Looking for Boss DF-2 schematic.. ?

[BDuguay]

A friend has asked me to work on his Boss Super Distortion Feedbacker. Has anyone had any experience with these or know where I might find a schematic?
Thanks in advance!
B.

[Mark Hammer]

I've got one.  I've got the schem.  I've tinkered.  What would you like to know?

[ExpAnonColin]

http://experimentalistsanonymous.com/diy/

In Schematics->DIstortion/boost/OD

-Colin

[BDuguay]

Oh hey Mark.
This is perfect, I was hoping you might respond. As it turns out my friend knows another guy who has one of these only his acts up on occasion, in a way he would like his too. I have a sound sample of the 'acting up' pedal but I don't know how to post it. The effect that the overtone knob adds is slightly vibrato-ish correct? The sound sample demonstrates the 'broken' pedal adds a much deeper and wider vibrato effect. I'm informed it doesn't do this all the time so that suggests to me that perhaps there is an intermittent component. Unfortunately, I don't have access to this pedal to inspect it. Can I go to the Mark Hammmer goodwill well of knowledge one more time please?
B.

[Mark Hammer]

A couple of years ago, a fellow who went by the name/handle of Tonda (from the Czech Republic, I believe) frequented here a lot (although quite frankly it could have been the pre-PHP version of the forum) posted a lot of queries and response/experiments concerning his DF-2.  I recall participating in a numberof those discussions, though sadly I did not save them and do not remember all the critical details.

HOWEVER, one of the key things discussed was the extent/degree of vibrato introduceable.  The CD4046 in the DF-2 functions as an oscillator, whose frequency is determined by the combined influence of the pitch-to-voltage detector labelled in the schematic as "fundamental detector" and an LFO formed by IC2a.  My guess is that the frequency of the LFO is set by the combination of C31/32, and the shaping of it is set by C35 and C37, seeing as how both of these will introduce enough lag or slewing to turn a square wave into something a little subtler (they SHOW a sinusoidal wave in the picture, but who the hell knows for sure until it's scoped).

I am going to further guess that either one or more of the components that make the LFO squarewave "rounder" is intermittent in some fashion so as to maintain the same frequency but make the frequency modulation more "jarring" from time to time, might be twitchy.  Alternatively, note that the LFO-derived modulation is gated by the CMOS switch based on IC8a.  Here we start to get into more complex territory, since the smooth on/off behaviour of this switch is contingent on the joint action of what we in the technical business like to call "a lotta stuff".

In general, though, what we are essentially talking about is influencing the degree/kind of influence the LFO has on the 4046, whether that is in terms of stability of smoothing, stability of LFO frequency, or amount of modulation exerted.  Somebody who knows more about those oscillators than I do needs to step in here.

[BDuguay]

So your saying it's entirely possible that there is an intermitent something or other going on here. It probably wouldn't hurt to hear the sample I reffered to huh? Just how does one go about posting MP3's?
Thanks Mark and Colin.

[Mark Hammer]

Damned if I know.

Just to add to my prior posting, the vibrato element is presumably to make the "feedback" sound more natural. Normally, if one was attempted to sustain a note for a long time while standing in front of a cranked amp, you would do so by maintaining string vibration through finger vibrato.  The LFO attempts to mimic that.  In the absence of any gradual onset and vibrato, it starts to sound more like microphone feedback and less like guitar feedback.

Of course, the $64,000 question is how much finger vibrato sounds like YOU.  Everyone has their own style from lazy vibrato like Robin Trower and Raul Kossoff, to more urgent-sounding styles like John Cippolina and Barry Melton to guys like the late Luther Allison.

Ont heother hand, I can see where there is musical utility in having something with unstable vibrato.

[marshal2107]

could someone separate for me the feedback stage? i don't exactly recognize what should i supress to eliminate the distortion circuit and just have the feedback.

[wordstep]

I happen to spend a lot of time with  4046 & DF-2.

If you want to kill the dist, the most easy way is just cut the D2 & D3.

After R4, it is a DS-1.

The output of 4046 is square wav, then go through filter.

The LFO, I believe it is just  there to keep the 4046 ready(might be wrong), once the switch is pushed, the LFO is cut away from the 4046.

[Fredenando]

[wordstep]

The LFO, I believe it is just  there to keep the 4046 ready(might be wrong), once the switch is pushed, the LFO is cut away from the 4046.

I must correct my comment, it is not true.