The Ming DA MC3008-AB is one of the most talked-about entry level Chinese tube amplifiers, often praised online for its supposed build quality and the scenic presence of the 300B. In this review I show what I actually found inside this unit, which arrived in my workshop with one silent channel. I analyze strengths, weaknesses, design choices and instrument measurements, offering a useful reference for anyone considering its purchase or simply wanting to understand how this model is really built and how it performs.
This amplifier was brought to me because one channel was silent. I was also curious to examine it closely since online you can find many contrasting opinions, some of which describe it as very well built. What I found inside was quite different.
An inexperienced eye may easily confuse tidy looking wiring with correct assembly, but once the amplifier was opened the picture was clear. There are no real mechanical fixing points for the components. I found industrial electrolytic capacitors simply glued in place, some glued right on the top where they should be able to vent in case of failure. The whole circuit appears to be supported by those glued capacitors and by the pins of the tube sockets, with a set of components tied together in a sort of web.
The unit is about five years old, single owner, and all electrolytics were already at the lower limit of their rated value, around minus twenty percent. Some capacitors had even come unglued, leaving entire portions of the circuit hanging freely. I also found a power supply CRC armored resistor resting directly on the metal chassis without any mounting. It heats up like an iron and instead of being fixed with screws and thermal paste it was glued as well. The glue had carbonized and the resistor stayed in place only thanks to the stiffness of the leads. Photos would not have conveyed this properly, so I made some videos.
The fault that caused the silent channel was fortunately just a bad contact on a tube socket. The amplifier works again, but a complete recap would have been necessary. I refused to do it because removing those glued capacitors would have made the entire supporting structure collapse. Even budget brands like Music Angel use small teflon supports and tie wraps. This web-like construction method is something I have only seen on very low end products. I formed my opinion, you can form yours.
Moving past the assembly, the circuit is the same as the mono version shown below. In this design the 300B operates as a cathode follower, so its function is mostly aesthetic with little contribution to the actual sound. A triode connected EL34 would have performed exactly the same task with no audible difference. This looks like a marketing choice rather than a technical one.
The circuit delivers twenty five watts RMS per channel with a damping factor of four and distortion below one percent at one watt. Below are the bandwidth plots on resistive and reactive loads.
Square waves at 100Hz, 1kHz and 10kHz
THD
The design uses a very sensitive input which in my opinion is unsuitable for most preamplifiers. It works properly only when connected directly to the source.
