MODEL HT AMPLIFER

The HT is currently for sale at $595 with $50 shipping and handling to all 50 U.S. states.

Model HT Description

The model HT stereo power amplifier is a hybrid design with a vacuum tube driver and a class AB MOSFET output stage. The driver stage is a conventional two stage voltage amplifier, it’s output is then fed to a push – pull MOSFET stage. The circuitry is simple and the performance is very good.

The MOSFET + / - power supply is rectified with a solid state diode bridge and is filtered with two 10,000 mfd capacitors to provide good regulation from no load to full load conditions. A power up time delay circuit is provided to eliminate any turn on noise. On power up, the front panel LED lights Red after a short time delay, the LED lights Green indicating that the amplifier is ready.

Specifications (Both channels driven)
Power Output: 100 Watts w/ 4 Ohm load and 65 Watts w/ 8 Ohm load.
Output Impedance: .09 Ohm
Damping Factor: 45 w/ 4 Ohm load and 85 w/ 8 Ohm load.
Power Requirement: 110 – 125 V 50 / 60 Hz. U.S. and Canada Only.
Power Consumption: 37 Watts (Standby) 340 Watts (Full power)

cdm 12 – 06 - 2025

 

The Circuit and Associated Parts

Input Circuit

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Power Supply

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MOSFET Output

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Low Voltage Power Supplies

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Power Up Timer

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The Square Waves

Square wave photos don’t capture the full picture, but they provide a useful indication of how flat the amplifier’s response is. As you can see, the performance is quite good across the entire range, from 10 Hz to 100 kHz.

While square wave performance doesn’t directly reflect how the amplifier will sound, it does suggest a wide frequency response and minimal "ringing."

For clarity, one channel is shown here, though both channels were driven during the test.