The revised schematic diagram with RCA8000 tubes.

As you will find from the Mingda3008AB original manufacturer schematic diagram, in order to change the power triode from RCA805 into RCA8000, the negative bias voltage has to be increased in order to adjust the RCA8000 bias current into 100mA (50Watts full load current about 200mA).

Upload one photo of RCA8000 power Triode tube.

The new toys made by me today!





最後修改時間: 2012-03-07 22:41:35

I bought one second hand Mingda 3008 integrated tube amplifier with 805 tubes, since I bought from eBay One pair of RCA8000 tubes which have the equal similar performance of WE-212 tubes.

I modified the 805 tube socket by adding a grid wire cap to fit RCA8000 tube, plus add a 1k/5W VR to increase the negative bias voltage eventually adjust the RCA8000 tube bias current into 100mA under 1000V Anode Plate Voltage, form pure class A configuration.

I try to run the RCA8000 tube amplifier for whole day with difference type of CD music, the sound quality is much much better than my 845 or 805 tube amplifier.

However I do not have WE-212 tube amplifier to compare with this excellent RCA8000 tube amplifier. Hope to share this amplifier modificaiton experience with other R33 interested members.

Dr. Richard Chan