Siemens MKV B25833 caps

reaction · 29th June 2004, 06:38 AM

Just bought a lot of NOS (made in 1984) 5uF Siemens MKV caps with marking B25833. Siemens/Epcos contends officially that all MKV caps are made of polypropylene in oil but I found a thread that some diyaudio guys claim that the B25833 line is made of polyester in oil.

So where is the truth? I’ll try some of these babies in my tube projects and will tell you about their sonic capabilities soon but now I am looking for some manufacturing info. The second option is to disjoint a piece of them and to see the type of the film. I know how the polyester looks like but I don’t know anything about polypropylene film.

Elso Kwak · 29th June 2004, 08:04 AM

Hi reaction,
Not all MKV caps are polypropylene. For example I have B25832-C4336-K0009 in my loudspeaker and the datasheet only states plastic, not polypropylene. Also for the B25839 only plastic dielectric is specified.
According to this site
http://www.fust-electronica.nl/fustica-info1.htm
MKV is polypropyleene in oil.
I would believe the datsheet.
Of course you can dismantle the cap, romove the oil and make a infrared spectrum of the foil. That should give conclusive evidence about the dielectrum.

reaction · 29th June 2004, 08:19 AM

Hi Elso Kwak,

All official Siemens/Epcos datasheets state only "plastic dielectric" for all MKV lines (B25832-B25839) so they are the last instance of truth. I have sent an inquiry to Epcos and waiting for clarification.

Dominique · 5th July 2004, 08:12 PM

You forgot to think of the huge difference in size between polyester/polypropylene caps!
Just compare the size of your caps to the values in a datasheet of both polyester and polypropylene caps (e.g @ wima.de) with the same capacitance and voltage rating as your caps and you'll know!

Cheers
Dominique

29th June 2004, 06:38 AM	#1
reaction diyAudio Member Join Date: Jun 2004 Location: Bulgaria	Siemens MKV B25833 caps Just bought a lot of NOS (made in 1984) 5uF Siemens MKV caps with marking B25833. Siemens/Epcos contends officially that all MKV caps are made of polypropylene in oil but I found a thread that some diyaudio guys claim that the B25833 line is made of polyester in oil. So where is the truth? I’ll try some of these babies in my tube projects and will tell you about their sonic capabilities soon but now I am looking for some manufacturing info. The second option is to disjoint a piece of them and to see the type of the film. I know how the polyester looks like but I don’t know anything about polypropylene film.

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29th June 2004, 08:04 AM	#2
Elso Kwak Banned Join Date: Dec 2001 Location: Zamboanga, City of Flowers, Mindanao	Hi reaction, Not all MKV caps are polypropylene. For example I have B25832-C4336-K0009 in my loudspeaker and the datasheet only states plastic, not polypropylene. Also for the B25839 only plastic dielectric is specified. According to this site http://www.fust-electronica.nl/fustica-info1.htm MKV is polypropyleene in oil. I would believe the datsheet. Of course you can dismantle the cap, romove the oil and make a infrared spectrum of the foil. That should give conclusive evidence about the dielectrum.

29th June 2004, 08:19 AM	#3
reaction diyAudio Member Join Date: Jun 2004 Location: Bulgaria	Hi Elso Kwak, All official Siemens/Epcos datasheets state only "plastic dielectric" for all MKV lines (B25832-B25839) so they are the last instance of truth. I have sent an inquiry to Epcos and waiting for clarification.

5th July 2004, 08:12 PM	#4
Dominique diyAudio Member Join Date: Jul 2004 Location: Berlin	You forgot to think of the huge difference in size between polyester/polypropylene caps! Just compare the size of your caps to the values in a datasheet of both polyester and polypropylene caps (e.g @ wima.de) with the same capacitance and voltage rating as your caps and you'll know! Cheers Dominique

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