• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Anyone have experience with the China made tube amps

Chinese amps

Jonny:

The consensus seems to be that these amps are VERY price competative but some at the lower end of the price scale use absolute cheap parts...the tube compliment are engineered to use the cheapest type tube available....the designs sometimes are unstable or very lacking in basic Hi-Fi implementation.
Stories of tubes giving out with a few hours of operation have cropped up...The DIY approach is that these amps are a good beginning to modify & upgrade to "esoteric" standards...increasing tonal quality, safety and engineering standards.
__________________________________________Rick (Former Oregonian)
 
The above poster put it all very well. It's a DIY experience - better to have some knowledge of circuits. There are even some aftermarket retailers that buy the amps and modify them so you can buy a quality controlled product.

But some of the amps sound terrific. A few friends bought the Music Angel 300b amp with 2a3 drivers and 3a5 input. Now that's an all-DHT amp and you just don't get that quality anywhere near the price. With good tubes it's quite superb - obviously decent iron.
 
My friend asked me to select a Chinese amplifier and I selected an 813 SE triode connection as shown in the attached photo.

I investigated inside of the amp and found following points.

12AX7 Voltage Amp >CR couple > 12AU7 (parallel) Voltage amp > CR couple >813 fixed bias

Plate voltage of 813 : 800V
Output Power: 20W
Over all NFB: 12dB
Coupling Capacitor: WIMA's polypropylene
Tubes: All made by ShuGuang

I modified it to reduce NFB to 6dB and got good speedy sonic which I suspect given by big size OPT as shown in the photo.
No hum was heard.

Chassis contraction was not sophisticated, such as tolerance and finishes of the surface. I purchased it by 700USD.
In net, it was not so bad shopping.

'73 de JA2DHC Kazuo Ohashi
 

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