The Sprague Bumble Bee gets way more respect than is merited.

Thank Gibson for putting them in your Les Paul, but for tube amps, if you see one replace it immediately!

These capacitors are over 50 years old and they did not age well with time.

Sure, they might read capacitance well on a new fangled digital capacitance checker, but leak test them at their rated voltage!

I've pulled hundreds, and haven't found one yet that passed a leak test.

What does this mean to you, the aspiring amp builder (aka tone hound)?

You will be replacing tubes often, (which we all know ain't cheap!) or worst case an output transformer.

Would I trust a $100 Mullard or Telefunken 12AX7 driven with a Sprague Bumble Bee?  Not no.. HELL NO!

Why? A leaky capacitor lets D.C. current through.

As an example, if your precious Bumblebee lets just 1 microamp of current through (most are way leakier!) to the standard 1M grid resistor, that is one volt less bias on the tube.

Seeing that preamp tubes only have a volt of bias or so...

You can do the math right? You ARE building an amp here!

Personally, I would look at all those Russian military surplus PIO caps out there now. A lot cheaper and more reliable than that Bumble Bee!

If you buy them for tone caps for your guitar, you are ok.

The millivolts you throw at them won't even register.

(I would however ask that  a leak test be done before i placed my bid. The seller should give you current verses voltage at at least the rated voltage. If  he can't or won't, he is either too stupid or too lazy!)

The leakage and inductance is probably what makes those Les Pauls sound so good. Who knows? (someone smarter than me that can scientifically define tone! Their ears must be better than mine...lol)

Rock On!

(Reason I wrote this guide? Sick of seeing crazy bids for a crap cap!)