The Tru-Fi Zosa Fuzz is a hand-made recreation of the famous Vox Tonebender, built by Tru-Fi in the USA. Tru-Fi describes it as a MkII style tone bender with a full sound, and the circuit uses three vintage Mullard OC75 germanium transistors, the kind of old-stock parts that give period fuzzes their character1.
Circuit and controls
The circuit is the same as the original Tonebender, with one addition Tru-Fi makes: an adjustable bias resistor so you can dial in the tone. Bias sets where the germanium transistors sit, and being able to adjust it means the pedal can be tuned to the specific vintage transistors in your unit1.
The controls follow the original layout: Level and Attack, just like the original. Tru-Fi's own guide to the Attack knob: between 9 and 12 o'clock you get a nice crunchy power chord punch, dial it up to 1 to 2 o'clock for lead tone, and full out gets crazy thick and gnarly, like the original1.
Transistor options
Tru-Fi lets you pick which Mullard transistors go in your Zosa, and the choice changes the feel of the fuzz1:
| Option | Character | Price |
|---|---|---|
| Mullard OC75 (standard) | Smooth and fat; fatter and thicker than the 81Z | Included1 |
| Mullard OC81 | A bit more grit and rock n roll | Option1 |
| Mullard 81Z | Less gainy than the OC75, dials back on the guitar better to clean up | $20 extra1 |
The 81Z option adds $20 to the price. Tru-Fi notes the OC75s are definitely fatter and thicker, so the choice comes down to whether you want that or the cleaner-up, less gainy 81Z response1.
Finishes and enclosure
The Zosa comes in a cigar box enclosure, which is how Tru-Fi ships it, true bypass with an LED1. Finish upgrades are available: Chrome or Polished Aluminum are $30 extra, and Sparkle Paint is $25 extra1.
On the show circuit
The Tru-Fi Zosa Fuzz ships in a cigar box enclosure, with true bypass and an LED indicator1. It lists at $224.953, with finish options priced separately: Chrome or Polished Aluminum at $30 extra, Sparkle Paint at $25 extra, and a Mullard 81Z option at $20 extra1.
Tru-Fi builds a wider range of fuzz pedals around vintage circuits, including the Tru-Fi Floyd Fuzz and the Tru-Fi Zonked Machine, if the Zosa's Tone Bender approach is not the flavor you are after.
Videos
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That Pedal Show
Questions
What is the Tru-Fi Zosa Fuzz based on?
Tru-Fi describes the Zosa Fuzz as a hand-made recreation of the famous Vox Tonebender. The circuit is a MkII style tone bender with a full sound, built with three vintage Mullard germanium transistors. The circuit is the same as the original Tonebender, with one addition: an adjustable bias resistor so the player can dial in the tone.
Does the Zosa Fuzz take a battery?
Yes. The Zosa Fuzz has an internal 9V battery clip, and it also takes a negative tip 9V DC power supply. Both power options are listed on Tru-Fi's product page for the pedal.
Is the Tru-Fi Zosa Fuzz true bypass?
Yes. According to Tru-Fi, the Zosa Fuzz is true bypass and sports an LED. The pedal also comes in a cigar box enclosure, which is part of how Tru-Fi ships it.
Where is the Zosa Fuzz made?
The Zosa Fuzz is made in the USA. Tru-Fi describes it as hand-made on the product page.
What does the adjustable bias do on the Zosa Fuzz?
The circuit is the same as the original Tonebender but with an adjustable bias resistor, so the player can dial in the tone. Bias sets the operating point of the germanium transistors, and adjusting it lets you make sure the fuzz sits where you want it, which matters with vintage transistor batches that vary.
Sources (3)
- Tru-Fi Zosa Fuzz Pedal Guitar Pedal, tru-fi.com
- Tru-Fi Floyd Fuzz guitar pedal in multiple versions of the EH Bug Muff design, Tru-Fi
- JHS AT+, Tru-Fi Zosa, Fulltone Mini Deja Vibe MkII, ZVex Instant Lo-Fi Junky, That Pedal Show, 2018-11-27
