Dark Rift Delay - Distortion/Fuzz in Wet Signal

[absolvism]

Hello!

I just finished building a Dark Rift, and everything seems to be working... except the repeated/wet/delay signal has a distortion/fuzz in it..

So the first pluck always sounds normal, but then all the succeeding delay signal has a very pronounced fuzzy/scratchy undertone to the whole thing. I've tried different amps and cables and it appears that it's definitely in the pedal itself. If I set the mix to 100% dry, there is no fuzz, it's just in the wet.

Besides pulling the whole thing apart and starting over, does anyone have any ideas or directions to troubleshoot that they might be able to help point me in? I can record example audio if that would help.

Thanks so much in advance,
Ellis

 

[zzzmalo]

Hello

I had the same distorted delay problem.

I follow instruction on Reddit, I 've replaced R7 and R18 to 27K,
and R13 to 33K (user named Spectronicles suggest 29k, but I didn't have one...).
It seems to work perfectly now. Nice.

 

[Chuck D. Bones]

Hello!

I just finished building a Dark Rift, and everything seems to be working... except the repeated/wet/delay signal has a distortion/fuzz in it..

So the first pluck always sounds normal, but then all the succeeding delay signal has a very pronounced fuzzy/scratchy undertone to the whole thing. I've tried different amps and cables and it appears that it's definitely in the pedal itself. If I set the mix to 100% dry, there is no fuzz, it's just in the wet.

The usual causes of distortion in a PT2399 are:
1. Input signal too large. Is there a boost or dirt pedal before the Dark Rift?
2. Bad PT2399. There are some PT2399s that exhibit this problem and there are others that do not. Did you socket your PT2399?

Besides pulling the whole thing apart and starting over, does anyone have any ideas or directions to troubleshoot that they might be able to help point me in? I can record example audio if that would help.

Thanks so much in advance,
Ellis

Post detail photos of your board.
Describe any parts subs or mods.
Describe how your Dark Rift is connected in your rig. What is up stream & downstream?
Perform a thorough visual inspection of both sides of the board. The vast majority of pedal problems are caused by workmanship.

Hello

I had the same distorted delay problem.

I follow instruction on Reddit, I 've replaced R7 and R18 to 27K,
and R13 to 33K (user named Spectronicles suggest 29k, but I didn't have one...).
It seems to work perfectly now. Nice.

Increasing R7 reduces the signal going into the PT2399, which increases headroom at the expense of reduced SNR. Increasing R13 recovers some of the signal level lost by increasing R7. Changing R17 does nothing because EQD screwed up the two output filters (IC3). C22 is connected to the wrong side of R17. Same goes for C18.

 

[DSFX]

Hello!

I just finished building a Dark Rift, and everything seems to be working... except the repeated/wet/delay signal has a distortion/fuzz in it..

So the first pluck always sounds normal, but then all the succeeding delay signal has a very pronounced fuzzy/scratchy undertone to the whole thing. I've tried different amps and cables and it appears that it's definitely in the pedal itself. If I set the mix to 100% dry, there is no fuzz, it's just in the wet.

Besides pulling the whole thing apart and starting over, does anyone have any ideas or directions to troubleshoot that they might be able to help point me in? I can record example audio if that would help.

Thanks so much in advance,
Ellis

I had similar issues with a space spiral clone and solved it by increasing the value of the resistor feeding the pt2399 to lower the input signal. I also fiddled with the resistor in the dry signal and the last gain stage to get unity back. I can’t remember the values but I posted it in a Reddit thread somewhere.

 

[DSFX]

Hello

I had the same distorted delay problem.

I follow instruction on Reddit, I 've replaced R7 and R18 to 27K,
and R13 to 33K (user named Spectronicles suggest 29k, but I didn't have one...).
It seems to work perfectly now. Nice.

Hah! Yes that was me, fixed mine perfectly, glad it worked for you too.

 

[DSFX]

The usual causes of distortion in a PT2399 are:
1. Input signal too large. Is there a boost or dirt pedal before the Dark Rift?
2. Bad PT2399. There are some PT2399s that exhibit this problem and there are others that do not. Did you socket your PT2399?


