QSCISA300Ti – 2-Channel Power Amplifier for 70V/100V Systems

 

Features

• Low-impedance outputs plus isolated 25, 70, and 100 volt outputs for distributed audio systems
• Rear panel gain controls for tamper resistance; 2-dB detents allow for quick and repeatable settings
• XLR and detachable Euro-style input connectors
• DataPort V2 for use with DPV2-compatible signal processing accessories (XC-3, SF-3, LF-3) and DSP-3/DSP-4 (with external power supply)
• Independent defeatable clip limiters for reduced distortion
• Selectable high-pass filters (50 Hz or 75 Hz) protect speakers and prevent speaker transformer saturation, with minimal effect on program material
• Front panel indicators include power, signal, and clip
• Covered barrier strip output connectors for safety agency compliance
• Automatic on-demand variable-speed fan: quiet normal operation, with maximum cooling when needed
• Rear-to-front air flow helps keep equipment racks cool
• Stereo, bridge, or parallel operating modes
• Comprehensive protection circuitry including DC, infrasonic, thermal overload, and short circuit protection

SPECIFICATIONS	ISA280	ISA450	ISA750	ISA1350	ISA300Ti	ISA500Ti	ISA800Ti
	OUTPUT POWER PER CHANNEL, STEREO MODE, both channels driven
8Ω, 20 Hz–20 kHz 0.1% THD 4Ω, 20 Hz–20 kHz 0.1% THD 2Ω 1 kHz 1% THD	185 W 280 W 430 W	260 W 425 W 700 W	450 W 650 W 1200 W	800 W 1300 W 2000 W	185 W 280 W 430 W	260 W 425 W 700 W	450 W 650 W 1200 W
	DIRECT POWER PER CHANNEL, STEREO MODE
70V, 20 Hz–20 kHz +0/-0.3 dB 0.5% THD	–	–	–	1500 W	–	–	–
	TRANSFORMER-ISOLATED OUTPUT POWER PER CHANNEL, STEREO MODE
70V or 100V, 50 Hz–16 kHz 0.5% THD 25V, 50 Hz–16 kHz 0.5% THD	– –	– –	– –	– –	300 W 200 W	500 W 300 W	800 W 500 W
	OUTPUT POWER, BRIDGED MONO MODE
8Ω, 1 kHz 0.1% THD 4Ω 1 kHz 1% THD	600 W 830 W	900 W 1400 W	1500 W 2400 W	2800 W 4000 W	600 W 830 W	900 W 1400 W	1500 W 2400 W
	TRANSFORMER-ISOLATED OUTPUT POWER, BRIDGED MONO MODE
140V or 200V, 50 Hz-16 kHz 0.5% THD	–	–	–	–	600 W	1000 W	1600 W
Signal to Noise (20 Hz-20 kHz)	100 dB
Distortion (SMPTE-IM)	Less than 0.01%	Less than 0.01%	Less than 0.02%	Less than 0.01%	Less than 0.01%	Less than 0.01%	Less than 0.02%
Input Sensitivity @ 8 ohms	1.15 V (+3.4 dBu)	1.07 V (+2.8 dBu)	1.07 V (+2.8 dBu)	1.24 V (+4.1 dBu)	1.15 V (+3.4 dBu)	1.07 V (+2.8 dBu)	1.07 V (+2.8 dBu)
Maximum Voltage Gain	33.4× (30.5 dB)	44.7× (33 dB)	56.2× (35 dB)	64.0× (36.1 dB)	33.4× (30.5 dB)	44.7× (33 dB)	56.2× (35 dB)
Output Circuitry	Class AB	Class AB	Class H, 2 tier	Class H, 3 tier	Class AB	Class AB	Class H, 2 tier
THX Approved	–	Yes	Yes	–	–	–	–
Weight – Net	36 lb (16.3 kg)	42 lb (19 kg)	47 lb (21.3 kg)	68 lb (30.8 kg)	44 lb (20.0 kg)	49 lb (22.3 kg)	57 lb (26 kg)
Weight – Shipping	42 lb (19.1 kg)	48 lb (22 kg)	53 lb (24.0 kg)	77 lb (34.4 kg)	50 lb (22.7 kg)	55 lb (25 kg)	63 lb (28.6 kg)
	ALL MODELS
Distortion (Typical) 20 Hz–20 kHz: 10 dB below rated power 1.0 kHz and below: full rated power	Less than 0.03% THD, 4 ohms and 8 ohms Less than 0.03% THD, 4 ohms and 8 ohms
Frequency Response 10 dB below rated output power	ISA 280, 450, 750 and 1350: 20 Hz–20 kHz, +0/-1 dB; -3 dB points: 5 Hz and 50 kHz				ISA 300Ti, 500Ti and 800Ti: Direct outputs: -3 dB @ 50 Hz, -0.5 dB @ 20 kHz; XF outputs: 50 Hz–16 kHz, +1/-3 dB
Damping Factor with 8Ω Load (direct outputs)	Greater than 200; ISA 1350 greater than 250
Output Regulation (isolated outputs)	Less than 1.5 dB
Input Impedance	10 kΩ unbalanced, 20 kΩ balanced
Input Clipping	10 V rms (+22 dBu)
Cooling	Continuously variable speed fan, back-to-front air flow
Connectors, each channel	Input: Active balanced; 3-pin Euro-style detachable terminal block and XLR (pin 2+) Output: Covered barrier strips DataPort V2: HD-15 connector
Controls	Front: AC switch Rear: Ch. 1 and Ch. 2 gain knobs, 10-position DIP switch
Indicators	PWR-ON: Green LED; SIGNAL: Green LED (1 per channel); CLIP: Red LED (1 per channel)
Dimensions (HWD) inches	5.25 x 19 x 15.9 / 3RU
Dimensions (HWD) mm	133 x 483 x 400 / 3RU
Amplifier Protection	Full short circuit, open circuit, thermal, ultrasonic, and RF protection; Stable into reactive or mismatched loads
Power Requirements	120 or 230 VAC, 50–60 Hz
Load Protection	On/off muting; Triac crowbar: ISA 750, 1350, and 800Ti; AC coupling: ISA 280, 300Ti, 450, and 500Ti

