Forming Caps Worth it

[talbany]

I notice in the Ceriatone startup procedure posted in the past thread and others provided in the past, nobody takes the time to form the filter caps..I know Ken Fisher was a big proponent on forming caps... I hear he was a big fan of the F&T's and formed all his recaps..I was always under the impression that the electrolyte in the newer caps were more stable than the older caps and didn't need forming...Ken said he could tell the difference in an amp with the caps formed.. Anyone have an opinion on the subject?... Curious!



Tony VVT

[M Fowler]

I think anytime you take the time to properly form the caps it is better.
But do I, not always. I'm in consistant and in a hurry. It would be a good practice.

Mark

[BobW]

According to a Nichicon rep, the electrolyte in paste form, usually begins to crystallize after 6 months. Reforming can be performed either by applying heat or voltage. I wouldn't recommend heating the caps unless you have a very well controlled oven, and the temperature remains below the operating temperature.

It may be overkill but, one of the rare suggestions from Gerald Weber that I actually follow is to use a variac while monitoring the input current and bump up the ac input voltage about 10 volts every hour until I have reached 120 vac. I also do this for any amp that has been sitting idle for over a year.

[Structo]

When I built my D'Lite I used the lighte bulb current limiter as I don't have a variac.

Does using this help form the caps any slower than just hitting with high voltage from the wall?

[talbany]

According to a Nichicon rep, the electrolyte in paste form, usually begins to crystallize after 6 months. Reforming can be performed either by applying heat or voltage. I wouldn't recommend heating the caps unless you have a very well controlled oven, and the temperature remains below the operating temperature.

It may be overkill but, one of the rare suggestions from Gerald Weber that I actually follow is to use a variac while monitoring the input current and bump up the ac input voltage about 10 volts every hour until I have reached 120 vac. I also do this for any amp that has been sitting idle for over a year.

Bob
Thanks for posting that.... I remember reading a post from a cap manufacturer.. stating that properly forming caps even new ones helps with the caps longevity..Somewhere I have that comment..If I can find it I'll post it..As for the sonic aspects you would need to start a list of a dozen or so amps, some formed some not and see if there are any benefits...Sounds like it may be worth the effort..

Tony VVT

[paulster]

I always stick a 100K resistor in series with the first cap and disconnect the bleeder/totem resistors. Then power it up and wait for the voltage drop across the 100K to get below 5V.

There's always a point during a build when I have time to do it, and it certainly can't hurt.

That said, I haven't swapped out the caps with unformed ones to compare and contrast because it's too much effort.

Form away...!

[BobW]

According to a Nichicon rep, the electrolyte in paste form, usually begins to crystallize after 6 months. Reforming can be performed either by applying heat or voltage. I wouldn't recommend heating the caps unless you have a very well controlled oven, and the temperature remains below the operating temperature.

It may be overkill but, one of the rare suggestions from Gerald Weber that I actually follow is to use a variac while monitoring the input current and bump up the ac input voltage about 10 volts every hour until I have reached 120 vac. I also do this for any amp that has been sitting idle for over a year.

Bob
Thanks for posting that.... I remember reading a post from a cap manufacturer.. stating that properly forming caps even new ones helps with the caps longevity..Somewhere I have that comment..If I can find it I'll post it..As for the sonic aspects you would need to start a list of a dozen or so amps, some formed some not and see if there are any benefits...Sounds like it may be worth the effort..

Tony VVT

Tony, that's a big undertaking to summarize the tonal aspects of the electrolytics available. I'd just go for the lowest ESR / ESL and highest ripple current caps available (or the best ones in the shop), which is why I like the Nichicons.

[talbany]

Bob

Thanks for the info!!!

[Nigel Tufnel]

I always stick a 100K resistor in series with the first cap and disconnect the bleeder/totem resistors. Then power it up and wait for the voltage drop across the 100K to get below 5V.

There's always a point during a build when I have time to do it, and it certainly can't hurt.

That said, I haven't swapped out the caps with unformed ones to compare and contrast because it's too much effort.

Form away...!

Agreed. I've used this method with great results as well, I picked it up from one of Novosibir's posts over at metroamp (thanks Larry!). I recently brought an old british tube pa back to life that probably had not been powered on in a decade or two. It had old radiospares cans and they came back just fine, it took a long burn in but it was worth the wait.