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Caps for a Not-So-Bright Idea
Caps for a Not-So-Bright Idea
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Old 7th July 2018, 03:44 AM   #1
Skip Pack is offline Skip Pack  United States
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Default Caps for a Not-So-Bright Idea

I have Altec 605B's in open baffles above 18" woofers in open-backed (big) boxes. Works pretty well. But there are always wrinkles. I use simple passive line-level cap-resistor bypass with series resistor shelving filter to correct some of the OB cancellation, but there are other FR wrinkles to deal with.

I chased a reference to the section of the liked page with the "Have Ya Ever Been Too High???". Do It Yourself DIY
It has five parallel shelving filters evenly spaced. It might work for me.

I thought it could be useful to put a switch on each filter so they each can be switched out of the circuit. I also thought that adding one more parallel leg at a lower frequency cold be helpful in my OB case.

My question for now is 'What do you suggest for a series of capacitors that would be matching/compatible in character over the range of values: .001uf, .002mf, .0047uf, .01uf, .022uf and .047uf?'

That range seems to demand one type of cap (film/film and foil) for the larger values and something else (silver mica?) for the smaller ones. Needing 12 caps, I dpn't want to spend a lot of money on these, at least until I've had a chance to listen to the results of an initial build. Any suggestions here?

Thanks, Skip

Last edited by Skip Pack; 7th July 2018 at 03:47 AM.
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Old 7th July 2018, 08:45 AM   #2
Zen Mod is online now Zen Mod  Serbia
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Caps for a Not-So-Bright Idea
just use proper industrial quality

I personally prefer Polycarbonate (MKC) , but there is - frankly- decision in same amount as actual preference based on listening

that way I sleep better and think less
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Old 7th July 2018, 09:24 AM   #3
Attila I is offline Attila I  Germany
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@Skip Pack
since you might want both sides as close as possible use vishay 1837 mkp. these are 1%

A.
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Old 7th July 2018, 04:34 PM   #4
Skip Pack is offline Skip Pack  United States
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Thank you both! Checking out the MKCs and the 1837s online, I see no values below .01uf. What other type of cap would be good for .001-.0047ufd? As an aside, I'm surprised that the small value Roederstein/ERO and Wima MKC caps are not as expensive as I thought they might be.

Skip
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Old 7th July 2018, 05:02 PM   #5
tomchr is offline tomchr  Canada
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There are plenty of ceramic options in the 1 pF - 100 nF range. Just pick one with an NP0/C0G dielectric.

Tom
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Old 7th July 2018, 05:11 PM   #6
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Caps for a Not-So-Bright Idea
for these - if not (selected) silver mica , I;m simply using biggest SMD I can find

if I need through hole , I just solder tiny wires on them
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Old 8th July 2018, 03:37 AM   #7
Skip Pack is offline Skip Pack  United States
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Once again, Thanks. I'm thinking that capacitance meter my be in my near future. Will an inexpensive unit that covers a good range be adequate for selecting the closest match from handful of caps?

Skip
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Old 8th July 2018, 07:32 AM   #8
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Caps for a Not-So-Bright Idea
it depends of your luck

some are cheap and good , some are drek
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Old 8th July 2018, 04:07 PM   #9
Skip Pack is offline Skip Pack  United States
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Worth a try. I can test the same group of caps multiple times over several days to see how consistent he results are. It's consistency rather than accuracy that would seem to matter here.Thanks again.
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Old 8th July 2018, 09:30 PM   #10
chede is offline chede  Germany
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Caps for a Not-So-Bright Idea
Quote:
Originally Posted by Skip Pack View Post
...What other type of cap would be good for .001-.0047ufd?

Skip
WIMA FKP2. I like to use them for the values that are too large for silver mica (FKP2 are available from 33 pF on) up to a few nF. When I can't get the value I'm looking for in FKP2, I try to move to WIMA MKP10.

You can get the FKP2's in 2.5% rated tolerance.

Best regards,
Claas
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