.0047 caps and 500k vs 250k pots in my 330
Posted: Sat Apr 06, 2002 4:08 pm
I'm considering some mods on my 330. I bought it used. It came with a UK warranty card, and what appears to be the original sales receipt from Bristol. According to the serial number, the Rickenbacker web page says it was made in Sept. 87.
I bought toasters for it. For what it's worth, they measured 6.25k d.c. ohms, not 7.4k as advertised on http://www.ricpage.com where I got them, although maybe they were publishing the actual impedance.
Of course, I also want to try some Pyramid flat wounds.
I have two issues on which I'd like some comments, although they may add up to nothing:
1) I want to do the .0047 cap mod between the bridge pickup and volume pot.
a. I want to use a push-pull pot so the mod is reversible. (more on this later)
b. Does the cap's composition matter that much? Polypropylene, silver mica, ceramic disk... I bought about a dozen .0047 caps, all different, and they vary in size by a lot. Think Volkswagen vs. Greyhound bus. I got a Sprague Orange Drop 716p. It's about the same size as the two .047 Sprague Atom tone caps combined, even though it is a smaller value. Does that seem like a good choice?
2) Since I want to change one pot to add the push-pull switch, should I change them all? The ones I could measure without unsoldering anything were the 5th knob, and the two tone pots. They were all around 500k. The current schematic indicates 250k, plus I've read postings by Mr. Arnquist indicating that 250k is right for passive single coils. The volume post have different markings than the 5th knob and the tone pots do, so they could be different value, but I didn't want to unsolder anything until I was ready to do it all at once, so I couldn't measure them.
The 5th knob/tone pots seem to be audio taper. Should they all be audio taper, and should I go for new 250k pots all around?
Thanks.
I bought toasters for it. For what it's worth, they measured 6.25k d.c. ohms, not 7.4k as advertised on http://www.ricpage.com where I got them, although maybe they were publishing the actual impedance.
Of course, I also want to try some Pyramid flat wounds.
I have two issues on which I'd like some comments, although they may add up to nothing:
1) I want to do the .0047 cap mod between the bridge pickup and volume pot.
a. I want to use a push-pull pot so the mod is reversible. (more on this later)
b. Does the cap's composition matter that much? Polypropylene, silver mica, ceramic disk... I bought about a dozen .0047 caps, all different, and they vary in size by a lot. Think Volkswagen vs. Greyhound bus. I got a Sprague Orange Drop 716p. It's about the same size as the two .047 Sprague Atom tone caps combined, even though it is a smaller value. Does that seem like a good choice?
2) Since I want to change one pot to add the push-pull switch, should I change them all? The ones I could measure without unsoldering anything were the 5th knob, and the two tone pots. They were all around 500k. The current schematic indicates 250k, plus I've read postings by Mr. Arnquist indicating that 250k is right for passive single coils. The volume post have different markings than the 5th knob and the tone pots do, so they could be different value, but I didn't want to unsolder anything until I was ready to do it all at once, so I couldn't measure them.
The 5th knob/tone pots seem to be audio taper. Should they all be audio taper, and should I go for new 250k pots all around?
Thanks.