Hyped Fuzz - muffled and quiet

[DGWVI]

So, I've got one of these almost ready to be boxed up, but the output volume is ridiculously low, and the sound in both fuzz modes in insanely muffled. Like my cabs are covered in drenched blankets. I've reflowed all the joints, made sure nothing was shorting out, and triple checked component values. I did use 2n5088s in place of the BC549s. Any idea what's going on with it?

 

[Robert]

Just to be sure, did you rotate the 2N5088s when installing? They have opposite pinout compared to the BC549.

 

[DGWVI]

Just to be sure, did you rotate the 2N5088s when installing? They have opposite pinout compared to the BC549.

Yup, all rotated 180 degrees

 

[Nostradoomus]

Pics? Sounds like a wrong resistor value somewhere

 

[Robert]

Yep, definitely, post a pic. Something is amiss.

This thing is a monster.

 

[DGWVI]

I also used 1/4w resistors, so getting pics of the color bands will be kind of tricky. I've also used a 3pdt to switch between the two fuzz modes, as I won't get any use out of the boost

 

[Nostradoomus]

Clean your board, every little metal dot on there is a potential grounding issue. Grab some 99% isopropyl alcohol and a toothbrush and go to town!

If the brush doesn’t pick up some of the bigger pieces, heat up your iron and quickly drag it over the spot, should come right up.

 

[DGWVI]

Cleaned off all the flux and solder bits, issue persists.

Voltages

IC1

1. 4.55
2. 4.55
3. 2.26
4. 0
5. 2.27
6. 4.55
7. 4.55
8. 9.19

IC2

1. 4.54
2. 4.52
3. 4.50
4. 0
5. 4.48
6. 4.51
7. 4.50
8. 9.08

IC3

1. 4.51
2. 4.51
3. 4.46
4. 0
5. 4.07
6. 4.50
7. 4.50
8. 9.08

Q1

1. 7.9
2. 2.63
3. 2.22

Q2

1. 2.12
2. 1.5
3. 1.33

Q3

1. 2.11
2. 1.2
3. 1.33

Q4

1. 9.08
2. 3.6
3. 3.8

 

[Nostradoomus]

I think you are going to have to go one by one over your components and verify they are correct. IC1 should be measuring similarly to IC2-3 (which seem fine). Your transistors are measuring quite strangely though, did you check and measure them before you soldered them in place?

 

[DGWVI]

I think you are going to have to go one by one over your components and verify they are correct. IC1 should be measuring similarly to IC2-3 (which seem fine). Your transistors are measuring quite strangely though, did you check and measure them before you soldered them in place?

I'll go over them one more time. I did not take care to measure the transistors before installation

 

[Nostradoomus]

Definitely start with R1, R2 and C1...these are all tied to your VREF to Pin 3 of IC1 and should come out to half of your voltage (4.5v)

 

[DGWVI]

I'm a jack ass... So, I misplaced the decimal point on the ceramic caps - what should have been 47p were all 47n. Fixed that, and this thing is goddamn gnarly, and plenty loud. Though, there seems to be quite level difference between scooped and full

 

[Nostradoomus]

Awesome!

How do you have your 3pdt wired for the toggle? There is normally a volume drop when changing tones due to the lack of mids, but it shouldn’t be anything major.

 

[DGWVI]

Wired straight across like a dpdt, the last set of lugs are waiting on LED wiring. Its definitely a loss of volume when switching to scooped. I'll play around with that section and see what I come up with

 

[Nostradoomus]

I’m not sure that wiring is correct as you are replacing a 3 way on/on/on dpdt with a 2 way 3pdt it wouldn’t be straight across. I’m at work so I can’t thoroughly research haha

 

[DGWVI]

As I'm not wanting to utilize the middle section of the On-On-On switch, the 3pdt will work in giving me just the up and down positions, and I have it wired as such, and it works, but there is a substantial loss of volume when in scooped. This is the the version before the last revision, so I'm swapping out components to get it to match the new one in the hopes that will rectify it

 

[DGWVI]

So, I got the parts swapped out to put it inline with the new build doc, and it certainly helped with the disparity, but it's still there. Guess I'll live with it. I like the Full mode more anyway

Edit: This thing feeding an opamp Big Muff is the end of the world fuzz I've always dreamt of. So raggedy, broken and heavy. Almost like Tad's layered guitars on the Inhaler album.
Should have this guy boxed up tomorrow as a 2-in-1 with a Promethium

 

[Robert]

Ahh I was going to ask which version you had, but I saw the TL072 and just assumed it was the new revision.

You could increase the value of R25 to bump up the volume in the scooped mode.

 

[DGWVI]

I was looking at that, but couldn't decide on a value. 250k?

 

[DGWVI]

Played around with it. 270k gets it to the same volume, I opted for 330k, as it makes the scoop ever so slightly louder, but the perceived volume is around the same