I was inspired by the mentioning of this post by Joe Gore to revisit frequency analysis of circuits http://freestompboxes.org/viewtopic.php?f=6&t=12118
For these tests, I ran 20 secs of pink noise through the "stock" Hotcake circuit (Gain @ 2:00, Presence @ 12:00, Level @ 1:00) to come up with a template
(http://i.imgur.com/E4H2h.png)
This can be compared to pure pink noise through the bypassed circuit
(http://i.imgur.com/4IVJb.png)
Together, Match EQ gives the response of the Hotcake circuit
(http://i.imgur.com/bjIUP.png)
Then, I exchanged the stock 0.047 uF output cap for a larger 0.47 uF cap. Mod compared to Stock
(http://i.imgur.com/KgMm3.png)
It's interesting to see the change, as it's not immediately noticeable by ear since other pedals and amps usually filter out some of those sub 50 Hz frequencies. I would like to do more tests with more caps and opamps.
Previously I analyzed the SHO, Neutrino, and Sunking using a different but equally accurate method in this thread http://www.madbeanpedals.com/forum/index.php?topic=2496.0