Go Back   Home > Forums > Blogs > RJM Audio Blog

If I put my notes here, I might be able to find them again later!
Rate this Entry

Ceramic capacitors : who knew?

Posted 12th May 2012 at 01:15 AM by rjm
Updated 28th May 2012 at 11:51 PM by rjm

This I have been experimenting - call it a hunch - on the effects of bypassing electrolytic capcitors (Nichicon FW and KW) with 0.1 uF TDK ceramics (Mouser 810-FK28X7S2A104K) with the diamond buffer circuit used in both my B-board preamp and Sapphire headphone amplifier.

This being a mod, I had to solder the caps to the underside of the boards, attached to the leads of the Nichicon 100uF electrolyic capacitors.

I used four ceramics per channel, one per active device in the diamond buffer if you like.

I did several other changes on the B-board at the same time, so it wasn't obvious until I modded the Sapphire in the same way what was the result of the bypassing. Anyway, with both the improvement was immediate and dramatic: any sense of "transistor-like" treble glare is completely quenched. The whole top end takes a step backwards, not in extension, but in prominence.

Less audiophile detail, more swinging mojo.

Update May 30th.

After a couple of weeks living with this mod, and having had it independently confirmed by another Sapphire owner, I can say that my assessment above has not changed. The addition of ceramic bypass capacitors makes the output subjectively quieter, with a lower noise floor, better spacial definition, and no "fizz" exciting the treble frequencies. However, the very same tendencies can be interpreted negatively, since it's now missing the poorly-controlled splash to the top end than can give the music a sense of energy and airiness. "Sucks the energy out of the treble." would not be considered a complement, but what if that treble energy was an artifact of amplifier circuit in the first place? At the end of the day it's what you prefer, not which is more correct. For myself I will be keeping the bypass caps in there, and they will be included in the Sapphire and B-Board BOMs going forward. People who already bought boards/kits can get the necessary caps from be on request to make the update.
Attached Thumbnails
Click image for larger version

Name:	810-FK28X7S2A104K.jpg
Views:	1885
Size:	13.2 KB
ID:	682   Click image for larger version

Name:	DSC_1368 1280.jpg
Views:	893
Size:	361.7 KB
ID:	683   Click image for larger version

Name:	DSC_1366 1280.jpg
Views:	654
Size:	288.6 KB
ID:	684   Click image for larger version

Name:	b-board bypass.png
Views:	883
Size:	24.7 KB
ID:	691   Click image for larger version

Name:	b-board GZ 10e board bypass.png
Views:	1364
Size:	26.0 KB
ID:	692  

Click image for larger version

Name:	pcb-sapphire-14s1-brd-bypass.png
Views:	2041
Size:	37.8 KB
ID:	694  
Views 2954 Comments 1
Total Comments 1


  1. Old Comment
    KMossman's Avatar
    I remember reading, years ago, that bypassing electrolytic capacitors, with say 0.1 uF caps was recommended.

    The reasons why are hazy - sign of old age? - something to do with the electrolytic capacitors not able to respond to higher frequencies as we would assume.
    Posted 5th February 2013 at 12:49 AM by KMossman KMossman is offline

New To Site? Need Help?
Copyright 1999-2017 diyAudio