensuring hours of fatigue-free listening. However, Ultrasone and HeadRoom always advise not to listen to music at high volumes to prevent any long-term hearing loss. So with just a pair of Ultrasone HFi 2400 and your favorite high-end audio device, prepare yourself for genuine 3-dimensional enjoyment!


  • Acoustic Seal: Open
  • Driver Type: Dynamic
  • Cord Type: Straight Left-Side
  • Coupler Size: Large
  • Ear Coupler Type: Full-Size
  • Cord Length: 10ft
  • Detachable Cable: Yes
  • Impedance @ 1kHz: 70
  • Weight: 292 grams w/o cord
  • Connector Type: 1/4
  • Headphone Type: Full Size
  • Manufacturer Warranty: 2 Years
  • Sensitivity: 94dB

Additional Resources:

Reviews At A Glance
2 Reviews
1 Reviews

Average Rating 
(Showing 3 of 3 reviews)

Excellent audiophile headphones
Posted by derbigpr on 2012-04-07

Recommend Product: Yes
Pros: Sound quality, fun sound signature, value, great bass, design and build quality, imaging.
Cons: Not the most neutral frequency response, a bit tight on the head when new.

This is my first pair of Ultrasone headphones, and I have to say, I am impressed.
Excellent pair of headphones from top to bottom, great value, some really awesome unique features, and no deal-breaking faults. I will compare them with some of my other headphones which I feel are in the same league, namely, the Sennheiser HD650 and AKG Q701.
Before I begin the review, let me just menition the equipment that I use with the headphones.
Source: Asus Xonar Essence ST
Amplifiers: Little Dot MkV, Pro-ject headbox SEII
All music files used are lossless.

Let me say that I've paid 180€ (260$) for these, which to me, is mindbogglingly cheap for the sound I got, especially considering that I've paid 450€ (650$) for HD650's and 350€ (450$) for Q701's. Both of those headphones are sort of a default recommendation for someone seeking an open back, mid-high end headphone. And I believe HFi 2400's perfectly fit into the same category, despite their much lower cost.
---- 10/10

Build and design:
These headphones are totally worthy of a "Made in Germany" tag, even though they're made in Taiwan. :) Excellent quality plastic, very solid, covered with a layer of smooth rubber on the headband to give it a even more expensive feel. Ears cups feature aluminum circles in the middle with a Ultrasone logo, which give the headphone a luxurious look and feel. Ear pads are very soft, and covered with a velvet material pretty much identical to that on Sennheiser HD650's.
Overall, they look and feel very expensive, much more so in person than on the pictures. I wouldn't worry about durability either, these would probably only be scratched if dropped from the top of a 10-story building.
---- 10/10

Now we hit a category in which these headphones won't get a 10/10. It's not that they're uncomfortable, but they're not the most comfortable headphone in the world. Their clamping force is quite high, especially out of the box. They're actually slightly tighter than HD650's, but with HD650's tightness is not a problem, since they go around the ear completely. HFi 2400's don't have as big ear pads, and they're circular, so they press on the bottom part of the ear a bit. Ear pad foam is softer than on Q701's, but slightly stiffer than on the HD650's.
I also wear eyeglasses, but I haven't found any difficulties regarding that.
In long terms, they're a bit less comfortable than HD650's, and much less comfortable than Q701's. They're also the heaviest of the three, but only when held in the hand. When on the head, they feel lightest, possibly because they fit so snug and they're not big, they don't stick out like AKG's or Sennheiser's.
Overall, they're comfortable, definitely among the more comfortable headphones, but they're not the best in that aspect.
---- 7.5/10

