GZRK 165SQ - Loudspeaker Ground Zero - Free user manual and instructions

Product Type	6.5" Midwoofer (Sound Quality)
Brand	Ground Zero
Model	GZRK 165SQ
Cone Material	Black anodized aluminum
Dust Cap Material	Black anodized aluminum
Surround Material	Rubber
Spider Material	Nomex
Voice Coil Diameter	25 mm / 1"
Voice Coil Wire	Copper wire
Motor System	Ferrite
Efficiency (SPL)	89 dB (1W/1m)
Impedance (Nominal)	4 ohms (Re: 2.9 ohms)
Resonant Frequency (Fs)	60.1 Hz
Frequency Response	35 - 4000 Hz
Power Handling (Nominal/Max)	110 / 160 Watts
Mounting Diameter	142.5 mm / 5.61"
Mounting Depth	68 mm / 2.68"
Outer Diameter	165 mm / 6.5"
Recommended Enclosure	20 L / 0.71 ft³ (up to free air)
Thiele-Small Parameters	Qms 4.28, Qes 0.76, Qts 0.65, Vas 11.5 L
Certification	KLIPPEL® verified
General Installation Notes	Never drill into gas tank or brake lines; keep wiring away from antenna and electronics; use adequate wire gauge.
Safety	Prolonged exposure above 85 dB can cause hearing damage; avoid levels that impair traffic awareness.
Disposal	Do not dispose with household waste; recycle at local facility (contains magnetized metals).

Frequently Asked Questions - GZRK 165SQ Ground Zero

What is the recommended enclosure size for the GZRK 165SQ?

The recommended enclosure size is 20 liters (0.71 ft³). It can also be used in free air (infinite baffle) applications.

Can I use the GZRK 165SQ without a crossover?

For optimal performance, it is recommended to use a passive or active crossover with a high-pass filter above 40 Hz to prevent damage at low frequencies. In a 2-way system, use a low-pass filter around 2500 Hz.

What is the power handling of the GZRK 165SQ?

The nominal power handling is 110 Watts RMS, with a maximum of 160 Watts (music power). Ensure the amplifier output does not exceed these limits to avoid damage.

What type of music is this speaker best suited for?

The GZRK 165SQ is designed for high-quality sound reproduction. It excels with instrumental, jazz, classical, rock, and any music requiring accurate midbass and midrange response.

Is the GZRK 165SQ compatible with the GZRT 25SQ tweeter?

Yes, the GZRK 165SQ is part of the Radioactive Series and is designed to be used with the GZRT 25SQ tweeter in a 2-way component system, combined with the GZRX 165.2SQ crossover.

What is the difference between the GZRK 165SQ and the GZRM 80SQ?

The GZRK 165SQ is a 6.5" midwoofer with a frequency response down to 35 Hz, while the GZRM 80SQ is a 3.15" midrange speaker (140 Hz - 4 kHz). The midwoofer handles lower frequencies and higher power, the midrange is for clearer vocals.

How do I clean the GZRK 165SQ?

Use a soft, dry cloth to gently wipe the cone and surround. Avoid liquids or abrasives. Do not touch the cone with sharp objects.

What is the warranty period for Ground Zero speakers?

Warranty is covered by regional distribution partners. Please contact your local retailer or distributor for specific terms, as warranty periods may vary by region.

Can I install the GZRK 165SQ in a car door panel?

Yes, with proper mounting depth of 68 mm (2.68") and diameter of 142.5 mm (5.61"). Ensure the door has enough space and use a suitable adapter ring if needed. Avoid drilling into fuel or brake lines.

Is the GZRK 165SQ magnet shielded?

The manual does not specify shielding. The motor uses a ferrite magnet, which is typically not shielded. Keep it at least 30 cm away from CRTs or magnetic sensitive devices.

USER MANUAL GZRK 165SQ Ground Zero

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 perfectly working products in any practical application. Continuous and advanced trainings for development employees ensure the highest possible qualification. KLIPPEL® is a registered trademark of KLIPPEL GmbH

Erlenweg 25, 85658 Egmating, Germany

Tel. [phone]

www.ground-zero-audio.com

RADIOACTIVE SERIES

Loudspeaker Components

Owner's manual / data sheet

(AWV2.1)

GZRT 25SQ – Sound Quality Tweeter

• Vented sound quality 25 mm / 1" tweeter
- Coated silk dome
• Vented neodymium motor
- Black finish compound housing and installation frame
• Hexagon protection grill

GZRM 80SQ – Sound Quality Midrange

• Sound quality 80 mm / 3.15" midrange speaker
- Black anodized aluminum cone
- Neodymium motor
• Resonance-free compound basket
• Hexagon protection grill

GZRK 165SQ – Sound Quality Midwoofer

• High-efficient 165 mm / 6.5" midwoofer
- Black anodized aluminum cone and dust cap
• Linearizing copper cap
- Rubber surround
- Nomex spider
• Resonance-free steel basket
• Hexagon protection grill

