Da Funk-2!

[Chuck D. Bones]

Boss DF-2 Feedbacker a.k.a. Backfeeder. One of the guys on the forum gave me this board. I got it working and boxed it up last fall. It's basically a DS-1 with a PLL added on that tracks the guitar's fundamental frequency and synthesizes a "feedback" tone. It doesn't cause feedback, it makes a tone that sounds like feedback when you step on the FEEDBACK switch. It's complicated as all Hell and works remarkably well. These days you could do all that with a Daisy. OVERTONE is a blend between fundamental and octave-up feedback tones. Only thing I changed was adding the Keeley seeing-eye mod to the DS-1 part of the circuit.

Yeah, Hamish, I know, the LEVEL label is not on straight.



About 90% of the parts are for making the "feedback" tone.

 

[dawson]

Ah- so that's what "DF-2" stands for!

Yet another cool build- I'll be building one of my own soon and I'm intrigued by this "seeing eye mod." I've researched it a bit and found what it does, but not how to do it- is the sorcery limited to swapping out that 1N4148 with a face-mounted LED? If it's not any more complicated than that, then the simple-to-cool ratio of this mod is off the charts- thanks for sharing, Mr. Bones!

 

[Chuck D. Bones]

There are two parts to the mod.
1. Replace one of the clipping diodes with an LED (pick your favorite color). Doesn't matter which clipping diode. It was convenient to replace D5 because I was also replacing C25.
2. Retune the TONE control by changing C25 to 33nF and C26 to 47nF.

#2 is not exactly the Keeley mod, but it's close and eliminates the dreaded mid scoop.

There are a plethora of other DS-1 mods, but I took it easy this time around.

 

[Mourguitars]

Looks awesome Chuck !

Mike

 

[Dali]

I 've own a "real" DF-2 since 1990 or so and it was my only dirt box until I started building pedals with PedalPCB's stuff...

Every 2 months I combat the urge to do a Backfeeder just for fun.

Very nice build.

Now I *really* want to make it...

 

[Chuck D. Bones]

Thanks, guys!

 

[McClinticSphere]

Hi Chuck, I'm buying parts for one of these now and wondering what you used for the transistors (I can't find original part #s except on eBay) and the G10k pot?

 

[Chuck D. Bones]

For the OVERTONE pot I subbed W20K for the G10K. If you can't find a B20K for the TONE pot, W20K will work there too. Nothing special about the transistors. Q2 should be fairly high hFE and low noise, so I'd recommend MPSA18, 2N5089, BC549C, BC550C. The other transistors can be the same thing, or use 2N3904, 2N2222A, 2N5088, etc.

As you can see from the gutshot, this board board is tight and has a lotta parts. 1/4W resistors will fit, but 1/8W resistors will be easier to install. Watch out for the size of the film caps. Take your time building it and inspect everything thoroughly as you go because it's a bitch to troubleshoot.

 

[McClinticSphere]

Thanks so much! That is extremely helpful.
I've been through the pain of the Duophase and a Sagan Delay so I feel like I've proven to myself I can do these high part-count, attention to detail builds. Triple-checking every step is in my nature ha.