Choosing the "best" caps for a fuzz

[duck_arse]

there's nothing I like more than a good dead horse flogging. unless I've stated otherwise previously.

[PRR]

> Here's a little read from Mouser.

Actually, from Gibson, defending their recent use of Orange Drops in their new amplifiers. And hardly complete coverage of complex physics and psychology.

[Kevin Mitchell]

> Here's a little read from Mouser.

Actually, from Gibson, defending their recent use of Orange Drops in their new amplifiers. And hardly complete coverage of complex physics and psychology.

Are you implying incentive to deceive? 

I think the horse just moved.

Okay it's not a page filled with data. But I still agree with their consensus.

[iainpunk]

Here's a little read from Mouser.
It explains the capacitor placebo effect as well as how most results are merely due to slight differences in capacitance alone.

funny how they put out such an article and also sold those 70$ bumble bee caps...

I even went the extra mile to find the foil side of each capacitor to place them for "best performance"

this does actually make a measurable difference, noise wise and i was even taught this in school, we had a class about noise reduction and mitigation.

On the other hand, aesthetic reasons are perfectly valid when deciding how to make a thing. Maybe a cap's brand/series/vintage/color/shape somehow evokes warm feeling of childhood bliss. If you put a picture of your ex wife on a pedal it can't possibly change how it sounds but it might change your perception of that sound. Ultimately you decide how the thing should behave, which includes how it sounds, looks, feels etc., isn't that one of the perks of DIY?

over looked this at first, but its a perfect point to sum up everything.
yes, i use transistors and caps because they look good, but i wouldn't go out and buy fancy tropical fish caps for their sound... the only reason i use tropical fish caps is because they were part of an inheritance form my great uncle, and use them in his honor. i wouldn't put tropical fish in a customer/commission build, they are way to fragile and prone to breaking, totally not shock proof... i dropped one of my own pedals once and a fish cap lost one of its leads off of one side.

cheers, Iain

[Fancy Lime]

I have in fact been trying to get a hold of the simple burgundy film caps (likely polyester) that are dipped in resin like the greenies. I have seen them in large values like 1u or even 2.2u looking really nice like a rounded cube. I'd love to use those in old school builds instead of the new style box caps. Because I like me a good looking circuit as much as the next guy. Alas, I have so far been unable to find them anywhere in values above 100n or to even find out the manufacturer. They seem to be the no-name option in some shops. Any clues? Alternatively, non-ridiculous axial film caps may also be an option but usually a bit less practical.

Thanks,
Andy

[amptramp]

I have shown a video where a microphonic ceramic cap was found.  The following is a site where the linearity of caps was tested:

http://diyaudioprojects.com/mirror/members.aol.com/sbench102/caps.html

No beatings.  No horses.  But no horseshit either.  Ceramic at low voltage is very non-linear.  At high voltage, less so.

[FiveseveN]

Ceramic at low voltage is very non-linear.  At high voltage, less so.

That data was referenced so many times in the last 10 years you'd think people would have actually read it:

The signal level was held constant at about 70 volts RMS at 600 Hz across the capacitors.

The "low" and "high voltage" refers to the cap's rating:

one a 100 volt Z5U part, one a 1000V Z5U

If a conclusion must be drawn, it's the opposite: distortion increases as the voltage approaches maximum, which is not where we find ourselves with 9 V supplies and 50 V caps. Plenty of other reasons to avoid ceramics, though.

[Gus]

ceramic can be one of the best, look up
COG NP0

some good stuff in the following link
look for voltage vs value
https://en.wikipedia.org/wiki/Ceramic_capacitor

[OiMcCoy]

Wow, this post really took off.

I have spent most of the time since making it paddling whitewater, so my brain has not fully turned back on yet, but if what I am understanding is correct it breaks down to this.

Greenies good.

Ceramics Bad.

Ceramics sometimes good.

My canoe skills bad.


I will reread everything after some coffee. But I think it's safe to say I am not going to get much of anything extra from the colour of the cap, but rather the tolerance of the value.

[OiMcCoy]

Alright, coffee had, brain turned on. Let's tackle this!

