The Demo Tape Fuzz from Mid-Fi Electronics is a fuzz pedal designed to recall a specific sound: a guitar plugged straight into a cassette recorder with the gain cranked until the tape overloads. Aion FX describes it as "a throwback to the days of running a guitar into a cassette recorder and cranking the gain to overload it and create distortion"1. It is not a tape emulator with pitch wobble or dropouts; it is a distortion box whose character comes from that overloaded-tape idea, built on an opamp circuit rather than transistors.
Controls and how it works
The pedal keeps things simple: a two band EQ plus volume and trim, which Tagboard Effects' IvIark described as "simple, versatile and practical tonal shaping"3.
| Control | What it does |
|---|---|
| Bass | Low band of the two band EQ2 |
| Treble | High band of the two band EQ2 |
| Volume | Output level2 |
| Trim | The gain-style control; Premier Guitar called it "the key to sending tracks into the red on your average 4-track, and it's just as vital" on the pedal2 |
Trim is central to the pedal's sound. On the circuit, the Trim pot is wired as a variable resistor, so only two of its three lugs are used3. Builders who have put the circuit together report that the gain sweep is uneven in a way worth knowing: one builder found that "gain is only really happening in the last 10% of the gain knob"3.
The circuit itself is built around a dual opamp IC. The published layout used a JRC4558, and because that chip contains two channels, "any dual opamp will in theory work such as TL072, NE5532 or" the Burr Brown OPA2134PA, as the Tagboard Effects layout puts it3. Most newer versions of the pedal shipped with TL072s installed3. Aion FX notes that the Demo Tape Fuzz is not based directly on any specific tape machine as far as they know, though a Tascam unit was no doubt one of the inspirations4.
The pedal runs on a standard DC adapter and is true bypass2.
What reviewers and builders said
Premier Guitar's review is the main published verdict. The reviewer described the enclosure as "dressed down with colorless, rough-hewn graphics and a cassette-like image, complete with chicken-scratched control names," and found the tone recalled a vintage Germanium 4 Big Muff Pi with a little more compression, which he called great for heavy rock leads and rhythm alike. His reference settings were Trim slightly above noon, Treble slightly below noon, and a touch of Bass2.
DIY builders who have assembled the circuit from the Tagboard Effects layout report a consistent picture:
- "Sounds crunchy and slightly broken down. What really shines is the separate Bass knob that can make it much fatter." (rickst's build)3
- "Not too fuzzy but has a nice and interesting character to it." (Eli_Klngsmkt's build)3
- "Just built this. Sounds amazing! Cleans up really well with the volume knob." (Kinski's build)3
- One builder liked the tone stack but found "its distortion isn't my cup of tea. i'm generally not a fan of opamp distortion," pointing to the circuit's opamp-based clipping character3
Taken together, the reports describe a pedal that sits toward the crunchy, compressed end of the fuzz family rather than the full-on fuzz end, with the Bass control doing a lot of the work and the guitar's volume knob cleaning it up well32.
DIY versions and related circuits
For builders, a vero (stripboard) and tagboard layout for the Demo Tape Fuzz was published on Tagboard Effects in February 2014, and builders have posted their results on that page in the years since3. Aion FX also offers the circuit as a DIY project under the name Torus lo-fi fuzz4, and sells a related 424 Tape Preamp project aimed at the same overdriven-tape territory4.
Mid-Fi Electronics has built several pedals around similar ideas; Tonebox also covers the Mid-Fi Electronics Peace Gun Fuzz, the Mid-Fi Electronics Another/An-other (Fuzz Version) and the Mid-Fi Electronics Rise/OverRun.
Videos
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Questions
Is the Mid-Fi Electronics Demo Tape Fuzz true bypass?
Yes. Premier Guitar's review notes that the unit is powered via a standard DC adapter and is true bypass, so the pedal passes your guitar's signal untouched when switched off.
What does the Trim control do on the Demo Tape Fuzz?
Trim is the gain-style control that gives the pedal its character. Premier Guitar called it the key to sending tracks into the red on a 4-track recorder, and just as vital on the pedal. On the circuit board, the Trim pot is wired as a variable resistor, so only two of its lugs are used.
Is the Demo Tape Fuzz an opamp circuit?
Yes. The circuit is built around a dual opamp IC, originally a JRC4558. Because that chip has two channels, any dual opamp will in theory work, and most newer versions of the pedal shipped with TL072s. The opamp design shapes the pedal's distortion character, which some builders associate with opamp-style clipping.
Can you build a Demo Tape Fuzz as a DIY project?
Yes. A vero (stripboard) and tagboard layout for the pedal was published on Tagboard Effects in February 2014, and builders have posted their results there since. Aion FX also sells the circuit as its Torus lo-fi fuzz project, and a related 424 Tape Preamp project exists.
Which opamps can be used in the Demo Tape Fuzz?
The original layout used a JRC4558 dual opamp. Since that chip has two channels, any dual opamp will in theory work: builders suggest the TL072, the NE5532, or the Burr Brown OPA2134PA. Most newer versions of the pedal itself came with TL072s installed.
Sources (4)
- Torus Lo-Fi Fuzz / Mid-Fi Demo Tape Fuzz, Aion FX, 2019-08-03
- Mid-Fi Electronics Demo Tape Fuzz Pedal Review, Premier Guitar, 2011-10-18
- Guitar FX Layouts: Mid-Fi Electronics Demo Tape Fuzz, tagboardeffects.blogspot.com, 2014-02-25
- 424 Tape Preamp / Tascam 424, Aion FX, 2025-03-28
