The TOA DA-250FH is a professional 4-channel Class D digital power amplifier specifically engineered for 70V line high-impedance distributed audio systems. Delivering 250 watts per channel at 19.6Ω (optimized for 70V constant voltage applications), the DA-250FH provides 1000W total system power in a compact, efficient 1U rack chassis designed specifically for commercial multi-zone installations.

Purpose-built for AV integrators working in commercial environments—including corporate offices, educational facilities, retail spaces, hospitality venues, and houses of worship—the DA-250FH combines the efficiency advantages of Class D technology with specialized 70V output optimization. Each channel features independent power sections for stable, isolated operation and superior fault protection, ensuring one channel's issues never compromise the entire system.

The advanced switching power supply architecture delivers exceptional energy efficiency while minimizing heat generation and weight—critical advantages in dense equipment racks and installations with limited ventilation. For applications requiring complete electrical isolation from speaker lines, the optional MT-251H output transformer provides galvanic isolation while maintaining full power output and audio quality.

TOA DA-250FH Key Features

  • 70V optimized design – 250W per channel at 19.6Ω for high-impedance distributed systems
  • 4-channel architecture – 1000W total system power for multi-zone applications
  • High-efficiency Class D – Superior power conversion with minimal heat generation
  • Independent power sections – Fault isolation ensures channel-to-channel independence
  • Switching power supply – Lightweight, energy-efficient, reduced thermal output
  • Ultra-compact 1U design – Maximum performance in minimum rack space
  • Optional isolation transformer – MT-251H provides electrical isolation from speaker lines
  • Lightweight construction – Simplified installation and reduced shipping costs
  • Professional thermal management – Intelligent temperature-controlled cooling
  • 70V system optimization – Designed specifically for constant-voltage distributed audio
  • Multi-zone capability – Four independent zones from a single amplifier
  • Comprehensive protection – Short circuit, thermal, overload, and DC offset safeguards
  • 24/7 operation-ready – Built for continuous commercial use
  • Integrator-focused design – Engineered for complex AV system integration
  • EIA-standard mounting – Standard 1U rack installation

TOA DA-250FH Specifications

Power Output

  • Rated Power (Per Channel):
    • 250W @ 19.6Ω (70V line optimized)
    • 250W @ 70V constant voltage
    • Compatible with 70V distributed speaker systems
  • Total System Power: 1000W (all 4 channels driven)
  • Channels: 4 independent amplifier channels
  • Optimized Load Impedance: 19.6Ω per channel (70V line standard)

Amplifier Performance

  • Amplifier Type: Class D digital switching amplifier
  • THD (Total Harmonic Distortion): <0.5% at rated output (1 kHz) (typical—verify)
  • Frequency Response: 20 Hz – 20 kHz (±1 dB) (typical—verify)
  • S/N Ratio: >95 dB (A-weighted) (typical for Class D—verify)
  • Damping Factor: >200 @ 70V (typical—verify)
  • Crosstalk: <-70 dB (between channels at 1 kHz) (typical—verify)
  • Efficiency: >90% (typical Class D efficiency)

70V System Characteristics

  • Nominal Output Voltage: 70V RMS (constant voltage)
  • Optimized Impedance: 19.6Ω (70V @ 250W calculation: V²/P = 70²/250 = 19.6Ω)
  • Speaker Load Range: 19.6Ω minimum to higher impedances (lower total wattage)
  • Distribution Capability: Multiple speakers in parallel up to 250W total per channel

Inputs (Per Channel)

  • Input Type: Balanced or unbalanced (verify exact configuration)
  • Connector: Phoenix/Euroblock screw terminals or XLR (verify model)
  • Input Sensitivity: Adjustable (typical range: 0.775V to 1.4V for rated output)
  • Input Impedance: 10kΩ or 20kΩ balanced (typical—verify)
  • Max Input Level: +20 dBu (typical—verify)

Outputs (Per Channel)

  • Speaker Outputs: Phoenix/Euroblock screw terminals (verify) or binding posts
  • Output Configuration: 70V constant voltage (19.6Ω optimized)
  • Connector Type: Screw terminal (professional-grade)
  • Independent Channel Operation: Each channel is fully independent
  • Isolation Option: Compatible with the optional MT-251H transformer for electrical isolation

Controls & Indicators

  • Front Panel:
    • Power ON/OFF switch
    • LED power indicator
    • Signal presence indicators (per channel—4 LEDs)
    • Clip/overload indicators (per channel—4 LEDs)
    • Protection status indicators
    • Optional: Input level indicators

  • Rear Panel:

    • Input sensitivity/level controls (per channel—verify location)
    • Input connectors (4 channels)
    • 70V output terminals (4 channels)
    • AC power input (IEC connector)
    • Forced-air ventilation openings

Protection Features

  • Short Circuit Protection: Automatic per-channel shutdown with auto recovery
  • Thermal Protection: Temperature monitoring with intelligent shutdown
  • Overload Protection: Current limiting prevents amplifier damage
  • DC Offset Protection: Prevents DC voltage from damaging speakers
  • Over-Voltage Protection: AC line monitoring and protection
  • Under-Voltage Protection: Prevents operation at insufficient voltage
  • Soft-Start Circuitry: Gradual power-up protects speakers and reduces inrush
  • Independent Channel Protection: Fault isolation—one channel failure doesn't affect others

Power Supply

  • Type: High-efficiency switching power supply (SMPS)
  • Advantages:
    • Lightweight design (no heavy transformers)
    • High efficiency (>85% typical)
    • Reduced heat generation
    • Wide AC input tolerance
    • Compact footprint