First off, a lot to digest here. But a few things stand out in relation to this project. I made a prototype using a vero layout but modified it with a 47nf-470nf input pot with the intention of getting feedback from guitarists to see what cap size they prefer. Turns out my opinions seemed to be reflected in everyone who played it, that the bigger the better. During the rotation of the pedal, I picked up a much better guitar amp. I noticed two disappointing things. The first is that it had a pretty honky mid-range that was there at every setting. The second being a high-pitched squealing. None of my friends made mention of either of these things, most likely out of being too nice, but they are definitely there. My best guess about the midrange was the transistors I used (2N3904 and a 2N2222), so I have been messing with different combos, and have fallen on really liking a pair of 2N2222As. It has certainly changed the mids, but it has me wondering if there is a value that can be changed to have any control on the mids. My best guess of the squealing was that it was an issue with the power filtering. But after reading this, it sounds likely that it may be coming from one of the two ceramic caps. Which would explain why I am having trouble replicating that squeal on the breadboard version. So I am left to believe I would be wise to invest in some poly alternatives when using pf-sized caps.

[iainpunk]

for ceramic caps to squeal, we are talking about REALY EXTREME VOLUME LEVELS, like a cranked 80W amp into an upright 4x12 cabinet.

what kind of power supply are you using, most fuzz circuits have really bad power supply rejection ratio (PSRR), so a good quality power supply is extremely important. especially with high gain pedals like this one.

you could still check if the ceramics are feed-backing by turning down the volume a bunch, if it stops at lover volumes, it probably the ceramic, if its persistent, its another problem.'

maybe time to whip out an audio probe!

cheers

[Gus]

The layout of the parts and wires matters a lot.

Search for layout, feedback etc.
There are threads about Fuzzes having feedback issues.

[OiMcCoy]

And the hunt continues!

Thanks, guys.

[garcho]

Transistors don't have "tone", circuitry does. If there is an EQ related issue, most likely there are some capacitor/resistor values responsible.

[OiMcCoy]

Transistors don't have "tone", circuitry does. If there is an EQ related issue, most likely there are some capacitor/resistor values responsible.

On a fuzz face style circuit, where would you be able to manipulate the mids?

[antonis]

Transistors don't have "tone",

Not true for high frequencies..
(but for audio applications, Yes.. Junction capacitances can be safely ingored..)

[mozz]

"Junction capacitances can be safely ingored" I don't think so. How often is a C-B capacitor added to dampen the highs or hiss because the junction does not have the higher capacitance of a earlier transistor?

[antonis]

"Junction capacitances can be safely ingored" I don't think so. How often is a C-B capacitor added to dampen the highs or hiss because the junction does not have the higher capacitance of a earlier transistor?

That's exactly why they can be ingored..!! 
(their values are low enough, even for Miller effect apparent values..)

[WoundUp]

I think Greenies are a pretty good choice. I don't know if they go quite as far back as the colorsound fuzz, but I know I was pulling them out of 1970's electronics back when I couldn't afford to buy caps. I've always considered them a "vintage" cap. Ultimately, they're a basic polyester film cap and won't give you a different sound from any other polyester film cap, but they do look the part. And with so few parts in these old circuits, that really counts for something.

Whatever you choose, make it beautiful and make it look like you cared about it, because you did!!

<edit>typo

It's funny you say that about pulling greenies out of vintage equipment. I got an old turntable out thata been in storage to see if it worked. Yea, it barely turns. So I pop the bottom off and out falls a greenie lol. This was an old dept store turntable. I forget the name. It comes in a small chest for lack of a better word.

Edit: it's an old Morse Electrophonic I believe. The cabinet fits on a tabletop and has a radio built in.

[Rob Strand]

 

I think Greenies are a pretty good choice. I don't know if they go quite as far back as the colorsound fuzz, but I know I was pulling them out of 1970's electronics back when I couldn't afford to buy caps. I've always considered them a "vintage" cap. Ultimately, they're a basic polyester film cap and won't give you a different sound from any other polyester film cap, but they do look the part. And with so few parts in these old circuits, that really counts for something.

I did the same in the 70's.   Funny thing is I don't think of them as vintage at all.

The earliest examples of green caps I can think of are Japanese products perhaps going back to the 1967 or so.    If you look up some old transistor radios you might be able to see a transition between the really vintage/odd-ball caps and the green caps.   I think the popularity (and availability) of the  radial electros over axials occurred about the same time.

[Edit: didn't try to find anything earlier but here's a 1967 radio with greencaps,
https://dansetteworkshop.blogspot.com/2013/11/rankdansette-medway-transistor-radio_20.html]