Electrolytic Capacitor type depending on usage

[Ansur]

Now that I have a basic grasp on resistors (thanks for the help!) I've been reading up on capacitors.
Am I correct in saying that for the electrolytic ones, one needs to see whether it's used in the signal path or the current path?
For the former, that would mean going for 'Audio grade' ones, for the latter you'd buy the ones with a high ripple current value (does these types have a purpose name as well?)

So for the Current Lover that would mean C6, C16, C17, C20 and C21 would be for power supply filtering, and C14, C15 and C24 for the signal (so audio grade)?
For the Road Rage they would all be for power supply filtering, except for C5 and C6.

[midwayfair]

IMHO, caps is caps. There are SOME situations where you MIGHT hear a difference between different types of materials if you are looking at the circuit board at the time. For a short time, I thought I could hear a difference between poly and ceramic, but after testing many many of the same caps to eliminate tolerance as a factor, I can't.

I wouldn't sweat over anything except:

--Sufficient voltage rating (16v for a 9v effect, 25v for 18V effects, etc.)
--Whether they're small enough to fit on the board and in the enclosure you're using.
--Whether they look cool enough.
--In the audio path, polarized or nonpolarized for uF values depending on whether you feel like determining the polarity.

"Audiophile" is a scam in my mind to charge more for the same function.

Again, my opinion, but agreeing with me would save you a lot of money in the long run.

Edit: there are occasional situations where material can make a small difference in noise performance. Also, sometimes polarity ostensibly matters, but I've used non-polarized caps in a phase inversion LFO circuit, even though that shouldn't work at all.

[jubal81]

Funny, I was just up late last night reading papers on different types of cap material. I'll add a link when I can find it.

I think I'm going to order some polystryene and whatever 'high end' caps I can find and do two builds when my OSHpark shipment comes in just to give it the ol' Pepsi challenge.

[Ansur]

Well I can imagine they're trying to sell off some more expensive stuff.

Though just to satisfy my curiosity, here are 4 similar capacitors. Their purpose, according to Mouser, is different though:
Low Impedance
Bi-Polar/Non-Polar
Audio Grade
General Purpose

The Low Impedance one does have a higher ripple current. Between the other ones I can't really say what's the big difference. Whether it makes a difference in sound/noise...

Could be interesting to go for those Low-Impedance ones for the power supply filtering caps...
In-between, are the cap number distinctions (PS filtering / signal path) I mentioned in my first post correct?

[jubal81]

In-between, are the cap number distinctions (PS filtering / signal path) I mentioned in my first post correct?

Yeah. I don't use electros in the signal path if i can help it.

[pickdropper]

IMHO, caps is caps. There are SOME situations where you MIGHT hear a difference between different types of materials if you are looking at the circuit board at the time. For a short time, I thought I could hear a difference between poly and ceramic, but after testing many many of the same caps to eliminate tolerance as a factor, I can't.

I wouldn't sweat over anything except:

--Sufficient voltage rating (16v for a 9v effect, 25v for 18V effects, etc.)
--Whether they're small enough to fit on the board and in the enclosure you're using.
--Whether they look cool enough.
--In the audio path, polarized or nonpolarized for uF values depending on whether you feel like determining the polarity.

"Audiophile" is a scam in my mind to charge more for the same function.

Again, my opinion, but agreeing with me would save you a lot of money in the long run.

Edit: there are occasional situations where material can make a small difference in noise performance. Also, sometimes polarity ostensibly matters, but I've used non-polarized caps in a phase inversion LFO circuit, even though that shouldn't work at all.

I generally agree with this for guitar pedals, but for other applications there are certainly instances where cap design can matter.  I won't argue a case for "audio" grade electrolytic caps as I haven't read up enough to know if there is any different or if it is just marketing BS.  I certainly won't claim that I could hear the difference between electrolytic caps.  I've never actually tried it, but it seems unlikely.

Now, there was a time when I built a headphone amplifier and I switched from a Wima polyester box cap to a BC components polypropylene cap and the differences were measurable.  I only put the brand name because Wima is considered by many to be an "audiophile" cap and the BC components not so much.  The reason I switched was because the DC offset of the amp was exacerbated by bass boost of the amp and the offset was creating too much of a shift in the armature of the earphones I was using, creating a potential for damaging them.  By switching to a polypropylene cap with a lower dissipation factor, I was able to reduce the DC offset significantly (not quite a factor of 10).  This was confirmed by measurements, not by a listening test.  There were no other changes to the circuit other than the cap choice.

