Boss BF-2 to HF-2

[Thewintersoldier]

So doing a deep dive on the HF-2 and I decided I want to build one. The HF-2 is built on the same board as the BF-2, and only has a few value changes from the BF-2. The biggest difference is the clock and BBD chip, with half the stages means moving the flange frequency range an octave higher. The only part of the circuit that has me confused is the input of the clock on the HF-2. Instead of pin one going to VD, this R/C is branching off of VD before going to pin one. What is this doing exactly? I looked at this example of the HF-2 board and it's not on there, so is it truly necessary? I want to build one on a fraudhacker board and I'm curious what it's all about.


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[jimilee]

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[Bio77]

Curious to see how this progresses. 

The overlapping traces you circled are not connected.  They are just overlapping wires.  When they are an actual node there is a dot. 

[Thewintersoldier]

According to Mark Hammer, this is what it's doing. I guess I could go without it.

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[Bio77]

I just read over the post you referenced at DIYSB.  #1 My take is that you are right.  The R65/C41 is not special to the HF-2 overall, just an improvement to reduce noise.  You might explore adding it in on tagboard (if possible) and see what difference it makes.  It might be a good mod to build into a BF-2.  #2 Just popping in the 3204 gets you an HF-2 with less maximum resonance from the pot. However, the resonance trim is 22k so you might have enough room to get to oscillation at max resonance.  If so, you wouldn't even have to sub the 39k->22k at R33.   

This has my wheels spinning for sure.  I used a BF-2 on my bass for years until I built the Flange-a-rama (Ibanez FL99), which has two 3204s.  Wondering if a 3204 in a BF-2 would be my new jam.

[Bio77]

Sorry, still nerding out over here I just went over the the FL99 schematic, it has two 3204s because the intensity foot switch gives you the option of using one or two of the BBDs, 512 or 1024 stages, i.e., it's like being able to switch between a BF-2 and HF-2. 

[Thewintersoldier]

Please geek out over this, I totally am. There will be a build report sooner rather than later 😂.