Tantalum Capacitors in Signal Path

Hi,

there is a lot of dicsussion on capacitors
anyway, but i've a special question:

Despite their bad reputation i've found tantalums
in the audio signal path of comercial products
from time to time.

My examples are :

Thorens PPA 990 :MC pre-pre-amp: tantalum as coupling
capacitor between discrete transistor stages

Marantz 2325 : Tantalum as input coupling capacitor in Phono
MM preamp

DENON POA800 : Tantalum in the inverter for bridge mode

You might have more examples. I admit, at least the Thorens
and the Marantz are somewhat vintage...not shure about the age
of the DENON design.

So if there are designers designing devices with say 50 +
electrolyts, and deciding to throw in a tanatlum at only one
out of 50 positions, i assume they have good reasons to do so !?
Most likely it is not the costs.

So are there any situations where a tantalum beats a standard
aluminium (or whatever) electrolyt?

My examples 1 and 2 could lead to the assumption, that a
tantalum is better, when there are yery low signal levels
together with relative high DC to block? Can someone
confirm ? Other Ideas?

Probably, nowaday's electolyts are better than those from
30 Years ago, so a tantalum would have been a valid choice
then but not today?

What would you recommend? Leave them in place, replace
against a new tantalum, replace against a regular low-ESR
electrolyt ? (Pleas no not suggest replace against foil etc,
I know, these are better then electolyts, but those foils
won't always fit)

Thanks a lot in advance for your valued comments,

regards,

Stephan
 

jcx

Member
2003-02-17 7:38 pm
..
tantalum electros have more measureable distortion than Al electros, they don't dry out though so replacing them isn't functionally necessary if they're not blown

lower audio distortion is found in bipolar Al electros with a full thickness oxide layer on both foils - higher voltage ratings are better as well

but even mylar should be a step up from any electro and you might be able to fit them in some cases
 
It depends on how you use the tantalum capacitors. My idea is not to put them in the signal path, but if they are there and not blown, you could leave them were they are. My cd player is modified with only tantalum as decoupling capacitor troughout the whole pcb, and it is sounds darn good.

René
 

jcx

Member
2003-02-17 7:38 pm
..
don't buy more tantalum caps

modern solid polymer electrolyte Al are better than older tantalums in decoupling apps too

African tantalum mining has bad ecological and humanitarian consequences, I won't design tantalum capacitors into any new product

TaN resistors use so little Ta that I will consider them, at least a case can be made for their audio superiority unlike capacitors where Ta is worse than the alternatives
 
Thanks for the replies so far.

Very intersting aspects, especially those regarding bad ecological and humanitarian consequences in Africa. Never thought about
that.

Anyway I have still some strong believe that the designers
knew what they were doing and that there were reasons
to use tantalums here and there in the signal path.

Probably the tantalums were placed into the circuit
JUST BECAUSE OF THEIR DISTORTIONS ?? Sounding ...
What kind of distortions do they generate.
Whow does it sound?

Two of my examples list tantalus in the input section of
Phono amplifiers. ´Can tantalums "compensate" some
distortions typically found when playing back vinyl?


Thanks,
Stephan
 
Hi there........tants are way better than electrolytics in signal paths esp in tube amps......cathode bypass is a typical place. Nearly all the low signal path tube circuits I've come across over the past 40 yrs sounded better with Tants in lieu of electrolytics......although there are many good quality low leakage electrolytics on the market. For those wanting to make an improvement on existing designs and not wanting to use tants -> go for electrolytic caps spec for use in switch mode power supplies.....i.e have low ESR. Price is swallable.

richj
 

ticktock

Member
2006-12-21 9:35 am
If special vibration-absorbing spikes ....

"If"

The truth is there is no "absorbing" spike. They do couple the chassis hard to the ground.

BTW, interesting topic as I still have some old Linn gear where there's lots of tantalums
in the signal path (LK1) and in the feedback path (LK2). Similar to Naim. The Brits seem
to love tants and when you know how older Linn and Naim sound, then you supect that
tantalums help to sound it this way.
 

Monte McGuire

Member
Paid Member
2013-07-28 2:58 am
Kemet makes Ta caps that actually work pretty well, and contrary to popular opinion, they can withstand a bunch of reverse voltage (up to 15% or so - see the data sheets). But, there are other technologies that probably make more sense. There are aluminum polymer caps that, like Ta - Mn02, do not wear out, but they perform a bit better. My interest in them is for power supply bypasses, where solid Ta caps work really well, but they fail short and catch fire if you abuse them with current spikes or reverse voltage without any limiting series resistance.

Long and short, if you want a Ta cap, Kemet IMHO makes the best, but they also make more modern stuff such as Ta with organic polymer or Al polymer - both very good alternatives to traditional Al electrolytics that will eventually dry out and need to be replaced.
 
My experience with tants is that they often fail short circuit when used in PSU's or regulators - causing havoc!
Bryston amps have several 'cos they're small I guess.
Ampex used them the decouple the rails as they entered each card.
Some were put in reversed polarised and would explode with acrid smoke eventually!
Sony used them too, but not many problems there; not many Sony failures on anything!
 

dontknee25

Member
2012-06-17 11:30 pm
[QUOTE schnullimaus
Anyway I have still some strong believe that the designers
knew what they were doing and that there were reasons
to use tantalums here and there in the signal path.
[/QUOTE]

In those days tantalum caps had better specs above 10kHz then electrolytics.

Jung and Marsh did some research back in the 80ies :

Picking Capacitors - Walter G. Jung and Richard Marsh
 
I just tested some Kemet T110 22uF 15V caps with my PSU adjusted to 32V (current limit was at 50mA, but there is significant capacitance on output)
T110 survived, drop type 16V tantalums were gone after one pulse of 32V REVERSE voltage.
Both survived 32V surge for the few second test period when applied with CORRECT polarity at room temp.

One point for T110!!!! Weee....luckily I have very many of these too :)
 
As far as I know tantalum capacitors have lower effective series resistance and, hence, less thermal noise voltage than equal-valued aluminium electrolytic capacitors, or at least that's what I've been told in the 1980's.

Still, I try to avoid them as much as possible for the reasons mentioned by jcx. Check the link below for more information on the relation with a civil war in Congo.

https://en.wikipedia.org/wiki/Coltan
 
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