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Claudio Dias RVIII Distortion
Illustration, not a photograph. Details may differ from the real product.
Claudio Dias

Claudio Dias RVIII Distortion

Distortion
Key facts
Typefuzz1
Maker / designerClaudio Dias1
Built forSérgio Dias of Os Mutantes1
Active deviceBC109 transistor (BC109c pinouts referenced in the layout)1
Layoutvero (stripboard) and tagboard1

The RVIII Distortion is a fuzz pedal made by Claudio Dias for his brother Sérgio Dias, the guitarist of Os Mutantes1. It sits on the fuzz side of the distortion family, closer to the circuits covered on Fuzz Pedals than to standard Distortion Pedals or Overdrive Pedals. The pedal itself is not a commercial product with a maker's manual behind it: what is publicly documented is a DIY layout published on the Guitar FX Layouts blog in September 2012, which lets builders recreate the circuit on vero (stripboard) or tagboard1.

What it does and how it is built

The circuit uses BC109 transistors, and the layout references BC109c pinouts, which matters when sourcing parts because BC109 variants are not all pinned the same way1. The layout includes a 1M pulldown resistor at the input, which is there to kill possible pop sounds from switching1.

The volume control was originally a 15k pot. The layout's author notes that in the case of this being just the volume control, a 20K pot should work fine as a substitute, which is useful since 15k is an uncommon value1.

A known limitation: low output

The most important thing a builder or player should know about the RVIII is its output level. The layout's author addressed it directly after builders raised it1:

"Well the good news is that low volume is normal for this pedal, so you have not done anything wrong. The bad news is tha..."1

In other words, the pedal cannot reach unity gain, and the low output level is not correctable with different transistors1. Players used to pedals that push an amp harder may want to pair it with a Boost Pedals style circuit downstream, though the layout itself makes no recommendation.

Low volume is normal for this pedal and cannot be fixed by swapping transistors, according to the layout's author1.

History of the layout

  • The RVIII Distortion is a fuzz pedal made by Claudio Dias for his brother Sérgio Dias1.
  • The layout published for it is a vero (stripboard) layout, part of a collection of vero (stripboard) and tagboard guitar and bass effect layouts1.
  • The circuit uses a BC109 transistor, with BC109c pinouts referenced in the layout1.

Anyone building from the original posting should make sure they are working from the corrected version that separates the transistor collectors1.

Sources (1)
  1. Guitar FX Layouts: RVIII Distortion, Guitar FX Layouts (tagboardeffects.blogspot.com), 2012-09-07