Fuzz Dog Big Fluffy Pie Bass Blender Trouble Shooting

Started by The Crooked Man, April 06, 2021, 07:09:57 PM

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The Crooked Man

I built a Fuzz Dog Big Fluffy Pie Bass Blender kit, Civil War version, with the AMZ Presence V2 and diode switch that I just can't get right, so I'm wondering if any of you good people could help to nudge me in the right direction since it's such a common circuit (though obviously with tons of variations, this one being a Sovtek Big Muff Civil War).

To make a long story short, I'm getting no low end at all out of this thing regardless of the tone, shift, or blend knob positions: it's like an insta high pass filter that nose dives around 225hz, and the relevant pots just kind of sweep the highs. 

I think the most telling symptom is that when the blend knob is set to dry, the level is significantly lower than the wet, and only upper mid/high frequencies can be heard.  I've built other Fuzz Dog kits with that same blend system and on dry, they sound exactly like the dry signal, just with a touch of level difference in one direction or the other. 

Anyone have any suggestions?  I can get far more detailed, post pictures, etc., but I figured I'd just write this explanation first in case there's some common issue that's known to everyone but me   ;D

PRR

> Fuzz Dog Big Muff Pi Bass Blender kit, Civil War version, with the AMZ Presence V2 and diode switch

Quite a mouthful. Schematic??

EDIT:

https://shop.pedalparts.co.uk/Big_Fluffy_Pie_Bass_Blender/p847124_16822088.aspx



There's only two caps, few parts total, in the dry path. Bad joint? Way-wrong resistor? (Like R29=1K?)
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The Crooked Man

Honestly, yeah, it's simple enough that it's gotta be down to something dumb like a 1k/100k swap (I did reflow right away).  I'm kinda color blind so I always measure and don't leave any up to vision, but on a circuit like this with multiple options/mods, it'd be easy enough to make a mistake like that.  I'll get on measuring everything again tomorrow.

The Crooked Man

Checked every component and reflowed solder yet again, nada.  This thing just has absolutely no low end whatsoever.  This one's a head scratcher. 

The Crooked Man

Wondering if anyone can see what could be filtering out the lows on this straight from the input, since CCW/clean on the blend is filtered as much as the wet.  I've triple checked every component and every solder point, so I'm thinking at this point it has to be a faulty component. 

duck_arse

have we seen photos of your build yet? what part number jfet have you fitted?
don't make me draw another line.

The Crooked Man

It's housed at the moment since I jumped the gun after getting wet and dry signal, and the flux is building up after doing a few reflows (this picture sure makes it look like there's a bridge on the ribbon, but there definitely isn't).  I've had to bend the pots to get to the solder side of the board already and I'm not sure how many I've got left before they snap.  JFET's are 2N5457 in the blend circuit, and 2N5088's everywhere else. 



duck_arse

you seem to have a 470k fitted at R19. please check against the circuit.
don't make me draw another line.

The Crooked Man

That's actually one of the resistor changes when using the AMZ 2 Tone Control http://www.muzique.com/lab/tone3.htm  I did mention that in the OP, but I definitely should've posted the schematic, so my bad on that.  Here's the schem and the parts they replace from the original BOM.



duck_arse

don't make me draw another line.