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This is the man responsible for the Tube Screamer. And the rest of the Ibanez 9 Series too…

Mere mention of a ‘green overdrive’ in current effector culture brings to mind one pedal, and one pedal only: the venerable Ibanez Tube Screamer. Look more closely at the original 9-Series line, however, and you’ll also find a more a vibrant verdant voice. The SD9 Sonic Distortion is altogether more ‘rock’ than the TS, eschewing smooth, vocal mids for harder, rasping bite. History tells us which has been the more popular pedal to date, yet the SD9 nonetheless retains a core of ardent fans and users.

To accompany a recent That Pedal Show episode, Mick sent some questions off to Susumu Tamura, former Maxon designer and yes, father of our favourite green ODs!

Mr Tamura, thank you for answering these questions. I understand that you worked on the whole ‘9’ line, and that these were essentially Ibanez-branded versions of the same-circuit Maxon pedals - Maxon for the domestic market and Ibanez for export via Hoshino Gakki. Is that correct?

“When Maxon and Ibanez’s original 9 series [pedals] were released, I was on the front line designing almost all of them. I had several assistants working on these designs. This is off-topic, but the ‘9’ in the 9 series comes from the series that runs on a single 9V battery. In the previous series, there were spatial effect pedals that could not be operated without two 9V batteries.

“The correct positioning of the Maxon and Ibanez brands is as follows.

Maxon is Maxon’s own brand. Hoshino Musical Instruments is the brand holder for Ibanez. At that time, Maxon only had the ability to sell its products to the domestic market. This led to Hoshino Gakki's request, “We only sell overseas and not within Japan, so we would like you to supply us as an OEM. This is how we started selling overseas under the Ibanez brand.

“Since the sales territories are completely different, even if the same pedal is sold under different brands, there will be no product conflict in the market. In addition, by supplying pedals to overseas markets under the Ibanez brand, the production volume could be multiplied several times over, and we could expect mass-production effects at the factory. At this time, there was no problem in selling pedals with the same shape but with different brands. As a result, it was generally said that Maxon was a domestic brand and Ibanez was an export brand.

“However, a few years later, Hoshino Musical Instruments started selling in Japan as well. If that happens, there will be various problems when pedals with the same shape are distributed in the domestic market under both the Maxon and Ibanez brands. For this reason, Maxon and Ibanez have released pedals that have the same internal circuit (PCB) but differ only in external design.

“Some pedals with the same design as Maxon and Ibanez were manufactured, but these were initially sold only domestically under the Maxon brand, and only overseas under the Ibanez brand.

“This is also off topic, but Hoshino Musical Instruments is not a manufacturer, but an import/export trading company, and does not own a factory that manufactures pedals. Current Ibanez pedals are manufactured at subcontracted factories.”

PHOTO: An original SD9 complete with a battle scar or three


Could you describe the main ways in which the original SD9 circuit differed from the TS9, perhaps in the context of its design brief? That is to say, we know the Tube Screamer was intended to be like an overdriving tube amp – what was the SD9 intended to be?

“Needless to say, both are distortion pedals, but I think the SD9 can be classified in the ‘distortion’ category and the Tube Screamer in the ‘overdrive’ category. Tube Screamer is a pedal specifically aimed at the sound of vacuum tube guitar amps, and can be used to create overdrive sounds that are distorted by the pedal itself, or to raise the level of clean sounds and use it as a booster pedal to drive amps. The SD9 is mainly used to create distortion using a pedal.

“Circuit-wise, the Tube Screamer uses diodes symmetrically placed in the negative feedback circuit of an operational amplifier circuit to obtain an overdrive sound. SD9 uses diodes placed symmetrically after the operational amplifier circuit to obtain a distortion sound.

“Both SD9 and Tube Screamer are equipped with a tone control circuit in addition to the aforementioned distortion circuit, and have a three-knob configuration. These days, tone control equipment is commonplace, but back then, the tone control knob was a unique feature. Equipped with this tone control, the range of distortion tones was increased, allowing a wide range of pedal sound settings to be made regardless of the type of guitar, pickup type, amp type, music genre, etc. Recently, many of these reissued pedals, updated pedals, and clone pedals still have the 3-control design.”

PHOTO: After the 808 came the TS 9. Mr Tamura designed them both

Once the SD9 hit the market, were you surprised by how it was being used, and the sounds it was making at the feet of various players?

“I am grateful that Scott Henderson and Michael Landau continued to use the Maxon reprint SD9 for over 10 years. They initially started with an Ibanez SD9. It was replaced by the reissue SD9 released by Maxon in 2002. The Maxon reissue SD9 uses the true bypass method, which removes the input/output buffer circuit and bypass/effect FET electronic switch circuit from the original SD9, giving you the true SD9 distortion sound.

“I think it is significant to point out that the Maxon SD9, which Scott Henderson and Michael Landau used for many years, was not given away by Maxon for free, but rather they went to a music store in Hollywood and purchased it themselves.

