Roederstein 'BAKELITE' series EK capacitors - "Living Legend" OR "Looney Legacy" ...? - Page 3 - diyAudio
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Old 20th December 2012, 02:05 PM   #21
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Hi again Elvee

There was some speculation earlier...
...that the casing's might be something OTHER than Bakelite...
...perhaps an 'improved' sort-of Bakelite.
( I believe Phenolic, was kinda the MKII Bakelite...
...sort-of anyhow ! )

Well...
...the brown/red case, is absolutely TYPICAL of Bakelite...
...which did seem to be made in 'certain' colours...
...including ORANGE.

A friend of mine showed me some Bakelite objects ( he collects them ! ).
Orange is/was an unusual-colour he told me.
He also told me BLUE is 'quite rare' and VERY collectable...
...I'll take his word on all that !

Just looked at a brown/red Roe-cap under a microscope.
The casing is 'ever-so-slightly' chipped.
And indeed !...
...SAWDUST was mentioned earlier as well...
( my collector friend also mentioned this )
...there are what looks, remarkably like small 'wood-colour' particles, emerging from the surface of the casing.
Impossible to see with the 'naked eye' of course.

I believe also the 'porousity' of Bakelite was mentioned earlier also.
Perhaps there IS a 'controlled-venting' from an otherwise, epoxy-sealed case...
...through slightly porous Bakelite.
Perhaps THIS was one of the main ideas of using the otherwise 'fairly obsolete' material; way into I think, the 70s' & 80s'.

Bakelite also seems entirely, non-resonant ( or fairly, at least ).
All these 'high-end' capacitor manufacturer's sales-pitches; are constantly on about, anti-resonance this, anti-resonance-that.
Maybe the 'top-boffins' at Roederstein had figured this out YEARS before...
...and implemented it as standard, at a normal, sensible cost ?

Cheers.

Si.
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Old 20th December 2012, 02:55 PM   #22
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by The Space Egg Corp View Post
Hi again Elvee

There was some speculation earlier...
...that the casing's might be something OTHER than Bakelite...
...perhaps an 'improved' sort-of Bakelite.
( I believe Phenolic, was kinda the MKII Bakelite...
...sort-of anyhow ! )

Well...
...the brown/red case, is absolutely TYPICAL of Bakelite...
...which did seem to be made in 'certain' colours...
...including ORANGE.

A friend of mine showed me some Bakelite objects ( he collects them ! ).
Orange is/was an unusual-colour he told me.
He also told me BLUE is 'quite rare' and VERY collectable...
...I'll take his word on all that !

Just looked at a brown/red Roe-cap under a microscope.
The casing is 'ever-so-slightly' chipped.
And indeed !...
...SAWDUST was mentioned earlier as well...
( my collector friend also mentioned this )
...there are what looks, remarkably like small 'wood-colour' particles, emerging from the surface of the casing.
Impossible to see with the 'naked eye' of course.

I believe also the 'porousity' of Bakelite was mentioned earlier also.
Perhaps there IS a 'controlled-venting' from an otherwise, epoxy-sealed case...
...through slightly porous Bakelite.
Perhaps THIS was one of the main ideas of using the otherwise 'fairly obsolete' material; way into I think, the 70s' & 80s'.
I don't know, I think it is a variety of Novolac, with proper additives and loads, but as I said, I am no material specialist.

Quote:
Bakelite also seems entirely, non-resonant ( or fairly, at least ).
All these 'high-end' capacitor manufacturer's sales-pitches; are constantly on about, anti-resonance this, anti-resonance-that.
Maybe the 'top-boffins' at Roederstein had figured this out YEARS before...
...and implemented it as standard, at a normal, sensible cost ?
Non-resonant (mechanically at least) is complete BS for me and it certainly was for the designers of these caps.
It is something audiophools are preoccupied about, but no serious engineer would care about it for more than half a second.
German engineers were down to earth and not superstitious at all (which is why they made such good products), and that is certainly not something they looked into.
Avoiding the movement of internal parts during vibrations and shocks is a concern, but with a radial capacitor filled with viscous liquid, that is not too much of a problem.
Electronic resonances could be more problematic, but they are well under control, and it has nothing to do with the bakelite or other case material.
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Old 20th December 2012, 03:11 PM   #23
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The casings certainly looks and acts like a wood flour filled, phenolic based resin. I've always found them to be excellent caps as long as they aren't run over temp or current.
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Old 20th December 2012, 04:05 PM   #24
Elvee is offline Elvee  Belgium
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Found one more example, a 470µ/16V (used). Esr @1K is 72mΩ
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Old 23rd December 2012, 05:01 PM   #25
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Exclamation Leo Baekeland

Invented by Belgian...
...Leo Baekeland...
...in 1907 !

( Bakelite, that is; not the capacitor ! )

Cheers.


Si.
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Old 25th December 2012, 10:59 AM   #26
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Talking Seasons Greetings

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Old 25th December 2012, 05:09 PM   #27
Elvee is offline Elvee  Belgium
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I found some more in my stock, including the grey one.

I don't know if this color has a special meaning.

The esr @1KHz for this NOS 100µ/35V is 131mΩ

The 220µ/40V of more conventional aspect measure 67mΩ. They date from 1980 and have served a harsh duty: they were filter caps in a modular DC/DC converter.
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Old 27th December 2012, 03:55 AM   #28
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Interesting coincidence, the other day at work I pulled some boards out of an old chart recorder. I noticed some of the boards have what look like ROE rectifiers in them. Same exact bakelite case, very interesting but with ROE and ~ on the surface and four pins. Plus a bunch of Frako Caps (west germany) and loads of other stuff. I didn't know much about the rectifiers but happened to see this.

Last edited by PedroDaGr8; 27th December 2012 at 04:00 AM.
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Old 27th December 2012, 05:25 AM   #29
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One way to find out what it is - touch an edge with a soldering iron. If it melts, it's not Bakelite, but something else. Bakelite is brittle, so it's a bitch to mold in thin cross-sections. The cap might use another material like PBT, a plastic commonly used to mold things like bobbins where injection vs. transfer molding is desired, but with a better resistance to heat than something like nylon.
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Old 28th December 2012, 09:21 AM   #30
MRupp is offline MRupp  Germany
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FWIW, It looks like Brinkmann still uses some Roederstein EKR caps in his products. If quality or reliability was an issue I guess he would throw them away: brinkmann audio
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