Notes on Coupling Capacitors
These are very general, loose descriptions of the tones of the coupling capacitors. Many things influence tone, so take these descriptions with a grain of salt, and keep in mind that "your mileage may vary."
Mallory 150 metalized polyester capacitors have been the affordable mainstay for amps such as Marshalls and Fender tweeds. They have a complex, sometimes "grainy" midrange character that can be very nice in some amps, and over the top in others. Their bass character is kind of "loose" or floppy, and the treble character is mellow.
Type 715P Polypropylene film Orange Drops have a broad, wide-open tone. They have tighter, fuller bass and "zingier" treble than Mallory 150s. Some may say that they are lacking in midrange character, others would say this is desired.
Type PS Polyester Film Orange Drops have a clarity that is almost austere and a unique midrange character. Reportedly used quite a bit by Dumble and in the voicing of some Trainwreck amplifiers.