Unknowndivide may earn a commission from purchases made through links in this post.
Some headphones chase trends. The Sennheiser HD 650 has stayed the course. It is an open back, high impedance headphone built for listening at home, and Sennheiser calls it the reference class. If you have a good amplifier and a quiet room, it is one of the classic ways to hear your record collection in detail. Here is what makes it tick.
What it is
The HD 650 is an open back, dynamic headphone from Sennheiser. The company says audiophiles will experience truly natural sound with it, and that it sets standards in comfort for long listening sessions at home.
Key details, according to Sennheiser:
- Design: open back, circumaural, dynamic
- Impedance: 300 ohms
- Frequency response: 10 to 41,000 Hz
- Sound pressure level: 103 dB at 1 V
- Total harmonic distortion: less than 0.05%
- Weight: 260 g
- Cable: detachable 3 m OFC copper cable with a 6.35 mm plug and a 3.5 mm adapter
- Transducer: 42 mm with a 38 mm diaphragm
- Ear pads: velour
What is inside
Sennheiser describes the HD 650's transducer in some detail. It uses a 42 mm transducer with a 38 mm diaphragm and an aluminum voice coil. Behind it sits a damping element made of fine acoustic metal mesh. Sennheiser says the 38 mm diaphragm and aluminum voice coil are specifically tuned for extended, critical listening.
Consistency is part of the design too. Sennheiser says it uses extremely tight production tolerances of plus or minus 1 dB and handpicked components. Each transducer is measured against rigid specifications and paired with a matching one, so both channels represent the full frequency range consistently. By reducing the differences between left and right, Sennheiser says, the headphone reproduces sound independent of room acoustics or speaker positioning. For a headphone meant for analytical listening, that matching matters.
The sound
Sennheiser calls the HD 650 a go to reference for analytical listening. It says the headphone reproduces the subtle details in your music with the same confidence as the highlights, with effortless treble and low frequency presence and a midrange reproduced with lifelike composure. It adds that open ear cups give each sound wave room to expand, for a dimensional soundstage. The open back design supports that. As beyerdynamic, another headphone maker, explains in its help center, open headphones sound a little more voluminous and detailed with a better feeling of space. Our guide to open back vs closed back headphones covers the trade offs.
Comfort
Sennheiser promises that long concerts in the comfort of your home are a certainty, and it built the HD 650 with that in mind. The circumaural velour pads surround the ears instead of pressing on them, and at 260 g, it is light for a full size headphone. Sennheiser also says most parts are modular and replaceable, so pads and cables can be renewed as they wear.
The cable
Sennheiser says the detachable cable is impedance matched with ultra low capacitance, and made from highly conductive OFC copper. Its 6.3 mm plug is the standard connection for headphone amplifiers, receivers and other hi-fi gear, and a 3.5 mm adapter is included for other devices. At 3 m long, the cable reaches gear deep in a shelf or a favorite listening chair.
Powering it
At 300 ohms, the HD 650 is a high impedance headphone. beyerdynamic's guidance on impedance is that higher impedance headphones need more voltage to sound loud enough, and are best with stationary systems and headphone amplifiers rather than phones. The HD 650 follows the same logic. Pair it with a dedicated amp or a good desktop DAC from our list of the best portable DACs and headphone amps. Our explainer on headphone impedance has the details.
The family
The HD 650 sits in a family of open back Sennheiser headphones. Sennheiser lists HD 600 series ear pads and cables among its spare parts for the HD 650. The HD 560S is a lower impedance option, at 120 ohms, that Sennheiser says works on virtually any device. If you want an open back headphone that runs from a laptop, the 560S is easier to drive. If you have the amplification and want Sennheiser's reference class, the HD 650 is the pick.
Who should buy it
Buy the HD 650 if you listen at home, care about natural sound and have, or plan to buy, a headphone amp. It is a great match for a vinyl setup or a lossless streaming system, and its detachable cable and modular parts mean it can last for years.
Skip it if you need isolation, listen mainly on your phone or commute. Open back headphones leak sound and let the room in, and high impedance headphones often sound too quiet on mobile devices.
Where to buy
Sennheiser sells the HD 650 directly, and hi-fi retailers carry it widely.
HD 650 at Sennheiser
Sennheiser HD 650 Open Back Headphones
Sennheiser HD 560S Open Back Headphones
For more studio and listening gear, browse our home studio picks.
