OmniScreamer v1.0
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4
Introduction
Before we start with the component list, it might be interesting to know how this PCB was designed.
Strictly speaking, you can break down this tubescreamer into 5 main sections and 3 optional mods.
The main sections are:
1.
Input buffer
2.
Output buffer
3.
Main clipping stage
4.
Tone/Volume stage
5.
Power section
Both the input (1) and output (2) buffers are made switchable, so I would suggest to add them and if
you do not like them, you can just switch them off.
The main clipping stage (3) is where the most fun is at. Most tubescreamer based effects will have a
wide variety of clippingdiode configurations. In this manual you will find a lot of these configurations
will be explained
and you can always decide to “mix and match”. A tubescreamer is an extremely
“modable” effect.
The tone and volume stage is built to fit almost all types of tone controls as found in a lot of
tubescreamer based effects.
The power section is not that interesting, but some versions use an a-symmetrical voltage divider to
form V
ref
. The only non-standard is that the polarity protection is changed to a (safer) serial
connection. This has no tonal effect what so ever!
The optional mods:
1.
Boost
2.
Offboard Clipping diodes
3.
Feedback loop
All these mods can be added to any version you want to build! In the separate configurations sheet
you will find which mod is standard for some of the configurations and which are not. Again you are
free to add these mods or leave them out.
The boost mod (
SW3
) is a mod found in the Tim
™
. The off board clipping diodes switch (
SW5
) can be
used to add extra clipping diode configurations instead of (or in addition to) the onboard clipping
diode section. The feedback loop (
SW6
and
R22
) will reduce the overall gain and brightness
depending on the capacitor that is switched in the circuit.
You should also take a look at the
Electrosmash Tubescreamer dissection
. It has a more in-depth
analysis (note that it also covers the JFET foot switching that is intentionally left out of this PCB)
The components needed for the different type of effects can be found in the separate configuration
sheet (pdf).
