Polypropylene versus metallized polypropylene

[VS]

Hi !

Which capacitors, Polypropylene (KP) or metallized polypropylene (MKP) are the best for audio? (E.g. bypassing electrolytic caps. in a signal path)

Opinions needed

Regards,
VS

[analog_sa]

Polyprop is consistently better sounding than metalised polyprop IME. Neither is best in an absolute sense.

[VS]

Thank you, but thecnicaly speaking.....what is the diference? Are the dissipation losses smaler? Is the dielectric absortion ?

Regards,
VS

[freakyone]

Does anyone have more to share on this!!

Im thinking of following kk design for the AX100 which calls for 2.2 MKP across the caps

Cheers in advance
Dan

[infinia]

Hi
Wima suggests these caps in their application guide
for High pulse rise time rating. High (surge) current carrying capacity.
http://www.wima.com/wima_neu/EN/tech...nformation.htm
look around there for more info
IMO in the past foil was superior for dv/dt but metalized has improved greatly.



MKP 10 (metalized polyp)
FKP 4 (foil polyp)
FKP 1 (foil ployp)

[AndrewT]

Hi,
from reading, I think the advantages of metalised could be:- smaller package, less inductance, self repair.
And advantage of foil could be:- higher pulse current, higher dv/dt, ?

polypropylene and polystyrene are reputed to be audio suitable. Teflon might be but at the moment too expensive.

Wima's foil are not true foil, they incorporate metalised for self repair in the constructions they show on their website.

For bypassing, stick with ceramic for lowest inductance, but only with the very shortest of component leg lengths and close to the current client (glitch producer).

For decoupling, use polarised (electro/tantalum) of the biggest size that fit the board. Aim for a minimum of 20 times (preferably 1000 times) the total bypass on the board.

[acenovelty]

http://waltjung.org/Classic_Articles.html

Classic everything you wanted to know article.

1980: 'Picking Capacitors, Part 1/ Part 2', co-authored with Dick Marsh, was published in Audio, in February of 1980. This two part article examined a number of capacitor types for performance characteristics relevant within audio applications.

Probably still relevant today.

[mzzj]

Originally posted by VS
Thank you, but thecnicaly speaking.....what is the diference? Are the dissipation losses smaler? Is the dielectric absortion ?

Regards,
VS

Metal foils show usually lower distortion than metallized. Cyril Bateman was suspecting non-ohmic contacs along the metallization and end plates to be a cause of this. I recommend C. Batemans series of articles in Electronics World(Capacitor sound parts 1&2&3&4&5...) if you are more intrested on subject.

[Vidalgo]

Note that there is stacked version of the metallized film capacitors. Construction is similar to multilayer capacitor. No winding = no inductance = excellent pulse responce.
Epcos produce such caps - look for series B32620, B32621.