C0G vs normal ceramic caps

Sergimm

Sergimm

Active Member
Hi,

I've seen several restorations (especially in some of Leestereo's) in which they replace traditional ceramic caps with a C0G version with the same properties. Apparently C0G caps are less noisy and better in almost every aspect.

What I haven't been able to find out is whether there is a visual difference between a C0G and a normal ceramic cap? DIY'ers always brush over about how they find out that the caps are not C0G. Is it just a matter of systematically replace all ceramic caps (or at least the ones in the signal path) with known C0G ones?
 
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The TDK FA caps are all medium blue in color and are generally a bit smaller in diameter than the plain ceramic caps but are a bit fatter, as seen in this second photo.

DSC05957.JPG

My best understanding is that the ceramic disk caps are piezoelectric and will introduce noise when vibrated, while the C0G(NP0) MLCC caps are the only type of ceramic caps that do not have those piezoelectric properties.

I hope that I am understanding your question correctly and this helps.

Cheers,
James
 
Also, using the service manual for the unit in question you can read through the parts list and all ceramic disk caps should be identified as such. The schematic will normally have a key somewhere that shows the different symbols used for each different type of cap.

In the above photos all of the red and pink caps are all film caps.

Cheers,
James
 
Bratwurst7s said:
The TDK FA caps are all medium blue in color and are generally a bit smaller in diameter than the plain ceramic caps but are a bit fatter, as seen in this second photo.

My best understanding is that the ceramic disk caps are piezoelectric and will introduce noise when vibrated, while the C0G(NP0) MLCC caps are the only type of ceramic caps that do not have those piezoelectric properties.

I hope that I am understanding your question correctly and this helps.

Cheers,
James
Click to expand...

Thanks a lot for your explanation, it is very helpful. I guess my question was about whether I could easily identify them to not have to replace them all (is it necessary to do them all, or just signal path?). All the ceramic caps in my unit (Marantz 1050) are plain brown ceramic caps, so I assume none of them are C0G(NP0).

Did you actually notice a difference in the amp sound?
 
One more question: In my schematic, someof the ceramic caps have a voltage specified and some don't. Is it ok to use a very high voltage on the ones without voltage specified? I guess I can measure the voltage at that point in the circuit...but is it worth it? If I go ahead and replace these with 200V-500V caps, could there be a problem?
 
Sergimm said:
...I could easily identify them to not have to replace them all (is it necessary to do them all, or just signal path?)...
Click to expand...

IMO, only the signal path ceramic capacitors should be replaced e.g., low-pass filter.

Sergimm said:
All the ceramic caps in my unit (Marantz 1050) are plain brown ceramic caps, so I assume none of them are C0G(NP0)...
Click to expand...
Some Marantz did have stock NP0 capacitors (e.g., 2270 P450 board), and they are identified as such on the part itself.
 
Sergimm said:
One more question: In my schematic, someof the ceramic caps have a voltage specified and some don't. Is it ok to use a very high voltage on the ones without voltage specified? I guess I can measure the voltage at that point in the circuit...but is it worth it? If I go ahead and replace these with 200V-500V caps, could there be a problem?
Click to expand...

Install C0G capacitors that are rated above the power supply rail voltages (B+, B-) indicated in the schematic; a quick reference is to use C0G capacitors rated above that of the main power supply capacitors.
 
Leestereo said:
Install C0G capacitors that are rated above the power supply rail voltages (B+, B-) indicated in the schematic; a quick reference is to use C0G capacitors rated above that of the main power supply capacitors.
Click to expand...

Thanks, that makes it all clear!
 
Original ceramics are easy to identify. They're mostly all perfectly circular with a rough, matte finish (yellow/brown/orange) that you can scrape with your fingernail like a nail file, while COG/NP0 MLCC's are usually not perfectly circular, but smooth, generally smaller/ coated with a shiny finish. A bit less "grit and grain" with the MLCC's (at least to these ears).
 
COG caps hold their value better over temperature, and have a lower capacitance change vs. applied voltage than other ceramic types. They also don't need to be de-aged after being heated to soldering temperatures for a minimum amount of time. They are among the best ceramic has to offer.
 
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