Guys ! Someone help me .. problem with biasing clone jcm800 50watt .. let’s start what I’m doing : connect 1ohm resistor from 8-1 pin both of el34 to the ground … I leave on standby the amp with the speaker connecting and the pots on zero … after 30 minutes I turn on the standby ,,,checking the pin 3 ( el34 plate ) and I wrote down 479 vdc ( I see the same with other el34 ) .. now I’m using this formula : 25/ plate voltage * 65% …for me is 0.0339 = 33-34 mV…. So I’m going and check the pin 1-8 and start to dial the trimpot ,, after 7-9 mV the speaker start makes a loud noise like (eeeeeeeeeeeeeee) …the one problem is that the other problem is , the mV of pin 1-8 of one el34 it doesn’t the same with the mV of pin 1-8 on other el34 , like on first el34 is 6.5mV and on other is 2.4 mV , something like that .. and the el34 are matched ….where is the f&@ing problem !?!?! Thank you
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The f&@ing problem for most probably most of us is that your writings are somewhat hard to understand 
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The 2nd issue is that your pics still keep opening new pages. Perhaps you want to modify this?
Well, anyway and first of all, biasing the output tubes doesn't have anything to do with the plate voltage (unless the plate dissipation ratings will be exceeded, of course). Then, 10 ohms cathode resistors will yield more reliable readings. Last of all, squealing noise means oscillations. I think you need to reverse the EL34s' plate connections.
Best regards!
.The 2nd issue is that your pics still keep opening new pages. Perhaps you want to modify this?
Well, anyway and first of all, biasing the output tubes doesn't have anything to do with the plate voltage (unless the plate dissipation ratings will be exceeded, of course). Then, 10 ohms cathode resistors will yield more reliable readings. Last of all, squealing noise means oscillations. I think you need to reverse the EL34s' plate connections.
Best regards!
sorry my friend for my bad english .. anyway you got it. .. so I will try to change the cathode resistor to 10ohm. and to reverse the plates of el34… to ask something else, the schematic has 22kohm trimpot for the bias setting .. I have put 50kohm .. I do not think this is a problem .. right?