Walrus Audio Iron Horse LM308 Distortion - 2025 Thunder Horse Edition

The Iron Horse LM308 Distortion - 2025 Thunder Horse Edition is a limited edition distortion pedal from Walrus Audio, issued in 2025. Walrus Audio describes it as "celebrating OKC's thunderous win by dressing up in classic jersey colors and a slightly more appropriate" name, a nod to the Oklahoma City Thunder's championship. Under the finish it is the same V3 circuit as the standard Iron Horse LM308 Distortion: a true bypass, high-gain distortion built on the LM308 op-amp, which Walrus Audio calls "our take on a classic distortion circuit that's thick, punchy, riffy, and rowdy"¹.

The pedal is now sold out on Walrus Audio's own page¹, so this page covers what the edition is, how the circuit works, and how it relates to the standard version, which remains in the lineup.

What the Thunder Horse Edition is

The edition is a cosmetic variant of the third-generation Iron Horse. Walrus Audio frames it as a limited release marking Oklahoma City's championship, with the enclosure finished in the team's classic jersey colors and the pedal carrying the Thunder Horse name for the occasion¹. The standard V3 enclosure, by contrast, is a gold finish with black ink, with artwork by illustrator David Hüttner featuring "a new battle ready stallion cloaked in armor"¹.

The circuit inside is the V3 revision of the pedal. Guitar World's Trevor Curwen calls it "this third iteration of the Iron Horse," noting it "has had quite a revamp over its predecessors"⁴. Gearnews reported the V3 as an update of the previous LM308 V2 when it launched³, and Guitar.com's Richard Purvis noted that the pedal's name had been changed from "Iron Horse V3" to "Iron Horse LM308 Distortion" on Walrus Audio's website by December 2021⁵.

Walrus Audio lists the V3 updates as top-mounted jacks, soft relay true bypass, a fixed volume drop-off at minimum distortion, and a blend-style clipping potentiometer replacing the hard clipping toggle of earlier versions². The Thunder Horse Edition carries all of these¹.

How the Iron Horse line has changed

Walrus Audio has issued other limited Iron Horse editions alongside the standard pedal, including a Halloween 2023 Limited Edition⁶.

The controls: Distortion, Volume and the Si/LED blend

The V3 control set is Level, Tone, Distortion, Si/LED and a bypass footswitch⁴. MusicRadar's review lists the same core controls: Level, Tone and Distortion⁷.

The Distortion knob has a wide range. Walrus Audio says the pedal "can be finely tuned for clear overdriven sounds or let the reigns loose for a full-on distorted onslaught"¹. GuitarPlayer's staff described the gain range as "very versatile, taking you from a tonally targeted clean boost right through to full-on distortion"⁸.

The Si/LED knob is the V3's signature control, replacing the three-position clipping toggle of the earlier Iron Horse and Iron Horse V2. It blends between two clipping types¹⁹²:

• Left: silicon clipping diodes, adding a high amount of compression¹
• Right: LED clipping with a smaller amount of compression⁹
• Noon: a blend of the two, using different ratios of the silicon and LED diodes for more complex clipping sounds¹

Because the two clipping types compress differently, the Volume knob needs attention when you move the Si/LED control. Walrus Audio notes you "will need to use the volume knob to adjust the overall output up or down depending on where you have the knob set"¹.

Is it a RAT-style distortion?

The Iron Horse is built on the LM308 op-amp, the chip associated with the classic Pro Co RAT circuit, and Walrus Audio pitches it as the maker's take on "a classic distortion circuit"². Reviewers have heard the family resemblance directly. Guitar World's Trevor Curwen, reviewing the pedal alongside the Walrus Audio Eras, wrote that "the sonic similarities are immediately apparent" when comparing it to a RAT, while finding classic distortion with optimal dialed-in variation overall and a RAT-like tone⁴.

The Si/LED blend is what separates it from a straight RAT clone. Where a stock RAT offers one clipping character, the Iron Horse lets you move continuously between compressed silicon clipping and more open LED clipping, with blended ratios in between¹. GuitarPedalx's buying guide lists the V3's controls as "Level, Tone, Distortion, Clipping : Si / LED" among its compact RAT-style distortion picks¹⁰.

Power and practical notes

The pedal runs on 9V DC at 10mA¹². MusicRadar's review likewise specifies a 9V DC adaptor, not supplied⁷.

All Walrus Audio products, including the Iron Horse, are covered by the maker's limited lifetime warranty².

Availability and pricing

The 2025 Thunder Horse Edition is sold out at Walrus Audio¹. The standard Iron Horse LM308 Distortion carries a list price of $219.99 in the maker's own distortion collection¹¹, and Walrus Audio has also sold blemished units at $186.99⁹. If a Thunder Horse turns up second-hand, the circuit and controls match the standard V3, so the regular Iron Horse LM308 Distortion page covers the same pedal in production form.

Questions