Description
The Quest QX4750 is a professional high-performance 4-channel Class-D installation power amplifier engineered for commercial audio systems, multi-zone distributed sound applications, hospitality venues, educational facilities, houses of worship, AV integration, and high-demand professional sound installations requiring exceptional output power, flexible impedance compatibility, and reliable continuous-duty operation. As part of Quest Engineering’s advanced QX Rackmount Series, the QX4750 combines powerful Class-D amplification, intelligent load sensing, and installation-focused DSP functionality within a rugged 2RU rack-mount chassis.
Designed for demanding commercial and professional AV environments, the QX4750 delivers 4 × 750W output power at 4Ω with bridgeable channel operation capable of delivering 2 × 1500W for both low-impedance and high-impedance speaker systems. Auto Load Sensing technology allows seamless operation with 4–16Ω, 70V, and 100V systems without requiring manual reconfiguration, greatly simplifying large-scale installation deployment.
The amplifier utilizes Quest’s UMAC™ full-bandwidth PWM Class-D modulation technology with ultra-low distortion, delivering outstanding dynamic range, exceptional efficiency, and clean high-output performance while minimizing heat generation and energy consumption. Individual channel controls include volume adjustment, 80Hz high-pass filter, 100Hz low-pass filter, limiter activation, standby mode, and bridge-mono configuration for maximum installation flexibility.
Built for professional reliability, the QX4750 incorporates comprehensive protection systems including thermal protection, over-current protection, DC protection, under-voltage protection, overload protection, and HF protection to ensure stable operation under demanding continuous-use conditions. The UREC™ universal switch-mode power supply with integrated Power Factor Correction (PFC) further enhances operational efficiency and power stability.
The QX4750 also supports optional Dante™/AES67 network audio expansion, making it suitable for modern networked AV infrastructures and enterprise-level distributed audio systems. Designed, engineered, and assembled in Australia, the amplifier delivers premium-grade performance for professional commercial installations.
Performance Highlights:
• Professional 4-channel 2RU Class-D installation amplifier
• 4 × 750W output power @ 4Ω
• Bridgeable to 2 × 1500W for low- or high-impedance systems
• Auto Load Sensing supports 4–16Ω, 70V & 100V operation
• Dante™ / AES67 expansion capability available
Why You Should Buy This Product
• ⭐ Extremely powerful 4-channel amplifier for large-scale commercial systems
• ⭐ Flexible low-impedance and 70V/100V operation simplifies installations
• ⭐ High-efficiency Class-D architecture reduces heat and power consumption
• ⭐ Advanced protection systems ensure reliable long-term operation
• ⭐ Dante™ expansion support enables modern networked AV integration
Key Features
• 4-channel professional power amplifier
• 4 × 750W @ 4Ω output power
• 2 × 1500W bridged-mono capability
• UMAC™ Class-D full-bandwidth PWM modulation
• Auto Load Sensing (4–16Ω / 70V / 100V)
• Individual HPF, LPF, limiter & standby controls per channel
• Dante™ / AES67 expansion card compatibility
• UREC™ switch-mode power supply with PFC
• DynamiQ Bass Technology®
• Euroblock balanced link connectors
• SpeakON speaker outputs
• Energy Star compliant standby operation
• Designed, engineered & assembled in Australia
Technical Specifications
General
• Product Type: Multi-Channel Installation Power Amplifier
• Brand: Quest
• Model: QX4750
Audio & Performance
• Amplifier Channels: 4 Channels
• Amplifier Class: Class-D
• Frequency Response: 20 Hz – 20 kHz (±0.3 dB)
• Dynamic Range: 111 dB (A-weighted)
• Noise Level: -72 dBu (A-weighted)
• Peak Output Current: 40A
• Crosstalk (1kHz @ 1W / 8Ω): -90 dB
• Gain: 26 dB / 32 dB
• Maximum Input Level: +24 dBu
• Total Harmonic Distortion (1kHz @ 1W / 8Ω): 0.004%
• Total Harmonic Distortion (1kHz @ 50W / 8Ω): 0.003%
Power Handling
• Output Power @ 8Ω: 4 × 400W
• Output Power @ 4Ω: 4 × 750W
• Bridged Output @ 8Ω: 2 × 1500W
• Bridged Output @ 4Ω: 2 × 1400W
• Bridged Output @ 70V: 2 × 1500W
• Bridged Output @ 100V: 2 × 1500W
• Low-Impedance Operation: 4–16Ω
• High-Impedance Operation: 70V / 100V
Processing & Controls
• High Pass Filter: 80Hz HPF
• Low Pass Filter: 100Hz LPF
• Input Limiter: Selectable
• Auto Standby Mode: Yes
• Wake-Up Time: 1ms
• Bridged Mono Mode: Yes
Connectivity
• Audio Inputs: XLR Balanced Inputs & Euroblock Links
• Speaker Outputs: SpeakON Outputs
• Optional Expansion: Dante™ / AES67 Network Audio
• Mains Connector: powerCON
Protection
• Thermal Protection: Yes
• Over-Current Protection: Yes
• DC Protection: Yes
• Under Voltage Protection: Yes
• Overload Protection: Yes
• HF Protection: Yes
Physical & Installation
• Rack Space: 2RU
• Chassis Construction: Metal
• Finish: Black
• Cooling System: Temperature-Dependent Fan Cooling
• Dimensions (H × W × D): 88 × 482 × 416 mm
• Weight: 10.2 kg
Power Consumption
• Standby Power Consumption: 4.8W
• Muted Power Consumption: 16W
• Idle Power Consumption: 28W
Configuration
• Amplifier Type: Multi-Channel Installation Power Amplifier
• System Type: Commercial Distributed Audio Amplifier
• Built-in DSP: HPF / LPF / Limiter Processing
• Transformer: Integrated Hi-Z Operation Support
• Mode: Low & High Impedance Professional Audio Operation
Included
• 1 × 4-Channel Power Amplifier
• 1 × Mains Power Cable
• 1 × Euroblock Connector Set
• 1 × User Manual
Payment & Security

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Refund Policy
Refund Policy
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Returns
Our policy lasts 14 days. If 14 days have gone by since your purchase, unfortunately, we can’t offer you a refund or exchange.
