Hello all!!!
I actually penned and posted these #34 mod instructions. To comment on the shielded wire technique, I never actually tried using a cap instead of the shielded wire. For the most part, I used it merely because it was utilized in the #39 AND #34 mods by Tim and Frank. One thing to consider when modifying your amp; it is the sum total of all of the mods that creates the end resulting sound. I'm going to guess that since using a single cap instead of the shield wire was an option when these mods were created, and that there is some benefit in using the shielded wire over the cap.
Someday when I’m feeling adventurous, I’ll swap the shield wires for some caps, and we’ll see what happens. 8)
Till then, it sounds so spot on that I hate to touch it!
Cheers!!!
Jay
BMW FREQ
jay@jjlcustoms.comI've always thought that attaching the shield to the anode was a strange idea.
Yes it increases the capacitance from the anode to the grid, which will be multiplied by the gain of the following stage +1. This can be employed to prevent oscillation or reduce top end response by limiting high frequency bandwidth.
However, it seems a bad idea as:
1) the extra capacitance will be poorly defined; you would be better off using a small capacitor of known value for reproducibility.
2) The shield will now be virtually ineffective as it now has a high impedance path to ground.
3) It's probably NOT a good idea have a high voltage on the shield as it may inadvertently end up somewhere it shouldn't.