Physical

  • Dimensions: 19" × 1.75" × 14.2" (483 × 44 × 360 mm)
  • Weight: Approx. 11-15 lbs (5-7 kg)
  • Mounting: Standard EIA 19" rack mount (1U)
  • Construction: Lightweight steel or aluminum chassis with efficient thermal design
  • Cooling: Forced-air with temperature-controlled variable-speed fan
  • Finish: Professional black with clear channel labeling
  • Ventilation: Front-to-rear or side-to-rear airflow 

Power Requirements

  • AC Input: 120V AC, 60 Hz (North American model)
    • International versions: 100-240V AC, 50/60 Hz
  • Power Consumption:
    • Maximum: 1200W at full output
    • Idle: 30-50W
    • Efficiency: >90%
  • Inrush Current: <30A
  • Power Factor: >0.95 

Operating Conditions

  • Operating Temperature: 32°F – 104°F (0°C – 40°C)
  • Storage Temperature: -4°F – 122°F (-20°C – 50°C)
  • Humidity: 90% RH or less (non-condensing)
  • Altitude: Up to 2000m above sea level
  • Ventilation: Minimum 2" side clearance, 6" rear clearance 

Certifications & Compliance

  • UL Listed (USA)
  • cUL Listed (Canada)
  • CE Compliant (Europe)
  • FCC Part 15 Class A (EMI/RFI compliance)
  • RoHS Compliant

Applications

Corporate & Office:

  • Multi-floor office buildings (distributed ceiling speakers per floor)
  • Conference centers (background music and paging)
  • Corporate campuses (building-wide distribution)
  • Reception areas and lobbies
  • Open office environments

Education:

  • Schools (classroom-to-classroom distribution)
  • Universities (building-wide paging)
  • Libraries (quiet background music zones)
  • Cafeterias and common areas
  • Gymnasiums and multipurpose rooms

Retail:

  • Shopping malls (distributed BGM throughout)
  • Department stores (floor-by-floor zones)
  • Grocery stores (department zoning)
  • Chain stores (consistent audio across locations)
  • Boutiques and showrooms

Hospitality:

  • Hotels (lobby, corridors, public spaces)
  • Restaurants (dining room, bar, patio, kitchen zones)
  • Resorts (multiple venue areas)
  • Convention facilities (breakout rooms)
  • Casinos (gaming floor distribution)

Worship:

  • Churches (sanctuary overflow, classrooms, fellowship halls)
  • Multi-building campuses
  • Parking lots and outdoor areas
  • Narthex and gathering spaces

Public Spaces:

  • Transportation terminals (airports, train stations)
  • Government buildings (distributed paging)
  • Museums and galleries
  • Healthcare facilities (corridors, waiting areas)
  • Sports facilities

Why Choose the TOA DA-250FH?

  • 70V specialist – Optimized specifically for 70V distributed systems
  • 4-channel efficiency – Four independent zones from a compact 1U chassis
  • Class D technology – High efficiency, low heat, lightweight design
  • Independent channels – Fault isolation ensures system reliability
  • Proven TOA quality – Decades of commercial audio excellence
  • Isolation option – MT-251H transformer available for special applications
  • Space-saving – 1000W total power in minimal rack space
  • Energy efficient – Reduces operating costs and cooling requirements
  • Integrator-focused – Designed for professional AV installations
  • Excellent value – Professional performance at competitive pricing

What's in the Box

  • TOA DA-250FH 4-channel digital power amplifier
  • IEC AC power cord
  • Rack mount ears/brackets and hardware
  • Phoenix/Euroblock connector plugs (for inputs/outputs)
  • User manual
  • Quick start guide
  • Warranty registration card

Frequently Asked Questions

Q: What's the difference between DA-250F and DA-250FH? A: The DA-250FH is optimized specifically for 70V @ 19.6Ω, while the DA-250F offers multiple impedance options (100V/70V/4Ω). Choose DA-250FH for 70V-only systems; DA-250F for installations needing flexibility.

Q: Do I need the MT-251H transformer? A: Not for most installations. MT-251H is needed when electrical isolation is required (ground loop issues, multi-building systems, long outdoor runs, lightning-prone areas). Standard installations don't require it.

Q: How many 10W speakers can I connect per channel? A: Maximum 25 speakers @ 10W each = 250W total. Recommended: 22-23 speakers (220-230W) to leave headroom.

Q: Can I mix different wattage speakers on one channel? A: Yes! Just ensure the total of all speakers doesn't exceed 250W. Example: ten 10W + five 15W + three 20W = 235W (acceptable).

Q: What wire gauge should I use? A: For 70V systems, 16 AWG is recommended for runs up to 500 feet. Use 18 AWG for shorter runs (<300 feet) or heavier 14 AWG for very long runs (>500 feet).

Q: Can I use 100V speakers with this amplifier? A: No, the DA-250FH is designed specifically for 70V. Use 70V-compatible speakers with 70V transformer taps. For 100V systems, use the DA-250F or other multi-impedance models.

Q: How do I calculate if my speaker load is correct? A: Add up all speaker wattages on each channel. Total must be ≤ 250W. Leave 10-20% headroom for reliability. Double-check all speakers are set to 70V taps, not 25V or 100V.

Q: What if I exceed 250W on a channel? A: The amplifier's overload protection will activate, shutting down that channel. Reduce speaker count or lower wattage tap settings until total ≤ 250W.

 

List price: $2,439.00
Price: $1,970.00
SKU: DA-250FH
Catalog: 
Commercial Amplifiers
Brand: 
TOA
Dimensions: 23 in × 23 in × 5 in
Weight: 21 lb