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Old 19th January 2011, 03:29 PM   #1
210 is offline 210  Germany
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Default Bypass capacitors in cd players

Does anyone measured or simulated the impedance curves
of bypassed capacitors typical used for modding CDPs ?

This would be Nichicon Muse ES (=bipolar) 22-47uF for the output stage,
or Wima MKS (when there's enough room to use film capacitors),
and Panasonic FC 100-4700uF for the power supply,
both bypassed with Wima PTF (SMD1812 or 2824) 0.1-2.2uF.
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Old 19th January 2011, 06:35 PM   #2
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I guess, the impedance curves of
3300uf-FC (RM7.5) parallel with 1uf SMD2824 (h3mm)
and 33uF-ES parallel with 100nF SMD1812 (height:3mm)
will be the most interest (fit the most circumstances)
and 22uF-MKS parallel with 470nF SMD1812 (5x3xh4mm).
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Old 19th January 2011, 07:45 PM   #3
Xoc1 is offline Xoc1  United Kingdom
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The best bi-pass cap for the output of a CDP is a wire link!
Often the DC blocking capacitor can be removed without causing any problems.
There is some interesting information on using bi-pass capacitors in this thread
Best electrolytic capacitors
The resonance between the different capacitor values is shown, and how this actually increases the impedance of the capacitor network at lower frequencies.
Neverless many people use bi-passed capacitors with good results.
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Old 19th January 2011, 09:54 PM   #4
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Thanks Xoc1!
I'd like to use a transformer (DM2-2RR) at cd outputs (which have offset)
so decoupling caps avoids magnetizing of the transformer (and subsonic).
It seems, that bipolar Muse-ES have quite high ESRs, alternatively
MKS caps should have a wide flat impedance curve.

Bypass caps for the big electrolytics of the power supply
are imho no problem as long as there are more regulators
and caps afterwards before supplying the analog stage.

Elsewhere I'd only bypass FCs if they just supply digital sections.
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Old 19th January 2011, 10:19 PM   #5
Bill_P is offline Bill_P  United States
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Here are impedance curves for a few ES capacitors.
Attached Files
File Type: pdf Nichicon ES Impedance.pdf (114.1 KB, 120 views)
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Old 20th January 2011, 03:30 PM   #6
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Thank you, Bill_P!
I'l bypass 22uF/25V-ES with 330nF-SMD1812
not just to increase their lifetime stability, but
to squeeze out the very last attoBel highs
for my whizzers.
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Old 20th January 2011, 07:35 PM   #7
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My previous post is not correct.
Bypassing with those little SMD caps
increases the impedance curve at first
and thereby reduce the output of upper highs.
The same for the PSU electrolytics,
an increased source resistance is also bad.

The little SMDs dont't have enough capacity.

The situation is maybe different when
networking with an output transformer.
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Old 21st January 2011, 09:17 AM   #8
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The RM for the output capacitors of cheap cd players is usually 5mm.
The biggest capacity of Wima SMD polyester caps that fits RM5mm is 470nF.
The minimum load resistance for cdp outputs is typically 10kOhm.
So the -3dB point of the 470nF-SMD alone will be 34Hz.
When working in parallel with (for example) a 22uF-ES
there will probably increased highs (even the ratio between
the resistance of the bypassed cap and the load is little),
but the resonant behaviour of the bypassed cap
in the bass region can be negative.
I'll try it...
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Old 21st January 2011, 10:07 PM   #9
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22uF-ES and 47uF-ES don't sound as they need a bypass cap.
I'll try bypassing MKS4-22uF with 470nF-SMD1812 next time
(MKS4/100V/RM27.5mm alone sounds quite harsh to me).
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Old 24th January 2011, 07:20 PM   #10
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There are some Murata SMD high caps with nice esr curves :

1uF/100V/X7R/G1206 (Murata grm31c72a105k)
and 4,7uF/50V/X7R/G1206 (Murata grm31cr71h475k)
(see attachments below).

I'll try the 4.7uFs for sound tuning some analog output caps
(hope to get a more punchy bass out of my DA500 (bypass 22uF/16V/Bipolar/Es)
and to get a somehow smoother sound out of my DPF3030 (bypass 22uF/100V/MKS4)).

Near the power supply pins of the DACs etc. are 10-100uF Electrolytics bypassed with Ceramics.
I'll exchange the Electrolytics with Tantal, bypass them with the high caps (1uF||10uF or 4.7uF||100uF)
and exchange the ceramics with mica (<1nF) or MKS2 (100nF).
Hope it will work fine and try some measurements later.


Here are some dissipation factors out of datasheets:

Ceramic(<50pF): <0.5% at 1MHz.
Ceramic(>50pF): <0.15% at 1MHz.
Mica: <0.15% at 1MHz.
MKS: <=1% at 1kHz.
MKS(<0.1uF): <3% at 100kHz.
X7R(100nF/50V/G1206): <=2.5% at 1kHz
Tantal(1uF-220uF): 4-12% (guess at 1kHz).
Panasonic FC (<1000uF/50V): 10% (guess at 1kHz).

X7R capacitance decreases (to 50% and less) when voltage goes up to Umax.
Attached Images
File Type: jpg grm31cr72a105k.jpg (78.3 KB, 321 views)
File Type: jpg grm31cr71h475k.jpg (96.1 KB, 310 views)
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