TWA Scott Henderson SH9 Distortion

The TWA SH9 Scott Henderson Signature Distortion is a distortion pedal from TWA, the maker's first signature model, designed in collaboration with Susumu Tamura, the creator of the Tube Screamer. It is built around the Maxon SD-9 Sonic Distortion circuit architecture that Tamura invented in 1981, re-worked to meet fusion guitarist Scott Henderson's standards¹. TWA describes the result as a thick, compressed, amp-like tone with improved bass and lower midrange response, in a die cast zinc enclosure with custom powder coat, made in the USA¹.

The pedal took nearly three years to develop². TWA announced it as the company's first signature model and its first collaboration with Tube Screamer creator Susumu Tamura¹.

The controls and battery power

The SH9 keeps the SD-9's three-knob layout. GuitarPlayer lists the controls as Distortion, tone and level³¹:

The biggest change from the original circuit is in the tone stack. Tamura shifted the center frequency of the Tone control and focused it in the lows and lower-mids, so there is no loss of bass frequencies when the Tone knob is turned up¹. Guitar World's review describes this as redesigning the tone stack to emphasize the lower-mids and increasing the output level².

Power comes through a 9VDC jack, with the adapter not included, and there is also a terminal clip for a battery inside the pedal³. The SH9 can optionally run at 18 volts, which TWA says gives increased headroom, less compression and an alternate drive signature¹. Delicious Audio likewise notes Tamura designed it to operate with 9- or 18-volt power⁴. Switching is true bypass, with a mechanical footswitch¹³.

A Maxon SD-9 circuit, built to order

The SH9's lineage is the Maxon/Ibanez SD-9 Sonic Distortion. TWA states plainly that Tamura took the basic SD-9 circuit architecture he invented in 1981 and re-worked it for Henderson¹, and Guitar Pedal X grouped the SH9 among Maxon SD-9 derivatives⁵. Where the original circuit's tone control could thin the low end, the SH9's redesign aims at improved bass and lower midrange response¹.

Henderson is the pedal's signature artist, and his endorsement appears on the maker's page¹⁴:

The pedal is available with two different faceplate screens: one with the SH9 logo in lime-green like the original SD-9, and one all-white with a replication of Scott's signature¹.

What reviewers said

GuitarPlayer's review, by Art Thompson, tested the SH9 with a Gibson Historic '59 Les Paul and a G&L ASAT Classic with Seymour Duncan pickups through a reissue '65 Fender Deluxe Reverb combo³. Thompson found the SH9 "made its case right off the bat in three ways: its thickness, how much distortion it delivers and the amount of" output on tap³. With single-coils, he reported smoothly textured grind with the distortion knob at one o'clock, the tone at nine o'clock or less, and the level around two o'clock, and found it worked well for lead and dirty rhythm riding the guitar volume. With a Les Paul, he found it easy to dial in a singing neck-pickup blues tone or a fat, sustaining bridge-pickup sound with highs that slice through when loud. He also noted the pedal's compression makes for a great feel when soloing, and that rolling back the guitar volume with distortion past two o'clock produced a ballsy crunch-riffing rhythm tone³. His summary verdict: thick distortion with smoothly tailored highs³.

Guitar World's Paul Riario went further:

Guitar Pedal X, rounding up 2023's new distortion pedals, characterized the SH9 as honed for upper fret legato playing, more of a melody and lead style than a rhythm pedal, and optimized for single coil pickup voicing, though noting that with clever EQ'ing and a low cut it can get very decent sounds otherwise⁵.

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