Multisection electrolytic cap = parallel caps?

[slidincharlie (Carlo P)]

Ok, this question gonna make someone smile I guess . Anyway...
I have a 16+16uF@500V multisection axial cap with one negative and two positive leads. I wish to use it to replace the first two 16uF filter caps in a Fender SF Deluxe Reverb, which are wired in parallel.
May I solder a lateral extension (a "branch") onto the negative lead and use it as if they were two separate caps?
Or may I simply use the single negative lead and solder it to ground?
Photo of the cap and modified cap attached.
Thanks in advance.
--Carlo

[Tom Phillips]

...May I solder a lateral extension (a "branch") onto the negative lead and use it as if they were two separate caps?
Or may I simply use the single negative lead and solder it to ground?...

Yes. Just use the single negative lead and solder it to ground. Make sure that you don't inadvertently break the original ground setup in the Deluxe Reverb. Specifically make sure that the negative lead is connected to the ground wire that is routed to the chassis ground next to where the PT center tap is grounded.

[slidincharlie (Carlo P)]

Thanks a lot Tom for confirming my idea.

[slidincharlie (Carlo P)]

Tom Phillips while we're at it:
can it hurt using some capacitance in excess in the filter section of a tube amp? May I safely use e.g. 22uF instead of 16uF? Just in case I find a larger cap than necessary.

[Tom Phillips]

Tom Phillips while we're at it:
can it hurt using some capacitance in excess in the filter section of a tube amp? May I safely use e.g. 22uF instead of 16uF? Just in case I find a larger cap than necessary.

Most people do use 22µF caps when replacing 16µF caps in old equipment. Most electrolytic caps had a tolerance rating of ±20%. So that 16µF could be anywhere between 12.8 & 19.2 µF. Back in the 1960s and earlier it was common to see a tolerance rating of something like -20% to +80%. Therefore, an old 16µF cap could be anywhere between 12.8 & 28.8µF when new and still be considered within spec. You will also find better and less expensive availability for 22µF caps vs. 16µF because 16µf is now considered a non standard value.

[g1]

The only worry would be exceeding the max. capacitance allowable for the type of rectifier tube in use. For 5U4 it is technically 40uF, but 44uF there should be no problem.

[x-pro]

The only worry would be exceeding the max. capacitance allowable for the type of rectifier tube in use. For 5U4 it is technically 40uF, but 44uF there should be no problem.

May be. But, the lamp does not heat up instantly. The capacitor has time to charge before the lamp goes into operating mode.

[The Dude]

g1 is referring to recommended tube specs/circuits in tube data sheets. Nothing magic.

[Chuck H]

I built a little amp that used a 5u4 with a 47uf. It was used as a harp amp for years before I had to retrieve it from the guy I'd loaned it to. I never figured it would be a problem and it never was. I dismantled the amp for parts a couple of years ago and still have that 5u4 tube in a box of old tubes.

[slidincharlie (Carlo P)]

Thank you guys.
I was thinking to use a GZ34 in this amp, like its blackface predecessor. I have opened another thread for this topic.
Tha max capacitance allowed for a GZ34 is 60uF (if I read the data sheet correctly). So, in case I should use two 22uF filter caps there, I would be in the ballpark.
Anyway I am learning a lot from this forum, as usual :-) .