Electrolytic vs film caps for smaller values.

[warpie]

I see many circuits that use electrolytic for smaaller values like 1uF, 2.2uF, 6.8uF, etc...

What are the benefits of using lytics over some film capacitors like MKS?

A film cap won't need recapping after some years and it will probably sound better. Is it simply a matter of cost?

 

[scott2000]

What are the benefits of using lytics over some film capacitors like MKS?

I would think it depends on the application. I've read there can be issues using lower esr electros were lesser specced electro caps were used as well.

 

[ruffrecords]

Film caps will generally be larger and more expensive and mpre reliable than their equivalent small value electrolytics but in most cases they perform better so unless you are a bean counter it is worth seriously considering film caps. I use 10uF 250V film caps as the output coupling in some of my tube designs. They are pretty big.

Cheers

ian

 

[Newmarket]

It's basically cost. The low esr issue is usually voltage regulator related. See datasheet detail and app notes.

 

[rock soderstrom]

Film caps will generally be larger and more expensive and mpre reliable than their equivalent small value electrolytics but in most cases they perform better so unless you are a bean counter it is worth seriously considering film caps. I use 10uF 250V film caps as the output coupling in some of my tube designs. They are pretty big.

Cheers

ian

+1

Film capacitors like MKS, MKP etc. last almost forever. I have had some vintage amps on my workbench, the electrolytics were long dead, the film capacitors from the same time were still within their tolerances.

If there is enough space always use the film cap!

 

[warpie]

I would think it depends on the application. I've read there can be issues using lower esr electros were lesser specced electro caps were used as well.

Not sure what you mean.

Film caps will generally be larger and more expensive and mpre reliable than their equivalent small value electrolytics but in most cases they perform better so unless you are a bean counter it is worth seriously considering film caps. I use 10uF 250V film caps as the output coupling in some of my tube designs. They are pretty big.

Cheers

ian

Why would you need 250V rating on the output?

 

[warpie]

As far as the sound is concerned, I don't want to step onto the audiophoolery territories but generally speaking does a MKS sound better than a lytic?

 

[zamproject]

Why would you need 250V rating on the output?

Ian say it's for his tube design, high voltage might occur

 

[scott2000]

Not sure what you mean.

Me neither. Just remember reading some things apart from the regulator considerations mentioned by Newmarket.... but these things could be old news by now. Like the medical field changing some beliefs, seems to happen as technology advances. But I think one thing I remember is something along the lines of like addressing ringing or higher esr was better for damping in some cases...but idk. Maybe was only relevant in some older designs if at all.

 

[ccaudle]

something along the lines of like addressing ringing or higher esr was better for damping

There were some regulator designs which had damping requirements for the output capacitors. If you used really low ESR caps you were supposed to add series resistors to damp the resulting LC resonance.

 

[ruffrecords]

Why would you need 250V rating on the output?

Because the output sits at 125V dc, and since the supply voltage is 250V I want to guard against the possibility the output might momentarily reach 250V before the heaters reach operating temperature.

Cheers

Ian

 

[Matador]

Capacitance per unit volume is one of the major benefits for electrolytics. You can get a 1uF/63V MKS for around 60 cents, and a 1uF/63V high quality electrolytic for about 20 cents. The MKS is about 3-4 times larger. Usually not an issue for DIY stuff.

For smaller than 1uF, a ceramic MLCC in C0G (NP0) beats both of them quality wise, if you can tolerate (mostly) SMD packages, and the high cost (nearly $1 each in small quantities).

 

[JohnRoberts]

It is basically a size/cost issue.

There is a topology called DC servos that combine small film caps with op amps to enable small film caps to work in place of large electrolytic caps.

JR

 

[scott2000]

There were some regulator designs which had damping requirements for the output capacitors. If you used really low ESR caps you were supposed to add series resistors to damp the resulting LC resonance.

I found one mention in this thread about opamp bypassing/power decoupling. Post #60..Maybe what stuck in my mind when thinking about using different caps? Not sure it's relevant though?...

"Very important is the provision for enough damping of the decoupling system--either by some small resistance in series with the rail, or the use of low-Q (electrolytic) capacitors. As far as I can tell from the limited info given about the systems where rail-to-rail decoupling has failed, insufficient damping must have been the cause. In a power supply system where no provisions for damping have been taken, the addition of a high-Q (film, ceramic) capacitor can easily provoke instability by shifting the resonance frequency into a region where the opamps have less PSRR."

https://groupdiy.com/threads/opamps-and-local-decoupling-of-rails-some-questions.37307/page-3

 

[CJ]

film caps can be mounted in any direction,

does anybody know why lytics increase in value as they age?

What happened to Brazil?

 

[efinque]

I just put a couple of NOS electrolytic capacitors (4,7uF/100V and 10uF/100V) in a 2-band equalizer in a mixer build.. they must've been from the late 90's/00's but never used afaik. The EQ I made sounded fantastic. (edit: gritty, but fantastic)

A little background; I sourced them from a mechanics engineer in his 60's I met at a bar and we went to check out his turntable/radio setup he had just fixed and he happened to have a bunch of components lying around so he gave them to me for free.

 

[sahib]

What happened to Brazil?

Drift on the penalty shoot-out.

 

[CJ]

what about that blind pass from Mesi?

film is i think better for the environment, tantalum i do not know.

i can not get anybody to pick these up,

yes, that gig bag has a built in Marshall, full of tone bending lytics,

 

[Ricardus]

As far as the sound is concerned, I don't want to step onto the audiophoolery territories but generally speaking does a MKS sound better than a lytic?

If you can hear it in double blind tests I will pay a reward.

 

[abbey road d enfer]

Film caps typically offer better distortion performance than 'lytics. However, since this distortion happens at LF and is inversely proportional to capacitance, it is often possible to replace a film capacitor with a lytic of higher nominal value. For a given LF distortion level, the lytic would need a ca. 10 times higher nominal value; that may result in unwanted effects such as motor-boating.
The main issue with replacing a lytic with a film cap is that for a given capacitance, the parasitic capacitance increases as the bulk increases. It may resuslt in HF losses or unwanted coupling between stages, that could lead to unstability.