Sound quality and signature:
This is a category in which I will not cut the sound into pieces, I will just comment on the general level of quality or sound resolution that these headphones produce. Also, the score that I will give is highly personal.
Even though HFi 2400's cost considerably less than both the HD650 and Q701, their sound quality is actually on the same level. They sound as clear, crisp, impactful, detailed, controlled, well defined and "expensive“.
Their sound signature is not neutral. The mid bass is slightly boosted, and highs are slightly recessed, but not in a bad way. Very often the term „recessed“ is used in a bad context, but in this case, its a positive thing. There's nothing missing in the high frequency region, it just means that the signature is on the darker side, actually remarkably similar to that of HD650's, but with some major differences that I will cover later.
HFi 2400's are very lush and full sounding headphones, but not veiled. Smooth and non-fatiguing, but unlike HD650's, they're not slow sounding. They're fast, and very dynamic. Changes in loudness and speed in music are easily audible, and very pleasant. They also play very loud with any distortion. Sound always feels under control.
Music doesn't sound flat and boring, not everything is always at the same volume, there are pieces of song that get louder, more energetic, more impactful, there are pieces that pop out and make the sound more engaging and musical. HFi 2400's are in fact one of the most fun and engaging open back headphones I've heard so far, but they achieve it without being aggressive or fatiguing. However, they are very punchy and offer lots of impact when needed. PRAT is excellent.
I like to say that there are two types of audiophiles. Those who listen to music trough their equipment, and those who listen to their equipment trough music. HFi 2400's are definitely not meant for the latter ones. They're not the headphones to be used as a reference phone in studio or to be used for testing audio equipment, they're a headphone meant for those who enjoy listening to music that is pleasantly reproduced.
---- 9.5/10

As I said already, lows on Hfi2400 are slighlty boosted, and by lows I mean mostly the mid bass region. This gives the bass great impact, much greater than on the Q701's, and totally comparable with HD650's. Bass is very controlled and tight, never bleeds into other frequencies. Despite being boosted, the bass never gets overemphasized. It's another charatheristic that is often looked upon in a negative way. Just because the headphones are capable of delivering huge bass, it doesn't mean they will always deliver huge bass, with any music, even when not needed. It's not the case. When bass is needed, its delivered. Extension is pretty good as well. Not as good as on the Q701's, but still comparable to HD650's. Overall, bass is very impressive for open backed headphones, with lots of impact and weight, definitely one of the best I've heard.
---- 10/10

I've heard some people complain that mids on these headphones are recessed. Honestly, I can't disagree more. There's nothing about the mids that could be described as recessed, there's nothing missing or lacking in volume, at least not too much. I guess if you're used to very mid-range-happy headphones, you'd notice something, but I don't notice anything, and I come from headphones with forward mids. There's nothing that would affect the sound reproduction in a negative way. Vocals are up front and sound great, especially the male ones, very similar to both Q701 and HD650's. Overall, mids are also very smooth and lush.
---- 9/10

Now, highs ARE slightly recessed. But as I already said, that is not a bad thing. Highs are still very crisp, and crystal clear, same as on Q701's and HD650's, but they're lower in volume compared to the rest of the sound, more similar to HD650's than Q701's. Again, there's nothing missing in the sound, there's no moments during music when you think : „Boy...I wish this part was louder and more clear“. Everything is still perfectly audible and of high quality, its just not fatiguing, harsh or agressive, instead its smooth and polite. Before buying the headphones, I've seen the frequency response on Headroom, and there seem to be a lot of spikes in the highs region. That had me worried, but in fact, I don't notice any of those spikes and dips. Also, there's no sibiliance with vocals, which is present in Q701's and even HD650's sometimes. Hfi2400's are great for long listening sessions.
---- 9/10

