Blue Yonder Schematic Question

jdduffield

jdduffield

Active member
I am attempting to build a Blue Yonder from the schematic. For Q1 and Q2, I’m using 2SK30A JFETs. I’ve noticed it is working, but quieter when the pedal is engaged in comparison to it being bypassed. Is there a resistor value I can swap to affect output volume?

Also, leg 1 of these trim pots go to ground, right? (See photo)
 

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Just a follow up. I put a booster circuit in front of it, which has a single transistor boost to bring the overall volume up. What I’m noticing now is that the gain control never did work properly. When the gain is all the way down I hear nothing (which is as it should be). However, when I turn the gain up about a quarter of the way, I get a clear output, but then any position above that “audible but clean” position sounds exactly the same both in terms of crunch and volume.
 
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Another question I have is around the JFET legs. Is the 1, 3, 2 meaning the leg number? (See photo) I think it does and I have the legs of the JFETs like this, where leg 2 and 3 are swapped. (See photo)
 

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bluedmc777 said:
Are you saying the pedal is quieter engaged but you failed to say where your volume and gain levels were set. I assume you mean it’s quieter even with both maxed? Can you not reach unity gain? Did you bias the pedal?
Click to expand...
Yes. Both maxed. I tried biasing both to 4.5v. I’m not used to JFETs and I think maybe that is my issue. I tried different JFETs and the result is the same. I tried the rat ones, and various 2SK30s. I tried reflowing the solder on everything.

The post above says the legs don’t need to be swapped, but maybe I wasn’t clear that this is on protoboard, not a PedalPCB circuit board. I just wanted to try building a simple overdrive and downloaded the schematic and went from there.

I’m also using P90s in my guitar which has a low output volume to start. I’ve been wondering if maybe my circuit is working but just doesn’t sound good because of the guitar I’m using.
 
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Were the jfets you initially used the same as the ones listed on the BOM? If not did they atleast have the same pin layout? If yes to either of those I wouldn’t think you’d need to swap the pins.

The Blue Yonder really doesn’t have a lot of output. I can dime the level on mine with the gain down low and still be just above unity gain from what I remember. Also, try biasing to where the pedals sounds good to you if you’re having trouble until you figure out what the issue is. Don’t expect Alot of gain out of the pedal though.
 
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jdduffield said:
...

Also, leg 1 of these trim pots go to ground, right? (See photo)
Click to expand...

No, the pot is wired as a rheostat, not a voltage divider. Leg 1 is not connected to anything.

It's good practice to not leave the leg floating, though, that way if the pot's wiper fails for some reason, the pot would go to max resistance;
so you would/could/should tie leg 1 to leg 2, in this instance.


Can we get some pics of you build? (use lots of light)
Also a copy of your layout would be helpful in the troubleshooting procedure.
 
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anevilspar7an said:
Just going to say never trust transistors off of scamazon, they will almost always be something else.
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I actually agree with this. I’ve started buying from mouser. These particular ones I purchased as a noob years ago.

I will say though, when I put the Rat JFETs in, which are from mouser, the results were the same. So, I think I’ve got something wrong with my circuit build.
 
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