GROUND ZERO GZUC 165.3SQ Loudspeaker System
Introduction
Thank you for choosing a GROUND ZERO product and welcome to your new URANIUM series loudspeaker! This is the owner´s manual providing instructions on the operation and installation of this loudspeaker system. Please, read it carefully. If you have any further questions, please contact your local GROUND ZERO dealer or our regional distribution partner. The loudspeaker system is one of the most important parts of your car audio system. However, it will only be able to deliver its full performance when each part of the whole system is tuned carefully matching each other. Therefore, we recommend consulting a car audio specialist to compile the desired sound system, as well as for installation and tuning. We hope you will enjoy the sound quality of an enthusiastic development by the GROUND ZERO engineering team.
URANIUM Series – Amazing Sound Quality
Products belonging to the GROUND ZERO URANIUM series stand for high-end sound quality or extreme power handling capability. Each product of the URANIUM line-up has been developed carefully to fulfill the demands of music enthusiasts with high audiophile expectations at a reasonable price level. Applying all of Ground Zero´s sound quality competition experience while tuning the product details carefully, results in emotional and amazing audio reproduction. The distinguished amplifiers point out the main purpose by their designation: SQ beyond the average! GZUC 165.3SQ/SQ-ACT is a loudspeaker system of the new URANIUM series, delivering an outstanding sound performance.
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 regional distributor.
General installation note
- Never drill a hole in the vehicle´s gas tank or brake lines, wirings, or any other important vehicle parts!
- Never pass wires over sharp edges or vehicle parts due 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
Features
- 3-way SQ component loudspeaker system
- Klippel® optimized 165 mm / 6.5” mid-woofer
- The black anodized aluminum cone
- GZ design aluminum cast basket
- High-efficient, linearized neodymium motor
- Durable rubber surround
- Gold plated terminals
- 55 mm / 2.17” SQ silk dome midrange
- 28 mm / 1.1” SQ silk dome tweeter with flush mount housing
- Variable 12 dB/oct crossover (not for ACT model) with level adjustment and 2-way semi-active option
- GZ design hexagon style protection grill.
Specifications
| Model | GZUC 165.3SQ |
| Speaker type | 165 mm / 6.5” 3-way loudspeaker system incl. crossover |
| Impedance (nominal) | 4 ohms |
| Frequency response | 40 Hz – 25 kHz |
| High pass filter | 4500 Hz @ 12 dB/oct. |
| Band pass filter | HP: 450 Hz @ 12 dB/oct. / LP: 4500 Hz @ 12 dB/oct. |
| Low pass filter | 450 Hz @ 12 dB/oct. (jumper in OFF position: 6 dB/oct.) |
| Power handling (RMS) | 160 Watts |
| Power handling (max.) | 250 Watts |
| Model | GZUC 165.3SQ-ACT |
| 165 mm / 6.5” 3-way loudspeaker system for active application |
| Model | GZUT 28SQ |
| Diameter (nominal) | 28 mm / 1.1” |
| Housing | Plastic |
| Dome | Coated silk |
| Voice Coil | 28 mm / 1.1“ copper |
| Motor | Neodymium magnet |
| Impedance | 4 ohms |
| Frequency response | 2500 Hz – 25 kHz |
| Power handling | 80 Watts RMS 130 Watts max. (12 dB/oct HPF @ 3 kHz) |
| Resonance frequency | 1300 Hz |
| Efficiency (SPL) | 90 dB |
| Model | GZUM 55SQ |
| Diameter (nominal) | 55 mm / 2.17” |
| Dome | Coated silk |
| Voice Coil | 55 mm / 2.17” copper |
| Motor | Neodymium magnet |
| Impedance | 4 ohms |
| Frequency response | 500 Hz – 11 kHz |
| Power handling | 90 Watts RMS 150 Watts max. (12 dB/oct HPF @ 600 Hz) |
| Resonance frequency | 353 Hz |
| Efficiency (SPL) | 88 dB |
| GZUT 28SQ | |
| Outer diameter | 54 mm / 2.13” |
| Mounting diameter | 48 mm / 1.89” |
| Mounting depth | 18 mm / 0.71” |
| Model | GZUK 165SQ |
| Diameter (nominal) | 165 mm / 6.5“ |
| Basket | Aluminum cast |
| Cone | Anodized aluminum |
| Voice coil | 50 mm / 2“ copper |
| Motor | Neodymium magnet |
| Impedance (nominal) | 4 ohms |
| Frequency response | 40 Hz – 3.5 kHz |
| Power handling | 120 Watts RMS 180 Watts max. (60 Hz HPF @ 12dB/oct) |
| Resonance frequency | 54.6 Hz |
| Efficiency (SPL) | 87 dB |
| Re | 3.2 ohms |
| Qms | 3.87 |
| Qes | 0.77 |
| Qts | 0.64 |
| Vas | 12.6 L |
| Mms | 16.3 g |
| BL | 4.84 N/A |
| Rms | 1.44 kg/s |
| Cms | 0.52 mm/N |
| LE | 0.17 mH |
| Xmax (excursion) | 12 mm / 0.47“ (p2p) |
| GZUM 55SQ | |
| Outer diameter | 90 mm / 3.54” |
| Mounting diameter | 69 mm / 2.72” |
| Mounting depth | 33 mm / 1.30” |
| GZUX 165.3SQ (w x h x d) | 85 x 42 x 140mm / 3.35 x 1.65 x 5.51“ |
GZUT 28SQ / GZUM 55SQ Dimensions 
GZUK 165SQ Dimensions
Crossover Setup (not for ACT model)
![]() | Tweeter level adjustment: The tweeter level can be set by positioning the jumper to the required level position |
| Midrange level adjustment: The midrange level can be set by positioning the jumper to the required level position | |
| Semi-active use IMPORTANT! If the mid-woofer is connected to a separate amplifier the mid-woofer section must be de-activated to use the crossover for midrange and tweeter only. Set the WF jumper to the OFF position | |
| IN | Input from head unit/amplifier |
| TW OUT | Tweeter connector |
| MID OUT | Midrange connector |
| WF OUT | Kickwoofer connector |
GZUC 165.3SQ Wiring
GZUC 165.3SQ Semi-active wiring
4-channel amplifier with integrated active crossover
GZUC 165.3SQ-ACT Wiring (example) 
Noise damping is – Essential basis for a high-quality sound experience
Simple or thin surfaces and panels of the car´s body and in the vehicle´s interior tend by stimulation to vibrations, in particular by vibrations that arise while driving or when playing music with the speaker cones. In order to reduce the resulting booming, the natural resonance, which means the frequency at which these surfaces resonate particularly strongly, must be reduced. For this purpose, the insulation of aluminum-butyl requires the largest possible mass. For this purpose, GROUND ZERO offers materials with different properties and basis weight. In addition, the GROUND ZERO range offers other products, such as self-adhesive aluminum plates or sound-absorbing foam mats, which improve the result even more. The bonding of these materials drastically changes the tendency of body parts to oscillate, which significantly reduces the unwanted noise level. A complete door damping set is available with GZDM DOOR KIT PRO.
Essential door damping is available as GZDM DOOR KIT PRO
Respect the Music
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 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.
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 www.ground-zero-audio.com. 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 components at a local recycling facility at the end of their practical use.
Ground Zero GmbH
Erlenweg 25, 85658 Egmating, Germany Tel. +49 (0)8095/873-830 www.ground-zero-audio.com.

























