Mylar/poly/metal film caps

[MmmPedals]

Is there any reason to use poly film caps over mylar film?
I know metal film caps can reduce noise in some circuits. Is there any other advantage or disadvantage to them?
What are the pros and cons of each type?
EDIT: I guess i should put ceramic disc in there also. I never use them because i heard they may cause a harsh sound. When can you use them "safely" and when should you avoid them?

[Steve Mavronis]

Let's add polarized tantalum caps to the list. Are they any better or worse than the radial electrolytic caps?

[MmmPedals]

Tantalum caps are a big no no in audio circuits. avoid them at all costs. they add noise and have an "unpleasant tone".

[Steve Mavronis]

Tantalum caps are a big no no in audio circuits. avoid them at all costs. they add noise and have an "unpleasant tone".

Thanks for answering that concern of mine. My dad gave me some and said they don't "leak" like radial electrolytic caps but I was reading how tantalum may produce a grainy sound which I don't really want. The pedal I'm cloning from doesn't use them so I'm leary of using any substitute part types.

[zombiwoof]

AFAIK, Polyester film caps are the same thing as Mylar (which is a brand name).  Then there's Polypropylene, and also Polystyrene (which was used in the original wahs).  So when someone says "poly film", you don't know exactly which one it is (although it probably is either polyester or polypropylene in most cases, polystyrene doesn't come up as often).  I wish more people would differentiate which "poly film" cap they are talking about, as it can make a difference.  I sometimes hear people say to use an "orange drop" cap, but there are different series' of Orange Drops, some are polyprop and some are polyester, and that can make a difference in some applications.

I wonder why polystyrene isn't used much in pedals and such, they used to be considered a "superior" type of cap at one time.  Is it because of how they sound or because you can't find them in a lot of values?

Al

[oldschoolanalog]

I wonder why polystyrene isn't used much in pedals and such, they used to be considered a "superior" type of cap at one time.  Is it because of how they sound or because you can't find them in a lot of values?

Expensive & large size/footprint.

[Greg_G]

AFAIK, Polyester film caps are the same thing as Mylar (which is a brand name).  

Yes, I think you're right. Mylar Film = Polyester Film

Also, I don't believe any capacitors contribute to "noise" in a circuit.. outside of microphonics.
Metal film resistors are quieter than carbon... not capacitors.

[IvIark]

Tantalum caps are a big no no in audio circuits. avoid them at all costs. they add noise and have an "unpleasant tone".

Tell that to the TS808 aficionados who believe them to be absolutely critical to the sound.  

Personally I've never found anything inherently unpleasant about Tantalum and the very fact that they will last much longer than the 2000 hours specified by some electrolytic manufacturers seems a good enough reason to try them to me.

[zombiwoof]

I wonder why polystyrene isn't used much in pedals and such, they used to be considered a "superior" type of cap at one time.  Is it because of how they sound or because you can't find them in a lot of values?

Expensive & large size/footprint.

I hadn't thought of that.  I have been thinking about trying some polystyrene caps in one of my guitars for the tone caps, if for no other reason that I've never heard of anyone doing it (although I'm sure someone has).

I've also considered using a tantalum in place of the 4.7uf electro in a wah, I wonder if it would have any affect on the sound in that position?

As far as the tantalums in a TS808, maybe the "unpleasant" aspect of them is part of the vintage sound there.  I know I've seen a lot of tantalums in Japanese pedals, even in MXR's, as I recall.

Al

[zyxwyvu]

This page may be useful: http://greygum.net/sbench/sbench102/caps.html

It has oscilloscope traces showing how linear different capacitors are. Only a few seem to be noticeably non-linear (and would thus add distortion).

[jacobyjd]

Just buck all the trends and start using monolithic ceramics

Any differences the crowd hears between caps will only really be in values and tolerances. Nobody else matters.

[mikemaddux]

nice post.  we were talking about this at work today....all the different variables that go into an electronic sound design like an amp or a pedal........my older buddy just stormed off and said "just use your fu*king ears!!!!!"

lol

[IvIark]

As far as the tantalums in a TS808, maybe the "unpleasant" aspect of them is part of the vintage sound there.  I know I've seen a lot of tantalums in Japanese pedals, even in MXR's, as I recall.

I think you've come up with the most important aspect of component selection in guitar effects.  What someone doesn't like in a DIY audio application may be fantastic in a comparatively lofi guitar effect.  I've heard ceramic caps called gritty before but they go to make terrific Big Muffs, so maybe any grittiness they impart just works well with some dirt pedals.

[Ed G.]

Polystyrene sounds very nice in the BSIAB, in the 470pf cap (mine is a 560 pf) cap that parallels the 470k resistor.
Very clear tone.

[R.G.]

I wonder if we should count the number of times that the question "which kind of capacitor sounds better?" or "which kind of capacitor should I use?" has appeared.

Writing it up and putting it in a FAQ doesn't seem to help.

[IvIark]

Maybe some people just like to talk about it and exchange their opinions rather than taking an FAQ as being everything you ever need to know.  That's what forums are all about.

[knealebrown]

Tantalum caps are a big no no in audio circuits. avoid them at all costs. they add noise and have an "unpleasant tone".

they are used in the ts 808 an ts9 plus the stratoblaster. all pretty successful designs in my opinion. plus they look cool and organic 

[alex frias]

The use of tantalum caps on TS's and the Harmonic percolator has some real impact to the resulting sound, but it's not exactly where I would call it the "audio pathway" in both projects.

[benjamin_izzo]

omg... R.G. and IvIark...

your comments on this subject are hilarious!
My face hurts from laughing.

thanks for the frank comments
and for giving so much to the DIY community.
you both have helped me out so much in the past few months
sincerely,
ben

[mistahead]

Maybe some people just like to talk about it and exchange their opinions rather than taking an FAQ as being everything you ever need to know.  That's what forums are all about.

Observation not of the quoted member, however here I was thinking it was trolling by 1 post new accounts, on tombstoned threads, concurrently to other threads on the same topic in which a low post count individual was stirring up the troubles.

Use ceramic across the board in dirt boxes, more dirt that way.