In addition to the Tutorials section, I think it would be helpful to have a collection of links to all the different detailed circuit analysis pages scattered around the internet. These are Not "How To's" like tutorials, but are detailed descriptions and explanations of well know circuits, not generalized concepts. Please post a link to any that I've missed.
Let's kick it off with none other than R.G. Keen's...
The Technology of the Tube Screamer
http://www.geofex.com/article_folders/tstech/tsxtech.htm
The Technology of the Fuzz Face
http://www.geofex.com/Article_Folders/fuzzface/fffram.htm
The Technology of the Univibe
http://www.geofex.com/Article_Folders/univibe/uvfrindx.htm
Here are all the wonderful ElectroSmash articles:
Tube Screamer
https://www.electrosmash.com/tube-screamer-analysis
Rat
https://www.electrosmash.com/proco-rat
Big Muff
https://www.electrosmash.com/big-muff-pi-analysis
Boss CE-2
https://www.electrosmash.com/boss-ce-2-analysis
Boss DS-1
https://www.electrosmash.com/boss-ds1-analysis
Crybaby
https://www.electrosmash.com/crybaby-gcb-95
Fuzz Face
https://www.electrosmash.com/fuzz-face
Klon
https://www.electrosmash.com/klon-centaur-analysis
MicroAmp
https://www.electrosmash.com/mxr-microamp
Distortion+
https://www.electrosmash.com/mxr-distortion-plus-analysis
DynaComp
https://www.electrosmash.com/mxr-dyna-comp-analysis
Phase 90
https://www.electrosmash.com/mxr-phase90
Sitar Swami
https://www.electrosmash.com/sitar-swami-analysis
Vox Wah
https://www.electrosmash.com/vox-v847-analysis
EMG 81 pickup
https://www.electrosmash.com/emg81
Back Talk
https://www.electrosmash.com/back-talk-analysis
PT2399 delay chip
https://www.electrosmash.com/pt2399-analysis
Other random analysis articles:
Boss MT-2
https://electricdruid.net/boss-mt-2-metal-zone-pedal-analysis/
LM308 opamp
http://www.righto.com/2016/12/inside-lm108-op-amp-superbeta.html?m=1
741 opamp
http://www.righto.com/2015/10/inside-ubiquitous-741-op-amp-circuits.html?m=1
555 Timer
http://sound.whsites.net/articles/555-timer.htm
I have a bunch of these kinds of things on my blog.
Friedman BE-OD - https://prentisseffects.blogspot.com/2018/01/thermionic-distortion-friedman-be-od.html (https://prentisseffects.blogspot.com/2018/01/thermionic-distortion-friedman-be-od.html)
JHS Andy Timmons (MI Audio Crunchbox, etc.) - https://prentisseffects.blogspot.com/2017/06/madbean-turnabout-jhs-mi-audio-crunchbox.html (https://prentisseffects.blogspot.com/2017/06/madbean-turnabout-jhs-mi-audio-crunchbox.html)
Couple of mods
Ernie Ball VP Mod (impedance discussion) - https://prentisseffects.blogspot.com/2017/01/ernie-ball-vp-jr-tone-suck-mod.html (https://prentisseffects.blogspot.com/2017/01/ernie-ball-vp-jr-tone-suck-mod.html)
Joyo Ultimate Drive (Freekish Blues mod) - https://prentisseffects.blogspot.com/2017/01/joyo-ultimate-drive-mod.html (https://prentisseffects.blogspot.com/2017/01/joyo-ultimate-drive-mod.html)
THIS IS GREAT!!!
Brought to you by the good folks at GEOFEX:
"The only way to get real tube sound in a stomp box ;)"
(https://www.dropbox.com/s/f7ei1zn1bnrbwta/realtube.jpg?raw=1)
I would also recommend Kit Rae's amazingly useful Big Muff site:
http://www.bigmuffpage.com/Big_Muff_Pi_versions_schematics_part1.html (and pretty much every other page on that side)
Storm Tide Flanger
http://jhaible.com/legacy/jh_storm_tide_flanger.html (http://jhaible.com/legacy/jh_storm_tide_flanger.html)
This is a clone of the Eventide Instant Flanger, the greatest analog solid-state flanger ever made. To get the PDF's to download on the links at the bottom, you have to right-click and choose "Save Link Target As...". Just clicking those links opens a blank page.
Here's a link to a PCB for newest version of this project. Just looking at the PCB, this would be by far the best/most complicated analog flanger you could ever build. Not bad for $74.
http://randomsource.net/haible/son_of_storm_tide_flanger (http://randomsource.net/haible/son_of_storm_tide_flanger)