300B PERFORMANCE HYBRID INTI AMP Solo II

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July photo update

Design Concept

 Tough and robust was the first virtue. All the major parts were arranged to be visible, especially the tubes were arranged in the center, making them feel the main character. In some ways, it may look like a jailbreak, but “the best protection” is the intended design concept.

Power supply concept

300B PERFORMANCE HYBRID INTI AMP Solo Ⅱ

To support the BTL output stage, we adopted a 2-wire BRIDGE circuit rather than a traditional center tap and used OP AMP to create a common ground.  

In order to improve the quality of the power supply, a proper choke coil and a high capacitance capacitor of 22000μF 100v per channel were used.

Input part concept diagram

The maximum linearity was secured by applying a constant current circuit to the triode load of the first stage. The operating point automatic correction circuit was added to OP AMP in consideration of deterioration of dynamic characteristics of the main pipe.

Output part conceptual diagram

 Our patented circuit is applied.

In spite of its many advantages, the power amplifier with NFB (Negative Feed Back) is rejected because the undesired noise component mixed with the strong back-EMF of the dynamic speaker affects the sound quality to be.

It was possible to obtain excellent frequency characteristics, very low distortion and high damping force of the NFB amplifier by feeding back to the input side from the virtual output point which can obtain the same signal as the final output.

Protection

PDF FILE in preparation

 A complete loudspeaker protection circuit is indispensable for a DC AMP with no transformer or capacitor at the output stage. In any case, since DC is output and the speaker should not be burned out, a double or triple protection circuit is built in. Nevertheless, there is no relay between the AMP and the output. The drain and source terminals of the final semiconductor before shipment are short-circuited, tested and checked for abnormality and shipped in principle.

Stabilization circuit

※ patent pending private

 Since feedback is not received from the speaker terminals, a DC OFF SET voltage may be generated across the speaker. A circuit for canceling this is needed.

Specification

  • 8Ω Load MAX 200w (THD = 2% or less)
  • 4 In Put RCA only
  • LP In Put Sensitivity = 72dB based on 1Khz and MC cartridges only.
  • FM/CD/DAC In Put Sensitivity= -3dbm MAX
  • Ac In Put = 220v / 60Hz ± 10%
  • Size = (WHD) 430 x 225 x 275
  • Weight = 30Kg
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