Headphone Reviews

Sound Quality
For the most part I'll be talking about the sound quality of the N90Q in Standard mode with the EQ set to mid-point unless otherwise specified.

Generally speaking, I found the N90Q fundamentally neutral with a tendance toward a dry and lack luster sound. There's an audio truism that an initial impression of "a bit boring" is better than "wow, exciting" as too much of anything can get annoying after a while, and "a bit boring" is often an indicator of simple neutrality that serves the music better in the long run. To a first approximation, I'd put the N90Q in the latter category.

Bass response is well extended and slightly elevated in the low bass delivering excellent punch and weight. Retrieval of bass texture is excellent; this is very good bass response in a headphone. Bass emphasis does not intrude on the midrange at all.

Midrange is smooth and well behaved in low and mid ranges. Upper midrange, though tonally close to target, is a bit hard sounding. There is a measured distortion peak around 1.2kHz that rises to about 1.2% at 90dBspl. I don't feel this is a serious problem, but I do feel it contributed to the overall character of the headphone and prevented it from delivering what might otherwise be a liquid, yummy response.

I also heard the low and mid treble to be somewhat uneven. Measurements show a significant dip 4-8kHz and a subsequent peak at 10kHz with the treble falling off after at an appropriate rate, but about 2-3dB higher than neutral. To my ears this gives cymbals less emphasis on their primary tones and more emphasis on their higher frequency overtones. "S" sounds develop an over emphatic "th" sound having what some might call too much air.

This problem seems to be mitigated significantly when activating the TruNote calibration, but the problem still remains after calibration. I also felt this problem somewhat worsened when engaging the Studio and Surround modes. I then did some EQ adjustments to minimize the problem.

In the plot above you can see I added a little emphasis around 5kHz, de-emphasized the 10kHz peak, and shelved down the treble above 4kHz a few dB. These settings did seem to produce a more natural tone in the treble and was less fatiguing. I would say this is the most serious problem with he N90Q—the slightly hot response with a 10kHz peak can become tiresome after a while.

At this point it may be worth mentioning that I did get into the habit of getting the headphones in a comfortable position and then recalibrating with TruNote at the beginning of each listening session. When I did remove the headphones and replace them on my head, I would again calibrate using TruNote. This would almost always make the sound smoother and more pleasing to some degree.

The N90Q dynamics, both macro and micro, seemed truly excellent to me. While the treble imbalance was always there, the overall impression of these cans was one of confident control. This seemed to me a very confident and well behaved headphone in general.

With the three available Stage Control modes, a simple statement about imaging is a bit complicated. In Standard mode, with no spatial processing, I would say these cans deliver a fairly wide and moderately deep normal headphone image, though generally better than average. In Studio mode I found the imaging really excellent, delivering a solid, coherent sense of space in which the sounds were stable and well positioned. Instrument separation and specificity was very good, marred only by the problem in the treble which may have contributed to a bit of smearing in the image. This is an excellent crossfeed circuit and I found myself using it about half the time with music material.

While Surround mode clearly delivered more distance and depth to the image, room coloration did, at times, distract from the impression of clean reproduction. None the less, on some material (mostly with movies) I did find it beneficial.

In the end, the question one has to ask is this: Is the AKG N90Q competitive with other headphones at this price? Say, the MrSpeakers Ether C Flow or Focal Elear? Tough question. From the perspective of a high-end headphone enthusiast with a serious front end on their cans, I'd say probably not. To my ears the troubles in the trebles of the N90Q are too reminiscent of the digititis of old—it's just too dry and lacking the liquid yummy of a bog rig. But I also feel that it takes a lot of expensive gear matching and possibly EQ to reign in the problems of these passive headphones that effectively double or triple the cost. Ask anyone who's spent years making their HD 800s sing beautifully, they'll know what I'm talking about.

On the other hand, if you look at the N90Q as the next step in producing a high-end alternative to a Bose noise canceling headphone for travel and portable use, I'd say it's a pretty sweet deal. The N90Q is way better sounding then any noise canceling headphone I've heard. All the spatial and EQ control is icing on the cake. For the traveling audiophile, the N90Q is stupendously good! It is possible to get a USB on-the-go adapter for Android, or Lightning to USB adapter for iOS devices, and plug the N90Q into a digital source portably removing the need for a big lump of amp/DAC strapped to the back of your smartphone. It's a killer enthusiast traveler headphone. I'll point out that spending a little time and effort on a nice EQ app on your phone will do good taming the treble of the N90Q.

My wish list for a Rev. 2 of the N90Q? I think the 2.5mm analog plug at the ear capsule is far too vulnerable. I'd prefer the 2.5mm plug to be buried deeper in the housing so that the body of the connector takes the strain rather than the plug itself..or another connector entiely. And either fix the treble imbalance, or provide an app that allows me to do some parametric EQ that can be permanently inserted into the N90Q DSP. My guess is that AKG engineers, like Audeze engineers regarding my comments about the LCD4, might disagree with my impressions of treble balance. This is an area of response that has a lot to do with individual ear shapes and there's plenty of room to be uncertain about what "the right response" might look like. My feeling is the right approach in future is to always provide the user an opportunity to adjust and permanently install a personalized EQ into the headset. The hardware is there, manufacturers will just have to surrender a bit of control to the user and their preferences.

Summary
The AKG N90Q is one sweet piece of headphone audio kit—especially for the headphone enthusiast business traveler. Though somewhat large, the headphones are very well made, comfortable, and nicely styled...though tending just a bit toward gaudy. Noise canceling and sound quality are very good. Accessorization is superb with a very nice hard shell case, a leather carry bag, four cables, and an extra storage battery for extending the 10 hour life of the headphone itself.

The noise canceling, EQ, Stage Control, and auto-calibration of the TruNote function are way better than I expected for this first-of-a-kind headphone. Its performance in this regard gives me great hope for DSP-based headphones in the future. Stage controls work very well and introduced only minor colorations problems in Surround mode. The Studio mode the introduces ITD and IAD psychoacoustic cues was excellent to my ears. The EQ control the emphasizes or de-emphasizes both bass and treble simultaneously was not as useful as I would have hoped. I would have preferred a tilt control that warmed or cooled overall response.

Sound quality was very good but for some unevenness of response in the low- and mid-treble. Bass response was powerful, punchy, and retained excellent microdynamic response. Imaging was above average in Standard mode, and improved significantly in Studio mode. Surround mode likewise increased depth of soundstage, but also introduced some mild room coloration that was a bit distracting at times, though worked well with some material (usually movie sound tracks).

While I don't think the AKG N90Q is quite competitive with passive headphones at this price due to what I can most easily chalk up as "digititis", I also need to point out that that view doesn't take into account the significant expense of, and time spent matching, upstream electronics needed to drive the passive headphones to their full potential. I think it makes much more sense to view the N90Q as the next logical step up for enthusiasts looking to improve on the sound from premium noise canceling headphones like the Bose QC35, JBL Everest Elite 700, or Sennheiser PXC 550. In those comparisons, the N90Q is clearly the better sounding headphone, and as such will establish a new high-water mark on the Wall of Fame noise canceler page. This is a terrific headphone for the well-to-do business traveler...and my new favorite for time in the aluminum sky tube. Ahhhhhh!

Video

Resources
AKG home page and N90Q product page.
Head-Fi.org reviews and impressions thread.