Can ´lytic caps have a too hi voltage rating?

[Michael Tibes]

I always thought that it wouldn´t matter what dc voltage an electrolytic cap runs at, as long as it isn´t higher than it´s specs and the polarity is ok.
Now I red this in Geoff Tanners forum:

...it isn't a smart move to put higher voltage electrolytics into much lower voltage circuits. They simply don't get enough polarisation and you would have been better off fitting a 6.3 volt in that location.

Is that correct? I´ve often used caps with higher voltage specs because they have higher mtbf ratings... not too smart, if he´s right.

Any thoughts?

Michael

here´s the link to the topic: http://www.auroraaudio.net/dcforum/DCForumID1/356.html

 

[Kev]

very generally and for power smoothing situations I'd say it's not that critical but Geoff is refering to the subtle effects on things like the BA283 and BA284

were caps are 4 and 6 volt
and they are replaced with 25, 35 and even 63 volts then I'd expect there to be a difference
when looking to make a clone and where audio can be such a subtle thing the details are important

Dan K has always said the magic is in the detail

same goes for the Tants

This is realy were DIY has the oportunity to settle the arguement
make two cards and change one component at a time
listen
prove it
come back and tell us your results

do it yourself


on Geoff
he has tons of experience and obviously with the older Neve stuff

That's my best guess as to why they didn't last long... the moral with Neve circuits is to replace like with like and no poetic licence adjustments!

when making a clone, do listen to Geoff

it is a good idea to have at least one clone made as close to original as you can
to use a a yard-stick to the other variants you may make
or to the not so clones like the Seventh and JLM and GreatRiver etc etc ...

 

[Gus]

I like to use electros at the min voltage rating I can use in a circuit.

 

[clintrubber]

[quote author="Gus"]I like to use electros at the min voltage rating I can use in a circuit.[/quote]
For alike reasons ? Or for board space or cost ? What's your take on the issue ?

Bye,

Peter

 

[Kev]

Geoff suggests it is the energy/voltage required to polarise the plates

inside Mic's and at the front of the mic-pre could be sensetive to details like this
... I guess some bias twists at the high gain sections could also show the difference to the sound

 

[clintrubber]

I'll have a chat with a colleague tomorrow. He has been working on e-caps in the past.

 

[CJ]

Gus, is there any diff between a radial and axial power lytic?
Construction wise, that is.
Thanks!
cj

 

[clintrubber]

[quote author="clintrubber"]I'll have a chat with a colleague tomorrow. He has been working on e-caps in the past.[/quote]
Some 'qualitative' remarks, not 'quantitative':

He told me that e-caps rated for higher voltages keep better HF-properties even when used at lower voltages.

So when wanting to accurately clone an old circuit one would say it'd be better to stick to the old voltage rating, even when a more modern part with a higher voltage rating would easily fit (physically).

And also then: for 'un-dulling' old circuitry the higher voltage e-caps could be better.

Regards,

Peter

 

[gyraf]

Also, electrolytic capacitor life is directly related to the diameter of the electrolytic (dunno why, but it shows in all data sheets) - the higher the voltage> the larger the diameter for a given uF> the longer expected working life.

Jakob E.

 

[Samuel Groner]

Electrolytic capacitor life is directly related to the diameter of the electrolytic (dunno why, but it shows in all data sheets).

They dry out less fast due to having more "skin".

Samuel

 

[jensenmann]

IIRC the dielectric absorption is higher at higher voltage ratings because the Al-oxide, which forms the dielectricum, is thicker.

 

[alk509]

About a year ago I had a long phone conversation with Gus, during which he told me about his experiences with caps' voltage ratings... Well, I wish he'd never called: now I have to stock four times as many caps! Thanks, Gus!

:razz:

Seriously, though: Thanks, Gus! :thumb:

Peace,
Al.

 

[Family Hoof]

Not too long ago I recapped a pair of Issue 13 1073 modules and was surprised to find that the original production caps had this syndrome. Can't remember exact numbers off hand, but all of the normally low-voltage caps on the 283 and 284 cards were the same (larger) value, with a higher voltage rating. Apparently, like most techs, Neve had economized their capacitor stock to the point of "so long as it's bigger than needed, it will work". I couldn't say how this affected performance or lifespan, as they were dried up just the same.