So there can be a difference, it just depends on the application.  A bit of an aside, but I found it sort of interesting so I thought I'd share.

This is also the case with resistors.  There are some cases where the lower noise of thin film resistors is preferable over thick film resistors (at much higher cost).  Unfortunately, that sort of thing tends to lead to audiophile claims that you need thin film in every circuit, which is not really the case.

[gtr2]

The audio grade electrolytics have a different dielectric, usually silk.  I don't feel that they make much of a difference in guitar circuits where you have a more focused frequency range.  They may make a difference in hifi audio equipment with a wider frequency range but I wouldn't know.  That being said, I do use the nichicon audio caps because they are quality caps and I like the color.

I think the bigger issue is using good electrolytics for power supply filtering and decoupling.  While I use Tayda's electros for prototyping stuff I no longer use them in my finished builds.  I've repaired some monitors and a tv of mine.  The problem was with the power supply caps on every one of them.  They were cheap brand caps.  The TV was a panasonic flat screen and ironically it didn't have panasonic caps in it!  Ask the arcade guys about caps.  They have threads upon threads about electro's.  Heat is the main problem for the games though...

Granted we are using small power supplies for our pedals but I'd rather pay an extra 5 cents per cap for something that won't give up the ghost in 5-10 years.  I've got some old equipment 30+ and they still have the original caps.  This will never happen with the disposable gadgets we are buying today.  Whatever is cheapest makes it in because they know we'll have to buy the latest and greatest thing.  I've heard numerous times from salesman that the new tv's won't last much past 5 years.  My in laws are still using a TV that is almost 30 years old!

Josh

[pickdropper]

I agree, Josh.  I'll get the ceramics and box caps from Tayda, but I won't touch the electrolytics.  Quality caps just aren't that much more expensive, especially if you are willing to buy 25 at a time from Mouser.

[GhostofJohnToad]

So what specifically is it about the Tayda electros that you guys don't like?

[gtr2]

Here is some info.

http://en.wikipedia.org/wiki/Capacitor_plague

The tayda caps test in spec capacitance wise but who knows how they function under load over time?  They just don't sell a reputable brand electro that I trust over the long haul.  I know it's just a pedal, but I'd like them to last for a while.  Temperature is a big cap killer at least we don't have to worry about that in guitar pedals.  I don't worry much about ceramic or film caps, but I do spend a little more $ buying quality tantalum as well.  Take a look at some of the knock off failing electro's as well... http://en.wikipedia.org/wiki/File:DellGX270CounterfeitNichiconCaps1024.jpg

Josh

[angrykoko]

Oh man, talk about always learning something new.
Built my multiplex with tayda electolytic caps, I didn't even think about them not holding up over time.. darn.

Is their brand known to have issues... or is it just that they are not well known so there is a bit of worry?

[Ansur]

Really amazing information, thanks!

Based on the information here I think I'll go for what I initially thought - Low Impedance ones for the capacitors that do power supply filtering and audio grade ones for the signal application.

Indeed the price difference isn't THAT different...

[pickdropper]

Oh man, talk about always learning something new.
Built my multiplex with tayda electolytic caps, I didn't even think about them not holding up over time.. darn.

Is their brand known to have issues... or is it just that they are not well known so there is a bit of worry?

For me, it's that they are cheap electrolytics which (as Josh showed) are not known for reliability.  It is possible that they are OK, but the cost of proven electrolytics just isn't that much more.

In general, I find that Tayda is sort of hit an miss as far as quality.  Some of the stuff is fine and other stuff, not so much.  It's inexpensive, so there are trade-offs.

[culturejam]

I'm probably jinxing myself here, but....

I've never had a cap of any type fail in a pedal, regardless of brand or cost (and that includes having used a TON of the Tayda electros).

I've smoked resistors, fried ICs, melted a voltage regulator or two, and even nuked a couple diodes. But I've not had a cap fail.

And I don't think I've ever heard a difference between cap/dialectric types.

[angrykoko]

Thanks, yeah I don't have any issues with them at all currently and the pedal sounds amazing.
I knew others stayed clear of them but I just figured it was because they were maybe DOA or just way off value, so I just ordered a bunch extra.

Meh.. I may still take the safe route though and order them from mouser (besides... like someone said earlier.. the audio grade ones look cool!)

Here is someone that does a comparison of different cap types in a guitars tone circuit:
http://www.youtube.com/watch?v=92G-jw4TqS4

PS> I agree, under normal circumstances (not like the video) a person would probably never know.