Sennheiser HD 800 S: Tweaked and Delightful...and a French DIY Response Measurements

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

Ed Note: The above plot is for the HD 800 S sent to me by Sennheiser and will be the topic of the following description. I have, however, put together a .pdf booklet of most measurements I took for this review, which includes the other two HD 800 S measured, and a number of other HD 800 measurements both stock and modified.

Raw frequency response plots show some changes in bass response with movement on the head. Impedance plots show the primary driver resonance at 110Hz; raw FR plots show ever decreasing bass below the primary resonance as a result of decreasing driver efficiency below resonance. Ideally bass should be around 3-5dB over baseline below 120Hz. While warmer than the earlier HD 800, the 800 S is still not a bass-heavy headphone.

30Hz square wave shows good shape; the slight downward bowing is from the slowly dropping bass below driver resonance and is not excessive, indicating there are probably no phase shift problems in the bass.

300Hz square wave is fairly good. Initial spike is not excessive; subsequent noise is a tad high, but not excessive. Similarly, the impulse response shows a very responsive initial transient, following noise could be lower, but is again not excessive considering the clean and fast impulse.

Bass distortion is markedly higher than than the previous HD 800. This, I believe, is due to extra 2nd harmonic distortion present in the HD 800 S as can be seen in the plot on page one of this review. Aside from the bass distortion, the HD 800 S has very low distortion elsewhere. An interesting observation is that the HD 600 has a similar bass distortion profile. At some point I'll have a look to see if it's mainly dominated by even order distortion as well. At any rate, I've never considered the bass in the HD 600 as annoyingly distorted.

Impedance plot shows a nominally 400 Ohm impedance headphone with a large primary resonance hump rising to about 650 Ohms centered at 110Hz. Isolation is poor by design in this open acoustic headphone.

With 219mVrms needed to achieve 90dB at the ear, this is not a good headphone for use with portable devices. It absolutely deserves the best amp and upstream sources you can acquire.

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