Electrolytic vs Tantalum

[Seven64]

I have read time and time again various debates for this subject.  Just wanting a simple-ish answer from you guys tho.  I am currently building a chorus pedal which uses a ton of 1uf and other small value polarized caps.  Obviously it calls for electrolytic caps, but I was wondering if I would see any benefits from using tantalums instead.  I just stocked up on them and was thinking of making use of my stockpile.  Some people say they should only go in distortion pedals, but my basic theory of you get what you pay for leads me to believe they will help being as they are MUCH more expensive than electrolytics.

FWIW its the topopiccione dimension c clone 

4 hours into it and have the board drilled and the resistors/diodes done, along with a few jumpers and IC sockets.

[DavenPaget]

I heard tanty's are horrible for audio , i'll challenge that using a 1.5uf tanty in my next gen stratoblaster .

[Seven64]

there is at least 1 in every boss pedal i have taken apart.  there has to be some reason that engineers and whoever else will approve a 60 cent part with a 5 cent part can be used.

or that is just the reason every boss pedal sounds "crappy"

[FastJunkie]

They're used for their temperature coefficient, the fact that they can withstand higher temperatures and maintain the same characteristics. At the end of the day 1uF is 1uF, whether it's made out of tantulm or a tin can is kind of moot.

[Mark Hammer]

I suspect as well that tantalums found their way into a great many pedals during "the golden era" because they could be easily bent over and laid flat.  That's certainly how MXR used them.  Lying them flat meant that circuit boards could be easily stuffed inside the standard 1590B chassis that they used.  I would be curious to know if there were EVER any tantalums used in any MXR products built into a 1590BB or larger chassis.

[amptramp]

Electrolytic capacitors depend on a thin film of aluminum oxide which has a relative permittivity (dielectric constant) of 9.1 whereas tantalum pentoxide has a dielectric constant of 27. so tantalum has an immediate advantage in reduced volume for a given capacitance.  You can go up to 600 volts with aluminum oxide whereas I have never seen tantalum above 75 volts.  Tantalum pentoxide provides a film with very few surface defects, so this results in much lower leakage current than aluminum oxide.  But tantalum pentoxide can turn into conductive tantalum dioxide at high temperature where there is a defect and since this conducts and self-heats, it turns more of the dielectric into the conductive oxide, resulting in a firestorm within the device.  To eliminate this problem, the dry slug tantalum capacitor must be used with a series resistance to avoid adding enough current to cause this self-heating, so it is ideal for timer applications due to low leakage and survives in coupling applications where series resistance is normal, but it doesn't necessarily provide good sound.  There are wet-slug tantalum capacitors and tantalum-case tantalum capacitors that are used for power line bypassing, but you rarely see them.  Whereas aluminum electrolytics have poor characteristics at high frequencies, dry-slug tantalum is exceptionally good - but it still needs series resistance.

I have heard complaints about tantalum sound before, but I am not sure what the problem is.

[Fender3D]

...I would be curious to know if there were EVER any tantalums used in any MXR products built into a 1590BB or larger chassis.

flanger and delay used tantalums too....

In my repairing life, I've subbed almost all tantalums I faced...

[Mark Hammer]

Once upon a time, tantalums were fairly small for their ratings (capacitance and voltage), compared to electrolytics.  They cost most, but if you could find ways to recoup the added cost, you might use them.  These days, there is very little reason to need to use them, unless there is some very specific characteristic of a circuit that is aided by the properties of tantalum.

Just out of curiosity, are there tantalum SMD caps?

[Tacoboy]

Yeps, SMD tantalum caps: http://hep.physics.lsa.umich.edu/alpha/images/avx_tps.pdf

[alparent]

So are you telling me that 90% of the time I see a Tant. in the BOM of a clone I want to build I could just use a Electolytic and it would be just as good? ....... or even better? 

[R.G.]

First of all, tantalum caps **are** electrolytic. Capacitors made from aluminum, tantalum, and niobium exist. They are all made by an electrolytic (!) process where the metal film is oxidized to form an insulating oxide layer in a bath of electrolytes (fluid with added chemicals to make it conduct electricity better) by an electric current.

Aluminum is cheap; tantalum oxide has a higher dielectric constant, letting tantalum caps be smaller for the same capacitance*voltage, and niobium caps are rare. I know they exist, but haven't ever seen one.

