EE Bookshelf: The ‘Sound’ of Capacitors

Today’s bookshelf isn’t a datasheet or a book. It’s actually just a webpage (which I suppose would make it an ‘EE bookmark‘), but it’s one that I like a lot, so I figured I’d share it.

Which capacitors sound better than others? Or perhaps, which ones distort the least? This is a contentious topic among audiophiles, musicians, DIY synth builders and occasionally HAMs as well. I don’t actually want to wade into this argument. My main purpose in writing this post is to share with you this excellent webpage over at greygum.net. I keep this one near the top of my bookmarks folder, and make sure it stays there when I migrate to a new computer.

This page dates from 1999, but the information is still good. It’s also a great example of an awesome late-90’s webpage.

The author, Steve, performed some tests to find the D-E curve of various types of capacitors (his test set-up is described at the bottom of the page). The results can be eye-opening.

The two worst performers on that page were electrolytics (which exhibit marked hysteresis, particularly the tantalum, above), and ceramic monolithics, which have  very noticeable distortion. The one thing both electrolytics and monolithics have in common is their relatively compact size, achieved in part by use of a very thin dielectric. It’s interesting to see that the high-voltage monolithic has less distortion than it’s low-voltage counterpart, perhaps in part because the HV version has a thicker and/or different dielectric.

While I had known from long-time experience that ceramic and electrolytic caps can muck up the signal path, I never had any data (visual or otherwise) to back it up — until I read about Steve’s experiment a few years ago. As such, I tend to relegate these caps to decoupling and bypassing, and use something else for anything that touches signal, usually polypropylene film.

Check out Steve’s page and see for yourself, and be sure to check out his followup on electrolytics as well.


Adafruit publishes a wide range of writing and video content, including interviews and reporting on the maker market and the wider technology world. Our standards page is intended as a guide to best practices that Adafruit uses, as well as an outline of the ethical standards Adafruit aspires to. While Adafruit is not an independent journalistic institution, Adafruit strives to be a fair, informative, and positive voice within the community – check it out here: adafruit.com/editorialstandards

Join Adafruit on Mastodon

Adafruit is on Mastodon, join in! adafruit.com/mastodon

Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Join over 36,000+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

CircuitPython – The easiest way to program microcontrollers – CircuitPython.org


Maker Business — “Packaging” chips in the US

Wearables — Enclosures help fight body humidity in costumes

Electronics — Transformers: More than meets the eye!

Python for Microcontrollers — Python on Microcontrollers Newsletter: Silicon Labs introduces CircuitPython support, and more! #CircuitPython #Python #micropython @ThePSF @Raspberry_Pi

Adafruit IoT Monthly — Guardian Robot, Weather-wise Umbrella Stand, and more!

Microsoft MakeCode — MakeCode Thank You!

EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey

New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — #NewProds 7/19/23 Feat. Adafruit Matrix Portal S3 CircuitPython Powered Internet Display!

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !



1 Comment

  1. I too, don’t want to wade into all of the psuedoscientific nonsense surrounding this topic, but I will say this-

    If you are building some kind of audio gadget, and are looking for a specific sound, you most likely will be disappointed if you focus only on the capacitor type. You must also look at the rest of the circuit- at the very least, the stage where the cap is located. Other components will have a profound effect on the “contributions” made by any cap, magic or otherwise.

    Of course, the best advice is to ignore anything that can’t be explained by scientific theory and sound engineering design practice, and of course, trust your ears. The human brain is very good at fooling itself, especially when it comes to buying into fashionable nonsense (The e
    extraordinary popular delusions and the madness of crowds, if you will).

    Learning a little about basic analog engineering and psycho-acoustics will get you much farther during your search for that special “sound.” That will put you miles ahead of the casual tinkerers who often come to well-intentioned, but erroneous conclusions due to their lack of knowledge of the basics.

    Finally- with the ready availability of cheap DSP technology, almost any “sound” can be modelled with a good parametric equalizer (and perhaps a compressor) and a little skill.

Sorry, the comment form is closed at this time.