To be eligible for a return, your item must be unused and in the same condition that you received it. It must also be in the original packaging.
Several types of goods are exempt from being returned. Perishable goods such as food, flowers, newspapers or magazines cannot be returned. We also do not accept products that are intimate or sanitary goods, hazardous materials, or flammable liquids or gases.
Additional non-returnable items:
Gift cards
Downloadable software products
Some health and personal care items
To complete your return, we require a receipt or proof of purchase.
Please do not send your purchase back to the manufacturer.
There are certain situations where only partial refunds are granted (if applicable)
Book with obvious signs of use
CD, DVD, VHS tape, software, video game, cassette tape, or vinyl record that has been opened
Any item not in its original condition is damaged or missing parts for reasons not due to our error
Any item that is returned more than 15 days after delivery
Refunds (if applicable)
Once your return is received and inspected, we will send you an email to notify you that we have received your returned item. We will also notify you of the approval or rejection of your refund.
If you are approved, then your refund will be processed, and a credit will automatically be applied to your credit card or original method of payment, within a certain amount of days.
Late or missing refunds (if applicable)
If you haven’t received a refund yet, first check your bank account again.
Then contact your credit card company, it may take some time before your refund is officially posted.
Next contact your bank. There is often some processing time before a refund is posted.
If you’ve done all of this and you still have not received your refund yet, please contact us at sanjay@audiomaxx.in
Sale items (if applicable)
Only regular-priced items may be refunded, unfortunately, sale / discounted items cannot be refunded.
Exchanges (if applicable)
We only replace items if they are defective or damaged. If you need to exchange it for the same item, send us an email at sanjay@audiomaxx.in and send your item to: 24, Kembros Estate, DP Road, Industrial Area, Sonapur, Bhandup West, , 400078 Mumbai MH, India.
Gifts
If the item was marked as a gift when purchased and shipped directly to you, you’ll receive a gift credit for the value of your return. Once the returned item is received, a gift certificate will be mailed to you.
If the item wasn’t marked as a gift when purchased, or the gift giver had the order shipped to themselves to give to you later, we will send a refund to the gift giver and he will find out about your return.
Additional Returns and Exchange Terms
1. Returns and Exchanges
At Audiomaxx India, we are committed to ensuring each customer has a hassle-free and enjoyable shopping experience. You may have received a Dead on Arrival or Malfunctioning Product, as such you must first approach the local service station of the concerned brand and seek remedy as per Warranty policy & terms of the company/brand wherein one can ask for free service, an exchange or refund for the former and only exchange for the latter with all spares & packaging.
2. Within how many days can most items shipped from Aduiomaxx be returned?
Most items shipped from Audiomaxx can be returned within 14 days of receipt of the shipment. However, certain products sold on Audiomaxx may have different policies that govern their return.
When you shop on the Audiomaxx website, we ensure that you have a smooth and easy returns experience. In the case of Refunds, we credit the entire amount that you have spent to your bank account.
3. When are returns not possible?
- There are certain conditions in which returns are not possible by Audiomaxx. These are when:
- The return request is made outside the specified time frame
- The product is damaged because of use
- The product is not in the same state as when you received it
- The item has been used and installed
- The product has been tampered with or has missing parts, accessories / serial numbers
- There is anything missing from the package you have received, including price tags, labels, and original packing.
4. When are refunds provided?
Audiomaxx provides refunds only when the product is dead on arrival and cannot be exchanged.
5. How do I cancel an order?
If you want to cancel your order, you need to get in touch with us along with your Order Number, before the item is shipped. On all such cancellation requests charge is applicable which varies from 5% to 10% depending on the product you want to cancel.
Shipping
To return your product, you should mail your product to: 24, Kembros Estate, DP Road, Industrial Area, Sonapur, Bhandup West, , 400078 Mumbai MH, India
You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable. If you receive a refund, the cost of return shipping will be deducted from your refund.
Depending on where you live, the time it may take for your exchanged product to reach you, may vary.
If you are shipping an item over Rs.5000, you should consider using a trackable shipping service or purchasing shipping insurance. We don’t guarantee that we will receive your returned item.
All pre-bookings, at the time of delivery rates as prevailing on that day, will be charged and the difference is any shall be payable before shipping.
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