Soundstage and imaging:
As you might already know, Ultrasone headphones are famous for their patented S-Logic technology. I'm not gonna spend any time on that, as you can read all about it on their web site. The point is, it works, but in a different way than expected.
I expected the soundstage to be very big, instead, its not really that big, at least most of the time. Its definitely much smaller than on Q701's, and somewhat smaller than on HD650's, but where it shines is imagining. Both the Q701 and HD650 have a very „left-right“ soundstage. Sounds never seem to come from in front or from behind, always from the sides. With Hfi2400's there's a stronger central image. Sound seems to come more from the front. It still comes from the sides as well, but it's somewhat surrounding you. One of the effects that S-logic should create is actually a natural surround sound, and it does that to a certain extent. It's nothing jaw-dropping, but it does work. It's kinda like a Dolby Surround sound, but without the weird and unnatural „large hall tonality“, there's no echo or funny frequency response.
However, I still find the soundstage of both Q701 and HD650 to be as competent overall. Ultrasones come with a demo CD full of binaural recording, specifically recorded to demonstrate the ability of S-logic, and ironically, I felt that HD650 and Q701 sounded just as good, without having any fancy patented technology. However, in music, I'd have to give an edge to Hfi 2400. In terms of imaging, positioning and illusion of space, it beats both HD650 and Q701. In terms of sheer size of soundstage, it's a bit behind them, especially the Q701. It's a precise soundstage on 2400's, but its closer to your head than with the other two, at least most of the time. There were moments in certain recording when certain sounds felt like they were coming from very far away.
---- Imaging 10/10
---- Soundstage size 8.5/10

Detail and transparency:
They're very detailed headphones without being analytical. Details are not in your face like on the Q701's, instead they're delivered with care and certain level of intimacy, similar to HD650's. The overall level of detail is on the same level as on the HD650's and Q701's, in that there's absolutely nothing that I can hear on those two, and I cant hear on the HFi2400's. But as I said, same as with HD650's, you have to listen to hear all the micro-details, they won't be shoved up your ear canals whether you want to hear them or not. Great for sound engineers working in studio? No. Great for someone listening to music? Yes.
Transparency is great as well. Sound is crystal clear despite being slightly dark.
---- 9/10

As far as fatigue goes, these get a big fat 10 out of 10. This is where S-logic comes into its own. I find that lack of fatigue and how headphones react to volume is the biggest advantage of that technology. I find it absolutely amazing how loud I can listen to these without discomfort. There's none of those uncomfortable eye-blinking impacts. Music SOUNDS impactful, but it doesn't FEEL impactful on my ears. It's quite hard to describe really, all you have to know they're much less fatiguing than any other headphone I've ever tried.
Another great thing I found is the fact that they sound great on low volumes, which is rare when it comes to headphones. Most headphones will sound either very thin and bass light, or very boomy and unclear at low volumes. HD650's and Q701's both lack impact and body when listened to at low volume, and when brought up to a volume level where they provide a proper impact, they get fatiguing and give lots of uncomfortable painful moments. There's none of that with Hfi2400's. Remember how I said that they're very similar to HD650 but with a few crucial differences? Well, these are the differences. They're the first headphones ever which actually make me reduce the volume from time to time, because there's no point of cranking them up and turning them into small speakers. They simply have impact on any volume level, they always sound full and crisp. Kinda like speakers. Imagine listening to big floorstanding speakers at low volume level. Everything sounds silent, but still, everything is there and perfectly audible. You still get a nice punch from bass and nice rumble from sub-bass.
---- 10/10

Power requirement:
Not that difficult to power. About the same as HD650's and Q701's. Not as picky about amps as Q701's or HD650's. Hfi2400 sound decent out of anything I've tried, although they scale nicely with better gear. Something like Little Dot MkV is perfectly fine for them in terms of power. They even sound extremelly good when used directly out of a Asus Xonar ST headphone amp.
Prefered genres:
I find they sound great with everything, but they shine at pop, rock, r'n'b, electronic, metal and hip hop. Basically, because of their bass. In those genres, I prefer them to Q701 and HD650. Anything from Dire Straits, Pink Floyd, G'n'R's, Led Zeppelin, Eagles, AC/DC, Rolling Stones, U2, to Sting, Chris Rea, Joe Cocker, Michael Jackson, etc. You name it, they sound great. They excel at older pop and disco music as well.
What about other gernes? Well they sound great with classical, jazz, acoustic, vocals, etc., they sound amazing with everything basically, but with certain genres (the ones without a lot of bass :P) they simply can't show their full potential.
I particularly like them with live recordings. For example, something like Eric Clapton-Unplugged sounds absolutely amazing.

