Audio T Verdict
The Sennheiser HD 650 have remained a favourite among serious headphone listeners for good reason. They bring voices and instruments into focus without pushing the treble forward to create an exaggerated impression of detail. Their balance is smooth, expressive and particularly easy to enjoy over a full album.
Within Sennheiser's open-back 600 Series, the HD 650 offer a slightly fuller and gentler presentation than the more neutral HD 600. The newer HD 660S2 reach further into the lowest bass frequencies and include a balanced cable, but the HD 650 retain a character of their own. These are differences worth hearing with familiar music rather than deciding from specifications alone.
Their 300-ohm impedance makes the quality of the headphone output worth considering. A capable amplifier helps the HD 650 show what they can do, although a separate headphone amplifier is not essential if your existing equipment drives them well. Add comfortable velour earpads, a detachable cable and replaceable parts, and this is a pair designed for years of listening.
Important: Fully Open-Back Headphones
The HD 650 allow sound to pass through the rear of their earcups. This contributes to their natural presentation, but they provide very little isolation from outside noise and other people nearby may hear your music. They make most sense in a quiet room, rather than on a commute or in a shared workspace.
Why the HD 650 Have Lasted
The HD 650 follow a straightforward idea: make a pair of headphones that lets you settle into the music. Their open construction gives sound room to breathe, while carefully matched left and right transducers help preserve a consistent stereo image. There are no wireless features, batteries or sound modes to navigate. The result depends on the recording and the equipment you connect to them.
That simplicity has made the HD 650 a lasting choice for dedicated home listening. They reveal differences between recordings and components, yet their smooth balance helps keep a less-than-perfect recording enjoyable. Vocals, piano, strings and acoustic instruments have the space and body to sound convincing without being forced forward.
A Carefully Matched Transducer
Each earcup contains a 42mm dynamic transducer with a 38mm diaphragm and an aluminium voice coil. Sennheiser measures and pairs the transducers to keep their performance closely matched between channels. Fine acoustic metal mesh helps control the sound behind the driver, while the open earcup avoids the enclosed character of a conventional closed-back headphone.
The HD 650 have a specified frequency response of 10Hz to 41,000Hz and total harmonic distortion below 0.05% at 1kHz and 1V. Those figures describe the engineering, but the practical appeal is how naturally the headphones handle the middle of the music, from a singer's voice to the texture of a guitar or the decay of a piano note.
Smooth Sound Without Losing the Detail
The HD 650 have a slightly rich, unhurried balance that many listeners find comfortable for long sessions. There is detail in cymbals, strings and room ambience, but the upper frequencies do not demand constant attention. Bass is controlled and supportive rather than deliberately boosted, giving instruments weight without crowding the midrange.
Their presentation is open, although it is more intimate than the exceptionally wide soundstage associated with models such as the Sennheiser HD 800 S. If you value natural vocals and a sense of connection to the performance, that closer perspective may be exactly what you want.
Comfort and Long-Term Ownership
Soft velour earpads sit around the ears, and the headphones weigh approximately 260g without the cable. Their full-sized fit and open earcups suit extended listening at home. As with any headphone, comfort is personal, so trying them on remains worthwhile if you can visit a store.
The HD 650 are made in Ireland and use a modular construction. The cable and earpads can be replaced separately if they wear over time, helping you keep a well-loved pair in use. Their supplied three-metre cable also gives you room to sit back from a hi-fi rack or desktop system.
Getting the Best From a 300-Ohm Headphone
The HD 650 have a nominal impedance of 300 ohms and a specified sound pressure level of 103dB at 1V. The latter is a sensitivity measurement, not a maximum volume limit. What matters in practice is whether your headphone output can provide enough clean voltage and headroom for the way you listen.
A good integrated amplifier or dedicated headphone output may already be suitable. If you listen through a phone, laptop or small USB adapter, performance will depend on that particular device; the presence of a 3.5mm socket alone does not tell you how well it will drive the headphones. Audio T can help you assess your existing equipment or compare options from our headphone amplifier range.
