The Boss TW-1 Touch Wah is an analog wah pedal from 1978 that sweeps its filter automatically in response to how hard you play, rather than to a foot-operated treadle. Boss describes the effect as "a classic wah effect that's controlled by the input signal level," with two controls adjusting the sensitivity and depth of the input filter12. It belongs to the family of touch-responsive wah and envelope filter designs, related in spirit to later auto wah pedals like the Boss AW-3 Dynamic Wah and the BOSS AW-2 Auto Wah, and sits alongside treadle wahs such as the Boss PW-3 Wah in the wider world of wah pedals.
What it does
The TW-1 provides a wah effect that's controlled by the level of the signal coming from your guitar. Its Sens control tailors the effect's sensitivity to your picking strength. That makes it a hands-free alternative to a treadle wah: the dynamics of your right hand do the work the foot would otherwise do143.
Two controls shape the response1:
| Control | What it does |
|---|---|
| Sens | Tailors the effect's sensitivity to your picking strength3 |
| Depth | Adjusts the depth of the input filter1 |
Circuit and character
Writing on Boss's own articles site, Rod Brakes describes the circuit as analog, built around a photocoupler like the one in the CS-1, "yielding a slightly slower, more fluid response for a distin[ctive character]"3. The photocoupler design is what sets the TW-1's response apart from faster envelope followers: the filter moves with a slight lag, which Boss characterizes as more fluid.
"Released in 1978, the TW-1 T Wah delivered the dynamic, touch-responsive filtering that defined a generation of fusion and funk."
History and where to find it today
The TW-1 was released in 19783. TONEHOME, an independent vintage effects reference, lists the pedal as produced from 1978 to 1979, with a T-Wah version continuing from 1980 to 19872. The original pedal is long discontinued, and a 1979 owner's manual survives in TONEHOME's archive2.
The original TW-1 is out of production. Boss has revived the effect as a software model: the TW-1 T Wah appears as an effect in the PX-1 Plug-Out FX unit, where Boss again describes it as a classic wah controlled by the input signal level with sensitivity and depth controls456. Guitar Pedal X, listing the early Boss pedals gathered into the PX-1, includes "1978 : TW-1 T Wah" among them65.
Videos
Boss Pedal Workbench
Gear Confessions
Gearfacts
Questions
How is the TW-1 different from a regular wah pedal?
A standard wah uses a rocking treadle that you move with your foot to sweep the filter. The TW-1 has no treadle: it listens to the level of your input signal and sweeps the filter automatically in response to your picking strength. Boss describes it as a classic wah effect controlled by the input signal level, with two controls adjusting the sensitivity and depth of the input filter.
Is the Boss TW-1 still available?
The original pedal is long out of production. TONEHOME lists it as produced from 1978 to 1979, with a T-Wah version continuing afterwards. Boss has revived the effect as a model inside the PX-1 Plug-Out FX unit, where the TW-1 T Wah appears alongside other early Boss pedals.
Sources (6)
- BOSS - PX-1 | Plugout FX, BOSS (www.boss.info)
- TONEHOME, TONEHOME
- The PX-1 Plugout FX: Timeless BOSS Pedals Reborn, BOSS (articles.boss.info), 2025-06-06
- BOSS - PX-1 | Plugout FX, BOSS (boss.info)
- BOSS - PX-1 | Plugout FX, BOSS (boss.info)
- Guitar Pedal X, Guitar Pedal X, 2025-08-28
Tim Mahoney
