Cap choice for analog stage filters?

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barrows

Member
2010-07-23 11:28 pm
I was wondering what type/brand of caps people like, and why, for the filter in the analog stage of DACs. Considering values from 500 pf to 15 nF or so. Polypropylene film/foil, vs polystyrene film/foil, vs. silver mica, vs. ?
Wima, Amtrans polypropylene film/foils, vs. REL polystyrene, vs. silver mica, vs. Vishay Sprague orange drop polyester film, vs???
 
Teflon first, evox/rifa PFR range film and foil, SMD PPS film (evox/rifa, Wima or panasonic films), Amtrans polypropylene film. then Vishay MKP-1837.

forget wima, in the size you are looking at the evox rifa PFR film and foil are better in every way, like being able to use a little mundorf supreme in a small 5mm lead package. close anyway. not so easy to find though and the range of capacitance is limited, but your 500pf->15nf is covered. (only up to 22nf)

wima are OK, but not worth the attention they get on this forum IMO, I think its the pretty red colour
 

barrows

Member
2010-07-23 11:28 pm
Thanks...

qusp. A mini Mundorf Supreme sounds great to me. Unfortunately an internet search did not result in much luck for me, unless I want to purchase 1000s of them.
I am looking for 1 nF and 10 nF, any ideas on sources? I only need a handful, perhaps 16 of each or so...
 
here ya go they have a good range of other caps there too. for example the legendary rifa PHE169 low Z PSU cap. probably the best power supply cap available. so I just linked to the rifa page, you'll see them there as the small blue leaded caps like wima or vishay size box caps. they have ampohm copper foil and film caps there too for output caps if you are keen. another good value. all others in this physical size are metalized polypropylene, not true film and foil

damn, they dont have the values you need, but maybe ask them. sorry I just new they had them and that they came in those sizes. they will order them in for you perhaps, they do that with their other caps
 
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barrows

Member
2010-07-23 11:28 pm
Thanks

qusp, I had found these guys-I will go ahead and see if they can get the values I need. I have some polyester orange drops (Vishay-Sparague) here as well-but these are steel leaded, I really would like to avoid steel leads.
For a future Legato board build, and some mods on other stuff...
 

jcx

Member
2003-02-17 7:38 pm
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I haven't found any polystyrene that explicitly state that they are extended foil construction - some of the NOS boxed types?

the common "jelly roll" fused polystyrene/foil will be inductive at frequencies where DAC switching glitches, clock feedthru components are expected

most of the current production Boutique audiophile polystyrene are physically too large (high parasitic inductance/low SRF), as well as too high in value
 
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jcx

Member
2003-02-17 7:38 pm
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I realize the glare from JC's halo makes it hard to see other poster's points - but the Blowtorch thread recently touched on caps again - and someone pointed out that extended foil polystyrene are available

LCR EXFS series boxed polystyrene should be superior in very high frequency performance to the Boutique caps - which should be important in a DAC output circuit

It was also pointed out in those discussions that for microphonics mass production caps made on high speed winding machinery could be better than the “hand wound by virgins” Aduiophile caps of the same materials
 

barrows

Member
2010-07-23 11:28 pm
Thanks...

JCX. I appreciate your concerns about avoiding potential inductance for high frequency filter circuits. The REL RTE are a "box" style cap, but I do not know if they are wound or stacked internally. These are small caps though, and I doubt that they are hand wrapped by either angels or virgins!
Do you have a source for the caps you are referencing?
 

jcx

Member
2003-02-17 7:38 pm
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viewing the rel cap site Reliable Capacitors it is NOT clear - the "RT" series is the only polystyrene listed - and doesn't go down to 1nF

some audio Boutique distributors have the 600 V RTE boxed caps - at ~$8 a pop - you get the 5 pc min of the LCR EXFS for the price of 1 RTE

but I don't see RTE speced on RelCap's site

I would be perfectly happy using current production, fully speced extended foil ps caps but "the story" isn't complete re REL from what can be seen online
 
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