Advanced Alpha Over-Ear Open Planar Magnetic Headphones Measurements

Measurements
Click on graphs image to download .pdf for closer inspection.

I've only shown the shallow pad measurements here for discussion as they are largely the same as the deep pad measurements, which can be found here.

Raw frequency response plots show an absolutely dead flat response from 20Hz to 1.5kHz. There is very little, if any, change in response with movement on the head until you get above 5kHz.

There is a small deviation between the left and right channel between 1.5kHz and 2kHz. You can also see a small feature on the impedance plot, and a fairly large increase in the distortion plot in this area. I think we're seeing the diaphragm going through some modal break-up here. I heard this 1-2kHz area as quite hard sounding.

Between 2kHz and 4kHz there is a fairly narrow and cleanly shaped peak in response. This narrow peak will cause some resonance at 3kHz, which can be seen as ringing at the leading edge of the 300Hz square wave and in the impulse response. Ringing at the leading edge of the 300Hz square wave can sometimes be fairly benign. For example, the Sennheiser HD 650 does it. But you can also see that each successive cycle is getting smaller; also note that while the raw frequency response peak at about 3kHz is a clean peak, it is also pointy rather than rounded, and has a wide bottom.

The Advanced Alpha, though not quite as bad, is more similar to the AKG K812 measurements. The AKG K812 has a hump at 3kHz similar to the Alpha, and you can see the first few ring cycles in the 300Hz square wave response don't diminish as rapidly as the HD 650 and are more pointed in shape. You'll also note a rise in distortion of the K812 in that area. Not good, the K812 was quite a harsh headphone to my ears. I didn't hear the Alpha to be as harsh as the K812, but it was heading in that direction.

Raw response above 5kHz is pretty much on target. This is a headphone that largely has good performance but for a fatal flaw between 1kHz and 4kHz.

30Hz square wave shows great shape. I did hear these cans as having authoritative, tight, well textured bass response.

300Hz square wave has the above mentioned pointy ringing, but other than that has good horizontal shape and is relatively noise free. Similarly the impulse response has a tight, clean initial transient, followed by a couple of rings with 300uSec period that shows it comes from the peak at 3kHz. The impulse response is fairly noise-free other than that.

THD+noise plot shows quite good distortion characteristics, even in the bass, other than the dramatic rise between 1kHz and 2kHz. Impedance is dead flat at 35 Ohms other than the significant blip at 1.5kHz. Something is going wrong at this frequency.

Isolation is typical of an open headphone, though the deep pads did show more isolation then the shallow pads.

Needing 189mVrms to achieve 90dBspl at the ear these will be driven to acceptable levels from a portable device.

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COMMENTS
thefitz's picture

Funny how 3kHz in the compensated curve is basically flat. Therefore, flat is very bad. Interesting.

metal571's picture

Tyll has said many times in the past that his independent of direction "stock" compensation curve is not to be considered after modern research shows preference for the Harman curve. At some point a graph generator with multiple compensations to choose from will be available and that will stop people from having to look for a down-sloping version of the ID curve and instead just a flat line.

TMRaven's picture

A 15db elevation at 3khz compared to lower midrange is considered neutral based off the harman curve.

This headphone measures very similarly to the HE-560, which sounds pretty damned good, but Tyll said he didn't like all that much. The EQ'd Sonoma Acoustics Model One is also +15db by 3khz, but also has a smoother transition from 1khz to 3khz compared to the HE-560 and this headphone.

Wonder what a pad swap would do. Changing pads on the HE-560 tamed its 3-4khz peak.

yanghetian97's picture

There are about 3db more on these than he560. And these have less 1k so makes it worse. IMO, not recommend it is a bit too harsh, should be better than that.

luvmusik's picture

3 More Planars in this <$800 Price Category, please consider a full review with measurements for -

Enigmatic Audio LFF Paradox and also Slant models.

Tidal Force Wave 5, not sure about this last one.

Thank You !

南开米饭's picture

received the Sundara and still say nothing? How dare you!

maelob's picture

I respect measurements but I wish Tyll would do his reviews in two parts. First initial impressions before any measurements, just tell us what you think of the sound. Then a second part with whatever measurements and conclusions he wants to write. But I find that when he talks about sound quality, the discussion start to get too technical. Although he combines his impression with the numbers. I am curious of his first impression without measurements, if that makes sense. I believe he listens first to headphones without measurements first, but I wish it would come across like that in the reviews. For example, "at first listen i didnt like the headphone and the treble was too much for me etc etc" follow with "the measurements comfirmed my impressions or not". Just my two cents

elmura's picture

As demonstrated with Audeze's historical measurements and product changes, planars are tricky to get right all the time. It's that tensioned diaphragm. Too loose and treble goes wonky. Too tight and bass suffers. Different materials have different properties.

I believe mid-range priced planars will be best suited to a 2-way approach having a dynamic tweeter handle the highs, and a simple crossover. Best of both worlds so to speak...

Do I foresee the future?

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