- Posted by JimBop (A) on September 26, 2009 at 09:14:15
Kevin:
I have some more questions about the CCS. The schematic is included.
- In my first experiment, I replaced the 2.05K resistor with the CCS, and set the current to 6mA (13V / 2K = .006). It worked fine and sounded fantastic. I then asked for recommendations on fine-tuning this implementation. After I posted the schematic, you (and others) implied this was not the correct location. (I chose this location because I assumed the 2.05K resistor is the plate load resistor for pin 2 of the 6SN7.)
- Following your advice, I then reinstalled the 2.05K resistor and installed the CCS in place of the 100K resistor at pin 1. The voltage drop here is around 160V. (160V / 100K = 1.6mA). This does not fall within your stated specs for the CCS. I tried it at about 2mA, but there was very little volume from the amps. The voltage drop across the CCS was only about 2V.
Since the 2.05K resistor is in series with the 100K resistor, it seems that my first implementation should be fine (still loading the plate), and the results I achieved seem to verify this.
It has also been suggested that I install the CCS in place of the 30K resistor at pin 3. Since this resistor goes to ground, is it dropping the full 125V present at pin 3? If so, would I set the CCS for 4mA? (125V / 30K = .004)
And lastly - which would be the optimal location:
- ahead of the 100K resistor at pin 1?
OR
- in place of the 30K resistor at pin 3?
Again, thanks for all your help (and patience).
Jim D