On aluminum vs tantalum, tantalum makes smaller caps, but has these quirks, not least that they can explode or catch fire under the wrong circumstances. Aluminum is cheap, so there has been a ton of work put into better processing. This has allowed aluminum caps to nearly catch up in the smallness race.  Tantalum has some reputed advantages in lower ESR (better filtering) and for audio work a less grainy tone. At least that's the reputation among the Golden Ears. I can't hear a difference, but I allow it as a possibility. Aluminum's price advantage, lack of so many quirks, and improved performance have led to the condition where "electrolytic" makes everyone think "aluminum" as though there was no difference.

So:
- 100% of the time when you see a tantalum in the BOM of a clone, you can use an aluminum electrolytic if you can find one which will physically fit and not ravage your aesthetic sense. Whether it's better or not depends on what you mean by "better". Cheaper? Yep. Better sounding? Very, very hard to tell. The other tantalum quirks, exploding and catching fire, are unlikely in pedal because of the limited power available from the power supplies.

[alparent]

Once again......R.G. makes it crystal clear!

Thanks

[wavley]

I suspect as well that tantalums found their way into a great many pedals during "the golden era" because they could be easily bent over and laid flat.  That's certainly how MXR used them.  Lying them flat meant that circuit boards could be easily stuffed inside the standard 1590B chassis that they used.  I would be curious to know if there were EVER any tantalums used in any MXR products built into a 1590BB or larger chassis.

Yep, me too, I was just inside a blue face dual 15 band eq rack (fixing an oscillation bringing one channel down) and they were all over the place.

[slacker]

Looking at the schematic I can't see any reason why you can't replace all the 1uF and smaller polarised caps with film caps if you want. These days it's easy enough and cheap enough to buy small sized film caps up to about 2.2uF or so, back in the day it wasn't which is probably why those caps were tants.

Obviously that then leads to more debate about whether there's any sonic differences between film and tant, sorry  

[artifus]

*sniffs cork*

http://wduk.worldomain.net/pdf/ClarityCap_Technical_Report.pdf
http://www.bext.com/replace.htm
http://www.hificritic.com/downloads/APassiveRole.pdf

and not to forget: http://studiozey.com/woodencapacitor/index.html

[amptramp]

Just to add to R. G.'s excellent post, niobium capacitors are rare because they are usually limited to a maximum of 15 volts.

[diagrammatiks]

Looking at the schematic I can't see any reason why you can't replace all the 1uF and smaller polarised caps with film caps if you want. These days it's easy enough and cheap enough to buy small sized film caps up to about 2.2uF or so, back in the day it wasn't which is probably why those caps were tants.

Obviously that then leads to more debate about whether there's any sonic differences between film and tant, sorry  

+1 to this. no reason not to use 1 and 2uf film caps.

[Gus]

People need to do more reading and testing.  In certain places in some circuits you can hear caps most of the time higher voltage circuits than 9VDC effects.

IMO question what you read on the web, test it if you can.  Don't believe what I am writing, test it, measure it etc.

One place a Tant is better than an Al electro is in the RAT feedback network.  ESR is lower in lower value tants than electros.  Look at the values in the two legs form _input of the opamp to ground.  Try  Al electros then try tants measure on a meter so the cap values are matched.  The ESR of an Al electro can be a bigger portion of the resistor values in the two - to ground legs.

Smaller value (under 10uf) I like to use films or tants in my builds.

Also the voltage difference across the plates matter.

Look for The C.B. cap PDFs on the web very good reading.  Shows distortion graphs of different caps and the effect of the DC voltage difference between plates.

Caps types in effects OFTEN don't matter as much because of the low voltage however some are microphonic and that can be part of the sound. something like a tone control cap in a guitar body with guitar amp speaker feedback going on. Example I installed pickups in a friends guitar and we tried different cap types and values film stacked and wound and ceramics.  The sound my friend liked was the stock large disk ceramic from the 70's that was microphonic.  I forget what lettering was on the cap for ceramic type.

When the dc voltage difference between plates is increased like in a guitar amp, PI to output tube(s) coupling cap(s) things can change.

[alparent]

Sorry kinda of a side question 
I have lot's of 10v caps......I always use 16v in my builds...but was wondering if using the 10v would be OK? or is 10v to close 
The footprint is smaller and that would be a plus in some builds.

[John Lyons]

Sorry kinda of a side question 
I have lot's of 10v caps......I always use 16v in my builds...but was wondering if using the 10v would be OK? or is 10v to close 
The footprint is smaller and that would be a plus in some builds.

If the voltage in the circuit (where the cap is in the circuit) is 5vish then they should be fine and with some leeway.
If you are using them at 9v then you are pushing it. I'm sure they will be fine but your right on the edge and it would be
best to use a higher rated cap just in case.