The Fryette Boostassio BST-1 is a tube power boost pedal built around an EF86 pentode preamp tube rather than the 12AX7 triode found in most tube pedals. Fryette describes it as a high-voltage pentode tube design that produces greater dynamic range than a typical pedal, delivering what the maker calls "real amp qualities similar to that which you would experience with a cranked, low powered vintage tube amp"1.
The EF86 tube and why it matters
The BST-1's character comes from its tube choice. The manual explains: "It utilizes an EF86 'Pentode' type preamp tube rather than the typical 12AX7 'Triode' type." Pentode tubes are a different design from the triodes used in most pedal and preamp circuits, and Fryette pairs the EF86 with a variable bias control to produce what the maker describes as a range of distortion effects with clean amp clarity1.
The factory installed tube is an EF86 selected for superior performance, low noise, and low microphonic sensitivity. Replacement is restricted: the manual states the tube requirement as "EF86/6267 or equivalent. NOT INTER-CHANGEABLE WITH A 12AX7 OR ANY OTHER TYPE!"1.
The warranty is only valid if the factory recommended tube is used. Stick to EF86/6267 types or equivalents when replacing the tube1.
The EF86 is shock-mounted inside the pedal and, according to Fryette, will last typically 2 to 3 years depending on usage and other conditions1.
The bias control
The BIAS knob affects the operation of the tube and is the pedal's main voicing control1:
| Setting | What it does |
|---|---|
| Fully left (BLISS) | Least distorted setting, with the most clean headroom1 |
| Turning right | Progressively more distortion and overdrive effects1 |
In practice, that means the BST-1 can sit at the clean end as a straight boost that preserves headroom, or be pushed toward overdrive and distortion territory without leaving the tube circuit. Players comparing it with other overdrive pedals or distortion pedals should read it as a boost with a wide drive range rather than a one-sound box1.
Bypass and the indicator LED
The BST-1 true bypasses through an internal relay. Fryette adds a safeguard: "If power to the pedal should be reduced or interrupted for any reason, the device automatically goes into bypass mode," so a dying supply will not kill your signal path1.
The indicator LED changes color with the pedal's state:
- Bypassed: the internal tube and indicator LED produce a warm amber color behind the tube vent grill1
- Effect activated: bright green1
Power requirements
The Boostassio is powered externally with a 12VAC power supply. This is the one specification that rules out most pedalboard habits1:
- Operating voltage: 12VAC1
- Current consumption: 500mA1
- Maximum voltage: 14VAC1
- Connector: 5.5x2.5mm barrel type1
The BST-1 is a fairly compact unit at 5" W x 4.75" D x 1.25" H and 1.5 pounds, so it fits alongside standard pedals on a board, but check the maker's specifications for its power needs before planning a supply output for it1.
Warranty and compliance
Fryette warrants the BST-1 for five years from date of purchase against manufacturing defects in materials and workmanship, with tubes, fuses, and speakers carrying a 90 day warranty. The pedal is declared compliant with European Union Directive EC1907/206 (REACH) and Directive 2002/95/EC (RoHS), and complies with the EMC Directive 89/336/EEC and Low Voltage Directive 73/23/EEC, examined by Electromagnetic Engineering Services, Inc. to EN 50081-1, EN 50082-1, and EN 600651.
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Questions
Can I use a 12AX7 in the Fryette Boostassio BST-1?
No. The manual states the tube requirement is an EF86/6267 or equivalent, and that it is not interchangeable with a 12AX7 or any other tube type. The factory installed EF86 is selected for superior performance, low noise, and low microphonic sensitivity, and the warranty is only valid if the factory recommended tube is used.
Is the Fryette Boostassio BST-1 true bypass?
Yes. The BST-1 uses true bypass via an internal relay. As an added safeguard, if power to the pedal is reduced or interrupted for any reason, the device automatically goes into bypass mode, so your signal keeps passing through.
How long does the tube in the Boostassio last?
Fryette says the EF86 tube, which is shock-mounted in the pedal, will last typically 2 to 3 years depending on usage and other conditions. When it needs replacing, use only an EF86/6267 type or equivalent.
Does the Boostassio BST-1 run on a 9V battery or 9V adapter?
No. The Boostassio is powered externally with a 12VAC power supply drawing 500mA, through a 5.5x2.5mm barrel type connector. A 9V battery or standard 9V DC pedal supply will not run it, so it needs its own spot on an AC-capable power source.
What does the LED color mean on the Boostassio BST-1?
When the pedal is bypassed, the internal tube and indicator LED produce a warm amber color behind the tube vent grill. When the effect is activated, the LED shows bright green.
Sources (1)
- BST Booklet_Cvr, Fryette (Steven Fryette Design, Inc), 2021
