Boss SD-1 vs Ibanez TS9 Tube Screamer

The Boss SD-1 Super Overdrive and the Ibanez TS9 Tube Screamer are two of the most widely used overdrive pedals ever built, and they are closer cousins than their different looks suggest. The SD-1 has been produced from 1981 to the present¹², while the original TS9 ran from 1982 to 1984³. Both are still easy to buy: the TS9 was reissued in 1993 and has been in more or less continual production since⁴, and ToneHome rates current TS9 availability as good, with original examples extremely collectible³.

The reason they get compared constantly is the circuit. Aion FX, which documents both designs, puts it plainly: the circuits are very similar, but parts selection gives them a very different sound, and with a handful of component swaps an SD-1 can be turned into a Tube Screamer and vice versa⁵. The differences that matter to a player come down to three things: how each pedal clips the signal, which op-amp chips and output sections they use, and how they have been reissued and modded over four decades.

The SD-1 and TS9 at a glance

Both pedals sit in the same slot on a pedalboard: a low-to-medium gain overdrive that most players run into the front of a tube amp. Guitar World's reviewer notes the SD-1's Level knob gives loads of output, so it can serve as a clean boost or really slam the front of a tube amp⁶. On That Pedal Show, the hosts found the TS9 has a little bit more headroom than the TS10 they compared it against².

Asymmetric versus symmetric clipping

This is the core circuit difference between the two pedals, and it is what a player hears first².

The Tube Screamer clips symmetrically. As Dan Steinhardt and Mick Taylor explained on That Pedal Show²⁸:

Symmetrical clipping means the positive and negative halves of the waveform are clipped equally, which produces a smoother, more even overdrive. The SD-1 takes the other approach. Analog Man notes that the OD-1 and SD-1 use asymmetrical clipping, on which Boss holds a patent⁹. Asymmetric clipping clips one half of the waveform harder than the other, adding even-order harmonic content. Guitar World's reviewer describes the result as asymmetric soft clipping that gives the SD-1 an amp-like overdrive that feels more organic than some other budget overdrives⁶.

The SD-1's clipping style is inherited, not invented for the pedal. ToneHome documents that the SD-1 contains the same asymmetric overdrive circuit as the Boss OD-1, which responds very well to the player's attack, plus an additional tone control the OD-1 lacked¹. The OD-1 itself was produced from 1977 to 1985¹⁰. Boss's own current description of the SD-1 makes the same point: it expands on the OD-1 design with enhanced voicing and a tone control¹¹¹²¹³. Analog Man adds that the SD-1 took over from the OD-1 in the mid 80s, though players still wanted the pure OD-1 sound⁹.

Beyond the clipping diodes, the two circuits differ in smaller parts. On That Pedal Show the hosts noted different input capacitors between the TS9 and SD-1, and that people talk about the different clipping diodes⁷.

Chips, parts and the TS9 output section

The TS9's relationship to the TS808 is mostly a story of the output section. The Tokai Registry review, republished by Maxon, states the TS-9 is almost the same as the TS-808 internally, with the main change in the output section, which made the Tube Screamer a bit brighter and less smooth¹⁴¹⁵. Aion FX gives the component detail: the 100R and 10k resistors on the output buffer transistor were changed to 470R and 100k respectively, and the op-amp was changed⁴. A 2001 ToneQuest Report interview with Analog Mike summarized it as the TS9 using the same printed circuit board as the TS808 with a few components changed, most notably the chip¹⁶.

Which chip an original TS9 has depends on when it was built. ToneHome's serial-number breakdown³:

Aion FX identifies the TA75558P as the op-amp of the original TS-9⁴, and the Tokai Registry review notes the 1993 reissue uses the Toshiba TA75558 chip and is basically identical to the last original TS-9s in sound, circuitry and appearance¹⁴⁴. The same review is blunt about chip quality in the later originals: some sound bad, especially the JRC2043DD chips¹⁴³. On That Pedal Show, examining a 1982 black label example, the hosts found straight green capacitors and the 4558D chip inside, noting some examples had it and some did not².

Versions, reissues and mods

Both pedals have long modification histories, partly because the circuits are so close to each other⁵.

SD-1 mods. JHS sells its Trans Am mod of the SD-1, which JHS describes as "a good sounding overdrive that is designed in the shadow of the mighty Ibanez Tubescreamer," with "gobs more available gain" than the stock pedal¹⁷. A separate SD-1 Supercharged Mod Service also exists as a modification service for the Boss SD-1 Super Overdrive pedal¹⁸. The SD-1's reach extends beyond mods: many boutique and vintage reissue overdrives have been based closely or roughly on the SD-1 itself, or on its Ibanez rival, the Tube Screamer¹⁹.

TS9 mods. Premier Guitar published a set of five DIY mods covering both pedals, written by Brian Wampler of Wampler Pedals. They include a true-bypass conversion for the TS9, which involves drilling a 1/2-inch hole in the middle of the case where it says "TS9" under the Ibanez logo⁸; swapping the stock silicon diodes for two LEDs running in parallel, which yields more headroom and volume with a warmer response; or two sets of series-wired diodes in parallel for more volume and headroom with slightly less clipping⁸. A feedback-tweak mod for either the SD-1 or TS9 uses .1, .22 and .47 microfarad film capacitors with 1k and 10k resistors⁸, and a final mod addresses what Wampler calls the "nasally mids that have long plagued the Tube Screamer and Super Overdrive"⁸.

Factory-modded versions. Susumu Tamura, the Tube Screamer's designer, has created the TS9 Tamura-Mod, built on the Ibanez TS-9 with the same Magic IC used in his TS808-TM mod, Vishay 1N914 diodes with a clipping signature distinct from both the stock TS9 and the TS808-TM mods, and a midrange peak shifted slightly higher to accentuate pick attack and improve articulation¹⁵²⁰. Godlyke's listing describes the same midrange shift, plus a variant with a +6dB level boost; both the standard Tamura-Mod TS9 listings were sold out at the time of writing²¹. The TS9DX Turbo Tube Screamer is a hot-rodded TS-9 with the exact same circuit as the original plus three additional modes, Plus, Hot and Turbo, with the Plus mode grittier than the original TS9²².

What reviewers and players said

Guitar World's review of the SD-1 praised its build and value:

The same review noted the launch price of $66 and a current price around $69, and found it hard to think of another pedal so cheap and reliable that so many famous players continue to use⁶. Documented SD-1 users include Baz Warne of The Stranglers, who used it for solos and to emulate the band's trademark scratchy guitar sound²³.

For the TS9, the Tokai Registry review names The Edge of U2 as using a TS9 for most of his overdrive tones¹⁴. On That Pedal Show's 2026 comparison of vintage Tube Screamers, Mick's 1982 black label example was his pick of the bunch, with a clarity that pays dividends when things are loud². In a 2024 episode, Mick found the Tube Screamer better suited than a Tube Driver for slightly fewer mids and without a vocal push in the mids higher up the neck²⁰.

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