Neumann KH 870 II – Flagship DSP-Controlled Subwoofer with Multichannel Bass Management

OVERVIEW

Powerful Reference-Quality Sub for Immersive Systems

The KH 870 II is the perfect subwoofer for larger rooms, providing powerful bass extension with Neumann precision. It includes a unique and flexible Bass Manager for stereo, surround and immersive systems up to 7.1.4. Analog and digital outputs provide flexible connectivity to up to 11 studio monitors.

Next Generation Subwoofer

The KH 870 II improves on its predecessor in acoustic performance and adds new features. Thanks to two novel long-throw 10” woofers with Extremely Linear Force Factor (ELFF™) technology and intelligent protection limiters, the KH 870 II ensures exceptionally low distortion even at maximum SPLs.

The KH 870 II extends low-frequency reproduction down to 16 Hz and delivers about twice the output of the KH 810 II. This makes the KH 870 II the perfect complement to midfield speakers such as the KH 420.

The KH 870 II is DSP-controlled for superior sonic performance and seamless integration via MA 1 Automatic Monitor Alignment (sold separately). When combined with analog Neumann studio monitors such as the KH 120 A (discontinued), KH 310, or KH 420, it offers sufficient DSP power for aligning an entire stereo, surround or even immersive system up to 7.1.4 via MA 1, optimising not only the frequency response but also the phase. Of course, the KH 870 II is also a perfect complement to Neumann’s DSP-equipped studio monitors. In surround and immersive systems, analog and DSP-equipped Neumann speakers can be combined and room-aligned using MA 1 with Multichannel Extension (sold separately). The KH 870 II is therefore much more than “just” a subwoofer: It is the perfect tool for upgrading existing systems and/or extending them for immersive audio.

Precision in Every Detail

As subwoofers are typically placed on the floor, robust grilles protect the drivers from accidental damage. The rigid cabinet features a highly efficient bass reflex system, which is carefully engineered and tuned for the tightest bass reproduction – with inaudible port noise.

Two analog XLR inputs and outputs are available to connect the subwoofer for stereo operation. For multichannel operation, the KH 870 II offers two Sub D25 connectors for up to 12 analog input channels and another two Sub D25 connectors for up to 11 analog output channels. All inputs and outputs are electronically balanced. Studio monitors can also be connected digitally via AES3 (BNC). For audio networking, this subwoofer is also available as an AES67 variant, the KH 870 II AES67.

The KH 870 II excels in music, film scoring, broadcast, and post-production studios for tracking, mixing, and mastering. Thanks to a novel power amp design, the KH 870 II combines superior audio performance with excellent energy efficiency. Its Auto Standby function can be deactivated in the MA 1 app.

KEY HIGHLIGHTS

Deep and Extremely Powerful Bass Down to 16 Hz

The KH 870 II extends the monitoring system’s low-frequency response down to an impressive 16 Hz, providing a powerful foundation for accurately assessing sub-bass content, low-end energy and the overall balance of a mix. Its two 10-inch long-throw woofers use Neumann’s Extremely Linear Force Factor™ technology to maintain exceptionally low distortion even at high excursion levels, while the bass-reflex enclosure is engineered for tight, controlled reproduction with minimal port noise.

The Perfect Complement to Mid-Size and Large Neumann KH Line Studio Monitors

Designed for larger monitoring environments, the KH 870 II provides substantial low-frequency extension and headroom for Neumann’s mid-size and large KH-series monitors. It complements monitors such as the KH 310 and KH 420 by taking over the deepest bass frequencies, allowing the main speakers to operate more efficiently while increasing the maximum SPL capability and reducing harmonic and intermodulation distortion across the monitoring system.

DSP-Controlled for Superior Sonics and Unparalleled Precision

The KH 870 II uses sophisticated 32-bit DSP with 64-bit double-precision processing to provide precise control over crossover, routing, delay and system integration. Its 80 Hz crossover with a 24 dB/octave slope, adjustable delay of up to 115 ms and advanced protection circuitry allow the subwoofer to be integrated accurately into demanding professional monitoring systems, while maintaining excellent phase and transient performance.

Room Correction via MA 1 Automatic Monitor Alignment (Sold Separately)

When used with the separately available MA 1 Automatic Monitor Alignment software, the KH 870 II can be automatically calibrated to the listening environment for a more accurate and consistent monitoring response. The system can optimise frequency response and phase while integrating the subwoofer with the connected monitors, helping compensate for the acoustic characteristics of the room rather than relying solely on manual adjustment.

