https://aionfx.com/app/files/docs/andromeda_deluxe_documentation.pdf

I really like how this build turned out quite a lot. I got to play it at volume recently and noticed a footswitch pop. I did some digging and found some threads where people said that the output cap can leak. I don't know if I'm measuring it right but between ground and - leg of my output cap, I see 200mV (!). So I think that needs replaced.

Problem: I only have 1uF film caps. The ODR-C specced 2.2uF film caps, which are hard to find and I had 2.2uF electrolytics lying around so I used those instead. The original ODR-1 used a 1uF.

Before I go unsoldering stuff to swap in a nice WIMA 1uF, because I am not ordering a special part for one build, does anyone know why the ODR-C uses a whopping 2.2uF output cap? That seems pretty darn big. The biggest ones I've seen is 1uF (e.g., DOD FX53) and that's the value of the ODR-1.

Bonus pics. The cap in question is the lower-right electrolytic.

I suggest looking at the input instead. The only thing I don't like about the ODR series is lack of a proper coupling cap at the circuit input. Ideally, the gate of the FET should sit a 0vDC. But, real world guitar pedals with switching is far from ideal. Even 50-100mV at the input could cause some switch pop. Take a DC reading at the fx input and see what you get.

BTW: a 1uF film cap with 150k pulldown at the output is more than enough.

Quote from: bean on July 11, 2024, 08:58:58 PMI suggest looking at the input instead. The only thing I don't like about the ODR series is lack of a proper coupling cap at the circuit input. Ideally, the gate of the FET should sit a 0vDC. But, real world guitar pedals with switching is far from ideal. Even 50-100mV at the input could cause some switch pop. Take a DC reading at the fx input and see what you get.

BTW: a 1uF film cap with 150k pulldown at the output is more than enough.

Interesting, I had not thought about the input! I just got done switching out the electrolytic for a film cap on the output. There is now 0 volts on the output as the lord intended.

On the input I've seen varying voltages in the 10mV or less range. I do still get a very slight pop but not nearly as bad as before. However I can't properly test until I get back to playing that amp at volume. I've been doing most of my testing at home on a Hot Rod Deluxe but most of my at volume playing is through a Princeton Reverb reissue. The other thread I found at https://forum.pedalpcb.com/threads/switch-popping.10742/ also was playing through a Princeton. Probably a coincidence but it'll help me rule it out for sure.

P.S. Love your site, I think I linked one of your pages to a friend (I doubt he's built anything with it but you never know).

Quote from: tootsMcgee on July 11, 2024, 08:19:47 PMdoes anyone know why the ODR-C uses a whopping 2.2uF output cap? That seems pretty darn big.

Because its designer doesn't know to what impedance you are going to plug-in it.. 

Building the same, interested to know how the amp on level test came out.

Quote from: matopotato on July 14, 2024, 06:59:11 AMBuilding the same, interested to know how the amp on level test came out.

I haven't gotten back to that amp yet but I just did some testing on my Hot Rod Deluxe. It has a bit of a pop still but at the same level as my other pedals (Distortion+, Bluesbreaker). So just be careful with your output cap and sub in a 1uF film cap if it pops too much with something else. 2.2uF if you can find it of course.

Quote from: tootsMcgee on July 14, 2024, 04:23:58 PM

Quote from: matopotato on July 14, 2024, 06:59:11 AMBuilding the same, interested to know how the amp on level test came out.

I haven't gotten back to that amp yet but I just did some testing on my Hot Rod Deluxe. It has a bit of a pop still but at the same level as my other pedals (Distortion+, Bluesbreaker). So just be careful with your output cap and sub in a 1uF film cap if it pops too much with something else. 2.2uF if you can find it of course.

Thanks. I have the 2u2 film in place.
Was thinking if a 100n on the input is needed. If so 100n on the in to ground?

Quote from: matopotato on July 14, 2024, 04:47:47 PM

Quote from: tootsMcgee on July 14, 2024, 04:23:58 PM

Quote from: matopotato on July 14, 2024, 06:59:11 AMBuilding the same, interested to know how the amp on level test came out.

I haven't gotten back to that amp yet but I just did some testing on my Hot Rod Deluxe. It has a bit of a pop still but at the same level as my other pedals (Distortion+, Bluesbreaker). So just be careful with your output cap and sub in a 1uF film cap if it pops too much with something else. 2.2uF if you can find it of course.

Thanks. I have the 2u2 film in place.
Was thinking if a 100n on the input is needed. If so 100n on the in to ground?

If you look at something like the OD-3 https://aionfx.com/app/files/docs/heliodor_documentation.pdf the input cap appears to come after the pulldown resistor, to allow the pulldown resistor to drain off any leakage (and set impedance). So I'm guessing you could tack a 100n between R1/R2 junction and the gate of the input buffer? Maybe someone else can chime in.

https://nordland-electronics.de/en/blog/odr-1.html claims that the input cap was left out to be more like a tube amplifier, which does not have the input cap usually. Whether or not that affects the sound measurably is outside my wheelhouse.

That input cap (C1) and Q1 Gate bias resistor (R2) form a HPF..

IMHO, any value bigger than 2.2nF should be OK..

edit: I refer to Heliodor schematic posted above..