QT18SA - Subwoofer Qtx - Free user manual and instructions

Product Type	Active Subwoofer
Brand	Qtx
Model	QT18SA
Driver Size	18 inches (457 mm)
Type	Active (built-in amplifier)
Amplifier Power (RMS)	1000 W
Amplifier Power (Peak)	2000 W
Frequency Response	30 Hz - 150 Hz
Maximum SPL	130 dB
Impedance	4 ohms
Dimensions (W x D x H)	600 mm x 550 mm x 700 mm
Weight	45 kg
Power Supply	AC 110-240 V, 50/60 Hz
Input Connections	XLR (balanced), 6.3 mm jack (unbalanced)
Output Connections	XLR Link Output
Cooling	Active fan cooling
Protection	Short-circuit, thermal, overload
Enclosure Type	Bass-reflex (ported)
Finish	Black textured paint
Features	Adjustable crossover, phase switch, volume control
Safety	Use grounded outlet; do not expose to moisture; operate in well-ventilated area.
Maintenance	Clean with dry cloth; check cables periodically; ensure ventilation slots are unobstructed.
Spare Parts & Repairability	Replaceable fuse; driver replacement available; amplifier module serviceable by qualified technician.

Frequently Asked Questions - QT18SA Qtx

How do I connect the QT18SA subwoofer to my mixer?

Use a balanced XLR cable from the mixer's main output to the subwoofer's input. If using two subwoofers, connect the first sub's XLR link output to the second sub's input.

What is the power rating of the QT18SA?

The QT18SA has a built-in amplifier rated at 1000 W RMS and 2000 W peak.

Can the QT18SA be used outdoors?

It is not weatherproof. Use under cover or with a suitable protective enclosure if used outdoors. Avoid rain and direct sunlight.

How do I set the crossover frequency?

Use the crossover knob on the rear panel. A typical setting for full-range speakers is around 80-120 Hz. Adjust based on your speaker specifications.

What should I do if there is no sound from the subwoofer?

Check power, audio cables, and volume levels. Ensure the subwoofer's on/off switch is on. Verify that the input signal is present and the phase switch is set correctly.

How do I transport the QT18SA safely?

Use a wheeled flight case or robust transportation with padding. Secure the subwoofer to prevent shifting during transport.

Can I daisy-chain multiple QT18SA subwoofers?

Yes, use the XLR link output to connect to the next subwoofer's input. Ensure the total load impedance stays within amplifier limits (usually 4 ohms per channel).

What is the phase switch for?

The phase switch (0° or 180°) aligns the subwoofer's output with the main speakers. Switch between settings to achieve the strongest bass response at the listening position.

How do I clean and maintain the QT18SA?

Wipe the exterior with a soft dry cloth. Do not use chemicals. Periodically check the power cable and input connectors for damage. Keep ventilation grilles free of dust.

Where can I find replacement parts for the QT18SA?

Contact Qtx customer support or authorized dealers for replacement drivers, fuses, or amplifier modules. Use only genuine parts to maintain performance and safety.

USER MANUAL QT18SA Qtx

QT Active Sub Cabinets

User Manual

170.751, 170.755

Features:

• High output sub driver
- Dual ported enclosure
- Variable X-over frequency
• 35mm pole-mount fitting
- Perforated steel grille

Introducon:

Thank you for choosing the QT series acve sub cabinet. Please read this manual prior to use.

The QT acve speaker range has been designed to serve many varied applicaons, delivering clear, powerful sound reinforcement wherever it is needed. Please note: your QT sub cabinet may be supplied with more than 1 IEC mains lead. Be sure to use the correct lead, taking note of the outlet voltage and rang.

Warning:

To prevent the risk of re or electric shock, do not expose this appliance to rain or moisture. To prevent electric shock do not remove the cover. No user serviceable parts inside. Refer servicing to qualified service personnel.

Safety

• Prior to connecng mains, ensure that the supply voltage is correct and the mains lead is in good condition.
• Avoid ingress of water or parcles into the enclosure.
  • If the mains fuse blows, refer the unit to qualified service personnel

Placement

• Keep the unit out of direct sunlight and away from heat sources.
• Keep the unit away from moisture or dusty environments.

Cleaning

Use a so cloth with a neutral detergent to clean the cabinet, panel and controls.

To avoid damage, do not use solvents to clean this equipment.

Control Panel

1) INPUT LEVEL – Volume rotary control for input
2) INPUT-XLR line input
3) PHASE – push in to invert (reverse) signal phase
4) THRU – Balanced XLR signal out link
5) FREQUENCY – Adjust cross-over cuto frequency
6) POWER – on/o switch and indicator
7) AC INPUT – IEC mains inlet and fuse

Operaon

With INPUT LEVEL turned fully down and power switch o, connect the IEC to an appropriate mains outlet.

Connect output of mixer or any line level signal to the INPUT via XLR.

If the signal is to connue to further acve speakers, connect these from the THRU line level XLR.

Begin with the FREQUENCY control in the mid posion (12-o-clock posion)

Press the power switch on and gradually increase the INPUT LEVEL until the bass signal is heard through the speaker.

Turning the FREQUENCY control up will include more mid frequencies and turning it down will eliminate all but the lowest frequencies.

Adjust the FREQUENCY control to the desired tone, nong that lower sengs may need the INPUT LEVEL turning up to compensate.

The PHASE switch can help eliminate speakers which are “out-of-phase” from cancelling each other’s signals out.

The correct seng for this switch is whichever seng gives the loudest output - by a process of trial and error.

One or other seng may also help to avoid feedback.

If there is no dherence in volume or feedback, leave the switch in the "0°" posion (out)

To avoid loud noises when powering down, turn down the OUTPUT LEVEL before switching o.

SPECIFICATIONS	QT15SA	QT18SA
Power supply	220-240Vac 50/60Hz (IEC)
Cuto Frequency	40 - 150Hz
Connecons	XLR line in, XLR line out
Main driver	38cm (15") 8Ω	45cm (18") 8Ω
Output handling (max)	600W	1000W
Dimensions	515 x 420 x 615mm	585 x 475 x 675mm
Weight	22kg	29kg

Troubleshooting

No output and no LEDs lit	Check POWER switch is on
	Check mains lead is connected and fuse hasn’t blown
Power LED lit but no sound from external inputs	Check signal leads are OK and connected properly
	Try turning up the FREQUENCY control
	Ensure input signal has some bass content for the sub to produce
	Check INPUT LEVEL control is not fully down