Supports Automatic Alignment Also for Analog KH-Line Studio Monitors (Patented)

A major advantage of the KH 870 II is its ability to extend MA 1 automatic alignment to compatible analog Neumann KH-series monitors, not just DSP-equipped models. This gives existing owners of analog KH monitors a pathway to sophisticated room correction and subwoofer integration, with sufficient DSP power to align an entire multichannel system for stereo, surround or immersive configurations up to 7.1.4.

FEATURES

• Bass extension of the monitoring system down to 16 Hz
• Increasing the maximum SPL of the entire system
• Decreasing harmonic and intermodulation distortion of loudspeakers
• MA 1 Ready for perfect alignment of the entire system and seamless subwoofer integration.
• MA 1 integration of analog KH Line speakers, enough DSP power for an entire multichannel system up to 7.1.4.
• Ultra-stiff wooden cabinet:
  • Tough painted finish and built-in rubber feet for acoustic isolation
  • Excellent self-damping properties leading to minimal cabinet resonances
  • No standing wave resonances inside cabinet
  • Ultra-tight bass reproduction due to very low group delay
•  Two in-house modelled long-throw bass drivers with Extremely Linear Force Factor™ (ELFF™) and robust resonance-optimised basket
• Damping of break-up modes brings low distortion at high sound levels
• Extremely linear force factor provides low harmonic distortion even at high excursions
• Reduced air noise and improved rocking modes
• Grille protects against mechanical damage
• XLR electronically balanced analog inputs and outputs (stereo):
  • Standard interfacing to professional equipment
  • Daisy chain input and output for subwoofer arrays
• Two electronically balanced SUB-D 25 connectors for up to 12 analog input channels and another two SUB-D 25 connectors for up to 11 analog output channels. The pinout follows the Tascam standard.
  Digital outputs (multichannel)
  • 192 kHz, 24-bit conversion
  • 7 x BNC: Channels 1-3, Channels 5-12, Daisy Chain Out
• Network connector using standard IP protocol and your existing network infrastructure
  • Loudspeaker system including analog KH-line monitors can be controlled via MA 1 – Automatic Monitor Alignment Software.
• Control function
  • Toggle switch for selection of two completely independent modes of operation and calibration: on the device or via the network using the MA 1 – Automatic Monitor Alignment software.
• Universal switched-mode power supply (100 … 240 V)
  • One version works in any country and is robust to poor quality mains supply.
• Ground lift to overcome ground loops
  • Inputs with very high CMRR to reduce noise induced by long cables in electrically noisy environments
  • Completely symmetrical internal signal flow to avoid electrical interferences
• Low heat dissipation amplifiers with large headroom and sophisticated protection circuitry
  • Improved transient response
  • Assured reliability and safety
  • Separate thermo limiter to protect the voice coil and power amplifier
• Soft clip and excursion limiters
  • Increase system reliability
  • Allow extraction of the maximum performance from the system
• Standby function
  • Reduces power consumption when the unit is not in use

