Shin's Music Dumbloid Standard

The Shin's Music Dumbloid Standard is an overdrive pedal from Shin's Music, a builder based in Tokyo, Japan. It is a Dumble-style drive: the maker's own marketing describes it as "One of the most iconic and sought after amps in history… in a pedal!" and says the pedals aim at the open uncompressed cleans and evenly compressed overdrive associated with those amps, adding that "This does not sound like a pedal…it sounds and reacts like an amp."¹

Inside the circuit: no clipping diodes and an OPA2134

The most detailed public look at the Dumbloid Standard comes from the circuit-tracing community at Guitar FX Layouts, which published a vero layout for the pedal in March 2014. Their analysis describes it as "95% of it is a Tubescreamer, but the notable differences is there are no clipping diodes in the feedback loop of the first opamp stage."¹

The build they traced uses an OPA2134 opamp and BC548B transistors.¹ The Accent control is the other departure from a stock Tube Screamer: it is an added control for the second opamp stage which alters the frequency response, and possibly the gain of that stage as well.¹

One builder in that thread, johnk, swapped the opamp for an MC33172N, which he described as "basically a dual LM741," and reported that "the fizzy decay is hardly there at all and completely gone if I turn the accent down a little. sounds great now."¹ Another commenter took the opposite view of that fizz: "I kind of like the fizzy decay. It almost has a fuzz-like quality to it. I can see how many say it is very amp-like."¹

A suggested mod from the same thread: swapping the 150K resistor from supply on the Q1 base for a 470K raises the input impedance.¹

Standard versus Special

The Dumbloid line has two main versions, and the difference is a single switch¹.

Guitar FX Layouts published the Special's layout as a separate thread in the same month, specifically to keep discussion of the two versions apart.¹

Is the Dumbloid a Tube Screamer clone?

Mostly, by the circuit analysis, but the missing clipping diodes and the Accent control change what comes out the other end. The builder mirosol summed it up: "So i would say it sounds like a mash of TS9, SD1 and Hotcake," adding that it was way louder and that the mid-honk was not as horrible as on a TS.¹

Price and value

The Dumbloid has never been an inexpensive pedal. In early March 2014 it was listed on eBay at $600, and a European listing priced it at 460 euros, both figures noted with some disbelief on the Guitar FX Layouts thread.¹ One commenter there wrote: "The tone variations with the accent and tone knobs are extreme. No I would not pay $600 for it."¹

DIY layout

For players who build their own pedals, Guitar FX Layouts posted a verified vero layout for the Dumbloid Standard on 4 March 2014. A later correction to that layout notes "there's 16 cuts, not 17," the count having probably not been updated while the layout was being made.¹ The Special followed as its own stripboard layout later that month.¹

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