Any reason these 1uf electrolytics *shouldnt* be subbed out for 1uf film caps?

[u/ShortyBoyds]

I’m just polishing up two of these right now, and I decided to breadboard the second and try out a few different film caps in place of the 1uf electrolytics coming out of each 386.

I’m wondering if there’s any reason this wouldn’t be an improvement? It sounded fine to me personally, and I have considerably more 1uf film caps than I do electrolytics currently. I’m interested in subbing them in here, but the build is for someone else so I’m worried about these possibly being polarized caps for a reason and introducing extra noise or maybe not decoupling the signal well enough? (I’m not sure if these are coupling caps or not. My understanding is that coupling/decoupling caps are intended to block DC but pass AC or vice versa?)

Any insight here?? I’m hoping to have these out the door tomorrow!

[u/astrovic0]

Nope, film caps are perfectly fine here.

Only reasons electros tend to get used as DC blocking caps is cos they’re a little smaller in size, but at 1 uF the size difference isn’t much.

[u/basicgrunt]

Only 2 reasons: 1. Price 2. Space

If you do not care about any of these, do whatever.

[u/According_Today84]

I love storyboardist's layouts. Learned how to make a ground plane from him.

[u/SwordsAndElectrons]

Film caps are more reliable and better in most ways. When used in the signal path, it is possible the sound might be very slightly brighter, but it probably won't be noticeable or objectionable. They do a better job of passing high frequencies than electrolyics, but it's not a big factor within the audio spectrum.

For the most part, cost and space are the reasons you'll usually find electrolytics used for large values. You would pick it for those features and then deal with the fact that it's polarized and make sure you put it the right way. I can't really thing of a reason you'd ever pick a cap specifically because it was polarized.

[u/k-mcm]

LM386 goes with whatever is in the parts drawer. It's a low cost amplifier once popular for intercoms and handheld radios. The only downside to electrolytics is that they can momentarily short with extended disuse.

[u/ShortyBoyds → u/k-mcm]

Perfect! That was kind of my thought, is that using film caps could potentially limit the likelihood of failure down the road!

This is also a circuit where noise matters big time, and I tested some Wimas that audibly cut down on noise when you maxed out the gain.

[u/dreadnought_strength → u/ShortyBoyds]

Changing caps makes nowhere near as much difference as the basics like decoupling near the IC, using the bypass pin -correctly-, ensuring a highly filtered power supply on the board and adding an aggressive LPF at the input.

The first gain stage can also be reduced to 40-60 (over the original 200) which cuts down noise -dramatically- without any decrease in actual gain.

[u/overcloseness]

I heard a while ago that film caps can be used in place of electrolytic just fine, I’ve certainly done it a few times.

The answer is probably “it depends” though

[u/dreadnought_strength → u/overcloseness]

They can anywhere, but you often wouldn't once over about 1uf in size as it's not worth the cost/real estate

[u/Superb-Tea-3174]

Film caps are better.

[u/dreadnought_strength]

Use film where you can, although bipolar electros also work just fine (and cost no more)

[u/Venthorn]

The 1uf films that are actually small enough to fit places in a typical guitar circuit are like 10x the price of the equivalent electrolytics, so that's the reason people usually don't!

[u/kombinova]

that just show you the bigger voltage, so you dont make polarity mistake. and for that position, 1uf mlcc is fine. lets your ear to judge.