Home » Audio » Thermionic Emissions » Fisher 500C-how hot is too hot?
Re: New day, more tinkering, new results [message #9192 is a reply to message #9191] Wed, 07 September 2005 13:23 Go to previous messageGo to previous message
Damir is currently offline  Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
With too large common cathode resistor (5k), you`ve "biased" your EL34s to about I=15/5000=3mA total, or just 0,75mA per tube!
The original thought was one 100-Ohms resistor between each cathode and ground - that way (with "combination" bias) you`d get probably less then 40mA per tube, OK. If you want one common resistor for all four tubes, then you can use 25 Ohms. But, better to "separate" two channels and use 50 Ohms for L (2xEL34), and 50 Ohms for R ch (2xEL34 again). Two capacitors, of course.

 
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