1985 BOSS TW-1 T Wah

Model Description:

The beige BOSS TW‑1 T Wah is a straightforward envelope filter made by the Japanese Roland Corporation. The ubiquity of the effect in the 1970s and 1980s was inspired by the granddaddy of all envelope filters, the Musitronics Mu‑Tron III. The filter sweep is triggered by the strength of the input signal, producing a ‘wah’‑type effect without requiring foot control like a conventional wah‑wah pedal. This made it popular with many funk and disco artists of the time. The early pedals manufactured in 1978 and 1979 featured a ‘Touch Wah’ model name. Subsequently, TW‑1s produced between 1980 and 1987 were labelled with the shorter and more obtuse ‘T Wah’ moniker. Thereafter, it was superseded by the short-lived FT‑2 Dynamic Filter (1986‑1989), followed by the AW‑2 Auto Wah (1991‑1999) and then the current AW‑3. The TW‑1 is unusual in the BOSS model line up in that, like the BOSS CS‑1 Compressor/Sustainer, it features a toggle switch. In a niche market, it was up against stiff competition from alternatives like the Electro‑Harmonix Doctor Q, MXR Envelope Filter and Ibanez AF9 Auto Filter.

Pedal Description:

Beige… really? Not the most exciting choice of colour for a guitar effect pedal. The printed label with the batch number is missing from the battery compartment, making it is a bit trickier to date accurately. The style, black ‘Made in Japan’ baseplate label, the silver ‘ACA Adapter’ label and the push‑on knobs suggest that it is from the later production runs. The original box has an old sticker with a valid batch/serial code that dates to February 1985, which seems eminently feasible, although it isn’t definitive. The pedal itself is in great condition and works just as it should. Envelope filters are an acquired taste and the TW‑1 is one of those ‘marmite’ effects that splits opinion with a sound all of its own. To me, the sound is quite edgy, thin and noisy, especially with bright single coil bridge pickups. It is, though, typically very analogue in nature and probably better suited to humbucking pickups. Envelope filters largely fell out of favour by the mid‑late 1980s and, while the originals aren’t particularly common, they remain relatively cheap entries to the vintage analogue stomp box market. The TW‑1 probably falls into the ‘moderately collectable’ (and beige) category.


  • Made in Japan by Roland Corporation in 1985
  • The ‘Sens’ knob controls the sensitivity of the effect to signal strength from weak to strong
  • The ‘Peak’ knob controls depth of effect applied from shallow to deep
  • The ‘Drive’ toggle switch controls the effect direction of the filter sweep ‘Up’ or ‘Down’
  • BOSS treadle footswitch turns the effect on and off
  • Red LED ‘Check’ light to indicate when the effect is in use
  • Standard ¼” input and output mono jack sockets
  • 12V DC (BOSS ACA) power supply or 9V battery
  • Black ‘Made In Japan’ label on the base of the pedal
  • Dimensions: 70mm (w) x 125mm (d) x 55mm (h)
  • Weight: 400g
  • Original box but no instruction manual

Detail Gallery:

 ← Return to ‘effects’ page

Like it? Why not share it?