glassman
Electron Herder
Re: Intermittent power drop...
GV: I use mostly Sprague Atoms which come in those values; my LCR meter also tells me that the Spragues are generally within 1% of their stated value. I have close to 100 different electrolytic values in my inventory and I use all of them tuning amps for different players so a wide dependable selection is important. Voicing an amp is fairly easy but tuning it for "feel" requires a different approach which requires a wide inventory.
G175: I agree totally with GV on all points and that the blue cap connected to the bias pot needs to be replaced too. Its not original and neither is the PI filter that it completes; not a bad thing though as a PI filter smooths out the ripple on the bias circuit and allows you to use lower values. That's a bias balance in there, not a bias control; the PI filter probably was put in there to adjust the rather cold SF stock setting to something a little warmer.
The two blue caps in the middle of the main board can stay; those are the cathode bias caps for the first two stages in the vibrato channel preamp. The third satge in that preamp still has the original whith electrolytic on it and I would definitely keep it there; if you replace it, the bass can get really farty when you turn up. An alternative would be to run a really worn 12AX7 in V4 when you do elect to replace it to keep the mid focus that the amp has now.
GV: I use mostly Sprague Atoms which come in those values; my LCR meter also tells me that the Spragues are generally within 1% of their stated value. I have close to 100 different electrolytic values in my inventory and I use all of them tuning amps for different players so a wide dependable selection is important. Voicing an amp is fairly easy but tuning it for "feel" requires a different approach which requires a wide inventory.
G175: I agree totally with GV on all points and that the blue cap connected to the bias pot needs to be replaced too. Its not original and neither is the PI filter that it completes; not a bad thing though as a PI filter smooths out the ripple on the bias circuit and allows you to use lower values. That's a bias balance in there, not a bias control; the PI filter probably was put in there to adjust the rather cold SF stock setting to something a little warmer.
The two blue caps in the middle of the main board can stay; those are the cathode bias caps for the first two stages in the vibrato channel preamp. The third satge in that preamp still has the original whith electrolytic on it and I would definitely keep it there; if you replace it, the bass can get really farty when you turn up. An alternative would be to run a really worn 12AX7 in V4 when you do elect to replace it to keep the mid focus that the amp has now.
