CCS Questions Revisited

75.71.207.145

Posted on September 26, 2009 at 09:14:15

JimBop
Audiophile

Posts: 1085
Location: Colorado Springs, CO
Joined: October 7, 2002

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

Jim, just build this.

Tre'

22:45:49 09/26/09

RE: CCS Questions Revisited

KevinC

10:08:17 09/26/09

RE: CCS Questions Revisited

JimBop

11:18:51 09/26/09

RE: CCS Questions Revisited

KevinC

12:42:06 09/26/09

RE: CCS Questions Revisited

JimBop

15:47:06 09/26/09

Jim, just build this., posted on September 26, 2009 at 22:45:49
Tre' Industry Professional Posts: 4845 Joined: February 9, 2002	Jim, Just build this. Tre' Have Fun and Enjoy the Music "Still Working the Problem"

RE: CCS Questions Revisited, posted on September 26, 2009 at 10:08:17

KevinC
Manufacturer

Posts: 1999
Joined: April 19, 2001
Contributor
Since: October 7, 2002

The voltage dropped across the CCS has nothing directly to do with the cuerrent flow. The CCS will drop whatever voltage it needs to in order to maintain the current at the setpoint. Running the 6SN7GT at 1mA is not likely to result in good sound. You might want to adjust the current setting of the CCS using the procedure in the instructions and then install the CCS. That way you will know what the current is. Simply remove the 100K plate resistor from the circuit and substitute the CCS with the "-" pad connected to pin 1 and the "+" pad connected to the 2.05K resistor.

Do the above before thinking about CCSs elsewhere.

Kevin Carter
K&K Audio
www.kandkaudio.com

RE: CCS Questions Revisited, posted on September 26, 2009 at 11:18:51
JimBop Audiophile Posts: 1085 Location: Colorado Springs, CO Joined: October 7, 2002	Any recommendations for a starting point for the current setting? Jim

RE: CCS Questions Revisited, posted on September 26, 2009 at 12:42:06
KevinC Manufacturer Posts: 1999 Joined: April 19, 2001 Contributor Since: October 7, 2002	Try 5mA with a 450-500 ohm cathode resistor replacing your 2K cathode resistor. Kevin Carter K&K Audio www.kandkaudio.com

RE: CCS Questions Revisited, posted on September 26, 2009 at 15:47:06
JimBop Audiophile Posts: 1085 Location: Colorado Springs, CO Joined: October 7, 2002	Kevin, Again, thanks for you help. I have a request: If you have the time, could you look back over my questions and provide some technical explanations so that I can continue to learn from this? Jim

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CCS Questions Revisited

75.71.207.145