GROUND ZERO GZHW 38XSPL-D1 Hydrogen Series SPL Subwoofer


  • High power 15” SPL subwoofer
  • Klippel® optimized
  • Efficient triple magnet
  • Massive aluminum cast basket
  • Reinforced paper cone
  • 3” copper voice coil
  • High-roll U-surround
  • Push terminal


Thank you for choosing a great GROUND ZERO product! We hope you will enjoy this product from the HYDROGEN series. This owners manual contains the information you need to use this product. Please read it carefully in order to achieve the best possible result. Your car audio specialist or our customer support will answer further questions about the product and its use. Subwoofers are an important part of your car audio system. Please keep in mind, however, that they can only achieve their full performance if all other components of the entire system are carefully coordinated with one another. It is therefore recommended to consult a car audio specialist dealer or workshop for the assembly of the system and its installation and sound adjustments.

High-Grade Technology


Products GROUND ZERO HYDROGEN series meet the requirements of even the most demanding customers. All models are characterized by an astonishing performance, great sound quality and extremely high sound pressure whenever required. The subwoofers have been developed to handle a huge amount of input power reaching extremely high bass levels to be used successfully even under competition conditions but also for everyday music reproduction. For limited installation space, the HYDROGEN series offers powerful but small and installation-friendly amplifiers for most applications.

General installation note

  • Never drill a hole to the vehicle´s gas tank or brake lines, wirings, or any other important vehicle parts!
  • Never pass wires over sharp edges or vehicle parts to avoid any kind of damage
  • Keep the wiring away from the antenna and electronic devices contributing to radio reception
  • Lay the power supply wiring always separated from the speaker wiring to avoid disturbance
  • Use adequately dimensioned power and speaker wires to connect the components

Safety instructions

Safety instructions: Keep all parts of the content and the packaging away from children and pets to avoid accidents and the risk of suffocation. Permanently extreme levels of over 85 dB can lead to irreparable damage to the hearing. Music systems with high amplifier output power can reach levels of 130 dB or more. Extreme levels can also hinder the perception of important traffic noises and distract from what is happening on the road. Ground Zero GmbH and its sales partners expressly assume no responsibility for hearing damage, physical damage or any damage to property or consequential damage resulting from improper or careless use or improper installation of its products. In particular, any claims are forfeited through the use under competitive conditions.
Manufacturer’s declaration: Hereby, Ground Zero GmbH declares that this product conforms to the rules of the following EU directives (including all applicable changes): 2011/65 / EU RoHS2 and 2001/95 / EC directive on general product safety. The full text of the EU declaration of conformity is available at Loudspeakers contain magnetized metals and some valuable raw materials and must not be disposed of with normal household waste. Please leave defective or no longer required.

Terms of warranty

The limited warranty for this product is covered by GROUND ZERO´s regional distribution partners and their terms and conditions. For further information contact your local retailer or distributor.


voice coil 75 mm / 3”
Impedance 2 x 1 Ω 2 x 2 Ω
wired in serial ) 1.92 Ω 3.66 Ω
Fs 43.40 Hz 39.0 Hz
Qms 10.02 9.09
Ages 0.84 0.70
Qty 0.77 0.65
Vas 22.19 L / 0.78 cu.ft 35.04 L / 1.24 cu.ft
MMS 594.8g 464.1g
Xmax (p2p) 45 mm / 1.77″ 45 mm / 1.77″
efficiency 86 dB 87 dB
BL 19.28 24.38
power handling 2000 / 3500 Watt / Watts (RMS/SPL)
Rec. amplifier power 1500 – 3500 WRMS

@2 Ohm (0.5 Ohm)

1500 – 3500 WRMS

@4 Ohm (1 Ohm)


outer diameter 390 mm / 15.35“
mounting cut out 360 mm / 14.17“
mounting depth 231 mm / 9.09“

Recommended power handling


Enclosure recommendation


recommended enclosure

90 l netto / 3.18 cu.ft. net
Port 16 cm / 6.3”
port length 260 mm / 10.24” 30 mm / 11.81”
frequency 42 Hz / 33 Hz 40 Hz / 31 Hz

The above-mentioned enclosure recommendations are just a few possible variations. Please note that you should find the perfect tuning, especially port length, based on your car and own taste.

