Electro caps vs MLCC SMD caps?

[Song Naga]

Hi all, I'm throwing together a pedal based on the 424 and am wanting to use SMD components where they make sense. I've built a lot SMD synth projects and find that it's easier and cleaner to build SMD rather than thru-hole, plus they take up less space and generally cost a little less to produce. I'm wondering if there would be any adverse effects to using 10uF MLCC SMD caps (like this one from Mouser) in place of electro caps. I know my synths do this all the time, so I guess that it works, but I'm curious what if any effect it might have on the sound quality of the pedal. I guess the same question goes for film caps as well, is there any advantage to using them on a SMD build when there are MLCC SMD equivalents available? Thank you for any input!

 

[z2amiller]

There's been a lot of 'ink' spilled on this on various forums. The general advice that I've synthesized is that MLCC caps are fine if you use NP0/C0G dielectric caps in the audio path, but that the other MLCC caps can be microphonic at audio frequencies (e.g. they can become both a microphone and a speaker due to piezoelectric effects). So for stuff like bulk bypass caps the X5R/X7R caps are okay but for things directly in the audio path they're not great.

In my designs I usually use C0G caps up to 220nF (1206 size) and then go through-hole film up to 1uF, then SMD electro.

Honestly though it's "probably fine" to use MLCC caps everywhere. I doubt most people can hear a
difference but I've never 'blind taste tested'. I haven't done it myself because the C0G and SMD
electros are cheap enough, though sometimes I do contemplate adding X7R MLCC caps to save board space
and PCB assembly cost (every electro is an 'Extended' component at JLC)

 

[Song Naga]

There's been a lot of 'ink' spilled on this on various forums. The general advice that I've synthesized is that MLCC caps are fine if you use NP0/C0G dielectric caps in the audio path, but that the other MLCC caps can be microphonic at audio frequencies (e.g. they can become both a microphone and a speaker due to piezoelectric effects). So for stuff like bulk bypass caps the X5R/X7R caps are okay but for things directly in the audio path they're not great.

In my designs I usually use C0G caps up to 220nF (1206 size) and then go through-hole film up to 1uF, then SMD electro.

Honestly though it's "probably fine" to use MLCC caps everywhere. I doubt most people can hear a
difference but I've never 'blind taste tested'. I haven't done it myself because the C0G and SMD
electros are cheap enough, though sometimes I do contemplate adding X7R MLCC caps to save board space
and PCB assembly cost (every electro is an 'Extended' component at JLC)

Thanks! I kludged this together which has SMD for everything but the 47u and 100u caps in the circuit. I'll order a couple and see what it sounds like! The circuit sure doesn't take up much space using these 0805 and SOIC-8 footprints!

 

[khanji]

For most pedal applications, good quality SMD MLCC capacitors work very well, even at 10µF. If you're looking for audio perfection, or for sensitive stages like op-amp coupling, high-quality film or electrolytic capacitors can provide a slight improvement.