Options
Before you start, you must decide which options you want to incorporate in the build. The original
Univibe™only has a Mode selector (Chorus/Vibrato). The Neovibe™(GeoFX) was one of the first
reconstructions of the original and followed by the Harbinger One™ (Madbean) which added an input
buffer and charge pump. In this build there is also an added Tremolo mode as well as a Tone selector
that works with all modes. In essence it is a 3 position switch that adds different combinations of
caps in the 4 different phase stages. The optional input buffer and chargepump are also
incorporated. I salute GeoFX and Madbean for their work and strongly suggest that you check all
their work!
If you want to be as close as possible to the original then you can opt out on these mods. If you want
to incorporate all options then you can skip this part and start soldering, but it is still a good read.
1. Capacitors
The original Univibe™ the 1uF caps were electrolytes. Most clones replaced them with SMF
(stacked metal film) caps. To give you the ability to keep it as original as possible, I marked
the polarity of these caps on the PCB so you can use electrolytes instead of SMF. You can
recognize these SMF caps on the PCB by their rectangle marking. If a capacitor is marked as a
circle, it is meant to be an electrolyte anyway.
If you decided not to use SMF 1uF caps then make sure you source your 1uF electrolytes with
care! Buy Nichicon or Elna quality caps to keep the sound quality as best you can.
It is reported that replacing the C6 with a 30p will brighten the overall tone.
There have been questions if C23-C28 caps should be SMF, but that would be a waste of
money. These caps are part of the LFO and thus are not part of the signal chain. The LFO only
makes the lamp blink and the normal (cheap) electrolytes do a great job there.
2. Input buffer
The original has no input buffer, but there are a lot of people who have a problem with the
volume drop when engaging the effect. To prevent this, there is an input buffer ready on the
PCB. But if you do not want to use it, please do the following:
DO NOT SOLDER: R3,R4,R5, C1, C2 and Q1
EXTRA JUMPERS: On SW1 row A and B connect pad 2 and 3.
Jumpers can be made by using excess lead wires that you cut off the resistors.
You can optionally replace R2 with a 2M2 to raise the signal to unity although it might get a
bit distorted.
