electronic industries
ST-70-C1

Description
Tube stereo power amplifier.

The amplifier used a stock Dynaco ST-70 chassis and transformers and substantially improved upon the original Dynaco ST-70 design. Some of the improvement over the stock Dynaco ST-70 included:

  1. The key upgrade was adding the Electronic Industries PCB-14 mother circuit board which featured 6 tubes and much better parts than the original board.
  2. Internally, the chassis added much better parts and better power supply regulation.
  3. The amplifier used the original Dynacol Octal plug in front, but it was internally disconnected.
  4. Added independent left and right volume controls on the back of the amplifier.

The ST-70 C1 did not have any labels to identify the unit that was added later on the Electronic Industries ST-70 C2.

The Electronic Industries ST-70 C1 is extremely rare with less than 50 units produced. All the units were offered factory direct, no kits were available to the public. William Z Johnson built most of the Electronic Industries ST-70 C1 amplifiers himself. The amplifiers were produced at the original Electronic Industries store/factory which was located at 2451 Hennepin Avenue S in Minneapolis, Minnesota.

Introduced
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Discontinued
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Revisions
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Options
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MSRP (US new retail)
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Specifications

Power output  
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Frequency response  
Input sensitivity  
Input impedance  
Output taps  
Output regulation  
Overall negative feedback  
Damping factor  
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Slew rate  
Rise time  
Hum & noise  
Power supply energy storage  
Power requirements  
Tube complement (2) OA2, (2) ECC-83, (4) 6FQ7, (4) EL-34, (1) GZ-34/SAR5
Other  
Dimensions  
Weight  

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