Simple SE Simple Power Drive?

Skorpio · 17th December 2010, 06:37 PM

If the output to the power stage grid resistor is taken from the CCS source terminal (top of current setting resistor), the driver stage will have an output impedance in the range of 300-400 Ohms, and the load from the power stage is isolated from the driver valve, increasing linearity...or?

I have done this with exelent results in a line stage using DN2540 MOS-FET as CCS, and can see no reason for this not working also in Simple SE...

Skorpio · 5th May 2011, 09:45 AM

My +B seems to be in the 400V range and I want to use LED bias on the ECC81/12AT7. I would consider half supply (aprox200V)on output. The only way to move this is to find right LED value (voltage drop at 10mA).

In datasheet ECC81 has 250V with 10mA and -2V grid bias. At -2.2V even higher (above 250V). So it would seem that optimum LED voltage would be in the 1.2V range for 200V at Anode?

But this seems quite low when compared to resistor bias (220R/10mA=2.2V)...

Am I missing something?

17th December 2010, 06:37 PM	#1
Skorpio diyAudio Member Join Date: Mar 2004 Location: Denmark	Simple SE Simple Power Drive? If the output to the power stage grid resistor is taken from the CCS source terminal (top of current setting resistor), the driver stage will have an output impedance in the range of 300-400 Ohms, and the load from the power stage is isolated from the driver valve, increasing linearity...or? I have done this with exelent results in a line stage using DN2540 MOS-FET as CCS, and can see no reason for this not working also in Simple SE...

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5th May 2011, 09:45 AM	#2
Skorpio diyAudio Member Join Date: Mar 2004 Location: Denmark	My +B seems to be in the 400V range and I want to use LED bias on the ECC81/12AT7. I would consider half supply (aprox200V)on output. The only way to move this is to find right LED value (voltage drop at 10mA). In datasheet ECC81 has 250V with 10mA and -2V grid bias. At -2.2V even higher (above 250V). So it would seem that optimum LED voltage would be in the 1.2V range for 200V at Anode? But this seems quite low when compared to resistor bias (220R/10mA=2.2V)... Am I missing something?