GZRC 165.2SQ - Component Speaker System

• Sound quality 2-way component speaker system
• High quality 12 dB/oct. passive 2-way crossover

GZRC 165.3SQ - Component Speaker System

• Sound quality 3-way component speaker system
• High quality 12 dB/oct. passive 3-way crossover

General installation note

• Never drill a hole to the vehicle's gas tank or brake lines, to wirings or any other important vehicle parts!
• Never pass wires over sharp edges or vehicle parts due 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 speaker wiring to avoid disturbance
  Use adequately dimensioned power and speaker wires to connect the components

GZRT 25SQ – Specifications

Cone material	Coated silk dome
Cone diameter	25 mm / 1"
Motor system	Vented neodymium
Efficiency (SPL)	89 dB (1W/1m)
Impedance (nominal)	4 ohms
Resonant frequency ( F_s )	1550 Hz
Frequency response	2500 Hz - 24 kHz
Power handling (nominal/max.)	70 / 110 Watts (high pass filtered @ 2500 Hz / 12 dB/oct.)
Outer diameter (incl. mounting frame)	54 mm / 2.13"
Mounting diameter	48 mm / 1.89"
Mounting depth	16 mm / 0.63"

GZRM 80SQ – Specifications

Voice coil type	Copper wire / aluminum former
Voice coil diameter	25 mm / 1"
Cone material	Black anodized aluminum
Cone diameter	61 mm / 2.4"
Dust Cap material	Black anodized aluminum
Motor system	Neodymium
Efficiency (SPL)	89 dB (1W/1m)
Impedance (nominal)	4 ohms
Q_ms - Q_es - Q_ts	2.86 - 0.44 - 0.38
M_ms - B_i - V_us	2.65 gr - 3.58 N/A - 1.5 L / 0.053 cu.ft
Resonant frequency ( F_s )	114 Hz
Frequency response	140 Hz - 4 kHz
Power handling (nominal/max.)	50 / 80 Watts (high pass filtered @ 150 Hz / 12 dB/oct.)
Outer diameter	94 mm / 3.7"
Mounting diameter	77 mm / 3.03"
Mounting depth	34 mm / 1.34"

GZRK 165SQ – Specifications

Voice coil type	Copper wire
Voice coil diameter	25 mm / 1"
Cone material	Black anodized aluminum
Cone diameter	118 mm / 4.65"
Dust cap material	Black anodized aluminum
Motor system	Ferrite
Efficiency (SPL)	89 dB (1W/1m)
Impedance (nominal) / Re	3 ohms / 2.9 ohms
Qms - Qes - Qts - Rms	4.28 - 0.76 - 0.65 - 1.3 kg/s
Mms - Cms - Bl - Le - Vas	15.2 gr - 0.46 mm/N - 4.7 N/A - 0.21 mH - 11.5.1 L / 0.41 cu.ft.
Resonant frequency (Fs)	60.1 Hz
Frequency response	35 - 4000 Hz
Power handling (nominal/max.)	110 / 160 Watts
Recommended enclosure size	20 L / 0.71 ft3 (up to free air)
Outer diameter	165 mm / 6.5"
Mounting diameter	142.5 mm / 5.61"
Mounting depth	68 mm / 2.68"

GZRX 165.2SQ Crossover

3-step individual tweeter level adjustment: The tweeter level can be set by positioning the jumper to the required level position at -2 dB / 0 dB / +2 dB

Tweeter cut-off frequency: The high pass crossover frequency can be selected with the jumper between low and high Low: Increase of the lower tweeter frequency response High: Linear frequency response for direct speaker alignment to the listening position

Speaker connection: IN Input from head unit / amplifier TW Tweeter connector WF Midwoofer connector

GZRX 165.3SQ Crossover

3-step individual tweeter level adjustment: The tweeter level can be set by positioning the jumper to the required level position at -2 dB / 0 dB / +2 dB

Midrange cut-off frequency: The low pass crossover frequency can be selected with the jumper between low and high Low: Linear frequency response for direct speaker alignment to the listening position High: Increase of the upper midrange frequency response

Speaker connection: IN Input from head unit / amplifier TW Tweeter connector MID Midrange connector WF Kickwoofer connector

Active Component Speaker Systems – Crossover Recommendation

Speaker Set	GZRC 165.2SQ-ACT	GZRC 165.3SQ-ACT
Recommended crossover (midwoofer)	HP >40 Hz / LP >2500 Hz HP	>40 Hz / LP >200 Hz
Recommended crossover (midrange)	- HP >200 Hz / LP	>2500 Hz
Recommended crossover (tweeter)	HP >2500 Hz HP >2500 Hz

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 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!

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.

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 to a local recycling facility at the end of their practical use.

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 perfectly working products in any practical application. Continuous and advanced trainings for development employees ensure the highest possible qualification. KLIPPEL® is a registered trademark of KLIPPEL GmbH

GROUND ZERO products are engineered in Germany GROUND ZERO - international sponsor of

Ground Zero GmbH

Erlenweg 25, 85658 Egmating, Germany

Tel. [phone]

www.ground-zero-audio.com