 

The QSC ISA300Ti is a 2-channel power amplifier engineered specifically for permanent installation in commercial audio systems. With a focus on reliability, long-term durability, and seamless integration, it delivers high-efficiency power output for 70V and 100V distributed loudspeaker systems commonly found in hotels, schools, churches, retail stores, and conference centers.

Offering 300 watts per channel into 70V/100V lines, the ISA300Ti is part of QSC’s renowned ISA Series—trusted by audio professionals worldwide for mission-critical applications. Its transformer-isolated design, robust protection features, and versatile connectivity make it a go-to solution for contractors and integrators alike.

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⚡ Consistent Power for Distributed Systems

The ISA300Ti is optimized for constant voltage speaker systems, enabling it to drive large numbers of loudspeakers across wide areas using long cable runs without signal degradation. It supports both 70V and 100V outputs, allowing installation flexibility for global markets and varied building codes.

Each channel can be independently configured, and the rear-panel dip switches provide control over input sensitivity, high-pass filters, and more—helping installers fine-tune performance to match their exact system needs.

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🔒 Built-in Protection for Peace of Mind

QSC has equipped the ISA300Ti with extensive protection circuitry to guard against thermal overload, short circuits, DC faults, and excessive clipping. Automatic clip limiting protects connected loudspeakers from overdrive damage, while independent output transformers ensure channel isolation and safety.

Additionally, a built-in high-pass filter helps eliminate low-frequency rumble or hum in paging and background music systems, improving overall clarity and efficiency.

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🧰 Flexible Connectivity and Integration

The amplifier provides balanced 3-pin Euro-style (Phoenix) input connectors and barrier strip outputs with clearly labeled terminals. With front-panel level controls and status LEDs for power, signal, and clipping, the ISA300Ti gives installers and tech staff quick visual feedback on amplifier health and performance.

It’s also rack-mountable (2RU), making it a clean fit in AV racks or network closets for professional integration in any venue.

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🏢 Ideal Applications Include:

• Churches, mosques, and houses of worship

• Educational facilities and auditoriums

• Conference halls and corporate centers

• Shopping malls and retail outlets

• Hospitality environments like hotels and restaurants

• Paging and background music systems in commercial spaces

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🔧 Key Features of the QSC ISA300Ti

• 🔊 2 x 300W @ 70V/100V transformer-isolated outputs

• 🛠️ Rear-panel switches for input sensitivity and HPF control

• 🔒 Full protection circuitry (short circuit, thermal, DC, clip limiting)

• 🎚️ Independent front-panel gain controls per channel

• 🔌 Balanced Euro-style inputs & barrier strip outputs

• ⚙️ Rack-mountable 2U chassis with rugged steel construction

• 🌐 Compatible with large multi-zone 70V/100V distributed audio networks

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✅ Why Choose the QSC ISA300Ti?

• ✔️ Engineered specifically for constant voltage systems

• ✔️ Transformer-isolated outputs for commercial-grade reliability

• ✔️ Trusted brand used in mission-critical installations worldwide

• ✔️ Versatile setup options for integrators and contractors

• ✔️ Designed to perform under continuous use for years

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🏁 Conclusion

The QSC ISA300Ti is a purpose-built amplifier for professional 70V/100V distributed audio systems, offering 300 watts per channel, flexible configuration, and the rugged reliability that QSC is known for. Whether you’re installing a paging system in a retail center or background music across a hospitality venue, the ISA300Ti ensures clear, consistent, and protected audio delivery.

For commercial AV installations that demand performance, efficiency, and longevity, the QSC ISA300Ti is a trusted choice that delivers without compromise.

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