polypropylene motor start caps for crossovers?

[redrooster]

Is there any reason why I can't use polypropylene motor start capacitors for my speaker crossovers? They seem to have all the right specs so I thought I might ask here to find out? I'm replacing all the electrolytic capacitors on my speaker crossover boards with polypropylene caps and this would be the cheaper way to go. If it works???

[kaboom]

Motor "start caps" are usually nonpolar electros, with values from 180-680uF. These come in a black phenolic case (usually), and have a seal/plug retained by a "star clip."

You're thinking of motor "run caps," which are oil filled film caps. Smaller values, typically under 100uF.

There's one good reason to not use them- space. Film caps tend to be large for the value.
They also typically come in "even" values- 1, 2, 3, 5, 7.5, 10, etc, not E-whatever series as used in electronic equipment.

http://www.capacitorguide.com/motor-starting-capacitor/

NPEs for crossovers usually come in even values, FWIW.

[redrooster]

Originally Posted by kaboom

Motor "start caps" are usually nonpolar electros, with values from 180-680uF. These come in a black phenolic case (usually), and have a seal/plug retained by a "star clip."

You're thinking of motor "run caps," which are oil filled film caps. Smaller values, typically under 100uF.

There's one good reason to not use them- space. Film caps tend to be large for the value.
They also typically come in "even" values- 1, 2, 3, 5, 7.5, 10, etc, not E-whatever series as used in electronic equipment.

http://www.capacitorguide.com/motor-starting-capacitor/

NPEs for crossovers usually come in even values, FWIW.

Thankyou Kaboom, that link was very educational and will save me a lot of money!