Molded Mojo?

[Gibsonman63]

Thanks for an analysis, Martin. I will say that the lead dress is much neater with the cloth covered wire, so the leads are much closer to the chassis. The original PVC coated wire was too stiff to make any adjustments, it would just spring right back to where it was.

[martin manning]

Just for fun, i placed a 55" piece of 22 AWG, 600V vinyl insulated wire in a loose coil flat against an aluminum chassis cover plate. Using an LCR meter, I measured 94pF for this "capacitor," 1.7pF/in of wire. BTW, this piece of wire has brown insulation, and it was held down using a copy of Bridget Jones' Diary, which is missing it's dust jacket ;^). This would be only a small capacitance for a typical 3-6" run, but maybe enough to add up to an audible difference when applied to the whole amp.

[Gibsonman63]

Sorry to hijack the thread. I thought you all might enjoy a little before and after.

err... after and before.

[martin manning]

Those pictures are good background for things that happened besides the cap change. I see the OD's were 715P's (FWIW), and you have twisted the control leads together, adding some parasitic capacitance between them as well as to ground.

Another simple test: 20" of a loosely twisted pair of 22 AWG 600V vinyl covered wire measures 20pF, so paralleled conductors of this type of wire create about 1pF/in.

['64DlxRvb]

This is all very interesting and educational for me. Learning alot here.

[Leo_Gnardo]

aren't the 150s metalized film?

AFAIK Mallory 150 are polyester film (aka Mylar). Whether it's a metallized film or separate layer I don't know. Going to have to sacrifice one for science.

I have some odds n ends caps by other manufacturers that look similar, also have that nice clear tone. F-dyne for instance.

I also used to order plenty of Xicon metallized polypro before I disovered the 150's. They also had a good bright neutral tone and hi reliability. If I'm not mistook they're out of the Mouser catalog now. I'm sure Panasonics will fill the bill just fine for MPP's.

[Diablo1]

Old style Mylar (polyester) film and foil caps are going to be physically larger than metallized film caps. That's because of the increased thickness of the metal foil layer. The metallized film caps can pack in more capacitance/volume, and also are self-healing. Jupiter caps are film and foil.