The detachable, dual-sided OFC copper cable ends in a 6.3mm stereo plug, the size commonly found on hi-fi components and headphone amplifiers. A 6.3mm-to-3.5mm adapter is included for compatible smaller sockets. The supplied cable is a conventional single-ended connection; a balanced cable is not included.
HD 650, HD 600 or HD 660S2?
All three are open-back members of Sennheiser's 600 Series, and all reward a suitable headphone output. Their different balances matter more than a simple ranking of old and new.
HD 650 or HD 600?
The HD 600 are the more neutral, reference-oriented choice. The HD 650 sound a little fuller and smoother, making them particularly appealing if you want revealing headphones with a relaxed long-term balance.
HD 650 or HD 660S2?
The HD 660S2 use a newer transducer design with stronger low-bass extension. They also include both 6.3mm and 4.4mm balanced cables. The HD 650 remain a compelling choice if their particular smooth, intimate presentation suits your music better.
If possible, bring a few familiar tracks to an Audio T store and compare the models through the same source and amplifier. It is the clearest way to decide which balance you would enjoy living with.
Key Features
- Open-back, around-ear hi-fi headphones
- 42mm dynamic transducers with 38mm diaphragms
- Matched left and right transducers
- Aluminium voice coils
- Fine acoustic metal mesh damping
- 300-ohm nominal impedance
- 10Hz to 41,000Hz specified frequency response
- Smooth, detailed sound for extended listening
- Soft velour earpads
- Approximately 260g without cable
- Detachable three-metre OFC copper cable
- 6.3mm stereo plug and supplied 3.5mm adapter
- Replaceable cable and earpads
- Made in Ireland
Frequently Asked Questions
Are the Sennheiser HD 650 still current?
Yes. The HD 650 remain listed in Sennheiser's current headphone range.
Are the HD 650 open-back?
Yes. Their earcups are acoustically open, giving the drivers room to breathe while allowing outside noise in and some of your music out.
Do the HD 650 need a headphone amplifier?
They need a headphone output capable of driving a 300-ohm load well. That might be a suitable output on equipment you already own, although a dedicated headphone amplifier can be a worthwhile match.
Can I use them with a phone or laptop?
The supplied adapter allows connection to a compatible 3.5mm socket. Whether a particular phone, laptop or USB adapter drives them well depends on its headphone output.
What plug and cable are supplied?
The detachable cable is approximately three metres long and has a 6.3mm stereo plug. A 6.3mm-to-3.5mm adapter is also included.
Is a balanced cable included?
No. The HD 650 are supplied with a conventional 6.3mm stereo cable. If you have a balanced headphone amplifier, ask us about a suitable compatible cable rather than assuming the supplied adapter provides a balanced connection.
Can the cable and earpads be replaced?
Yes. The HD 650 have a detachable cable and replaceable earpads as part of their modular construction.
Where are the HD 650 made?
Sennheiser states that the HD 650 are made at its production facility in Ireland.
What is the difference between the HD 650 and HD 600?
The HD 600 are generally the more neutral and reference-oriented of the two. The HD 650 offer a slightly fuller, smoother balance. Both are 300-ohm open-back headphones and are well worth comparing directly.
How do the HD 650 differ from the HD 660S2?
The HD 660S2 have a newer transducer design, stronger low-bass extension and a 4.4mm balanced cable in the box. The HD 650 have their own established tonal character and a longer three-metre standard cable.
Do they have Bluetooth or noise cancellation?
No. The HD 650 are passive wired headphones without Bluetooth, a battery or active noise cancellation.
How long is the manufacturer's warranty?
Sennheiser provides a 24-month manufacturer's warranty for the HD 650, subject to its warranty terms and proof of purchase.
Related Products and Guides
Hear the HD 650 at Audio T
Choosing between the HD 600, HD 650 and HD 660S2 is about the sound you prefer and the equipment you will use with them. We can help you compare the models, assess your current headphone output and find an amplifier if your system would benefit from one.
Contact your local Audio T store to discuss the HD 650 or arrange a demonstration where available. Bring your own music, and we can help you find the combination that makes you want to keep listening.