Stewart Audio DA-70-2 Owner'S Manual Download Page 17

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Specifications

8 Ohm Stereo Power 35 Watts/Ch

4 Ohm Stereo Power 70 Watts/Ch

Frequency Response (+0, –0.5 dB,

1W)

20 Hz—20 kHz

Full Power Bandwidth (20-Hz-20 kHz) ± .7 dB

Signal to Noise >93 dB

THD+N < .25%

Input Sensitivity 1V (0 dBV)

Standard Voltage Gain 17X (25 dB)

Input impedance (Balanced / Unbal-

anced)

20k Ohms / 5k Ohms

Class Damped Ternary Modulation

Input Connectors Phoenix Type

Output Connectors Phoenix Type

Power Supply High Speed Switching

Cooling Convection (No Fans)

Controls Power on/off, Channel Gain

LED Indicators Power & Clip

Construction Steel & Aluminum Chassis

Dimensions (height, width, depth) 1.75”H x 8.26”W x 10.6”D

Max Weight 3.4 lbs (1.54 kg)

Warranty 3 years Parts & Labor

Summary of Contents for DA-70-2

Page 1: ...DA 70 Series Professional Power Amplifiers Owners Manual ...

Page 2: ... REMOVE COVER OR BACK NO USER SERVICABLE PARTS INSIDE REFER SERVICING TO QUALIFIED SERVICE PERSONENEL CAUTION RISK OF ELECTRICAL SHOCK DO NOT OPEN The lightning flash with arrowhead symbol within an equilateral triangle is intended to alert the user to the presence of uninsulated dangerous voltage within the product s enclosure that may be of sufficient magnitude to constitute a risk of electrical...

Page 3: ...aced on a rug sofa or similar surface which impedes the airflow across the chassis Airflow through the ventilation openings should be unobstructed The amplifier should only be connected to a properly grounded AC outlet as indicated under AC Power Connections in this manual Do not defeat the ground or polarization of the power plug Route all power cords and other cables so that they are not likely ...

Page 4: ...wer Amplifier utilizes a new high speed switching power supply and Damped Ternary Modulation Digital output topology The amplifier will deliver over 70 Watts of power per channel and may be purchased in either a 2 or 4 channel configuration This remarkable performance comes in a very compact package weighing a mere 3 4 pounds and occupying just one half standard rack space The DA 70 Series Amplifi...

Page 5: ...oting 15 Technical Information 17 For The Record In the spaces below record the Model Serial number and Purchase information of your Power Amplifier Model Number ____________ Serial Number ____________ Purchase Date ____________ Purchased From ___________ Retain this information for future reference 4 ...

Page 6: ...rs to amplify analog signals produced by a DAC Analog designs have low efficiencies because of the power consumed in the active components as a result of the voltage difference be tween the amplifier s output and it s power supply This con tinuous control of the supply voltage results in peak efficien cies of about 50 As a result a large power supply and heat sink are required Class D switching am...

Page 7: ...he figure below shows the advantage of the damped ternary compared to binary modulation for a sine wave In binary the cancellation of two full level signals is required for small outputs Thus the amplifier is continuously providing full output This represents wasted power It also produces unwanted RF energy that must be kept from radiating In contrast the damped ternary design only supplies power ...

Page 8: ...l amplifier design is the power supply For years Stewart Audio has pioneered leading edge power supply technology All Stewart Audio amplifiers feature a High Frequency Switch Mode Power Supply Because of this use of advanced technology some explanation is in order Conventional Power Supplies operating at 60Hz standard line frequency recharge only 120 times per second requiring their storage capaci...

Page 9: ...our old standard supply Power Factor Correction Models with a PFC designation utilizes Power Factor Correction circuitry in their power supply This circuitry automatically adjusts the power supply to provide stable full output over a wide range of mains voltages typi cally from 90VAC to 240VAC This feature makes the DA 70 Series oper able anywhere in the world and is a very useful feature when ope...

Page 10: ...Stewart Audio power amplifiers These amplifiers remain simple and intuitive to operate even while incorporating some of the most advanced technology available today Power On Off and LED Clip Indicators The front panel provides visual feedback of the amplifiers status The front panel power switch is accompanied by an LED which will illuminate upon power up Note there is an initial delay of up to 30...

Page 11: ...ype connector which may be used to con nect loudspeakers See Output Wiring in the section on Installation Page 13 for more de tails AC Power Connection All DA 70 Series amplifiers are equipped with a IEC socket on the rear apron for AC connections Models DA 70 2 and DA 70 4 may only be connected to 120VAC mains Models DA 70 2 PFC and DA 70 4 PFC are Power Factor Corrected and may be connected to a...

Page 12: ... rack shelf or used as a stand alone product Thermal Considerations Cooling of the DA 70 Series amplifiers is achieved by Stewart s unique whole chassis heatsink design which utilizes the entire chassis as a heatsink to cool the heat generating components inside In the event the internal ambient temperature reaches 85 degrees centigrade the protection circuit will shut down the power supply until ...

Page 13: ...is sitting on a shelf or hard floor the four rubber feet must remain mounted to the bottom of the amplifier Under no circumstances should the amplifier be placed directly on carpeting or similar surfaces AC Power Considerations Your Stewart Audio DA 70 2 and DA 70 4 amplifiers are designed to operate on 120 volt 60 Hz AC current Your Stewart Audio DA 70 2 PFC and DA 70 4 PFC amplifiers are designe...

Page 14: ...round Output Speaker Wiring Your DA 70 Series amplifier is provided with a two conductor Phoenix Type connector for each output The connector may be wired by connecting the speaker line to and as marked on the chassis over each output Caution Due to the ternary design of the output stage Bridging of this product line is not possible Do not tie any output pin to any other pin or to ground Never con...

Page 15: ...y inch of wire Make sure that the connector set screw seats on copper not insulation Keep in mind that other components in the system can cause problems which may appear to be caused by the amplifier systematic troubleshooting will allow you to isolate the source of difficulty If you fail to correct the problem by following the outlined chart on the next page do not attempt to open or repair the u...

Page 16: ...l controls input and output cables input signal and speakers Low volume in one or more chan nels Check input level controls input wir ing and input signal levels Be sure speakers are the same impedance Amplifier overheats and or shuts off Review section on Thermal Considerations Check clip lights for indication of overdriving NOTE overdriving for a long period of time can cause thermal shutdown Di...

Page 17: ...tage Gain 17X 25 dB Input impedance Balanced Unbal anced 20k Ohms 5k Ohms Class Damped Ternary Modulation Input Connectors Phoenix Type Output Connectors Phoenix Type Power Supply High Speed Switching Cooling Convection No Fans Controls Power on off Channel Gain LED Indicators Power Clip Construction Steel Aluminum Chassis Dimensions height width depth 1 75 H x 8 26 W x 10 6 D Max Weight 3 4 lbs 1...

Page 18: ...Notes Stewart Audio 1000 Technology Drive Columbia Ca 95310 Tel 209 588 8111 Fax 209 588 8113 www Stewartaudio com ...

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