Wiring options


Verified with KLIPPEL

GROUND ZERO is using the worldwide accepted KLIPPEL® R&D Analyzer KA3 measurement system for speaker development during the German in-house development as well as for QC reporting for most production lines at the factory. The results of LPM and LSI measurements are the basis for evaluating and verifying further development enabling to offer of perfectly working products in any practical application. Continuous and advanced training for developing employees ensures the highest possible qualification. The Linear Parameter Measurement (LPM) module of the KLIPPEL® Analyzer System is dedicated to identifying the electrical and mechanical small signal (Thiele/Small) parameters of electro-dynamical transducers with high accuracy. It is based on the electrical impedance by measuring the voltage and current at the speaker terminals. An additional benefit of displacement measurement is the identification of the suspension creep parameters, resulting in better accuracy of the loudspeaker model at low frequencies. The LPM provides tools to identify and avoid typical problems such as poor signal-to-noise ratio and malfunction due to nonlinear effects of the driver or amplifier limiting. The Large Signal Identification (LSI) module measures the linear, nonlinear and thermal parameters of transducers operated in free air. The transducer is operated under normal working conditions (vertical position and fixed clamped in a laser stand or enclosure). Starting in the small-signal domain, the amplitude is gradually increased up to limits admissible for the particular transducer. The maximal amplitude is determined automatically using the identified transducer parameters and general protection parameters describing the thermal and mechanical load. The identification of the model parameters is performed in real time with an adaptive system. It is based on the estimation of the back EMF from the voltage U(t) and current signal I(t) measured at the electrical terminals. The identified model allows locating the sources of the nonlinear distortion and their contribution to the radiated sound. The dynamic generation of a DC-part in the displacement, amplitude compression and other nonlinear effects can be investigated in detail. After the initial identification, a temporal parameter variation and long-term thermal effects can be investigated.
KLIPPEL® R&D hardware and dB-Lab software for LPM/LSI measurements meet the following standards:GROUND-ZERO-GZHW-38XSPL-D1-Hydrogen-Series-SPL-Subwoofer-fig5 Consumer Electronics Association
CEA-2031(LSI module)
International Electrotechnical Commission
IEC 60268-5, IEC 60268-7, IEC 60268-22, IEC 62458,
IEC 62459, IEC WD 63034
European Standards
BS EN 54-24
Audio Engineering Society
Institute of Electrical and Electronics Engineers
IEEE 269, IEEE 1206, IEEE 1329, IEEE 1652

Respect the MusicGROUND-ZERO-GZHW-38XSPL-D1-Hydrogen-Series-SPL-Subwoofer-fig6

Listening to music can be emotional, impressive, relaxing or enjoyable. At that, it doesn´t really matter what kind of music is the personal favorite, whether it´s Instrumental, Jazz, Electro, Latin, Classic, Rock or any other music direction. However, audio reproduction quality at each desired volume is elementary. Some music styles require higher levels while others prefer the soft tones. GROUND ZERO considers all the different wishes of customers during the development of new products. Along with this, the target is to create the most realistic sound, to transfer the soul of the music and the intention of the performer. Summarized to one phrase: RESPECT THE MUSIC!

GROUND ZERO Produkte werden in Deutschland entwickelt
GROUND ZERO products are engineered in Germany
GROUND ZERO – international sponsor of

Ground Zero GmbH
Erlenweg 25, 85658 Egmating, Germany
Tel. +49 (0)8095/873 830 Fax -8310

Documents / Resources

GROUND ZERO GZHW 38XSPL-D1 Hydrogen Series SPL Subwoofer [pdf] Owner's Manual
GZHW 38XSPL-D1, Hydrogen Series SPL Subwoofer, GZHW 38XSPL-D1 Hydrogen Series SPL Subwoofer, SPL Subwoofer, Subwoofer


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