 

[Michael Tibes]

[quote author="gyraf"]Also, electrolytic capacitor life is directly related to the diameter of the electrolytic (dunno why, but it shows in all data sheets) - the higher the voltage> the larger the diameter for a given uF> the longer expected working life.[/quote]

Yes, that's what I always thought, but Mr. Tanner says it is in fact not so. That's why I wonder what's right. He sais that running a higher voltage cap at a low voltage would reduce it's lifetime significantly, so that it wouldn't make sense to use higher voltage caps - as I often did, following that particular data sheet 'knowledge'.
I don't want to say he wasn't right and I knew better, I generally agree with his opinions (basically: don't mess with it, someone put a lot of thought into it a while ago) and had worked that out for myself even before I got to know his site. Just this one point surprised me and I would be happy to have some more knowledge about the topic.

[quote author="clintrubber"]e-caps rated for higher voltages keep better HF-properties even when used at lower voltages.

So when wanting to accurately clone an old circuit one would say it'd be better to stick to the old voltage rating, even when a more modern part with a higher voltage rating would easily fit (physically).

And also then: for 'un-dulling' old circuitry the higher voltage e-caps could be better.[/quote]

[quote author="jensenmann"]IIRC the dielectric absorption is higher at higher voltage ratings because the Al-oxide, which forms the dielectricum, is thicker.[/quote]

Aren't these 2 points contradictive?

Michael

 

[Gus]

Caps are cheap. Try it yourself.

 

[khstudio]

I tried several different brands & voltage ratings in my API style pre's (the cap on the GAIN control pot)

Since the API is so basic with little components it was very noticable & a good learning experience :wink:

It calls for a LOW 4 volt e-cap, others recommend aprox = 10 volts.

I swapped out caps for days & didn't like the lower voltage ones very much at all... I ended up using a NICHICON PW 1000uf / 35 volt. The lower voltage caps seemed gritier and less extended at the top & bottom - all around less musical to our ears in the studio.

Your application & ears "may" preffer something else.

I'm with you on refferencing others & their opinions that's why I'm sharing mine in detail... but you will eventually have to hear it for yourself to really learn.

I got one word - timeconsumingshit.

Good luck,
Kevin

 

[Michael Tibes]

[quote author="khstudio"]I'm with you on refferencing others & their opinions that's why I'm sharing mine in detail... but you will eventually have to hear it for yourself to really learn.

I got one word - timeconsumingshit.[/quote]

Well, hearing is not the most difficult part, but having to redo a refurbishment after a short while because the caps fail after a too short period would really be annoying.

That's what my question was mostly about: how the lifetime would be influenced by the polarization voltage.

For me the part cost are nearly unimportant compared to the hours of work and I always try to get the most stable parts in order to achieve the longest lifespan possible. Of course there is no DIY-way of working that out unless I build a laboratory for 'artificial aging' (don't know the proper english word...) which is certainly beyond my capabilities and also not my main interest.
I have refurbished my 24 Neve 1073 modules maybe 10 years ago and have not used low-voltage caps where they were originally used because I just read the data sheets and also came to the conclusion that higher voltage ratings should last longer - and I luckily haven't run into problems yet. The units are used nearly every day and there have been very few failures since, so I am in fact running a long-term test myself already. The only cap-failues I had were in the psus which were included with the racks I bought for the modules...
I was just surprised to read the opposite opinion from Mr. Tanner on what I thought I had understood from the data sheets and was hoping to get a better understanding - which could probably also be intersting for others here.

Michael

 

[khstudio]

That's what my question was mostly about: how the lifetime would be influenced by the polarization voltage.

Sorry I missed that... I was just sharing my experience about actually liking the "sound" of the higher voltage cap (in that application at least)

I'm interested in your question as well.

So far, the
higher voltage = better hi end
Lower (recomended) voltage = Longer life & shorter life :?

C O N F U S I N G.

kEVIN

 

[jensenmann]

there´s some good read in the press room on this site:
http://www.cde.com/new/news/