• 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.

ming da mc 845 aa modification

bottaccio

Member
2015-12-23 4:02 pm
[IMGDEAD]http://s30.postimg.org/tmkxo74oh/schema_ming_da.gif[/IMGDEAD]Good morning. someone has changed an amplifier with 845 by changing the driver stage? in my ming from there are 2 6SN7 vore and replace them with 34 or other power tubes have a pattern circuit THANKS
 
Last edited:
Good morning. someone has changed an amplifier with 845 by changing the driver stage? in my ming from there are 2 6SN7 vore and replace them with 34 or other power tubes have a pattern circuit THANKS
The Lampizator site is great for anything tube amps.
If you Google Lampizator 805 you will find this useful Ming-Da report with extensive MC3008 805 topcap mods inclusive at input stage.
ming-da
Though I dont see why one would replace the 6SN7 tube, the 6SN7 family are inexpensive and one of the sweetest tube sound avaliable.
300B are expensive and manufacture quality varies.
 
Last edited:
There are many amplifiers out there named ming da.
They may come from different factories or even small back room makers.
There are many different designs and circuits with different valves.

Warning!
They (the Chinese) are well known for using components especially rectifiers that only just meet specification. Any change in supply voltage or load can push them to fail.
Check the quality of all components and replace any that do not look safe to use.
 
thanks I would like to calibrate the bias but does not know the bias voltage of 845 someone knows

Measure between the marked bias point and ground, be careful at some parts inside there is over a 1000 volts!
Adjust the 33k pot.

H83c4XW.png


Hope this helps. :)

For the full size edited PDF please contact me.