Tube Screamer vs Klon Centaur: The Two Most Important Overdrive Pedals Ever Made

Bill Finnegan built the Klon Centaur because he hated the Tube Screamer. That is not a simplification — it is essentially what he told Premier Guitar in an interview years after the fact. He had tried a TS9 (Reverb) and then a TS808 (Reverb) and found both unsatisfying: too compressed in the transient response, too prominent in the midrange, too thin in the low end. He wanted something that would add gain to his signal the way a cranked tube amp does — openly, dynamically, without imposing its own EQ character on top of his guitar's natural voice. So he recruited a friend with an MIT engineering degree and spent four years building it.

The result, introduced in 1994, was the most expensive, most coveted, and most argued-about overdrive pedal in history. Understanding why the Klon sounds different from the Tube Screamer — at the circuit level, not just the adjective level — is understanding how overdrive actually works. And understanding that is the whole game.

What the Tube Screamer Actually Does

The Tube Screamer's clipping stage sits inside the negative feedback loop of its op-amp. This is the configuration that Susumu Tamura invented at Nisshin Onpa in 1979 and that nobody had used in a guitar pedal before. Clipping inside the feedback loop produces soft clipping — the waveform is rounded off gradually rather than chopped hard at a threshold. Soft clipping sounds more like a tube amplifier than hard clipping does, which is why the Tube Screamer sounds warmer and more organic than a Boss DS-1 or an MXR Distortion+ at equivalent gain settings.

After the clipping stage, a passive EQ network rolls off low frequencies below roughly 720Hz and boosts the low-mids. This is the mid-hump. It is not an accident or a side effect — it is an intentional design decision. Tamura was competing with the Boss OD-1, trying to make guitars cut through a band mix. The mid-hump does exactly that: it moves the guitar's fundamental frequencies forward in the mix and tightens the low end so the signal does not compete with the bass. Run the Drive low and the Level above unity gain into a cranked tube amp — the way Stevie Ray Vaughan used his — and the mid-hump adds authority and presence without adding apparent distortion. It works.

What it also does is color the signal. Engage a Tube Screamer at any setting and the EQ of your guitar changes. The low end thins. The mids push forward. The top end softens slightly. Whether this sounds good depends entirely on the guitar, the amp, and what you are trying to do. On a single-coil Stratocaster into a Fender amp, it can sound magnificent — the pedal fills in the frequencies that Fender amps naturally lack and the guitar that naturally lacks low-mid weight. On a humbucker Les Paul into a Marshall that already has a midrange emphasis, it can sound congested and thick in a way that is hard to fix with amp controls alone.

What the Klon Actually Does

The Klon's circuit architecture is more complex and more unusual than the Tube Screamer's. It starts with a voltage doubler — an IC MAX1044 chip that converts the standard 9-volt pedal power supply to 18 volts. Running the op-amp at 18 volts rather than 9 gives it significantly more headroom before it clips. More headroom means more dynamic range, which means the pedal responds more dramatically to variations in picking attack. Dig in hard and it gets louder and more saturated. Play lightly and it cleans up more completely than any Tube Screamer will. This dynamic response is what players mean when they describe the Klon as feeling “alive.”

The signal then splits into three parallel paths. The first path is the distortion stage: the signal goes through a TL072 op-amp and two 1N34A germanium diodes configured for hard clipping. Hard clipping — as opposed to the Tube Screamer's soft clipping — chops the waveform more aggressively at the clipping threshold. On paper, hard clipping sounds harsher than soft clipping. In practice, the Klon's hard clipping stage sounds gentler than you would expect because the germanium diodes have a lower forward voltage than silicon diodes, which means the clipping threshold is reached earlier and more softly than it would be with silicon. The result is hard clipping that sounds relatively smooth — firmer and more immediate in the transient than a Tube Screamer, but not aggressive.

The second path carries unaffected low frequencies directly to the output. This is the key difference from the Tube Screamer. While the TS rolls off bass before and after clipping, the Klon preserves low frequencies in a separate path that bypasses the clipping stage entirely and recombines at the output. Your low end goes through the pedal intact.

The third path is the clean blend, and it is what makes the Klon's gain control behave uniquely. As you turn the gain clockwise, the distorted signal increases while the clean signal simultaneously decreases. At minimum gain, you have almost entirely clean signal with a slight push — a nearly pure boost. At maximum gain, you have almost entirely the distorted signal. At middle settings, the two blend in a ratio that produces a layered, complex distortion with the natural dynamics of the clean signal underneath. No other overdrive of the era did this. It is why the Klon at moderate gain settings sounds more three-dimensional than a Tube Screamer at equivalent settings.

The Transparency Question

The word “transparent” is the most contested term in the overdrive conversation. Transparent pedals are supposed to add gain without altering your tone. The Klon is universally described as transparent. This description is mostly accurate and slightly misleading.

The Klon does preserve low frequencies and overall tonal character better than the Tube Screamer. The clean blend ensures that your guitar's natural voice stays present in the mix even at high gain settings. At low gain settings it functions as a genuine clean boost — volume up, character unchanged. In these respects it is more transparent than the Tube Screamer.

