Rockman Headphones Amps

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Rockman Headphones Amps


If Boston is the band that has created the Adult Oriented Rock sound, the Rockman is the device that enabled creating the guitar sound of the eighties. From Sports by Huye Lewis - as soon as 1983 - to Satriani's Surfin' with the Alien via ZZ Top (Eliminator, Recycler, etc...) and Don Henley's "Building the perfect beast", the Rockman sound was omnipresent throughout the whole decade.

This black box was a real revolution. Considered now as the ancester of the modern digital multieffects, the Rockman was much more than a portable practice amp.

It was, more than anything else, the first amp simulator ever made available as a commercial product.

Objective and history

When Tom Scholz has created the Rockman, he had two different objectives in mind:

  1. Create a device that would allow him record Boston's music without the huge and cumbersome tube Marshall stacks: an amp simulator
  2. Create a commercial product for his young company, Scholz Research & Development: a headphones amp

The first SR&D product, the Power Soak, was a honourable success. Its nature (a professional tool) was not suitable for a wide distribution to the end-consumers.

The Rockman was launched in 1982: it was an instant hit. In 1982, there was no homestudios, no DAW's, and playing DI through the band mixer was too exotic for a majority of guitarists. So the Rockman was completed by a fancy accessory: headphones! The name itself, Rockman, was based on Sony's Walkman , and a set of headphones was actually the most convenient way to provide quality stereo sound.

Stereo was a fantastic and really new feature. Today, in 2008, we have forgotten what mono was: only old chaps like me remember the mono record players and tape recorders we used in the seventies! The younger generations don't even know that there was mono AM radio before the stereo FM they are used to...

Ahead of its time? No. The Rockman was right on time, and arrived exactly when the market needed such a tool. That's the key factor of all the success stories...

Inside the Rockman

If you want to understand what a Rockman is and why it sounds so good, the first thing to do is to ...forget the headphones!

Think of the Rockman as a stereo amp simulator, designed to be connected directly into the soundcard of your PC, or in the mixer of your band. Once that said, let's take a look at the internal structure of a Rockman.

One can roughly identify two parts: a first mono section, that corresponds to the amp simulator in itself. Then a stereo effects section, with a stereo chorus and a stereo reverb.

All in all, you connect your guitar to the Rockman. The signal goes through:

  • A compressor
  • A distortion unit (or nothing in clean modes)
  • A cab sim

That's the amp simulator. Then the stereo part, where the Rockman creates two different versions of the signal:

  • One channel is based on the dry, original sound, plus some reverb
  • The other channel goes through a short delay modulated by an LFO (thats the chorus effect) plus another reverbed sound

You have now two channels, left and right, with a huge spatial image due both to the stereo chorus and the stereo reverb. About the use of these two effects, you can read the section called "Rockman - the Concept" for an extensive analysis

The cab sim of the Rockman was, in 1982, a truly innovative concept: certainly the first circuit designed to reproduce the frequency response of a guitar speaker in such a small device. The concept was so new that SR&D didn't even think about calling it "cab sim". It was simply called "complex filter", and the following curve shows its frequency response.

If this cab sim mimicks the frequency response of a guitar speaker, it cannot duplicate its dynamic response. And that was critical!

The main difference between a real amp and any amp simulator is that that the speaker has some physical, mechanical inertia that levels the tough peaks of a guitar signal. The attack of an electric guitar is way too strong to be pleasant to hear, and that's why we need these big speakers: they kinda compress these unpleasant attacks.

Compression? Well, there is a compressor in the Rockman! And that's the real secret of Tom Scholz guitar sound, much more than EQ's, filters and saturation.

The above diagram shows how the simple compression circuit of the Rockman limits the attack of the note, and attenuates the difference between the initial peak of the note and its decay. That's what a guitar speaker does with its mechanical inertia, and that what makes the Rockman sound realistic, combined with the cab sim.

A few words about the Rockman Distortion. If you are receptiveto the marketing speech of these common stompboxes manufacturers, I'm sure that you think the Rockman distortion had something special.

Well, the Rockman distortion is the only classic part of the circuit!

A distortion stage is nothing: compression, that alters the dynamics, and filters, that process the harmonics balance of a sound, are the critical factor. The Rockman Distortion in itself doesn't have any real importance, just like tubes or solid-state has a very limited impact on the final sound of a guitar amp: its design is from far more important.

And here's a proof of this statement: though they sound alike, the Rockman and the X100 don't have the same distortion circuit...

The following diagram describes the clipping (saturation) stages of both the Rockman and the X100. They are clearly different, and the corresponding waveforms are also different. The Rockman uses what is called a "soft-clipping circuit" with 4 diodes, while the X100 is based on a "hard-clipping circuit" with 2 LED's.

Note: the terms "soft" or "hard" clipping refer to the position of the diodes in the circuit, not to their number. The Soloist has a 2 diodes soft-clipping circuit, for example.

Does an X100 sound really different from a Rockman IIB ? No, of course: even if the clipping was made with a tube in one case, and an OpAmp only in the other one, the results would be very similar! The compressor before the clipping stage, along with the cab sim after the clipping stage, are the two elements that really make the sound.

The compressor and the cab sim, joining their functions, have the role that a speaker has in a guitar amp.

The message can be summarized as follows.

When you listen to someone playing electric guitar, what you get is:

  1. The player himself
  2. The cab
  3. The electronics

The electronic part of an amp has a limited impact on the sound. That's the reason why the Rockman allowed easily to replace these huge Marshall stacks: their electronics had a very little influence on what was recorded, and Tom Scholz managed to capture the response of a recorded guitar cab inside his little black box!

