The Morley Rex Brown Old Blue Wah is a signature wah pedal for Rex Brown, the Pantera bassist, made by Morley. It is a modified recreation of the Pro Series II Wah that Brown has called "Old Blue" and kept on his board for nearly three decades1. The new pedal keeps the original through-hole components and circuit layout but changes the sweep to match Brown's preference, which Morley says captures the sound of the famed 1970s Morley wahs he grew up with1.
The Old Blue Wah is Rex Brown's signature Morley pedal, built with the same through-hole components and circuit layout as the original Pro Series II Wah, but with a modified sweep per Rex's preference to sound like the original 1970's Morley Wahs21. For a bass player looking for the wah sound on late-period Pantera records, it is a direct route to the pedal Rex Brown kept on his pedalboard for over three decades, on albums including The Great Southern Trendkill and Reinventing the Steel345.
History: Rex Brown's Pro Series II Wah
Rex Brown acquired his Pro Series II Wah, nicknamed "Old Blue", in the 1990s4. Since then it has found use on Pantera records including The Great Southern Trendkill and Reinventing the Steel, and it has been a constant feature of his live pedalboard5. Morley describes it as the pedal he has used trustily for nearly three decades1.
The Pro Series II itself came out of Morley's 1992 redesign, which introduced Switchless Activation and converted the classic wah circuits to use modern optics instead of the mechanical potentiometer found in most wah pedals2. That lineage carries into the signature model.
"Old Blue has been used on countless gigs and on multiple Pantera albums, including The Great Southern Trendkill and Reinventing the Steel."
Circuit and design
The Old Blue Wah starts with the same through-hole components and circuit layout as the original Pro Series II Wah, but the sweep has been modified to Rex's preference so it sounds like the original 1970s Morley wahs3. Through-hole construction means the components are mounted with leads through the board rather than surface-mounted, the way the original was built.
Morley says a key feature of the old school design is that it prevents any frequencies from being shaved off, which gives it an intense, monstrous sweep like Morley's original 1970s wah pedals3. For a bass player, that claim matters: a wah that cuts low frequencies can thin a bass signal out, and Morley positions this design as keeping the full range intact.
A Premium Buffer circuit is built in, which Morley says ensures pure instrument tone and output3.
Controls, power and housing
The control set is minimal. There is a single Wah Level knob with 15 dB of headroom3, which sets the intensity of the wah effect rather than switching anything on or off.
| Control | What it does |
|---|---|
| Wah Level | Sets wah intensity, with 15 dB of headroom3 |
| Treadle | Engages the wah when you step on it, switchless6 |
Power comes from a 9-volt battery or a 9V adapter, and the pedal is compatible with most 9V adapters3. The housing is rugged cold-rolled steel in classic Morley construction, measuring 9.13" x 5.88" x 2.75", with LED indication and a one-year warranty3.
Switchless activation
Like the Pro Series II it descends from, the Old Blue Wah uses Morley's Switchless Activation2. There is no toe-switch to click: the wah turns on when your foot hits the treadle and off when you lift it. Morley is known for switchless activation and optical wah designs generally, using light and a photoelement rather than a mechanical pot to read the treadle position, which avoids the scratchiness a worn pot causes6. Players comparing it with a switchless model like the Morley Bad Horsie Wah will find the same basic operating principle.
The Classic Series and where to buy it
The Old Blue Wah launched Morley's new Classic Series pedal range on January 15, 2025, as its first release, with more pedals planned for the line4. Pedal of the Day later reviewed it as the first release of the new Classic Series, with more coming in 20254.
Morley's own product page presents the pedal as Rex Brown's signature Morley, using the same through-hole components as the original1. The pedal carries a one-year warranty and runs on a 9-volt battery or a 9V adapter, compatible with most 9V adapters3.
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Questions
What wah did Rex Brown use in Pantera?
Rex Brown has used a Morley Pro Series II Wah, nicknamed "Old Blue", since the 1990s. It appears on Pantera records including The Great Southern Trendkill and Reinventing the Steel, and has been a constant feature of his live pedalboard5. The Morley Rex Brown Old Blue Wah is a modified recreation of that pedal4.
Is the Morley Old Blue wah a switchless wah?
Yes. Its circuit is derived from Morley's 1992 redesign, which introduced Switchless Activation and converted the classic wah circuits to modern optics3. The wah engages when you step on the treadle and disengages when you lift your foot.
Where can you buy the Morley Rex Brown Old Blue Wah?
At launch in January 2025 the pedal was available exclusively from Sweetwater, priced at $1795. Morley's product page also lists Sweetwater availability1.
What is Morley's Classic Series?
The Classic Series is a pedal range Morley launched in 2025, beginning with the Rex Brown Old Blue Wah as its first release, with more pedals planned for the line4.
Sources (6)
- Rex Brown Old Blue Wah Pedal, Morley, 2025-01-15
- Morley Unveils the Rex Brown Signature Old Blue Bass Wah, Bass Magazine, 2025-01-16
- Rex Brown Old Blue Wah, Morley Products
- Morley Rex Brown Old Blue Wah, Pedal of the Day, 2025-03-30
- Pantera's Rex Brown teams up with Morley for Old Blue wah, Guitar World, 2025-01-16
- “We want an entire new generation of players to be able to experience the exact same pedal that Cliff used”: Morley salutes late Metallica bass icon Cliff Burton with the Tribute Power Wah Fuzz reissue, MusicRadar, 2024-02-20
Rex Brown
