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Old 18th February 2009, 02:03 AM   #14561
SY is offline SY  United States
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Just to be clear, by "temperature sensitivity," I'm referring to reliability rather than tempco.

syn, what's so special about the PPS caps? It's an OK dielectric and certainly thermally stable, but what does it bring to the table that I wouldn't get with an ordinary polypropylene cap?
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Old 18th February 2009, 02:03 AM   #14562
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I suppose I'm wasting my time suggesting that some folks here try reading these C. Bateman articles on capacitors.
Oh well. One more try.

http://tinyurl.com/bwsh9b

capsound1.pdf -- capsound6.pdf

These are free downloads.

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Old 18th February 2009, 02:06 AM   #14563
anatech is offline anatech  Canada
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Hi syn08,
Quote:
Very good, most likely better than silver micas.
Thank you.
Yes, I agree these days. 10 years or so ago I probably would have disagreed with you. So is the power of the audio press. I'm glad I started testing some before I opened up my mouth!

Quote:
Try this one, if it won't make you happy then nothing else on this planet will.
Those are the ones I have been using lately. I don't have an opinion on whether they are better than the others I use, but I can't see anything at all wrong with them. They even look nice, each one looking much like the next instead of some that are "bloby" looking.

Hi Andy,
Quote:
Here's what Cyril Bateman has to say about NP0:
That is one source that made me reconsider my stance on these capacitors. I think quality may come into play here, much as it does with Mica capacitors. The one thing I don't like about some Ceramics is that they may short around the outside edge. I think that is due to poor manufacturing but I may be wrong there. Man, can they ever burn!

-Chris
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Old 18th February 2009, 02:07 AM   #14564
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Quote:
Originally posted by zapnspark
I suppose I'm wasting my time suggesting some folks here try reading these C. Bateman articles on capacitors.
Yes, those are excellent. Nothing like real data! My quote of Cyril Bateman above was from one of the files on his CD I purchased. It's not in the freebie downloads.
 
Old 18th February 2009, 02:12 AM   #14565
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Originally posted by anatech
That is one source that made me reconsider my stance on these capacitors. I think quality may come into play here, much as it does with Mica capacitors. The one thing I don't like about some Ceramics is that they may short around the outside edge. I think that is due to poor manufacturing but I may be wrong there. Man, can they ever burn!
Hi Chris,

Not sure if you've seen this, but here is the Bob Pease "soakage" (DA) article from back in the '80s that made me think of this. I was working with S/H circuits for military apps at the time, and it definitely influenced my choice of hold capacitor.
 
Old 18th February 2009, 02:16 AM   #14566
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I've heard stories about very good silver mica caps from Germany, here's one: http://www.diyaudio.com/forums/showt...2788#post22788
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Old 18th February 2009, 02:16 AM   #14567
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Hi SY,
Quote:
Just to be clear, by "temperature sensitivity," I'm referring to reliability rather than tempco.
Yes. Sorry, I was unclear also.
Most Polystyrene capacitors die when being soldered in or reworked. Do not resolder these without good reason. It helps a lot to use some type of metal clip between the body of the part and the lead you are soldering. Get it soldered and remove the heat as efficiently as you can. I still use some component lead heat sinks I bought from Radio Shack way back in the 70's. Some early transistors were equally touchy about heat.

Quote:
syn, what's so special about the PPS caps? It's an OK dielectric and certainly thermally stable, but what does it bring to the table that I wouldn't get with an ordinary polypropylene cap?
I didn't notice anything so far. They are just another possibility when the other types are out of stock for me.

I look for capacitors that don't do bad things more than the "drops of pure heaven" these days. Many good capacitors don't sound much different, and they don't appear any different on my THD meter or spectrum analyzer. Some capacitor changes do make a measurable difference on even a THD meter (HP 339A). Even my old Leader THD meter could measure a small but repeatable difference between nasty ceramics (or tantalum) and a better replacement. I figure that I the difference is so small that I have to really work to hear the difference, so will the customer and I'm not about to expose that person to more cost than required.

-Chris
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Old 18th February 2009, 02:26 AM   #14568
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Hi Andy,
Quote:
Not sure if you've seen this, but here is the Bob Pease "soakage" (DA) article from back in the '80s that made me think of this.
Yes, that was also a good article. I found it later and was relieved to find it re-enforced the views I was coming to accept. I came across that one while building a DVM circuit.

Thank goodness for the test and measurement field! It seems they demanded the parts we require for audio use. That's probably the only reason those parts existed in the first place. I guess I was lucky to have interests in both instrumentation and audio. Otherwise, much of what I learned would not have been available to me.

Quote:
I was working with S/H circuits for military apps at the time, and it definitely influenced my choice of hold capacitor.

What more can I say? The T&M industry will always get it right. It's too important to make errors there and that industry has enough cash as a result to do these studies. Far more rigorous standards for the better equipment than audio. Often the required bandwidth is far greater as well.

-Chris
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Old 18th February 2009, 02:50 AM   #14569
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I wonder what Robert Harley's opinion of NP0 ceramics is?

Could any high-end designer afford to put such capacitors in his designs without risking the scorn of a bunch of self-important blowhard audio reviewers?
 
Old 18th February 2009, 03:08 AM   #14570
syn08 is offline syn08  Canada
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Originally posted by SY
syn, what's so special about the PPS caps? It's an OK dielectric and certainly thermally stable, but what does it bring to the table that I wouldn't get with an ordinary polypropylene cap?
As you said, better temperature stability (e.g. dissipation factor is constant up to 100 degrees centigrades). But one to another an excellent cap that makes teflon look like an unjustified expensive option, together with $1000 power cables and unbleached cotton insulated silver wire. Give me one shred of proof (beyond "sounds good") that teflon is bringing anything special to audio.
 

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