[sdiy] High-K ceramics and audio

music at atypical.net music at atypical.net
Thu Nov 30 18:03:24 CET 2023


The newer poly tantalum capacitors avoid such a steep derating via 
improved device packaging.

Read all about it from Kemet:

https://nextcloud.atypical.net/s/ELJePAYmSfDCbM8 is their original tech 
note about this from August 2000.

Since then they've relaxed the rules to 10% for rated voltages <= 10V, 
and 20% for rated voltages >10V. Also, the knee in the derating graph 
vs. temperature moves up from 85C to 105C, again because of the improved 
packaging.

See their current training module: 
https://www.digikey.ca/en/ptm/k/kemet/derating-guidelines-for-surface-mount-tantalum-capacitors/tutorial

Given this information, and the improved device characteristics overall, 
tanalums are an excellent choice in certain audio applications.... 
except for the whole conflict mineral issue.

-Joan "no free lunches" Touzet

On 2023-11-30 09:41, Richie Burnett wrote:
> 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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