Recap - replacing '60's era Mallory filter caps in a fender

[Mike McCardle]

I need to replace the Mallory filter caps in a 1968 bassman. What would be the best way to go, get NOS Mallory caps or use good electrolytics?

Since these are filter caps on the power is this really a matter to ponder?

What brand would be a good replacement for the Mallory filter caps if finding NOS Mallorys is not the way to go?

Thanks!

[MWJB]

Electrolytics typically have a recommended working life of 7 years or so (though I wouldn't necessarily bother replacing original e-caps unless they were 20yrs+), so NOS caps would be next to useless.

Good brands to use as replacements would be Sprague or F&T (also sold as German made, selected values under the TAD brand).

Replace the 2x 70uf/350v main filter caps with either Sprague 100uf/350v or TAD/F&T 220uf/350v. 20uf/500v caps will be fine in the rest of the power supply unless you have particularly high voltage at the screen node (470v+), in which case I'd go for the TAD/F&T 20uf/550v. You may see 20uf/600v Spragues advertised, these will NOT fit in your amp's cap pan.

Be sure to replace the preamp cathode bypass caps (Sprague 25uf/25v or 25uf/50v) and the e-caps in the bias supply, replacing any 50uf/70v caps with 100uf/100v. In all cases be sure to observe correct polarity.

[Mike McCardle]

Electrolytics typically have a recommended working life of 7 years or so (though I wouldn't necessarily bother replacing original e-caps unless they were 20yrs+), so NOS caps would be next to useless.

Good brands to use as replacements would be Sprague or F&T (also sold as German made, selected values under the TAD brand).

Replace the 2x 70uf/350v main filter caps with either Sprague 100uf/350v or TAD/F&T 220uf/350v. 20uf/500v caps will be fine in the rest of the power supply unless you have particularly high voltage at the screen node (470v+), in which case I'd go for the TAD/F&T 20uf/550v. You may see 20uf/600v Spragues advertised, these will NOT fit in your amp's cap pan.

Be sure to replace the preamp cathode bypass caps (Sprague 25uf/25v or 25uf/50v) and the e-caps in the bias supply, replacing any 50uf/70v caps with 100uf/100v. In all cases be sure to observe correct polarity.

Excellent - thank you!! I do a lot of solid state, new circuit, work - so I appriciate the input on this kind of circuit. I will let you guys know how this turns out.