I usually have the square shaped caps as per the Shruthi kit, but have sourced the flat, round ones.
Is there a difference and will it affect audio quality?
Totally noob question I know, but I figured it wouldn´t hurt to ask (except for my pride; ))
Unless it’s a different grade of ceramic, no. You want C0G/NP0 in temperature-critical parts like filters, if these are just decoupling caps they will be fine even with X7R, Y5V or some other lesser grade.
Hum…wish I knew the grade.
Does the shape coincide with a given grade?
Voltage is 50v
How would you find out what grade they have?
The round ones were bought at Tayda, can´t find any mention of grade on their ordering page or the labels.
The shape doesn’t necessarily tell. From the temp range and tolerance it looks like Y5R. They should go fine everywhere but in a VCF or an analog VCO core.
Shape just means it is a disc (single piece of ceramic dielectric, old school, round) or monolithinc (lotsa layers, squarish, smaller). Works the same. If they don’t say what grade they are then assume the worst. Sometimes discs have a black dot on their top to let you know thy are C0G/NP0-also a J after the value usually means they are 5% tolerance so X7R at worst, usually C0G. The ones you sourced would be fine for bypassing (that size’s typical usage in the Shruthiversum).
I usually use Murata square ones, but sometimes Reichelt only has the disk type in some sizes. Didn’t encounter any issues so far, as said before unless you use them for critical parts, when you need a certain quality…
Thanks for the info guys. I am still in doubt if I should use them or not. Didn´t cost much, so no huge loss, but I would hate to have troubleshooting-sound quality issues.
The worst for me is that sourcing parts takes at least 10 days, so projects would be on hold till I get my new caps.
Here´s a photo of the caps I have. Some (18p, 10p) had the black marking on the very top of the disk. Others don´t.
I have to use them in a Polivoks and a Yellow Magic. Particularly 220p, 100n, 5.6n, 560p.
Would it make a sound quality difference? Would I have any other issues to know about?
There will be no difference in sound quality, unless it’s the VCF capacitors. Then the resonance wouldn’t be as deep. This has been explained when discussing high-precision “Styroflex” caps. Search and take a quick read.
The 100n for the Polivoks are decoupling caps. They´re not the in audio signal path and aren’t very critical at all. The sensitive parts of the Yellow Magic are pointed out like so: Add the film capacitors (2x 33nF, 2x 1nF, 2x 6.8nF or 5.6nF). They are clearly labelled with their value, and are not polarized. Do not put unknown ceramics here. C0G/NP0 should be fine however.
I used the same ones and they worked fine, one place I did not use them was the timing capacitors for the resonator (clock) for the Mega chip. I did not trust them there. I did not use them in the filter either.
As you have no other Caps to compare - how would you know it has an impact on sound?
Just put Film/Styro caps in wherever stated, the tolerance adds to the analog feel. If you want 100% tracking accuracy DIY is not your world
And btw: open an old anlogue classic synth and will discover they used mainly the good old disk type ceramics.
If they use any caps at all, my fellow russian engineers!
The thing that worries me is that the synth designers of old often had no clue when it came to designing PSUs… Plus that the components often were shit - lesson: You gotta know where it counts and where you can get away with not being too picky.
Good points for using these caps.
Of course I was planning on using them wherever the BOM states Ceramic Cap, not film/styro. I have those covered with the appropriate components.
I know electronics of old have these, I was just wondering since MI designs seem so well thought out, that the quality difference might play a role. Or that the digital aspect might have required them. You know, I read about how every last drop of part usability/function seems to have been extracted and taken advantage of in the Shruthis.
It is not that I am aiming for the highest sound purity. Analog feel is fine in my books, heck, even sought after. And I guess it suits the YM and Polivoks character.
I do have the kit-assembled SMR mkII for (relative) purity.
I just hate the feeling that sometimes in DIY, you use what you have, and you end up “restoring a Michelangelo with pre-school watercolors” so to speak.