Dream Fuzz : Too loud ?

[SandyD]

Hey all, wondering if anyone can help with this..

I put together the dream fuzz and it sounds pretty much like a big muff should as far as I can tell, but it is so loud that as soon as I notch the volume on at all it's well above unity and putting it anywhere near 12 o`clock is sort of unusably loud

Would changing the volume pot to a logarithmic help? I read somewhere that can have adverse effects on the tone though

Or changing the pot to a different B value? Or the value of R16 resistor?

Or is everything working fine and I just don't know how to big muff?

Thanks!

 

[music6000]

What colour are the Resistor bands on R7 - 560K, R10 - 8K2 & R14 - 5K6 ,

 

[SandyD]

Thanks @music6000

R7 = green blue black orange brown

R10 = grey red black brown brown

R14 = green blue black brown brown

I did deliberately swap R18 4K7 for 8K2 to turn down the brightness of the LED, could that have caused me some grief?

 

[music6000]

No, R18 only effects On/Off Led.
Can you show a good Picture of the Solder side of the PCB?

 

[phi1]

What’s that thing above c7 (yellow cap near volume pot)?

 

[music6000]

A bonus!. leg of the led?

 

[SandyD]

haha yes that is a bonus leg of a resistor or something, it was just loose debris though and I brushed it off after the photo. Just a curveball to make trouble shooting more difficult.

I will upload a solder side shortly, I didn't take a photo before getting it in the enclosure so I just need to detach power etc.

 

[SandyD]

I've gone over the solder side thoroughly and I can't see anything that looks dodgy to me. Looks very much the same to the pedals I've put together that have worked well.
Underneath the tone B10k looks fine and the pot isn't touching the solder joints either.

I didn't measure the op-amps because, well, I have no idea how to - so could that be something?

These are the ones I used:
https://www.taydaelectronics.com/njm4558-4558-dual-operational-amplifier-general-purpose-ic.html
https://www.taydaelectronics.com/ua741cp-ua741-741-ic-op-amp.html

 

[music6000]

I've gone over the solder side thoroughly and I can't see anything that looks dodgy to me. Looks very much the same to the pedals I've put together that have worked well.
Underneath the tone B10k looks fine and the pot isn't touching the solder joints either.

I didn't measure the op-amps because, well, I have no idea how to - so could that be something?

These are the ones I used:
https://www.taydaelectronics.com/njm4558-4558-dual-operational-amplifier-general-purpose-ic.html
https://www.taydaelectronics.com/ua741cp-ua741-741-ic-op-amp.html

Can't read the value of the top 2 Potentiometers, Did you use a B250k or B500k for Volume pot?

 

[SandyD]

B100k for volume

 

[music6000]

B100k for volume

With Volume pot in the Middle, What resistance are you getting from Legs 1 & 2 , 2 & 3, 1 & 3 ?

 

[SandyD]

1 & 2 = 22k
2 & 3 = 22k
1 & 3 = 10k

unless I'm very much mistaken... should it look more like 50k, 50k, 100k?
I've never really check pots so far until just now
But the values change depending on what the tone and sustain controls are doing too

with the tone-cut switch on 1 & 3 = 30k

 

[music6000]

Here 's a Resistor Calculatort, Check all your resistor values, The bands are hard to read in the Picture!

Click on Bands for 5 Bands:

Resistor Calculator

Resistor Calculator is an App developed by CherryJourney to help the user find the value of a resistor.

resistor.cherryjourney.pt

 

[giovanni]

1 & 2 = 22k
2 & 3 = 22k
1 & 3 = 10k

unless I'm very much mistaken... should it look more like 50k, 50k, 100k?
I've never really check pots so far until just now
But the values change depending on what the tone and sustain controls are doing too

I think those values are reasonable. Keep in mind that when measuring resistors in a circuit you cannot measure the individual resistor, you always get the Thevenin equivalent as seen across the nodes, which is a fancy way to say that you are measuring the pot in parallel with any other resistors across its pins. For example the 22K you see is close to 50K in parallel with 50K (the two halves of the pot in parallel!) which seems reasonable to me. When you measure 1&3 you are measuring the parallel of 100K and the output resistance of the circuit, which is probably close to 10K (actually quite high, as you expect in vintage fuzz).

 

[giovanni]

Oh and that’s also why as you move the tone pot you get different values: the parallel resistor changes.

 

[fig]

I think those values are reasonable. Keep in mind that when measuring resistors in a circuit you cannot measure the individual resistor, you always get the Thevenin equivalent as seen across the nodes, which is a fancy way to say that you are measuring the pot in parallel with any other resistors across its pins. For example the 22K you see is close to 50K in parallel with 50K (the two halves of the pot in parallel!) which seems reasonable to me. When you measure 1&3 you are measuring the parallel of 100K and the output resistance of the circuit, which is probably close to 10K (actually quite high, as you expect in vintage fuzz).

Outstanding explanation.

 

[phi1]

Just to make sure I understand, with volume at minimum, it the sound muted, and then as you turn it up ever so slightly, it’s too loud? Like, it’s hard to find a unity setting, with the knob just barely on? I ask because the soldering on pad 1 of volume pot doesn’t look very strong (hard to tell from the pics, honestly I’d say it’s probably enough for contact, but trying to think of things that would affect it). If that pad wasn’t connected, it wouldn’t mute at minimum volume.

also, it the volume similar in both modes? As I understand it, it should be in the same ball park, but if it’s not that could lead us to other clues.

if everything seems perfect, I’d change it out for 100kA. Won’t change your tone at all, just make it easier to dial in lower volumes.

 

[music6000]

B100k for volume

phil1 has a Valid point, Reflow Solder on Volume Pot Leg 1.
Even on the Picture of the Solder side, You can see right through the Pad, could be a Dry joint:

 

[fig]

Wow I can see my house from there.

 

[SandyD]

@giovanni ah thanks that makes sense about the pot

Yes that's a bodgy solder on the pot, but it was working, I've reflowed it anyway.

@phi1 yes that's pretty much it, it does mute on zero but then I've found it very difficult to get a unity gain, basically as soon as it's notched on it's the loudest thing in my rig by far.

may just try an A pot as that seems like it could make things easier to manage

Or after all this maybe I don't know how to muff :/ Haven't owned one before, I used to have a Swollen Pickle which I remember being a little easier to dial in. Reevaluating my rig now and working out how best to use it

Thanks all