A while back, I had some pcb's fab'd.. (think all SMD Arduino and waveshield merged into one board)
and I assembled a couple by hand using some solder paste and a toaster oven..
I purposely left off a few resistors/caps... so I could test different values there while the pcb was in a breadboard.
some/most were just wires with female ends on it so I could stick a through hole resistor/cap in and test..
when I found values that worked for me (ie: sound decent to my ear).. so I keep this one in my breadboard for testing in other projects I plan on using this board as the main board.
I then assembled a few other pcb's taking the values I had/have in the breadboard.. and using SMD versions for the final product.
The version in the breadboard sounds MUCH better than the version that has the matching components on-board.. The later sounds like it has the volume to high in certain parts of the audio and distorts.
I'm curious as to why this is?
I took pics to help visualize things..
The pot I have wired to test tweak values/components R5/R6
Testing values for the R8, C18, C21 components (although in the final board assembly, I am only messing with R5/R6 and R8.. all other smd components on the final board mirror the smd components on the pcb in the breadboard... ie: C18/C21)
took another pcb that had wrong values for R5/R6 and R8.. removed the SMD components there.. and soldered in the same values being used on the breadboard..
R8 = 3.3k R5 = 7.8k (measured at pot) R6 = 1.8k (measured at pot)
but the solo board sounds not as good as the board pcb in the breadboard? I am not clear why though?
Here is a pic of the schematic for that portion as well..
I have also tried a value of 10k at R8 originally..
R5 R6 R8 are the ones of focus..
I have since altered the pcb design and added an SMD pot for components R8 and R5/R6 in hopes of not having to worry about nailing down a specific value for those areas again. :(
I got to thinking maybe I fat-fingered a cap somewhere.... how do you check what values the caps are when they are SMD ones?
I'm very non-experienced in the audio department... please keep that in mind. :)