X7R MLCC - R U scared of them? Should I be? Should we all?

[Diynot]

Just to clarify, where are you using said MLCCs? I have really only ever used/seen them in the power section for filtering, not in the direct audio path (aside from pf sized values across clipping diodes).

 

[jwin615]

Just to clarify, where are you using said MLCCs? I have really only ever used/seen them in the power section for filtering, not in the direct audio path (aside from pf sized values across clipping diodes).

Off the top of my head, madbean Degenerator (which calls them out in the build doc), and I believe the fuzzy britches as well. I've generally used them anywhere a plain ceramic is called for.

 

[finebyfine]

This is exactly what I was looking for! Thank you. That response chart in section 2, page 6 is terrifying. That's honestly way worse than I would have imagined. Hope it's okay for me to repost here for the sake of future readers.
Yeah, I can't see myself utilizing these in any "clean" audio path moving forward. In a gnarly fuzz box, maybe just for the added nonlins,.but I'd still question if their additional would benefit the overall tonality. 0.15% THD from a singular passive component is a pretty wild. Even though that measurement is not completely in line with where we typically operate, especially with the higher DC bias, it's still rather indicative of their potential issues.
I'll be reading more into that paper this evening when I have time. Thanks for the link.
Have you read the Self book? Would you recommend it at the $60 price tag, or is there another one you would? I have several, but I circle back to the old Audio Cyclopedia more than most of my others. But it's a little hefty at 1700+ pages and the binding is starting to dry some so I have to baby it a bit.View attachment 53705

no problem for the link! I would have posted those graphs here if I hadn’t been too lazy.

The Self book is really good. I was able to snatch up a used copy for $20. I couldn’t personally justify paying the full (or close to) college textbook price but if you’ve been eyeing it for a while I think it’s worth it. I think only the 3rd edition covers guitar stuff explicitly and it’s a short chapter. But obviously everything is applicable.

I found it refreshing that it isn’t “project” oriented like guitar pedal books. I’m not a learn by blowing stuff up kind of guy when it comes to electronics and Self’s structure “builds up” as opposed to “dives in.”

The other book worth mentioning alongside Small Signal is Dailey’s Electronics for Guitarists (~$40 new). It is more project oriented than Small Signal, but not overbearingly, and all of it is geared specifically towards guitar signals. It’s math heavy, which I personally enjoyed.

There’s more circuit sketches worth ripping off entirely from Self than Dailey. One of Self’s high input impedance BJT stages (6MΩ with like 10 parts) basically lives on my breadboard now as the input buffer.

I’d see if you can find previews of either and see if you like the writing style / structure. Both have been valuable to me with where I’m at with my electronics knowledge and my learning goals.

 

[darwin999]

This has been discussed in another thread (https://forum.pedalpcb.com/threads/...ce-from-all-you-pros.19936/page-3#post-248760)

It's worth being aware that some MLCC ceramic capacitors (e.g., specifically Class II MLCC's such as XR5, X6S, X7R,...) use materials that can have surprisingly large capacitance changes (e.g., some can shift by 20-50% or more) due to large enough AC and DC voltage (e.g., sometimes just a few volts).

Hence,

1. Look at the data sheets, good manufacturers will provide data on the voltage-driven shift - and some products are better than others.
2. Think about where you use class II MLCC capacitors in a circuit. I.e., will the AC &/or DC voltage at that location be large enough to significantly alter the capacitance - and - will it matter?

On #2 above, what I mean is that if a specific capacitor's change shifts a high pass frequency from 7Hz to 10Hz, then it has no audible impact.
But, if a capacitor's change instead shifts the "knee" frequency for a tone control from 700Hz to 1kHz, then it's probably a different story.

Here are 2 readable links on this topic:

• From Murata (a quality capacitor manufacturer): https://www.murata.com/en-us/support/faqs/capacitor/ceramiccapacitor/char/0005
• From Digikey (an electronics supplier): https://www.digikey.com/Site/Global/Layouts/DownloadPdf.ashx?pdfUrl=863968494F2E4E13BBEA65B55A358443

I hope this helps. There's no reason to be scared of MLCC's, they just need to be used wisely.