Post detail photos of your board.
Describe any parts subs or mods.
Describe how your Dark Rift is connected in your rig. What is up stream & downstream?
Perform a thorough visual inspection of both sides of the board. The vast majority of pedal problems are caused by workmanship.


Increasing R7 reduces the signal going into the PT2399, which increases headroom at the expense of reduced SNR. Increasing R13 recovers some of the signal level lost by increasing R7. Changing R17 does nothing because EQD screwed up the two output filters (IC3). C22 is connected to the wrong side of R17. Same goes for C18.

I hadn’t noticed the issue with the output filters!

 

[Chuck D. Bones]

Any thoughts on why the PT2399 was being overdriven? Hot or active pickups? A pedal upstream of the Space Spiral with too much output?

 

[captainboom]

Hi everyone,

This is my first post here. I've been lurking a little bit and start being quite addict to this hobby!
I've 3 builds done, and just finished this one. I got the same fizz/distortion effect on the wet signal and the green led is doing the trick.
I think I will trim down the signal before the PT as some people suggest here.

One question though, I got a quite low signal compare to the original. Even with the mix pot all the way down, the dry signal is significantly low. Still usable, but I'd like to know if it's a normal behavior and/or if the TL072 could be pushed a little bit more to compensate?

Thanks for all the information I've found here

 

[jwin615]

Hi everyone,

This is my first post here. I've been lurking a little bit and start being quite addict to this hobby!
I've 3 builds done, and just finished this one. I got the same fizz/distortion effect on the wet signal and the green led is doing the trick.
I think I will trim down the signal before the PT as some people suggest here.

One question though, I got a quite low signal compare to the original. Even with the mix pot all the way down, the dry signal is significantly low. Still usable, but I'd like to know if it's a normal behavior and/or if the TL072 could be pushed a little bit more to compensate?

Thanks for all the information I've found here

More likely a wrong value resistor or cold joint than a bad 072, assuming you sourced the 072 from a reputable vendor. I haven't built this circuit so maybe this is a feature and not a big. Perhaps other will chime in.
Start by double checking your resistor values and checking for any solder bridges and cold joints. If you haven't mastered reading the bands, search the forum for a build report with clear gut shots and visually compare each resistor.
Regarding the delay distortion, pt2399s can vary in performance pretty greatly. Not just lot to lot but unit to unit. It's good to keep several on hand. Amplified parts has the best price from reputable dealers at 1.70/each. If trimming the input doesn't fix that, gonna need more chips. I'd suggest getting at least 3 more.
If you still have issues after checking values and swapping the chip, it may be worth starting your own thread.
Good luck

 

[Chuck D. Bones]

Hi everyone,

This is my first post here. I've been lurking a little bit...

If you've been lurking in the Troubleshooting forum, then surely you have seen how we do it here.
1. Start a new thread for troubleshooting your pedal.
2. Post detailed pictures of both sides of the board.
3. Recheck all of your component values and orientations against the build docs. We're here to help but you need to do your due diligence.
4. Explain all of your mods or parts subs.
5. Be prepared to make and report voltage and continuity measurements.
6. Be methodical. Do not start swapping parts at random unless you are 100% sure the part is the wrong one. Do not assume that an opamp or delay chip is bad.

Good luck and welcome to the forums.

 

[Feral Feline]

Damn, Dave, that post right there should be a sticky.

 

[captainboom]

If you've been lurking in the Troubleshooting forum, then surely you have seen how we do it here.
1. Start a new thread for troubleshooting your pedal.
2. Post detailed pictures of both sides of the board.
3. Recheck all of your component values and orientations against the build docs. We're here to help but you need to do your due diligence.
4. Explain all of your mods or parts subs.
5. Be prepared to make and report voltage and continuity measurements.
6. Be methodical. Do not start swapping parts at random unless you are 100% sure the part is the wrong one. Do not assume that an opamp or delay chip is bad.

Good luck and welcome to the forums.

Sorry for this. I didn't see the rules above. Thanks for the reminder. I'll open my own thread if I still struggle finding the issue.