Adding Grid Stoppers to a 6V6 tube amp

[tube-a-lou]

Hi all,
I'm restoring a Fender Deluxe amp and was wondering if added two Grid Stoppers
would be good for the tube, I have a few 1.5K 1 watt resistors but my question is
what pins to put them on?

Thanks

 

[gadget73]

pin 5 is the grid on a 6V6.

 

[primosounds]

Usually the pin 6 is open so one can put the grid stopper on very short leads. Most of the time a carbon comp is used for the grid stopper.

 

[tube-a-lou]

So should I move the wire from pin 5 grid to pin 6, then put the resistor from
pin 6 to 5 because it's open.

 

[RWood]

Yes.
Often on later Fenders you'll see screen resistors mounted on the power tube socket. Your amp might not have even used screen resistors, which are a protection feature not affecting tone. Not stock though.

Here's an example:

Btw, you don't have to use 1W resistors for the grids.......1/2W is fine.

 

[triode17]

Hi all,
I'm restoring a Fender Deluxe amp and was wondering if added two Grid Stoppers
would be good for the tube, I have a few 1.5K 1 watt resistors but my question is
what pins to put them on?

Thanks

Specify which grid you are talking about? Also, the internal model #. e.g. 5C3, AA763, etc.

 

[tube-a-lou]

Fender 5B3, just need to know that I could use it on this amp?

 

[billyz]

Yes.
Often on later Fenders you'll see screen resistors mounted on the power tube socket. Your amp might not have even used screen resistors, which are a protection feature not affecting tone. Not stock though.

Here's an example:

Btw, you don't have to use 1W resistors for the grids.......1/2W is fine.

The 470 ohm screen resistors are added protection but certainly do affect the tone. They add an amount of compression, the higher the value the more compressed it sounds.

The biggest benefit is they can act as a fuse if the tube screen shorts, I think fender used 1w for this purpose.

 

[billyz]

Fender 5B3, just need to know that I could use it on this amp?

You can use them, they are usually used to control parasitic oscillations, RF, Blocking distortion etc. You can hear them, but the standard 1.5K is hardly noticeable and may actually smooth the signal under heavy drive.

 

[tube-a-lou]

Hi bill, what pins should I put them on?

 

[billyz]

Hi bill, what pins should I put them on?

There are several ways. If you are only using the grid resistors then, Connect the resistor and connection from the Phase invertor to pin 6, then attach the other end of the resistor to pin 5. Pin 5 is the control grid input of the tube. pin 6 is unused by the tube.

If using the screen grid resistor then install the screen connection to pin 6 and the screen resistor ( 470 ohm 1w) from pin 6 to pin 4. you can install the grid resistor from pin 1 to pin 5 , PI connected to pin 1. Make sure pin 1 is not connected to 2 . Pin 2 is the cathode. Pin 1 is not used by the 6v6, its just a convenient tie point like pin 6.

Or you can fly the grid resistor , ala marshall, connect the PI to the end of the grid resistor and then the other end of the resistor to pin 5. this is not really the best way, but marshall did it because the el34 has a different pinout , grid 2 is not internally connected to the cathode, pin 1 is the connection to grid 2 . This is the diagram as posted by RWOOD .

I suggest googling fender layouts for the 5e3, and AB763. The problem comes when you try to use the original wiring, as the leads may not be long enough to run the PI to pin 1.


But , honestly this amp is fine as wired originally. The potential problems arise when amps have higher gain and or higher voltages and the wiring is more complicated.

 

[tube-a-lou]

Thanks Bill! I just want to cover all the bases. One thing to note this amp sounds
really nice when it get's going, when I walk into a Guitar Center now I think something
is different because a lot of the new amps sound so bright and thin, maybe it's the
way the people playing them have them set up I don't know.

 

[tube-a-lou]

I decided to try the resistors out and so far it does sound cleaner, it did before I tried them
it sound a bit messy I think I'll try them for awhile.