[sdiy] High-K ceramics and audio

Thu Nov 30 15:41:00 CET 2023

In my experience that is wise advice at least when dealing with surface 
mount Tantalum capacitors.  I witnessed a bunch of Panasonic Tantalum caps 
go short-circuit when operated at 80% of their rated voltage.  And this was 
with new devices from a reputable supplier, operated at room temperature in 
a well designed circuit with minimum current ripple and no voltage 
overshoots due to switching transients, etc.  The 50% voltage de-rating 
factor for tants is a lesson I learned the hard way!  And it was quite a 
shock when standard aluminium electrolytics often have a short-term "surge" 
rating that is above the maximum working voltage.

-Richie,

-----Original Message----- 
From: Mike Bryant
Sent: Thursday, November 30, 2023 9:59 AM
To: synth-diy mailing list ; Ben Bradley
Subject: Re: [sdiy] High-K ceramics and audio

A certain Bill Hewlett beat them to it by over half a century.  We were 
never allowed to go over 50% of the rated voltage on a tant when I was 
there.

From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Ben Bradley 
via Synth-diy <synth-diy at synth-diy.org>
Sent: 30 November 2023 02:18
To: synth-diy mailing list <synth-diy at synth-diy.org>
Subject: Re: [sdiy] High-K ceramics and audio

According to this presentation, apparently from 2011, for best
reliability you should never put more than HALF the rated voltage
across a tantalum capacitor:
https://web.archive.org/web/20151010013327/http://www.kemet.com/Lists/filestore/Derating%20Guidelings%20for%20Tantalum%202011%20(3).pdf

On Wed, 29 Nov 2023 at 17:59, Mike Bryant <mbryant at futurehorizons.com> 
wrote:
>
> Indeed so.  But those data sheets are aimed at applications where the 
> whole product will be in landfill within 5 to 10 years.  Audio is rather 
> unusual in that we still use stuff from the 70s, possibly even earlier.
>
> ________________________________
> From: brianw <brianw at audiobanshee.com>
> Sent: 29 November 2023 21:56
> To: Mike Bryant <mbryant at futurehorizons.com>
> Cc: Andrey Salomatin <filipovskii.off at gmail.com>; synth-diy mailing list 
> <synth-diy at synth-diy.org>
> Subject: Re: [sdiy] High-K ceramics and audio
>
> If you pay close attention to data sheets and design guidelines from chip 
> makers, even modern ones, you'll find that tantalum are often the first 
> type of capacitor that is recommended. Granted, my recollection is that 
> this was generally for power supply circuits - I don't recall seeing 
> tantalum recommended for audio circuits (but that doesn't mean it's a 
> rule).
>
> Brian
>
>
> On Nov 29, 2023, at 1:35 PM, Mike Bryant <mbryant at futurehorizons.com> 
> wrote:
> > In the 70s there were two sorts of tantalums.  One sort was highly 
> > reliable and recommended for design by companies such as HP, and on the 
> > Voyager spacecraft, that didn't allow electrolytics except where 
> > absolutely necessary.  And the other sort were cheaper and crap - they 
> > suddenly died after 10 to 20 years.
> >
> > Guess which type all the modern SMD tantalums are ?  Obviously the 
> > technology has improved, so they don't die after 10 years, but the aging 
> > process of aluminium electrolytics is now well understood and it's much 
> > easier to design a product to last a long time.
> >
> > Which in other words means you don't have to 'decap' every electrolytic 
> > in your classic mixer :-)
> >
> >
> > From: Andrey Salomatin <filipovskii.off at gmail.com>
> > Sent: 29 November 2023 20:07
> >
> > Why not?
> >
> > On Wed, Nov 29, 2023, 20:56 Mike Bryant <mbryant at futurehorizons.com> 
> > wrote:
> >> No :-)
> >>
> >>
> >> From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Andrey 
> >> Salomatin via Synth-diy <synth-diy at synth-diy.org>
> >> Sent: 29 November 2023 18:57
> >>
> >> Curious, are people using tantalum for those applications at all?
>
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