Fromel Blues Driver pedal mod

[dude]

A friend asked me to install a Fromel BD screamer pedal mod. I printed the instructions from Fromel and seems pretty easy. But in the parts bag from Fromel there are 10uf Poly caps and in some the places they're specified there are electrolytic caps. The BD board does not have any polarity marking where these are to be replace with non-polarized poly film caps. Is it possible that the stock BD used 10uf eletro's where 10uf ceramic or poly-film could have been used..? Again when taking the E-caps out there is no polarity marks on the bd.  I've never seen a pedal PCB bd without + or - where E-caps were used. 
This is a pic of the modded bd, some of the blue 10uf poly film caps were E-caps, same value, no polarity marks were on the bd.

[acheld]

Is it possible that the stock BD used 10uf eletro's where 10uf ceramic or poly-film could have been used..?

This is just a guess, but the PCB "looks" vintage.  It may not be old old, but it is probably a decades old design. 

Since 2010, there have been huge advances in miniaturizing caps -- so it seems plausible that electrolytic caps were used out of necessity. 

[dude]

By necessity, not sure what that means..? Yes, this pedal was made around 2016, Fromel says only the older bds like this can take the mod.
Are you saying they use E-caps, cause cheaper or easier to obtain or whatever, where ceramic could have been used..?

[acheld]

An electrolytic cap is able to hold a huge charge at high voltage compared to a film cap of similar size, and at lower cost.  This is, of course, an oversimplification, but it's a good rule of thumb.  That said, I often use large film caps in my filter sections despite their size/cost -- they are extremely robust.

Ceramic caps -- depending on the materials used -- have an advantage of having high voltage ratings, but are not available in large capacitance values (yes, they are volumetrically challenged).  Some folks disparage ceramics for being vibration sensitive, and some are!  But, Class I ceramics are very stable with regard to temperature and vibration and are suitable for use in a guitar amp -- they really have their place in resonant circuits within radios and such.

The main thing to know is that each type of cap has its range of uses.  And, over the past decade or two, capacitor engineering has advanced considerably. Just look at the specs of the radial electrolytics now, compared to the venerable but huge (in cost and size) of a Sprague Atom.

Wikipedia has readable (but tedious) sections regarding film and ceramic caps.   Merlin's book on HiFi Pre-amps has a great chapter on caps.

Yeah, I fell down that rabbit hole.

[dude]

Thanks for the reply. I’ll just follow Fromel’s mod instructions he sent my friend, parts were included. 
He’s a pedal guy and has a good reputation and high marks for his Blues Diver mod. I’ll replace the small e-caps with the parts sent. Sluckey says no problem and he’s usually right. I’ll
post the results when done. Thanks again for the info