Sennheiser HD 650
The reference open-back a generation measures everything else against — smooth, unhyped, honest. Here is exactly how it measures, and how to make it sound like your reference.
Our take
If you want to hear what a recording actually holds, the HD 650 gets out of the way. Bass is even and unboosted, the mids are its whole reason for being, and the treble is polite — some call it dark. EQ can lift that top end without breaking the tuning, which is exactly what Attune is for.
Measured on a Head Acoustics HMS II.3 artificial head — raw response, left/right averaged, normalized to 0 dB at 1 kHz. From the Sonic Temple Archive(2008–2014, one unit per model). Honest limits: seating variance runs ±0.4 dB in the mids to ±3.9 dB above 12 kHz, and open headphones read bass-light on this fixture — don’t read fine treble detail as settled. How we measure →
Common questions
Straight answers — the same ones our measurements support.
Does the Sennheiser HD 650 need an amp?
It benefits from one but does not require a big one. At 300 Ω it wants voltage more than current, so a decent USB-C dongle or any competent headphone output drives it to honest levels. A dedicated amp mainly buys headroom, not a different tuning.
HD 650 vs HD 600 — what is the difference?
Small and real. The 650 is a touch warmer with slightly more upper-bass and a gentler top end; the 600 is a hair brighter and more forward. On the graph they are close cousins — pick by preference, not price.
Is the HD 650 good for mixing?
For tonal balance and midrange decisions, yes — it is a longtime studio reference. Its relaxed treble means you should check your highs on a second source, which is true of most headphones.
Why does the treble look like it rolls off?
Part is the headphone’s relaxed voicing, part is the measurement rig: above ~10 kHz, fixture and seating variance dominate, so treat the top octave as directional, not exact.
If you like the HD 650
Close on the graph, or a deliberate step in one direction.
Sennheiser HD 600
A hair brighter and more forward. The other half of the reference pair.
Step upSennheiser HD 800
Wider stage, more treble energy and detail — less forgiving, more revealing.
Cross-shopBeyerdynamic DT 880 (600 Ω)
Similar neutrality with a brighter, airier top. A different flavor of honest.