But it is not fully transparent. The Klon adds a subtle upper-mid emphasis — centered slightly higher in the frequency range than the Tube Screamer's 720Hz hump — that makes notes cut and articulate more clearly. You can hear it most easily by engaging the pedal with the gain at zero and the output at unity. The tone shifts slightly: brighter, more present, more forward. This is not the Tube Screamer's EQ shaping — it is subtler and more natural — but it is there. Finnegan later added a small resistor in a 1995 revision to give the circuit “a very small amount of additional low-mid response,” specifically to add “a little more roundness when used with, say, a Strat into a Super Reverb.” Even he was adjusting the EQ after the fact.

The honest description: the Klon is more transparent than the Tube Screamer, not fully transparent.

Who Used What and Why

Stevie Ray Vaughan used the Tube Screamer. Specifically a TS9 run with Level near maximum and Drive near zero, boosting the front end of cranked Fender Vibroverbs. The mid-hump filled in the midrange that single-coil Strats and Fender amps naturally lack. It was the right tool for that specific signal chain.

John Mayer uses both — sometimes simultaneously. The Tube Screamer sits earlier in his chain for its midrange character and compression. The Klon sits later as a cleaner boost and lead enhancer. Running them together, Tube Screamer first then Klon, layers the mid-hump underneath the Klon's transparent top end, producing a gain stack that is thick but not muddy. This is the most advanced application of both pedals.

Jeff Beck used a Klon Centaur in his later career, favoring its dynamic responsiveness and the way it preserved his fingerpicking attack. Beck played without a pick, and the Klon's clean blend meant his picking dynamics transferred through the pedal more accurately than any mid-focused overdrive would have allowed.

Joe Perry used a Klon for lead boost rather than primary drive — the same function Vaughan used the Tube Screamer for, but in a different direction. Perry wanted volume and presence without EQ coloration; the Klon's clean output stage provided that.

Kirk Hammett used a Tube Screamer in front of high-gain Mesa amps. The mid-hump tightened the low end of the Mesa's heavy distortion and gave the lead tone more definition and cut — a technique that became standard in metal production. The Klon would not have worked in this application. The Mesa was already saturated; the Klon's clean blend would have introduced muddiness rather than tightening the signal.

The Clone Economy

Finnegan built approximately 8,000 Klon Centaurs by hand between 1994 and 2008, working alone on a folding table in successive small apartments in Boston. He sold them for $225. When he discontinued production, the secondary market exploded — original Centaurs now sell for $2,000 to $5,000 depending on condition and serial number.

The circuit became public in 2008 when schematics appeared online, having been reverse-engineered from units whose epoxy coating had been carefully removed. The conclusion: it was exactly the circuit Finnegan had described, with no hidden components or magical additions. The epoxy had protected a genuinely original design, not a secret.

What followed was the clone market. Every major pedal manufacturer eventually released a Klon-derived pedal. The EHX Soul Food (Reverb) is the entry-level version — $50, sounds like a Klon at low and medium gain settings. The J. Rockett Archer (Reverb) uses original germanium diodes and is generally regarded as the closest circuit match. The Wampler Tumnus (Reverb) uses silicon diodes and sounds nearly indistinguishable in blind tests, which is the most honest argument against the germanium mythology. The JHS Bonsai (Reverb) covers both universes — nine Tube Screamer variants in one pedal, including the Keeley mod.

In 2014 Finnegan released the Klon KTR (Reverb) : same circuit, surface-mount components, smaller enclosure, $269 retail. He printed on the faceplate: “Kindly remember: the ridiculous hype that offends so many is not of my making.” It was immediately hailed as the definitive Klon. It is now also discontinued and selling used for over $1,000.

The Analogman King of Tone occupies a separate category. It is not a Klon clone or a Tube Screamer clone but a dual-channel design with its own circuit topology, drawing from both traditions. The wait list is often over two years. It is, by general consensus among players who have used one, worth it.

Which One Do You Actually Need

The answer depends on what problem you are trying to solve.

If your amp is already breaking up and you want to push it harder without changing its character — more gain, more sustain, more volume — and you want the pedal to stay out of the way tonally, you want the Klon approach. Clean blend, preserved low end, transparent top end. The EHX Soul Food does this at $50. The KTR did it at $269. Any honest Klon-style pedal does it. You do not need an original Centaur.

If your amp is clean or only mildly dirty and you want the guitar to cut through a full band mix with more midrange authority and tighter low end, you want the Tube Screamer approach. The TS9 at $100 does this. The Maxon OD808 (Reverb) does it slightly more faithfully to the original circuit. The Keeley Red Dirt (Reverb) does it with more dynamic range. You do not need a vintage TS808.

If you want both — the Tube Screamer's mid-hump for band-mix cutting and the Klon's transparent top end for clarity and sustain — run them in series, Tube Screamer first. The Tube Screamer shapes the EQ and tightens the low end; the Klon adds volume, headroom, and dynamic range on top. John Mayer has used this combination for years. It is not accidental.

The one thing both pedals agree on: neither one sounds best as a primary distortion source into a clean amp cranked to bedroom volumes. Both were designed to work with tube amplifiers that are already contributing something — a little breakup, a lot of headroom, or both. The pedal pushes the amp. The amp does the work. That principle has not changed since 1979 and it is still the most important thing to understand about either of these circuits.

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