TECHNICAL SPECS

Acoustics
Free field frequency response ±6 dB	16 … 750 Hz
Free field frequency response ±3 dB	18 … 310 Hz
Self-generated noise at 10 cm (with input gain set to 100 dB SPL for 0 dBu)	<20 dB(A) SPL
Minimal self-generated noise at 10 cm Self-generated noise / Input gain setting/output gain setting	<20 dB(A) SPL
Sine wave output with a THD < 0.5 % at 1 m in half space	95 dB SPL (33 – 200 Hz)
Bass capability: Max. SPL in half space at 3% THD at 1m (averaged between 50 Hz and 100 Hz)	114.9 dB
Max. SPL for subwoofers: on floor; against the wall; in the corner	114,9 dB; 117,9 dB; 120,9 dB
Dolby DARDT. Max SPL bass managed	123 dB SPL
Acoustical Principle	Bassreflex, Ports at the front
Analog Inputs & Outputs
Analog input(s)	2 x XLR: electronically balanced; 1 x SUB-D 25: 8 x electronically balanced; 1 x SUB-D 25: 4 x electronically balanced
Analog input impedance	>12k Ohms
Max. input level	24 dBu (CH 1…3, 12); 21 dBu (CH 5…11)
Common mode rejection ratio (CMRR), XLR / Sub-D	> 56 dB @ 15 kHz
Crosstalk (1 kHz), level matching, XLR / Sub-D	-90 dB; ±0.1 dB
Remote volume control	via MA 1 software
Volume control range; resolution	0 … -∞ dB; 0.1 dB
Analog dynamic range; THD+N (A-D-A), XLR / SubD	120 dB(A)(CH1…3,12); 116dB(A) (CH5…11) <0.003% (-90 dB)
Signal routing modes	analog
Analog output(s)	2 x XLR: electronically balanced; 1 x SUB D 25: 7 x electronically balanced; 1 x SUB D 25: 4 x electronically balanced
Digital Inputs & Outputs
Digital input(s)	1 x BNC: Daisy-chain in
Digital output(s)	7 x BNC: 11 x Monitor out; 1 x daisychain out
Digital converter: resolution; design	24 Bit
Digital converter: sampling rate	32 kHz..200 kHz
Digital internal sampling rate	48 kHz
Output sampling rate	48 kHz
Dynamic range A-D	CH 1, 2, 3, 12=124 dBA; CH 5…11=121 dBA
Dynamic range A-D-A (Converter)	CH 1, 2, 3, 12=121.5 dBA; CH 5…11=116.2 dBA
Dynamic range D-A	CH 1, 2, 3, 12=125 dBA; CH 5…11=118 dBA
Digital sensitivity	-18 dBFS = 100 dB SPL at 1 m
Latency ADA / DA	2 ms (A-D-A)
Delay: User adjustable delay range	0 … 115 ms
Delay: Resolution: time; distance	20.8 µs; 0.71 mm (0.28 “)
Delay: Max. frames Audio-video synchronisation (lip sync)	2 (40 ms) frames; 2.75 (33 ms) frames
Delay: Time-of-flight maximum distance	Out of 115 ms, FW based
User Interface
Status Indication	Illuminated Neumann Logo
Ground Lift	Yes
Control	Local; Network
Mains Switch	Yes
Mains Voltage	Universal Power Supply 100 V~ … 240 V~
Electronics – Controller
Controller design	Digital; active
DSP resolution	32 Bit Audio, processing 64 Bit double precision
Crossover frequency	80 Hz
Crossover slope	24 dB/oct; 4th order
Supports automatic room calibration via MA 1	Yes; Subwoofer and connected analog loudspeakers
FIR phase linearization	for connected analog loudspeakers in combination with MA 1
Protection circuitry	soft clip, peak and thermo limiters; Woofer excursion limiter; thermo limiter for the electronics and amplifiers
Remote control	via Ethernet and MA 1
Display: On; Normal Operation	Neumann logo “White”
Display: Identification	Neumann logo “Rosé”
Display: Limit / Clip / Errors / Protection /Boot Mute / Shut Down Mute	Neumann logo “Red”
Logo Brightness	via MA 1 software
Electronics – Amplifiers & Power Supply
Output power woofer amplifier (THD+N with limiter activated: 0.1%)	360 W
Mains Power Supply: input voltage; frequency	SMPS: 100-240 V; 50/60 Hz
Power consumption (230 V / 100 V): Standby	<=300mW
Power consumption (100 V): Idle	41 W
Power consumption (230 V / 100 V): Idle	41 W
Power consumption (230 V): Idle	41 W
Power consumption (100 V): Full output	510 W
Power consumption (230 V / 100 V): Full output	510 W
Power consumption (240 V): Full output	472 W
Standby	Automatic, 20 mins (default)
Amplifier Standby	Disabled; user defined in software
Mechanics
Cabinet material	Wood cabinet, aluminum electronics panel
Cabinet surface finish; colour (front/back)	Painted; metallic anthracite (RAL 7021) / black (RAL 9005)
Operating conditions	+10° C to +40° C (+50° F to +104° F); <75% RH, non-condensing
Transport/storage conditions	-25° C to +60° C (-13° F to 140° F); <90% RH; non-condensing
Woofer	2 x 265 mm (10″) with protective black metal grille
Mounting points	35 mm flange on top panel
Product dimensions (height x width x depth)	737 x 330 x 645 mm (28.9″ x 13″ x 25.4″)
External net volume	157 liters
Product weight	44.5 kg (98 lbs 2 oz)
Packed dimensions (height x width x depth), mm (inches)	839 x 454 x 749 (33″ x 17.9″ x 29.5″)
Packed weight	51.2
Packaging weight incl. Cables and manuals	6.7
Packed cube	0.285 m³
Delivery includes	1 x KH 870 II Mains cables EU/KC; UK; US; China 1 x Getting Started Quickly guide 1 x Operating Manual
Acoustical Axis horizontal	165 mm
Acoustical Axis vertical (from bottom)	365 mm

DIAGRAMS

KH 870 II/ AES67 Frequency response

KH 870 II / AES67 Frequency response Subwoofer + Satellite

KH 870 II/ AES67 Group Delay Subwoofer + Satellite

KH 870 II/ AES67 Harmonic Distortion at 95 dB SPL

KH 870 II/ AES67 Maximum SPL at 1 m