Bias Caps for old Fenders?

[drewl]

What's a good quality filter cap for 60's Fenders you guys using?

The Blackface amps usually have those black Nashville caps, 50uf at 50v when there's usually like 65v across them due to higher wall voltages.

Even though he schems list them as 25uf, they are usually 50uf.
Any newer caps I try have a higher ripple, like 160mv compared to 60mv with the originals.

Or am I being too picky?

[nevetslab]

Try the Nichicon VX series Axial Electrolytics. 47uF/100V or 100uF/100V. They have good ripple current rating, and they're a low-loss linear part...low ESR. The ESR & ripple goes up as the voltage rating goes down, so stick with the 100V rating.

[Leo_Gnardo]

It is a good idea to get the ripple down to a minimum on the bias supply, it will show up as hum in the audio. Nichicon makes perfectly good caps, lots of values available from Mouser.

Sometimes I'll add a "helper" small value cap on the back of the bias adjust pot, from wiper to ground. Cuts hum from the bias supply to nothing. 4.7 or 10 uF here is plenty.

For the high voltage caps, I buy quantities of the house brand from Ruby/Magic Tubes. The F&T caps sold by Antique/CE/AmplifiedParts are also good. Some folks use JJ - same as the tube company - haven't seen a bad one yet.

[drewl]

Thanks.