These headphones really surprised me. I bought them as something more mid-fi, but I ended up with a proper audiophile headphone, absolutely comparable to the famous HD650's and Q701's in every way, I even prefer them to both with most music.
Are they the most natural and realistic sounding headphones? Nope. Are the a top choice for someone working in a studio? Nope. Are they for someone who loves headphones that put a smile of their face? Definitely yes. Are they worth the price? Yes! Honestly, this is by far the best value audio product I've ever bought, exceeding even the value of Asus Xonar ST sound card, which I though will never be taken off the throne. Remember,Hfi2400's come at a fraction of the price of HD650's and Q701's, but they're in the same league in absolutely every way, beating both of those in several areas. If I had auditioned these before buying them, and was asked how much I thought they cost, I'd say 400-500 dollars. They're that good.

Overall, for their price, they get a 10/10.
If they were priced at 500$, they'd get 9/10.

Sound Quality
Look & Feel

7 out of 8 people found this review helpful. Did you?

Superb Headphones
Posted by LazBro123 from Montreal, QC on 2012-03-19

Recommend Product: Yes
Pros: Sound Quality, Design, Comfortable, Non-Fatiguing Sound, Durable, Value
Cons: No 1/8 inch adapter provided

These headphones are outstanding. Sound quality, durability, design and comfort are all excellent. These are open headphones, so these are expected to not have the best noise isolation, but it's acceptable. These sound fantastic out of any source. :) For 300 dollars, these are a steal....... Seriously.

Sound: 9/10......The sound quality is fantastic. Detail retrieval, soundstage, imaging, lows, mids and highs are all excellent, as expected with a $300 pair of headphones.

Design: 10/10......These look sick. The black and grey look stunning. These also feel amazing and extremely high quality.

Comfort: 10/10....... These are the most comfortable headphones I have ever worn. The velour padding is extremely comfy, which is good for long listening sessions.

Isolation: 6.5/10....... For open headphones, the isolation isn't that bad. The isolations isn't great, but it's not bad. These leak a lot of sound in and out.

Durability: 8/10.......These are very durable, but metal would bring durability from a 8.0 to a 10.0.

Sound Quality
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4 out of 4 people found this review helpful. Did you?

Very Solid
Posted by jaechung253 from Mississauga, Canada on 2011-04-14

Recommend Product: Yes
Pros: Impactful bass yet I can still hear some details, Non fatiguing
Cons: Have to get used to the earpads, slightly recessed highs.

At first... this headphone did not wow me. I burned it in and what a difference. I think these headphones definitely need to be burnt in so the details can come alive. The sound staging and imaging is pretty decent. It honestly feels like speakers right by your ears instead of enclosed headphones. Does the S-Logic work? To a sense, yes. S-Logic does affect sound staging but do not expect it to blow your mind. I can honestly wear this pair of headphones for 8 hours straight. The sound does not tire you out at all.

The bass is perfect... not overboard and messy... but tight and controlled and called for when the recording asks for it. The impact is amazing. I wish the highs were a little more defined but that is being nit picky... all in all they are a very fun pair of headphones. Listen to hiphop and electro? These are MADE for them. It leaks ALOT of sounds but... heck they are open headphones what do you expect.

I did not have a great experience with the HeadRoom service as I believe they ignored my USPS shipping request twice and removed my order from my history. They ended up shipping using UPS and I had to pay brokerage fees (I live in Canada). The service I have experienced will not bring me back again as a customer. But this is just MY experience as I am sure HeadRoom has provided excellent service to others before. (No one is perfect).

All in all... awesome product.

Sound Quality
Look & Feel

12 out of 12 people found this review helpful. Did you?

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Ultrasone S Logic Technology

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