Aion Refractor Sounds "Spitty" after 30 Seconds

[eskimoquinn]

Well I have an interesting problem (to me anyway). I have built an aion refractor and for the first 30 seconds, sounds amazing. However after that point, it sounds like it is power starved. It gets real spitty and sounds like well, spitty. This only happens when the gain is all the way up. As soon as I turn it down, it sounds good for a little while. Eventually it gets spitty again. I can keep decreasing the gain like this for awhile. My only idea is that I have a leaky capacitor of some kind. But that's really just a guess.

I built this pedal mostly to the instructions here: https://www.dropbox.com/s/4xhwadzx2rxbm8z/aion-refractor-centaur-documentation-v2.pdf?dl=1

The only change from those plans is that I did the tone capacitor mod which changes C14 to 8n2.

Also I have an audio debugger and it sounds good up until about C5.

This is a fairly complicated build (again for me), so help is greatly appreciated. Am I on the right track with thinking capacitor?

[eskimoquinn]

Made a video to demo what I am hearing.

The first 20 seconds are when the pedal sounds spitty. Then I unplug it and plug it back in and it sounds fine for a bit.

(Loud warning)
https://youtu.be/3Ovr32-2Sxo

[Slowpoke101]

Check C16. If it is installed with the wrong polarity the effect will do what you describe (if it works at all).


After a closer look at your pictures, C16 is certainly installed with the wrong polarity. Remove it and replace it with a new one (if you have one) and see what happens. If everything else is OK then it will work.

[eskimoquinn]

Well slowpoke101, you are my hero. And I have learned that tantalum capacitors do in fact have polarity. I thought it was like a ceramic.

Btw man does this sound great now! Thanks again!

[Slowpoke101]

Always happy to help. It is good that you got it working. Have fun with your new toy.

Don't feel too bad about installing the tantalum backwards. It is a very common error and you are in good company.
The small printing on the capacitor's body makes it hard to tell the polarity and quite often the printing is skewed or misaligned which does not help. A bit more confusion can occur due to the fact that on most electrolytic capacitors the negative leg is the one that is marked. On a tantalum it is the positive leg which is marked. Most people are familiar with electrolytic capacitors and quite reasonably think that tantalum capacitors would be marked the same.

The best way to determine a tantalum's polarity is to see which leg is the longest one -that is almost always the positive leg.

[EBK]

Why is C16 a tantalum cap anyway?  Why not a film or electrolytic cap?

[thermionix]

Why is C16 a tantalum cap anyway?  Why not a film or electrolytic cap?

A tantalum is an electrolytic.  Probably someone thought it sounded better there than an aluminum electrolytic.  A film cap would be quite a bit larger, also maybe sound different.