SOLVED XC Phase not phasing

[VanWhy]

Could use another set of eyes on my XC Phase build. Plugged in I got sound, like a boosted signal but no phasers. Quad matched set of smd jfets from Lectric FX. I had the adapters in the opposite way and still the same thing. I'm 76% sure they are oriented right. Can this symptom be attributed to the transistors? Or something else? Only other thing is I have a 200k trim pot in there since don't have a 250k.

 

[Robert]

I'm not familiar with those adapters but if they're 2N5952 you have them oriented correctly. 2N5457 is opposite pinout.

Have you adjusted the trim pot?

 

[mkstewartesq]

Which JFETs are you using - 2N5952 or 2N5457s? Both will work but I believe the pinouts are opposite.

OK, probably two stupid questions but, just to be safe:

1. Did you move very slowly through the trim pot sweep? The area in which there is phasing is actually a very tiny amount of the sweep. You get no phasing, then in a very tiny area, phasing, then no phasing again. The 200 K pot should be fine(in fact, I believe that’s what I and others used as well.)

2. Is your input jack grounded? I just don’t see a ground wire running from it. (doesn’t address your issue, but just thought I would ask).

EDIT-Dammit, ninja’d by @Robert

 

[Robert]

EDIT-Dammit, ninja’d by @Robert

Your answer was a lot more thorough.

 

[jwin615]

Your answer was a lot more thorough.

Sorry for the highjack VanWhy.
Any chance of a modified footprint for the more sensitive circuits to use 3296 trimpots? Seems like multiturn could be beneficial in some instances, for those who choose.
Or is vertical clearance an issue?
I've yeat to figure out why these are so avoided in the hobby. Yeah. You can spin them out, but you only do that thrice until you learn your lesson...

 

[Robert]

Any chance of a modified footprint for the more sensitive circuits to use 3296 trimpots?

Let me pull the datasheet and check out the pin spacing and dimensions. It should be as simple as adding an additional pin in the dead center of the current hybrid footprint.

Something like this:

 

[jwin615]

Let me pull the datasheet and check out the pin spacing and dimensions. It should be as simple as adding an additional pin in the dead center of the current hybrid footprint.

Something like this:
View attachment 60578

Bonus points if it's 9mm pot compatible.
But going to need an extra build doc page or sticky to explain it.

 

[VanWhy]

I'm not familiar with those adapters but if they're 2N5952 you have them oriented correctly. 2N5457 is opposite pinout.

Have you adjusted the trim pot?

They are actually the smd version of 2N5457. So maybe they are in backwards? Would they work at all if backwards?

@mkstewartesq I did go through the trim pot but not super slow. I will try that. I stopped using the ground connection on the output sleeve when I saw @Guardians of the analog do it. Its worked on all my last builds since i started it.

 

[VanWhy]

Sorry for the highjack VanWhy.
Any chance of a modified footprint for the more sensitive circuits to use 3296 trimpots? Seems like multiturn could be beneficial in some instances, for those who choose.
Or is vertical clearance an issue?
I've yeat to figure out why these are so avoided in the hobby. Yeah. You can spin them out, but you only do that thrice until you learn your lesson...

No worries. Got to strike while the irons hot sometimes.

 

[Robert]

Yes, if they're 2N5457 they need to be installed backwards.



Once you have them installed correctly try turning the trim pot back and forth while listening, you should hear a phase shift while turning the pot.

 

[VanWhy]

I think this build is cursed. Never had this happen before. I replaced and still no phasing. Im almost positive the transistors are oriented correctly.

 

[Robert]

Im almost positive the transistors are oriented correctly.

Yep, I agree.


Do you hear any change whatsoever when turning the trimpot?

 

[VanWhy]

Yep, I agree.


Do you hear any change whatsoever when turning the trimpot?

Nope, no change. Hooked a loop up to it last night and turned the hell out of it.
Sign of faulty transistors maybe?

 

[mkstewartesq]

Agreed that your JFETs seem to be oriented properly.

I see you replaced one of the TL072s with a TL022, which was a fix I found and promoted here when my XC Phase wasn't working properly (ticking, distortion in some modes). It fixed mine and also similar problems others were experiencing.

But not everyone experienced the problems I did, and some reported that the XC Phase functioned just fine with the 3 TL072s as per the docs. Maybe you're in that camp where you should try the "stock" build (all TL072s) just to be sure?

M

 

[Fuzzbuzz78]

Sorry to bump in after the party. Looking at your build and it looks like you are missing a ground that should be connected to your input jack (to the right of your negative lead feeding your AC power.

 

[KR Sound]

Sorry to bump in after the party. Looking at your build and it looks like you are missing a ground that should be connected to your input jack (to the right of your negative lead feeding your AC power.

They’re all connected via the enclosure. That connection is basically a failsafe if the jack gets loose and doesn’t have a good hold on the box.

 

[southpaw-dd]

Let me pull the datasheet and check out the pin spacing and dimensions. It should be as simple as adding an additional pin in the dead center of the current hybrid footprint.

Something like this:
View attachment 60578

3266W will work in the existing footprint as a 12-turn trimmer. I used that for a recent XC Phase build.

https://www.bourns.com/data/global/pdfs/3266.pdf

 

[VanWhy]

Welp, I finally got around to swapping the transistors and BOOM! She is phasing now! I got an extra set of 2SK208-GR's from AionFX and they are working great now. Not sure what was up with the set from Lectric Fx. Could have been user error.