Rockman Sustainor

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The Sustainor is the heart of every Rockman rig. It is certainly the most complex and the most charismatic of the Rockmodules: its development required several years from a complete team of engineers, probably working separately on sections of the Sustainor.

Though its sound signature is immediately recognizable, the possibilities and versatility of the Rockman Sustainor are almost endless, still over twenty years later.

Certainly the first high-end analog amp simulator ever built, the Sustainor is, still today, an outstanding device, far above the classical preamp image that some people have of it.

Objective and history

The basis of the Rockman Sustainor is the amp simulation of the Rockman headphones amps. If one considers that the Rockman and the X100 are semi-professional devices, then the Sustainor stands as the professional extrapolation: while the headphone amps are based on four preset sounds, the Sustainor was extended by several complex, smart and useful inventions.

The Rockman headphone amp was created by Tom Scholz and issued in 1982. SR&D improved it continuously between 1982 and 1986, without significant changes: only minor circuit tweakings.

In the meantime, Tom Scholz had imagined the improvements that would give birth to the Sustainor:

  • Adjustable gain stages, volume controls and filters.
  • A noise reduction circuit: the Smart Gate
  • A truly amazing feature: the Autoclean
  • A 4x12' cab simulation: the Phase Notcher

When did the studies for the Sustainor begin? Probably right after the issue of the Rockman: 4 years is not much when the deal is to stuff 1kg of components in the volume of a pocket book! All in all, the Rockman Sustainor was issued as a commercial product in January 1986, along with the Rockman Chorus/Delay.

The Sustainor, like all the Rockman products, was continously improved. The first commercial items correspond to the REV03, knowing the last commercial release, in 1989, was REV09.

The first models had this blue logo that make us call them "Blue face", and the rear plate was stamped "100" (as a matter of fact, all the Rockmodules are stamped 100 and it's more an enclosure type than anything else). SR&D sold almost 9000 Sustainors in 1986. In February or March 1987 (circa S/N 10000), the rear plate was stamped 100A, and the blue logo was still here. These 100A Sustainors have nothing special: they are just the last Blue-Face Sustainors, a sort of transition model before the change of logo.

In October 1987, the logo on the frontplates of the Rockmodules (i.e. the Sustainor, the Chorus/Delay and the Instrument EQ) received a white logo instead of the original blue one. The Chorus/Delay was actually discontinued, and the existence of white-faced C/D's or blue-faceed EQ's as commercial products is not proved.

The change of logo was accompanied, for the Sustainor, by a change of rear plate: it was now stamped 200 instead of 100. The front plate was slightly modified, and all these changes make us speak about the Sustainor 200, though the 200 is just a continuous improvement of the 100, not a different product.

All in all:

  • A total of over 21000 Sustainors were made and sold between 1986 and 1992
  • The early Sustainors are called 100 or "blue face" and can be identified by their blue logo
  • The later Sustainors are called 200 or "white face" and can be identified by their white logo
  • The best Sustainors are the younger ones, and the manufacturing date, along with the Serial Number, is the key to choose one

Inside the Module

The Sustainor is complex. Very complex. While the amp simulation circuit of the original Rockman took only 6 OpAmps controled by only one mechanical switch, the Sustainor is made of 28 Opamps with a complete network of mechanical and J-FET switches.

Let's have a look the structure of a Sustainor to see what are all these OpAmps and Switches are made for. We can compare it to the structure of the X100's amp sim for an easier understanding:

The first addition is the Smart Gate, placed right after the compressor, i.e. right before the distortion stage. As a matter of fact, noise doesn't come from distortion itself: the distortion overamplifies evrything, and the most discrete breathe can become a real wind sound! The Smart Gate is here to suppress all the breathe noise that the compressor can generate.

What does the Smart Gate do? A classical noise-gate does two things:

  1. Compare the signal level and a threshold
  2. Cut the sound if the signal is below this threshold

Of course, a noise gate cuts the noise, but it cuts the signal too! The Smart Gate operates differently, and does two things:

  1. Follow the signal level instead of comparing it to a threshold
  2. Opens or closes a low-pass filter proportionnaly to the signal level

Closing the filter cuts-off the high frequencies where noise is present, an never, never cuts off the main part of the note. This principle is derived from a more general principle called "adapted filter", a math-based noise-reduction approach that usually requires very complex circuits (such as the circuit of Rocktron's Hush). Scholz just did the same thing with classic components and a lot of time spent tweaking his circuit...