“The setup photo of the Maxon reproduction SD9 installed on Scott Henderson's pedalboard appeared in domestic and foreign music magazines, but I've always been curious about the fact that the tone knob was at around eight o'clock and the level knob was at almost full position.

“I talked to Kevin [Bolembach] at Godlyke about this and told him that the settings were too extreme and I wanted to improve it to make it more user-friendly. Kevin contacted Scott Henderson to modify the SD9. Due to the coronavirus pandemic, we were unable to meet in person to evaluate the sound output of the modified prototype.”


How did the SD9 circuit evolve after the 9 series was replaced? Did it make it into the next Ibanez line, and/or evolve as a Maxon product?

“I have never written about the roots of SD9, but I took this opportunity to research and summarize them. SD9 Sonic Distortion is a product added from the 9 series, but its root is Maxon D&S2 (D&SⅡ) Distortion & Sustainer. Maxon D&S2I think it was released in 1977, and it is listed in Maxon's official catalog. An Ibanez product with an equivalent circuit is ‘Overdrive II’, which was published in the 1979 Ibanez official catalog. The circuit configuration of these is almost the same as the SD9, but the tone circuit uses an active tone control circuit similar to the TS. The bypass switch uses a mechanical push switch.

“Later, in 1980, the model was changed to Maxon D&S2 (D&SⅡ) OD802. The model number of OD802 is listed. The circuit configuration has been changed from the initial D&S2, and the tone circuit has been moved to the front stage of the distortion circuit, making it an active tone circuit and pre-tone. I don't remember why it became pre-tone. Other changes include electronic switches using FETs, input/output transistor buffers, and caramel switches for the bypass switch. Ibanez's equivalent is the Overdrive II OD855.

“In 1983, the SD9 was introduced. It was released at the same time as the famous Ibanez TS9 and Maxon OD9 9-series models. The circuit configuration has been changed from Maxon D&S2 (D&SⅡ) OD802's pre-tone to post-tone, and the passive tone circuit that is also used in the current Maxon SD9 Sonic Distortion. Pre-tone was probably not well received. Ibanez also has SD9 Sonic Distortion, and other than that the brand is Maxon or Ibanez, everything else is exactly the same.

“In 2002 Maxon begins selling the current reissue SD9. The basic circuit configuration is the same as the 1983 SD9, but the bypass has been changed to a mechanical true bypass method. From this point on, Maxon stopped supplying pedals to Ibanez.

“Ibanez then launched the Ibanez SD9M Sonic Distortion Modified in 2012. This is a product originally produced by Hoshino Musical Instruments, but since it seems to have already been discontinued, the details are unknown, but from the outside it looks like a gain and mids toggle switch has been added.

PHOTO: One of the many modded Maxon SD-9 pedals, this one by AnalogMan

Moving forward to the SH9, what were Scott's main requirements for his signature TWA pedal?

“Scott Henderson's signature Distortion SH9 didn’t suddenly become an SH9, but started out as an improved modification model of the Maxon SD9, the SSD9 Supersonic Distortion.

“We started with a plan to make the Maxon SD9 – which Scott Henderson had been using for many years – easier to use, so that the knobs could be set with more leeway rather than extreme settings, and to bring it closer to the sound that he prefers.

“I made an SD9 with improvements that I thought would be better and sent it from Japan to the United States. I had Scott check the sound, but it didn’t pass. He pointed out aspects that did not meet his wishes, and we made a sample that reflected those points, sent it from Japan to the United States, and had him check it four times over a period of more than a year and a half.

“We were planning to sell the SD9 modified model approved by Scott Henderson as SSD9 from Godlyke, but the distribution agreement between Maxon and Godlyke has expired, and the original SD9 is no longer available from Maxon… Therefore, the SSD9 was discontinued after only a small number of sales, and it was decided to sell it as a newly designed product called TWA SH9.

“SH in SH9 stands for Scott Henderson's initials. The body color, purple, is Scott's favourite colour. I had heard this story, so I decided to use purple for the internal printed circuit board as well.”


Finally, perhaps this is a slightly difficult question, but I'll go with it… The players that use the SD9-type pedals tend to be 'feel' players with a great deal of touch sensitivity and dynamics in their tone. Is there something specific to the SD9 that helps enable this kind of touch-responsive playing?

“I know that the SD9 tends to be used by players with a discerning ear. However, I don't think the SD9/SH9 is superior to the player's touch nuances or tonal dynamics. I tried re-measuring with an audio analyzer again, but my opinion remains the same.

“I believe that the Modified TS-type overdrive which I am involved with and is equipped with a magic IC, is the best at enabling overtone (even/odd order) response performance with excellent touch nuances and dynamics of the player.”

For more on the TWA SH9, head HERE

For more on the Modified TS Types with the magic IC, head HERE

Special thanks to Kevin Bolembach at Godlyke Distributing & TWA for enabling this conversation.


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