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Old 23rd June 2011, 05:35 PM   #11
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FWIW, here's my philosophy. The feedback network components are entirely outside the feedback loop. Any non-ideal property of the passive components used for that network will be directly impressed on the amp. If the divider sucks, the amp sucks. Other "stuff" in the circuit is inside the loop, and imperfections will be corrected to one degree or another. The one place where you want "perfect" components is that feedback divider and anything related to it. IMO, there's no problem with modern electrolytics not having a bias voltage, though I never use very low voltage electrolytics (like 6V) as they're lousy in most regards and not terribly reliable. It seems like they fail first in test equipment. Tantalums are bad in audio circuits, though I admit it's of little consequence if no AC voltage ever appears across the part. I'd use at least a decent quality 25V or greater, 220 uF conventional electrolytic for C11. Brand and type can be anything you see a consensus on as being decent- I like Panasonic, Rubycon, Nichicon and Illinois Cap, but I'm pretty cheap.
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Old 23rd June 2011, 05:48 PM   #12
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Quote:
Originally Posted by Andy5112405 View Post
220uF is too large to be fabricated from non-electrolytic type caps.
Says who ?

(e.g. Roederstein MKP1848)
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Old 23rd June 2011, 06:09 PM   #13
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OK. The PCB can't accomodate fields of capacitors when it was designed for some kind of electrolytic.
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Old 23rd June 2011, 06:14 PM   #14
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Only pulling your leg (though you'd be surprised how small a +200uF foil cap in a 100V rating can be)

Me doubt you'll do better with other than the already mentioned fine quality caps.
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Old 23rd June 2011, 06:24 PM   #15
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I'll see how much difference the Pansonic FC makes.

It does sound so much better without the PUMPKIN though.
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Old 23rd June 2011, 08:32 PM   #16
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Elna Silmics will smoothen the highs. Takes about 100 hours to burn in.
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Old 24th June 2011, 09:30 AM   #17
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Just ordered some Elna Simics as well from Hi-Fi Collective.

As they are awkward to change in my set-up I'll go straight to the Elnas when they arrive.
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Old 24th June 2011, 10:55 AM   #18
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Freebee : www.cde.com/catalogs/SEK.pdf

(what-fck, Mallory by CDE ? Oww, 0R6 ESR for the 220uF/63Vdc)
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Old 24th June 2011, 12:42 PM   #19
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For C11 I'm going for Elna Silmic II 220uF / 16V

C8 and C9 are Low ESR Panasonics - what series I'll look when I get the boards out.

All the low value caps are silvered mica.

From what I am learning, C11 would appear to have the most influence on the sound quality ??
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Old 24th June 2011, 06:55 PM   #20
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Don't sweat C8 and C9 to much. They do not have a significant influance and you can tweek them later for the sound you like. C11 is the significant cap and where quality counts.
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