SOLVED Magnetron delay helicopter/zipper noise

[blackhatboojum]

I’ve been searching the web and this forum to find a solution to my problem but I’m coming up blank. My magnetron delay build that I just completed, has a fast paced thumping noise almost like a helicopter. The more you turn up the level control, the louder it gets. The more you turn down the delay time, the faster it gets. I tested all the caps and resistors before I installed them to make sure they were good. Triple checked my solder connections, reflowed any and all of the ones that might be questionable. Looked for solder bridges but didn’t find any. I also tried 2 different power supplies but the noise remains. All the controls on the pedal work as I expected, there’s plenty of repeats with the feedback knob, the modulation works fine, delay time works fine, it’s plenty loud enough just, this damn noise. All of my research kinda points me to zipper noise caused by the pt2399 chip but I don’t know for sure. Any help would be greatly appreciated


Here’s a video link to the noise.

 

[giovanni]

It sounds like the delay time oscillator is leaking to the output. Not sure how that can happen, but the first question I have is: where did you get the PT2399 from? I have heard plenty of bad ones...

 

[blackhatboojum]

Thanks for the reply. I purchased it from Tayda and only purchased one. Now that I've done some research on the pt2399 I realize... I should've purchased several.

 

[zgrav]

try moving your input and outupt wires to different spots inside your enclosure to see if that makes a difference.

 

[blackhatboojum]

try moving your input and outupt wires to different spots inside your enclosure to see if that makes a difference.

I tried that. It didn't help. I currently have the guts outside of the enclosure and it's still making the noise.

 

[chongmagic]

The best practice with ICs is to use sockets, then you can remove them more easily. It does sound like the PT2399 could be a dud.

 

[blackhatboojum]

The best practice with ICs is to use sockets, then you can remove them more easily. It does sound like the PT2399 could be a dud.

I totally had thought while I was soldering everything in but, impatience got the better of me. Lesson learned the hard way. I'll be using sockets from now on. This isn't my first pedal build but, the first of this magnitude. Also my first delay build. Thanks for the input.

 

[blackhatboojum]

Problem is now solved. It was the pt2399 chip. I bought a dozen through Amazon and tried everyone until I found my favorite. These chips are definitely hit or miss. One was DOA. One produced some of the freakiest noise I’ve ever heard, and another one sounded just like the first chip I put in. Thanks again for everyone’s input .

 

[giovanni]

I built a delay years ago and it was super noisy and now I think I need to try a few more chips

 

[blackhatboojum]

I built a delay years ago and it was super noisy and now I think I need to try a few more chips

I would give it a go. I was amazed how much of a difference there was between them