VFE circuit walkthroughs

[icecycle66]

lThis link is to his Tube Screamer, he does this for a bunch of his pedals. It helps see what different circuit sections are for.
I especially like the walkthroughs and part sourcing tabs.


http://www.vfepedals.com/the-scream.html

[culturejam]

VFE is a class act for sure.

[selfdestroyer]

Wow, I have never heard of this builder. Very cool business model for sure. I have been trolling around their website for the last 45   minutes and they have some really cool info on there. I like the "design your own pedal" and they supply the Eagle files and components... pretty cool.

Cody

[sonarchotic]

That phantom power for pedals looks pretty awesome. http://www.dcvoltage.net/products/p3_xk

[drolo]

Any idea what that "Variable HCC circuitry" is that he mentions in the circuit notes?

[mgwhit]

Any idea what that "Variable HCC circuitry" is that he mentions in the circuit notes?

The "Features" section of that site says:

"Variable HCC circuitry allows you to fine tune the harmonics, compression, and clipping character of your tone."

That explains the acronym, but still doesn't tell anything.  It sounds like it's probably just a way of keeping all his clipping options in the feedback loop, but controlling how much each set of clippers affects the signal by placing variable resistance in series with the diodes.  I would guess that the LEDs span the loop with a fixed resistor in series (or none) and that the symmetric and assymmetric bundles each come off the outer lugs of the HCC pot with lug two and the far side of the diodes spanning the loop.  That kinda jives with their explanation of how the control functions:

"It provides variable series resistance that affects the compression & output level from the gain stage. The typical of clipping component that is responsible for creating the distortion affects the harmonic content. The most dynamic setting is at 12:00, with more compression and distortion as you turn toward the two ends of the sweep."

So if it works the way I guessed, at 12:00 the symmetric and assymetric options would each have equal series resistance and the LEDS would have the most influence on the clipping.  Assuming a high forward voltage on the LEDs, you would get less compression and more headroom.  As you turn the HCC pot in either direction, either the symmetric or assymetric silicon diodes would take over the clipping and you'd get more compression and more distortion as described.

Just a guess.  Might be fun to play with.

[drolo]

I see ... :-)
Interesting approach indeed