The Shin Ei 8TR Fuzz Wah is a Japanese combination pedal from Shin-ei that puts a fuzz and a wah in one box. TONEHOME calls the Fuzz-Wah pedal 8Tr "one of the most popular pedals of Shin-ei," and notes that it was sold under a dozen of brand names, including Avora, Companion, Jax, Maya and National. The example documented there is the rare Maya version, built in 1975 or early 1976 according to component dates1.
A Super Fuzz feeding a wah
The signal order matters to how the pedal behaves: the fuzz comes before the wah, so the wah is filtering an already heavily distorted signal rather than the other way round. Builders on Guitar FX Layouts, who traced the circuit and published a stripboard layout in March 2017, describe it simply as "a superfuzz running into a wah"2. Builder SouthIslandSplit, who built the fuzz section, reported "Loads of saturation and volume on tap!"2.
How it relates to the Super Fuzz and the 6TR
The fuzz section is nearly a straight copy of the Super Fuzz. Comparing the two, builders found "literally 1 component value difference in the superfuzz, the rest is straight up identical to the standard super"2. In other words, the 8TR is basically a Super Fuzz with the wah circuit above it, with a few component value changes and a different wah component3.
Many variants of the circuit exist. A builder working from an actual pedal in 2020 found the layout "more similar to the Superfuzz and not the 8TR schematic that I was able to find online," with only minor differences, so examples may not all match published schematics exactly2.
The 8TR's layout differs from a single-board build in one practical way: instead of one massive board, it uses 2 separate boards, which gives more options for placement inside an enclosure2.
Building one today
The published DIY layout splits the pedal into two separate boards instead of one massive board, which gives more options for placement inside an enclosure, and the two sections are wired according to the dual effect wiring shown in the offboard wiring tab2.
Two things have caught builders out:
- The wah section: in the published diagram, the 470 ohm resistor from the emitter was left "hanging in free air" instead of going to ground. One builder asked, "Shouldn't the 470 Ω resistor from E go to ground?" and confirmed that bridging the loose end to ground fixed it: "I just now bridged the loose end to ground and it's up and running." The transistor symbols in the wah section are also drawn reversed compared with the fuzz section2.
- The fuzz section: verified working, with a wiring correction on the Balance pot, whose lugs run top to bottom as 2, 3, 12.
Videos
timhulio
CutterM900
Brett Kingman
Questions
Does the fuzz come before the wah in the Shin Ei 8TR?
Yes. The circuit is a Super Fuzz style fuzz stage running into a wah, so the signal is saturated first and then filtered by the wah. Builders who have traced the circuit describe it as a superfuzz running into a wah, and the fuzz section is reported to have loads of saturation and volume on tap.
How is the 8TR different from a standard Super Fuzz?
Very little, as far as the fuzz goes. Builders comparing the 8TR with the standard Super Fuzz found literally one component value difference in the fuzz section, with the rest identical. The 8TR is essentially a Super Fuzz with the wah circuit added above it, plus a few component value changes and a different wah inductor.
What is the difference between the Shin Ei 6TR and 8TR?
The two are closely related: the 8TR is described as basically a Super Fuzz with the wah circuit above it, with a few component value changes and a different wah component compared with the 6TR layout. Both were laid out for DIY builders on Guitar FX Layouts, the 6TR in March 2017 and the 8TR the following day.
Why would a DIY build of the 8TR wah section not work?
A builder found that in the published layout the 470 ohm resistor from the emitter was left hanging in free air instead of going to ground, which stopped the wah section from working. Bridging that loose end to ground got the wah up and running. The transistor symbols in the wah section are also drawn reversed compared with the fuzz section.
Sources (3)
- TONEHOME, TONEHOME
- Guitar FX Layouts: Shin Ei 8TR Fuzz Wah, tagboardeffects.blogspot.com, 2017-03-17
- Guitar FX Layouts: Shin Ei 6TR Fuzz Wah, Guitar FX Layouts (tagboardeffects.blogspot.com), 2017-03-16
