# Dream Fuzz noise and very low output on tone bypass.



## e_man_89 (Oct 22, 2021)

I just finished my first build in a long time.  Been wanting a fuzz so I went with a Dream Fuzz.

This thing roars!, but I have a couple of challenges;  
-  There is a low freq oscillation that is always there and,
-   when I switch to tone bypass the level drops to below the bypassed volume even with the volume @ max).

All I could find for C7 was a ceramic.  Would this contribute to my symptoms?

Thanks for any help, and for a great forum and product.


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## Coda (Oct 22, 2021)

What are you using for IC2?


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## e_man_89 (Oct 22, 2021)

It's a UA741CP.


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## e_man_89 (Oct 22, 2021)

I just discovered something.

The sustain pot (B10k) has a restriction in its rotation.  I thought I was at zero in its rotation but was actually at around 9 o'clock. 

I've scrubbed it through the rough spot and it has improved, but it is definitely NOT smooth.  This was brand new from Tayda, so go figure...


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## zgrav (Oct 22, 2021)

Some questions about what "always there" means.
is the oscillation there when nothing is plugged in to the input?  
is it there when the fuzz control is at minimum?  
does the oscillation change frequency when any of the controls are adjusted?
does the oscillation change when the volume on your guitar is turned down?


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## e_man_89 (Oct 22, 2021)

Yep, the pot is bad.  only passes signal at the rough spot and 180 degs. opposite.

Don't suspect that this is the source of my noise and my tone bypass trouble, but I guess it needs to be the first thing I straighten out.


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## e_man_89 (Oct 22, 2021)

Thanks for your interest zgrav.

- the oscillation is not there when nothing is plugged in and the effect on (silence when the effect is off).  There is some high freq. hiss but hey, it's a fuzz pedal.
- I have recently come to realize that the "sustain" pot is bad. See above.
- The oscillation does not change frequencies when controls are adjusted.
- The oscillation decreases in volume when my guitar is turned down but does not stop.


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## e_man_89 (Oct 22, 2021)

I have no 10k pots.  How would a 5k affect the effect? (see what i did there?)


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## Chuck D. Bones (Oct 23, 2021)

5K will work for the sustain pot.  

You installed 47Ω for R19 & R20, should be 47K.  I stopped checking component values when I found those two errors.  You might want to inspect and recheck all of the other components.


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## e_man_89 (Oct 23, 2021)

Dude!!!  Thank you SO much.

Nothing like the eye of experience!  I'm checking every component value.  And thanks for the tip on the 5k pot.

I REALLY like this place...


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## e_man_89 (Oct 23, 2021)

Went through the whole board and found one other resistor I made a mistake on.

Replaced all three and the sustain pot.  Everything sounds great.  Not a lot of variation in the amount of fuzz (sustain), but I'm not really looking for light fuzz.  I've got some 10k pots on the way and will pop one in when they get here.

And thank you again Chuck D. Bones, you definitely gave me a big head start on finding the trouble.


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## e_man_89 (Oct 23, 2021)

Oh BTW, the low freq. oscillation has improved, but is still there.

Think i'm going to try some different IC's just for fun...


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## Coda (Oct 23, 2021)

The fidelity of the 741 is a tad worse than a wet cheese doodle. I bet that is the source of the oscillation…


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## e_man_89 (Oct 23, 2021)

Do you have any recommendations?


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## Coda (Oct 23, 2021)

TL071 is a good Swiss Army knife op-amp. Higher fidelity than any of the old “mojo” op-amps…like the 308 and the 741.


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## Chuck D. Bones (Oct 23, 2021)

e_man_89 said:


> Oh BTW, the low freq. oscillation has improved, but is still there.



Try a different power supply or a battery, see if the oscillations stops or changes.



e_man_89 said:


> Went through the whole board and found one other resistor I made a mistake on.



Visual inspection saves the day once again!


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## e_man_89 (Oct 23, 2021)

You da man Chuck...

I'll try to find a TL071 on amazon.  Thanks Coda.


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## e_man_89 (Dec 16, 2021)

What changes could I make to this circuit (component value wise) that would decrease the low end slightly? I don't want any drastic reduction, just a little less.

thanks.


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## Chuck D. Bones (Dec 16, 2021)

Did you ever kill the low-freq oscillation?


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## Chuck D. Bones (Dec 16, 2021)

e_man_89 said:


> What changes could I make to this circuit (component value wise) that would decrease the low end slightly? I don't want any drastic reduction, just a little less.


Make C6 smaller for less bass.  I'd recommend something in the range of 100nF to 1μF.  R6 is sofa king large that cutting it in half will still let a shit-ton of bass thru.

You should have a HUGE sustain range, even with a 5K sustain pot.  Are you _sure _that R9 is 47Ω?


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## e_man_89 (Oct 22, 2021)

I just finished my first build in a long time.  Been wanting a fuzz so I went with a Dream Fuzz.

This thing roars!, but I have a couple of challenges;  
-  There is a low freq oscillation that is always there and,
-   when I switch to tone bypass the level drops to below the bypassed volume even with the volume @ max).

All I could find for C7 was a ceramic.  Would this contribute to my symptoms?

Thanks for any help, and for a great forum and product.


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## e_man_89 (Dec 16, 2021)

Thanks for your reply Chuck.

Well, I changed the sustain pot to the spec'd B10k, but I still have almost full gain right off of zero.  At 9 o'clock it sounds about the same as 3 o'clock (the gain control that is).

When I changed the erroneous resistors it helped the oscillation. 

 When I bump the body of my guitar with my hand I get a low freq. "boom" through the amp.  I thought adjusting some values might help with that and the seeming excess of gain (I know that sounds a bit contradictive in reference to a fuzz).  

I cannot dial in a low gain setting with this pedal.  It seems to be kinda all or nothing...


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## e_man_89 (Dec 16, 2021)

BTW, I spent time this evening going resistor by resistor verifying values (for the third time). They all checked out.

R9 reads; yellow, violet, black, green, brown.


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## Chuck D. Bones (Dec 17, 2021)

Yellow = 4
Violet = 7
black = 0
green = 000,000
brown = 1%

That 4th band would be gold for a 47Ω resistor.


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## e_man_89 (Dec 17, 2021)

Forgive me Chuck, my notes had a "G", it is in fact gold rather than green.

Sorry.


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## Chuck D. Bones (Dec 18, 2021)

It is my opinion that the SUSTAIN pot should be A-taper.  B-taper crowds the bottom end of rotation and that may well explain the "all or nothing" behavior you're observing.


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## e_man_89 (Dec 18, 2021)

Thanks Chuck, I appreciate your time.

I had actually wondered about this.  I checked other schematics here and there, but all had essentially the same pot value shown.

I've got an A100k.  It's certainly worth a try.

I'm annoyed by the nature of this problem.  So many others have built this one and don't have any troubles with it.  I've checked the component values and solder joints repeatedly (as well as changing op amps) and find nothing indicating a problem.  

I'm starting to think I have 1 or more faulty component.


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## Chuck D. Bones (Dec 18, 2021)

Don't use A100K, it's too large and won't solve the problem.  Before you change any parts, let's make a few measurements.  Check the DC voltage on IC1 pin 7 and on IC2 pin 6 with no signal, then report back.  It does not matter how the knobs are set for this test.


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## e_man_89 (Dec 18, 2021)

10:4 Chuck.  Thanks for your thought and energy on this.

I'll try to get to it this weekend.  Got some other stuff going on...

Stay tuned, I'll report back.

Thanks.


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