Got a '68 SF Champ: Pics and Questions Inside

[Commodore 64***]

Don't know about this one, what exactly do you do to install this mod?

You bridge some lugs on the cap can, which is supposed to lower the plate voltage a little which is better for the tubes.

If you swap out the electrolytics on the preamp tubes' and power tube's cathodes, you can use from about 1uF to 10uF. The stock value is 22uF which can make the amp sound to flubby.

For the 6V6 you can use a fairly large cap, like 1,000uF to 2,200uF even 4,700uF, but make sure the voltage rating is over 50v or so. The only problem is that those caps are very big, physically.

OK. I ordered 25uF for the preamp and power tubes. What do you mean by flubby? I'll consider the other values, especially because I may need to order another resistor, so I need to make shipping worthwhile. If I plan to retrofit this amp someday with a 10" speaker, would that "flubby" be something I wish I had?

[tunghaichuan***]

OK. I ordered 25uF for the preamp and power tubes. What do you mean by flubby? I'll consider the other values, especially because I may need to order another resistor, so I need to make shipping worthwhile. If I plan to retrofit this amp someday with a 10" speaker, would that "flubby" be something I wish I had?

By flubby, I mean trying to push too much bass through the small 8" speaker, it sounds just plain bad, IMHO. It doesn't depend on speaker size, either. I use 12" speakers with the Champ circuits I've built and I've found that 2.2uF or 4.7uF sound good.