DIY Headphone Amplifier YAHA MODIFY

I build based on the following.

YAHA amp
　
　

　
　
Schematic
　

　
　
Distortion  RL=30 OHM
　



Frequency Response  RL=30 OHM

　
There are two differences of this Amplifier and yahaAmp.

The first point is that putting a resistor to the cathode.
The second is there is no LM317.　Because heater voltage is 12V.

5687 is Hot. Because there is much heater current as 300 mA.
The tube exposed from the case will gather external hum noise. 
Since it was unavoidable, the main part of a tube was shielded on the aluminum tape for kitchens.
　
　
　

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■■■■■　　0dB HyCAA  is a headphone amplifier　　■■■■■

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Hybrid classAA Headphone Amplifier　
　

This is a vacuum tube and an op-amp using headphone amplifier.
The op-amp part is using the classAA circuit of technics.

I called HyCAA.

Although YAHA is interesting to a characteristic sound, there is too much distortion and it sound was tedious.
I tried to reduce distortion, though the merit of YAHA was harnessed.

Since the cathode follower circuit was used, a gain is 0dB.

I arrived to the goal at last.

　
The circuit diagram is the following.

　
It is an actual condition wiring diagram of an op-amp part.

Two steps are loaded with the op-amp.

First of all, it is a wiring diagram of the lower stage. 　TOP VIEW.

　
　
Next, it is the upper stage. TOP VIEW.

It leaves 4 and 8 pins of a power supply, and opens a pin horizontally.
Solder attachment of the up-and-down op-amp is carried out by 4 and 8pin.

This is a photograph of an actual substrate.

　
　
Waveform at 1mW   RL=30 OHM
　

　
　
　
Distortion  RL=30 OHM

　
　
Frequency Response  RL=30 OHM

　
　
　
RMAA software

　
　
s/n : 100dB (a-wait 500mV)

I am pleased.
It can be heard very comfortably even if it hears to a louder sound.
Good Sounds.　Thank you.