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DA Fuzz Face sound issue

Started by stevewitt, November 16, 2011, 05:28:36 PM

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stevewitt

Hi, new here. Thanks for having me.

I'm new to this whole thing, but I have a red DA Fuzz Face with NKT275s that I've been poking around at for a while. All the connections look good and clean, the power source is good, and I've just swapped out the two electrolytic caps (2.2uf and 22uf) for posterity.

Single note lead parts sound pretty killer. Really ripping tone, although not a whole lot of perceivable volume even with the volume pot cranked. However, when playing chords/even power chords through this thing, the sound is just crushed. It's like the pedal is on monophonic mode and it just can't pass a thick sounding chord for me. Sounds almost like there is some sort of gain ceiling, set very low... ???
I realize this thing has among the simplest circuits out there, so I'm wondering if somebody can give me a clue as to what component could typically be acting up to cause this. If my explanation is unclear I can try and post a clip later on.
Thanks all
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@stevewittmusic

jkokura

That sounds like it's a bias problem to me. What voltage are you getting on the transistors?

Jacob
JMK Pedals - Custom Pedal Creations
JMK PCBs *New Website*
pedal company - youtube - facebook - Used Pedals

JakeFuzz

Its broken, you should probably just send those NKT's to me  ;D

Seriously though, I would try and rebias like Jacob suggests. I assume this is an older Fuzz Face? I would get a set of trimmers or at the very least sockets for the two collector resistors and the feedback resistor. You could also (carefully!) desolder the transistors and rebuild the circuit on breadboard to find values that will work (this is what I would do). Then while the transistors are out replace the resistors with the values you found.

What are the voltages at the collector of Q1 and Q2? I would start troubleshooting with Q2's collector resistor, then the feedback (100K) resistor; these values usually have the smallest working range and small changes can have drastic reflections on the tone.

You should post some pics too. I would love to see the inside of an OG NKT fuzz :D

stevewitt

Great, thanks guys/girls.
I'll measure the transistors tonight or this weekend and post back.. Thanks!
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@stevewittmusic

jkokura

I have an NKT275 Fuzz also. I could send you a picture of that if you'd like Paul. Can't guarantee it would be quick though...

Jacob
JMK Pedals - Custom Pedal Creations
JMK PCBs *New Website*
pedal company - youtube - facebook - Used Pedals