1. DA-250F/DA-250FH TOA Corporation

2. Features

3. DA Series Multi-channel Digital Amplifiers

4. DA Series

5. DA Series Models DA-250FH: 4x 250W (70V/100V) DA-250F: 4x 250W (4 ohm)

6. DA Series Models DA-250FH  4x 250W (70V/100V)  2x 500W bridged mode (140V) *120VAC Version only  Limiter

7. DA Series Models DA-250F  4x 250W (4 ohms) / 170W (8 ohms)  2x 500W bridged mode (8 ohms)  Limiter

8. DA Series Four 250 Watt amplifier channels in one rack space!

9. DA Series Features  Class D design – 85% efficient!  60% lower power consumption than conventional amplifiers  Compact, single rack-space design  Stack up to 5 units without open spaces between units  Lightweight 6.6kg (14.6 lbs.) – 120VAC version 6.8kg (15.0 lbs.) – 220-240VAC version  Independent power supply for each channel

10. DA Series Features  Low heat dissipation  Recessed stepped attenuators  Comprehensive protection circuitry  Removable dust filters for easy maintenance  Optional 250W output transformer, model MT- 250H

11. DA Series Front Panel Channel #1 Channel #2Channel #3 Channel #4

12. DA Series Front Panel Recessed stepped attenuators Input, Output, Peak and Protect indicators Power On/Off Removable Dust Filter

13. DA Series Rear Panel Removable AC connection Power amplifier outputs w/ protective cover plate Balanced inputs (+4/-10 dBu)

14. DA Series Input Section CH1 to All Switch Bridge 2 Switch Bridge 1 Switch

15. DA Series Power Supply Separate power supply on each amplifier channel!

16.  Stack up to five units!  Twenty amplifier channels in only five rack spaces! Rack Mounting

17. Class D Advantages  High power efficiency  Smaller heat sink and power supply  Less heat  Increased reliability

18. Digital Amplifiers

19. DA-250FH: Block Diagram 120VAC version

20. DA-250F: Block Diagram

21. MT-250 Matching Transformer  Low frequency response down to 30Hz!  Up to 250W

22. Technical Fields

23. Working Outline Class-ABClass-D

24. The method of Class-D Amplification Class-D Amplifier changes input signals into digital pulse signals in PWM and then amplifies it. Output signals are also come out as digital pulses, and audio signals are extracted by using LPF. Class-AB amplifier linearly amplifies input signals. A waveform amplified does not change after amplification. Amp Input signal Output signal PWM Input signal AmpLPF Output signal Digital pulse Output signal