The next significant addition is the circuit called Autoclean. We all know that turning down the volume pot of the guitar reduces the gain of the distortion: to a certain extent, we can go down from plain distortion to light overdriven sounds. To a certain extent only: the balance between the treble and the bass frequencies is messed up, and we lose a lot of dynamics. Moreover, it is virtually impossible to go as low as a clean sound with this technique.

Well, all in all, the Autoclean circuit allows doing all that: total control over the saturation without signal loss, without dynamics loss, from the guitar volume pot! It is even possible to reduce the gain down to the clean sounds range.

Though the basis of the Autoclean circuit doesn't look complex, it was actually very tricky to design, and as a matter of fact, only the younger Sustainors have an Autoclean that really works great.

Then the Phase Notcher. The Rockman cab sim (see the Headphones Amps review for details) simulates the behaviour of a plain single-speaker cab. Some guitarists are used to the weird response of a multi-speakers cab: this technique was used in the sixties when the speakers had very low sensitivities, cause it was the only way to make an amp sound loud. It became 100% useless over the years, but the habit is still here: some people love the feeling of a 4x12' cab, as if they were playing in the Shea Stadium everyday. Well, multi-speakers cabs have a sonic drawback: there are interferences between the speakers that cancel some frequencies...

The objective of the Phase Notcher is to simulate this default: it produces a nasal sound, that you may like or not. The following curve depicts the frequency response of the Phase Notcher:

The Sustainor has another smart trick that can be really helpful: the rhythm volume footswitch. This turns down the global output volume a little, and at the same time scoops the mid frequencies to leave room to the lead instruments or vocals within a mix. Simple and efficient!

Last but not the least: the Sustainor has a special loop designed to host a pre-distortion equalizer. Placing an EQ before the distortion stage and another EQ after the Sustainor is the key to all the possible sound variations, from mellow to harsh and from classic rock to modern sounds (refer to the Rockman Concept section for details).

Usage and limitations

The endless parameters combinations of the Sustainor make it an extremely complete and versatile tool.

The first contact may be a little surprising: if you play alone during the first test, you will probably find the sound a little nasal! That's perfectly normal, if you consider that the Sustainor was designed to play guitar within a band, i.e. with other instruments. A guitar is always mixed with an emphasis on the mid frequencies (except in this weird death-metal-trash-core teenagers' stuff!), and the Sustainor pre-processes the sound in this spirit. In a second approach, you can try to play along with any classic rock record (Lynyrd Skynyrd, ZZ Top, etc...) and you will hear the magic happen!

Any limitations? Well, it is highly recommended to use the Sustainor with a pair of Rockman EQ's if you want to dial your own sounds. One could also regret that only 2 modes out of 4 can be controled by the footswitches: a modification is necessary to access the 4 of them.

Apart from this secondary issues, the Sustainor is what it was made for: a professional analog amp sim for the most demanding musicians.

Collectibility and conclusion

Buying only a Sustainor, without the rest of a Rockman rig, is of course possible. Yet, one can very rapidly see that it's a sort of nonsense: the Sustainor is the heart of a Rockman rig, so the question of its collectibility as a stand-alone unit is pointless. Either you need one, either you don't.

Moreover, the Sustainor is not rare at all: with over 21.000 items on the market, there are always several Sustainors for sale on eBay, with prices ranging from $100 to over $400.

The question is more "which Sustainor should I buy", knowing the 4 possible choices are:

  • A Sustainor 100: the cheapest and the oldest
  • A Sustainor 100A: slightly better, but not much
  • A regular Sustainor 200, still affordable
  • A "young" Double-IC Sustainor 200, quite expensive for what it is

Buying a Double-IC because of this Lead-Leveller feature only is fairly stupid: as a matter of fact, nobody can tell the difference with or without Lead-Leveller. But there's another factor that must be taken into account: take two Sustainors and make an A/B comparison, and you will always hear a difference. So, all in all, since you cannot try a Sustainor before you buy it, the only rule to follow is "the younger the better": hence the Double-IC domination on the second-hand market.

Buy a 100 if funds are an issue, buy a 200 if you want less noise and a better Autoclean. Buy a Double-IC if you need a garantee to have the youngest possible engineer revision, hence the best Autoclean.

And most of all, remember that a Sustainor with its original electrolytic capacitors needs a thorough refurb before sounding the way it deserves! The Rockmodules are 20 years old now, and their caps are at the end of their life.

The Sustainor is, still today, an excellent amp simulator. Truly mandatory for any Rockman fan, it can also be the first module to buy for a newcomer. Worth buying anyway because of its endless possibilities.

Copyright 2008