Beyerdynamic DT 770 PROClassic black/grey · 80 ohm · 474746- Nominal impedance
- 80 ohmThis one: 300 ohm
- Rated sensitivity
- 96 dBThis one: 103 dB SPL (1 kHz, 1 Vrms)
HEADPHONES
Sennheiser HD 820
Black · wired, with 6.35 mm and 4.4 mm cables · Sennheiser part 507435
- Acoustic design
- Closed-back
- Wearing style
- Over-ear (circumaural), closed-back dynamic headphones
- Nominal impedance
- 300 ohm
The HD 820 (article 507435) is Sennheiser's reference-class closed-back audiophile headphone, with a 56 mm Ring Radiator dynamic transducer behind concave Gorilla Glass reflectors, 300-ohm impedance, a rated 360 g without cable, and both 6.35 mm unbalanced and 4.4 mm balanced cables in the box.
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THE ACTUAL PRODUCT
Compare with Beyerdynamic DT 770 PRO
Specifications checked 26 Sept 2026Manufacturer specifications, not a hands-on test.
The nearest checked headphones by key specifications, with what differs from the Sennheiser HD 820. The first matches the Compare button above.
Beyerdynamic DT 770 PROClassic black/grey · 80 ohm · 474746
Beyerdynamic T5 (3rd generation)717789 · 3rd generation · 32 ohm · wired- Wearing style
- Over-ear (circumaural), closed-back wired headphonesThis one: Over-ear (circumaural), closed-back dynamic headphones
- Nominal impedance
- 32 ohmThis one: 300 ohm
Beyerdynamic DT 700 PRO X737704 · 48 ohm · black- Wearing style
- Over-ear (circumaural), closed-back wired studio headphonesThis one: Over-ear (circumaural), closed-back dynamic headphones
- Nominal impedance
- 48 ohmThis one: 300 ohm
Key strengths
Both an unbalanced 6.35 mm cable and a balanced 4.4 mm cable are supplied, each 3 m long, and an optional XLR-4 balanced cable is available for headphone amplifiers, DACs and other components.
Sennheiser attributes ambient-noise attenuation to the closed-back construction but publishes no attenuation figure.
Sennheiser publishes 12–43,800 Hz at −3 dB and 6–48,000 Hz at −10 dB, 300-ohm impedance and 103 dB at 1 kHz, 1 V.
Before you buy
Sennheiser states the distortion test two ways: below 0.02% at 1 kHz and 100 dB in the specification table, and 0.02% at 1 kHz, 1 Vrms in the feature list.
The supplied cables end in 6.35 mm and 4.4 mm plugs; no 3.5 mm plug or adapter is listed in the box, and the XLR-4 cable is optional.
The supplied cables are 3 m long, with 6.35 mm unbalanced and 4.4 mm balanced plugs.
Every specification. With its source.
Full specifications
Exact configuration: 507435 · Black · wired, with 6.35 mm and 4.4 mm cables
16 specifications in 5 groups. Values are manufacturer specifications unless a row says “Measured result” or “Calculated from cited specifications”.
Design & fit
3 items
- Acoustic design
- Closed-backSource
- Wearing style
- Over-ear (circumaural), closed-back dynamic headphones
- Weight
- 360 g
Without the connection cable, per Sennheiser's UK store data ('360 g without cable'); the product-page table gives 360 g.
Connections & battery
4 items
- Wired / wireless connections
- Wired analogue; detachable 3 m cables with 6.35 mm unbalanced plug (fitted) and 4.4 mm balanced plug, both supplied; XLR-4 balanced cable optional
Sennheiser's box list names only the 6.35 mm unbalanced and 4.4 mm balanced cables; no 3.5 mm plug or adapter is listed.
- Battery life
- Not listed by the manufacturer
The reviewed exact sources do not explicitly establish battery life or that no battery is required for operation. A wired/dynamic audio path, omitted charger or Battery included N is not an explicit operating-power requirement.
Source - Cable length
- 3 m
- Connectors
- 6.35 mm unbalanced (3-pin) and 4.4 mm balanced (5-pin) supplied; XLR-4 balanced (4-pin) cable optional
Audio specifications
6 items
- Nominal impedance
- 300 ohm
- Rated sensitivity
- 103 dB SPL (1 kHz, 1 Vrms)
Voltage reference (dB/V), not dB/mW.
- Driver construction
- 56 mm Ring Radiator dynamic transducer with concave Gorilla Glass reflectorsSource
- Driver size
- 56 mmSource
- Rated frequency range
- 12–43,800 Hz (−3 dB); 6–48,000 Hz (−10 dB)
- Rated total harmonic distortion
- <0.02% (1 kHz, 100 dB SPL)
From the product page's specification table; the same page's feature list states 'Total harmonic distortion: 0.02 % (1 kHz 1 Vrms)', a different test condition.
Source
Calls & noise control
2 items
- Active noise cancellation
- Not listed by the manufacturer
The reviewed exact sources do not explicitly establish active noise cancellation absence. Preserve separately sourced acoustic design and passive attenuation; they cannot turn omitted ANC into a false capability.
- Microphone
- Not listed by the manufacturer
The reviewed exact sources do not explicitly establish microphone absence. Omission from a package or technical inventory, a stereo audio connector, and a without-remote statement do not establish microphone=false.
Source
In the box
1 item
- In the box
- Headphones, cable with 6.35 mm unbalanced plug (fitted), cable with 4.4 mm balanced plug, instruction manual, storage box, microfibre clothSource
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