Capacitors for guitar or bass

• What are the differences between guitar capacitors?
• The sound a capacitor produces is down to personal preference.
• With regards to sound, the rule is the higher the value, the more treble roll off you will have. Eg .047uf will roll off more treble than a .022uf.  
• The voltage rating is more of a size relevance when it comes to guitar electronics.  You can use almost any voltage rating as long as the cap will fit.  Generally, the higher the voltage and value rating, the bigger the cap.