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.

 
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Previous Topic: One output transformer hotter than the other
Next Topic: DRD 45's in gear.
Goto Forum:
  


Current Time: Sun May 05 04:07:49 CDT 2024

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Smith & Larson Audio
Smith & Larson Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest