[sdiy] VCF caps in modern synths

Roman Sowa modular at go2.pl
Mon Jan 11 11:41:26 CET 2021



W dniu 2021-01-08 o 17:31, Mike Bryant pisze:
> No 1mV is large and worrying.  What brand was it ?   For 1-10uF I only use Samsung
I can't be sure, I took it from my P&P spit-it-out bin. Might have been 
Murata or AVX.
I don't use Samsung since the time I saw them cracking in pieces while 
soldering. Only few of them, but never experienced that with other 
brands. Again this may be more my personal trauma with Samsung rather 
than scientificaly proved lack of quality.
> If you recall the first mobile phones had lots of 'handling noise' as they were stuffed full of microphonic components, not just SMD capacitors but even microphonic connectors, as well as poor microphones.  It was a good decade before they were properly quiet.
Actually I can't recall any handlig noise, but I was using cellphones 
only since 1998.

>
> Agreed that sounds like dielectric effect.  Only expect to see that sort of percentage with electrolytics.  Definitely well out of spec - 2.5% is the worse spec I've seen even on crap Chinese brands.
>
> Surprised you even had a 1nF X7R to hand - at that size the price difference is minimal.
Whatever the reason was it got into my hands, was not the price. It was 
probably sitting 10 years in my drawer. Maybe at the time of purchase 
the store didn't have C0G of that value so I got X7R for a project that 
wasn't so immune to dielectric type.
For some reason today you can still buy sub-pF capacitors in X7R, as 
well as 0.1uF electrolytic caps.

Roman



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