Please help, two Tone Machines Acting Strangely

[Filament]

I've recently built two Tone Machines from Gaussmarkov's layout...

http://gaussmarkov.net/layouts/foxx/foxx-perf.png
http://gaussmarkov.net/layouts/foxx/foxx-schem.png

...and decided to see how they sounded compared to one another.  I was surprised to find that one seemed to have more bottom end and to be quite a bit louder.  Since I built both of them I was confident that they were identical but opened them both up to see if the were indeed the same.  All but two components were the same. Firstly, in the bottom heavy unit's C10 is a .0033uf cap and the thinner unit has a .0027uf cap at C10.  Would that slight difference in capacitance make that much difference in tone?

The second component is not exactly different as it is backwards.  On the bassier unit C4 is actually backwards.  It's the same value in both of my builds just one is built correctly and sounds kinda thin and the other is built incorrectly and sounds fantastic. 

Does anyone know if those two small differences could account for the differing bass response and the difference in volume?  I like both incarnations of the FTM but I have to say I'm curious about this one. 

[Mark Hammer]

C10 allows mids and highs to pass safely while the signal at the R17/C11 junction has been lowpass filtered.  When the tone pot is set in a particular position, this combination of highpass (via C10) and lowpass forms a midscoop filter.  As the wiper of the tone pot moves towards R19 it becomes easier for the lowpassed component to pass safely without attenuation and harder for the upper signal via C10 to pass.  So the tone gets bassier.  Moving the wiper towards C10, the resulting signal consists mostly of what mids and highs pass through C10, and substantially less of what is coming through R18; hence thinner and squawkier.

If C10's value is dropped, the point where the mids get chopped moves higher up in the frequency spectrum.  Making that cap larger in value lets more mids through when turned fully to the treble side.  Since what passes through C10 is always present in at least some small measure, the smaller C10 is, the less midrange "cut" you will tend to have.  Since you've built it already, and used a 2n7 cap because I gather you didn't have a 3n3 value handy, you can just tack on another small-value cap (470pf or even 1000pf) in parallel on the copper side of the board.  That should fix the thin-ness issue.

As for C4, you probably want to reverse its orientation to that of the schematic for optimal octaving.

[Filament]

Mark-

Thanks for the reply, that's just what I was looking for.