Author Topic: Hipster not fuzzing right. Ground loop resolved, maybe I need diff. transistor?  (Read 1846 times)

pauloman80

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So the ground loop issue was because it wasn't grounded. It's a tiny enough build, putting it in the box wasn't a big deal. The issue now is it's not sounding like a fuzz should. Borrowed a friend's fuzz in the meantime for this gig, but I still want to finish this one for myself. I'll post values whenever I get the chance. Thanks.
« Last Edit: February 11, 2015, 11:24:37 AM by pauloman80 »
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pauloman80

midwayfair

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Take voltages on each pin of the transistors.

http://www.madbeanpedals.com/forum/index.php?topic=902.0
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m-Kresol

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hmm, this does sound strange.
As Jon said, voltages will help. Also, post some pics of your build. To me it kind of sounds like a problem with your voltage supply. getting weird noises when the pedal is off OR on could support that
Did you check for continuity between ground and DC and did you make sure you wired your DC jack, as well as in- and outputs correctly (grounded via case...)
I build pedals to hide my lousy playing.

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pauloman80

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For the purpose of further clarification, the noise is essentially really wicked ground hum. Like, DISGUSTINGLY AWFUL. Very consistent, though.

FIRST ERROR: I confused the transistors, and they both appear to be working as intended. Having mentally corrected that, I'm also remembering how to do troubleshooting steps, and I'm finding a very interesting issue.

First, FWIW, here are my board values...

9V in @ board: 9.45V
Ground in @ board: 0.00
Q1: Pin1= 0.00 Pin2= 0.59 Pin3= 2.45
Q2: Pin1= 1.78 Pin2= 2.45 Pin 3=4.51

I honestly don't know what any of that actually means other than it's voltage, I'm just a player who really like building & assembling stuff.

I remembered that I made an audio probe a few years ago. Whipped that out, downloaded a tone generator to my iPad, and began testing. Everything appears to be absolutely fine and perfect until I actually plug a cable into the output jack. That's where everything goes out the window. If I touch the audio probe to the tip of the output jack, I get the sound I'd anticipate (although I discovered I used the wrong Alpha 9mm's, so my pots are backwards). However, something about the cable is what's overriding everything and creating the noise. It's probably something hyper obvious, but help a brother out! =D
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pauloman80

pauloman80

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hmm, this does sound strange.
As Jon said, voltages will help. Also, post some pics of your build. To me it kind of sounds like a problem with your voltage supply. getting weird noises when the pedal is off OR on could support that
Did you check for continuity between ground and DC and did you make sure you wired your DC jack, as well as in- and outputs correctly (grounded via case...)

I didn't ground via case, because the rule is to rock it before you box it. Maybe I'm rocking it pre-boxing it wrong...? I just have the circuit out in the open, and I'm feeling a bit foolish because maybe that's the trick. I don't have any ground occurring except for that coming from the power supply.
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pauloman80

m-Kresol

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You're absolutely right about boxing before rocking, but you'll have to ground BOTH jacks then, In and Output via the sleeve connectors. When boxed, you usually just connect one of them as the other one is connected via the enclosure which is also grounded from the jack. Your guitar normally doesn't introduce much noise, that's why you don't have it on the input, but after the effect that's a very different story. As you connect your amp/speaker to it, it will pick up any fluctuation between tip and sleeve, which is basically your signal (it's just a difference in voltage between hot and ground wire and you didn't put the ground on ground, so it's just on a random fluctuating level thus introducing what we consider noise.)
hope that solves the problem!
I build pedals to hide my lousy playing.

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My etching tutorial

pauloman80

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That certainly makes sense. Decided to be brave and box it so I could determine what's what. (For the future, I'm going to build a Beavis Audio-style prototyping/troubleshooting board so I can test in a more fool-proof fashion.) AND IT WORKS! No hum. However, the sound isn't quite correct. It's not ballsy at all. I know the FF isn't supposed to be a massively huge-sounding pedal, but it's really mild. I  have to dime the volume knob & the fuzz knob doesn't really help matters much.

I'm not exactly sure how to bias it other than it's done via the trim pot and the Bias pad that's offshooting from Q2, so I'm guessing I run power through it and place one of my DMM probes on the Bias pad; the question is, which probe, and where do I place the other probe? While much of my building knowledge has come back, biasing is something I've never done before.

In the meantime, I'll post some values again when I'm able, hopefully later today. I'm running out of time to finish this puppy before my gig. Thanks for helping a brother out, all!
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pauloman80

m-Kresol

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Taken from the build doc:
Quote
Adjust the BIAS trimpot until you read approximately 4.5v on the collector of Q2 (use the Bias pad on the lower left corner of the PCB with your DMM to set the bias voltage). 3.5v 5.5v is the nominal range so feel free to experiment with your bias setting. A setting of between 3.0v 4.0v will be compressed and very squishy sounding similar to some Eric Johnson fuzz tones.

Just put one of your probes on the bias pad and the other one to ground and measure DC voltage. then do as stated above and you should be fine :)
I build pedals to hide my lousy playing.

My projects are labeled Quantum Effects. My shared OSH park projects: https://oshpark.com/profiles/m-Kresol
My build docs
My etching tutorial

pauloman80

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I did read that section from the tech help guide, but it was the extra info you provided that I needd. Thanks! Hoping to have a bit of time tomorrow to work with it, we'll see. I'll post results if I'm able.
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AntKnee

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I had a wicked noise from a recent build and found that I swapped the input and output wires. Since you boxed it, Check your wiring and make sure you didn't make a simple error.
I build, and once in a while I might sell, pedals as "Vertigo Effects".

Bret608

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Glad folks were able to help you out with the ground issue. As far as it not sounding that strong, I would double-check you don't have one or both of your transistors oriented the wrong way. Some fuzzes just won't work if that happens, but others will work but just be quite weak. If you're looking directly at the flat side of the silkscreened transistor image on the PCB, the emitter tab on your BC109 should be on the left side.

Let us know how it works!

pauloman80

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Glad folks were able to help you out with the ground issue. As far as it not sounding that strong, I would double-check you don't have one or both of your transistors oriented the wrong way. Some fuzzes just won't work if that happens, but others will work but just be quite weak. If you're looking directly at the flat side of the silkscreened transistor image on the PCB, the emitter tab on your BC109 should be on the left side.

Let us know how it works!

I went over the transistors quite diligently as I was trying to figure out the physical pinout order in relation to its schematic layout. I'm pretty sure I get that part now, but I'm still not getting the desired result. You'd think for such a simple circuit I wouldn't be having so many challenges. :o I also have to shelve that one for a bit as a friend of mine who fell in love with my v1 Sunking build asked me to build him one, so I just finished a v2 Sunking and it's not working either::) I think it might be related to the ICs, but not sure. That'll be another post looking for help if I exhaust my self-troubleshooting resources.
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AntKnee

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Post a pick of your build. Maybe you created a ground loop?
I build, and once in a while I might sell, pedals as "Vertigo Effects".