ZPSDX with MLCCs

[aballen]

I put together my ZPSDX, and I used MLCC.  I have to say I'm not thrilled with the sound.  Does film really make that much of a difference?

If so I'll desolder and reclaim as many of this caps as I can, but that is a real pain.  I figured I would ask before I waste my time.

[madbean]

Can you describe more what you are hearing? What are you not liking about it?

I cannot say whether or not using MLCC for the SDX makes a difference or not since I have only used film caps in that one. But, the Micro version is still very similar and I have built that with MLCC. I guess I need more info on what you are not liking about it.

[stecykmi]

logically, replace key values first and work through the most important components until you get a sound you like. i would start with the caps in the input and output amps, and the feedback filters.

however, i can't say whether there would be any audible difference in sound! what is it about the sound that you dislike?

[aballen]

Sorry Brian, that was a pretty bad post.  It was sounding quite flat.... It is also a bit noisy.

A little too quick to judge on my part, because I think there is something wrong with it.

I've been playing with it more today and I seem to be getting self oscillation in the first 25% of the feedback pots travel.   

I think I need to fix the feedback pot before making comments on how it sounds, clearly I've messed something up....

I'll take suggestions on the feedback thing though

[aballen]

ok here are a couple of pics, I thought maybe the pots were wrong but I've checked them over and over, and I think they are good.

[murdog47]

I'm having the same feedback issue. Haven't had time to tinker with it 

[aballen]

That's weird, any chance you used mlccs?

[aballen]

Ok I fixed the bad sound.  I had my input wired backwards.

Now it sounds a lot like my echo base, but like an echo base on steroids.  Pretty good and I think I'll be able to get a lot more out of this pedal once I play with more.


Still have the feedback issue though.

[madbean]

You were probably hearing a sort of out of phase sound with it like that.

Anyway, changing the Feedback behavior is easy-- just increase R41. Socketing would be a good idea. I would try 10k or 12k.

The different modes have slightly different output levels so some will go into feedback sooner. Also, having the Path switch engaged may also make it go into feedback sooner. R41 is the easiest way to balance it out to your liking.