Evolutions & Features

The original Rockman (1982) was followed by five similar guitar products:

Type Birth Clipping Sounds Chorus Reverb
Rockman 1982 Soft CLN2/CLN/EDGE/DIST Yes Yes
Ultralight 1983 Soft CLN2/CLN/EDGE/DIST Yes No
X100 1984 Hard CLN2/CLN/EDGE/DIST Yes Yes
Soloist 1984 Soft CLN/EDGE/DIST Yes No
Guitar Ace 1990 Soft CLN/EDGE/DIST No No
Metal Ace 1994 Soft CLN/EDGE/DIST No No

  • Note 1: the Ultralight was strictly a Rockman IIB without reverb.
  • Note 2: the Soloist was a real new product with its own design: actually, a simplified Rockman circuit.
  • Note 3: the Guitar Ace has no effects. It is basically the amp simulation part of a Rockman.
  • Note 4: the Metal Ace is a Guitar Ace with more gain and a different voicing.

The Rockman & X100 line was in constant evolution. As a matter of fact, there were 7 revisions (from REV1 to REV7) for the Rockman, called Rockman, Rockman II and Rockman IIB, and 3 revisions for the X100 (from REV8 to REV10). There are minor external changes that can help identifying the actual REV# of a Rockman, but the only reliable solution is to read it on the PCB, inside the enclosure.

  • A Rockman I can be a REV1 or a REV2
  • A Rockman II can be a REV3 or a REV4
  • A Rockman IIB can be a REV5, 6 or 7
  • The REV8 is stamped Rockman on the front, and X100 on the back
  • An X100 without power supply TRS mini-jack can be a REV9 or a REV10
  • An X100 with a power supply TRS mini-jack is a REV10

Apart from the soft versus hard clipping difference described above, the Rockman differed from the X100 by an additional switch, actionned mechanically by a folded metal square: Tom Scholz has always been fond of these mechanical tricks!

The square pushes the additional switch when the Rockman is in EDGE or DIST mode. In the X100, this trick has disappeared: its purpose was to shift a filter that was necessary in the Rockman.

The square was often lost on the old Rockman's, causing an unpleasant sound in distortion modes.

Bass headphones amps

The guitar headphones amps range was completed by two bass products:

  • The Bass Rockman, in 1984
  • The Bass Ace, issued with the Guitar Ace in 1990

The two units are totally different: while the Bass Ace is an economic mono product with minimum features, the Bass Rockman is a genuine stereo professional product with amazing features for its size:

  • Built-in DBX compressor
  • Stereo chorus, specially voiced for the bass
  • Several filters providing various EQ settings
  • Distortion stage
  • Anti-click filter for people playing bass with a pick

In other terms, the Bass Ace cannot really be used without post-processing, while the Bass Rockman can provide a complete range of finished stereo sounds, directly useable for a professional production.

Usage, samples and limitations

The users themselves have certainly been really creative with the Rockman, and it's impossible to make an exhaustive list of the configurations that people have used since 1982. Basically, in 2008, here are the most common usages of a Rockman headphones amp.

  • Practice amp
  • This is the immediate function of the Rockman: pick up a headphones set, connect your guitar to the Rockman, and enjoy this huge stereo sound! You also can connect an mp3 player and jam along with your favorite songs, or work with a backtrack.

  • Homestudio
  • That's where the Rockman becomes really interesting. In 1982, homestudios were the privilege of some happy fews. We are in 2008, and if you read these lines, you have a PC and probably a soundcard - hence a homestudio.

    The first function of the Rockman is the amp simulation, designed for DI. Connect your Rockman into the stereo input of your soundcard, and you will really appreciate its ease of use and its sound quality.

  • Rehearsal
  • Tired of hauling your heavy amp and effects rack between home and the rehearsal room? Take your Rockman and walk! Thousands of people have done it before you, for rehearsal, studio sessions or even stage use. In 2008, I wouldn't recommend using a Rockman on stage, because of its limited switching features, and a professional studio has of course many ways to achieve the same results. But in everyday's life, the magic little black box still does its job, and does it well!

    How does a Rockman sound? That's, after all, an important question! If you have really never heard one, you will find plenty of samples on this dedicated page. The best being of course to buy one and try it by yourself...

    What are the limitations of the Rockman? As stated above, the switching system is really poor, and makes it difficult to envisage a constant usage on stage: real time sound change is almost impossible.

    The Rockman is based on presets (the 4 basic sounds) and the chorus and reverb have fixed settings: don't expect creating your own sound with a Rockman!

    The only real drawback of the Rockman is the fact that you can turn off the chorus or the reverb, but not the both of them at the same time. This is weird, but that's the way it is... In case you want a non processed Rockman sound, you have to pick up the rare Ultralight, or turn towards the economic Soloist and Ace.

    Collectibility and conclusion

    The total quantity of Headphones amps produced by SR&D is certainly above 40000: they are not rare at all, and are now cheap compared to what they originally costed in the eighties.

    Depending on your budget, you can pick up a Guitar Ace for $50, or go above $100, sometimes $150 for an X100 in good shape. A complete model with its original box and accessories will of course call for more.

    Due to the continuous improvements brought by SR&D, it is recommended to look for the latest model, i.e. a REV10 X100, recognizable by its side power-supply mini-jack. Remember that the early Rockman models require a Rockadaptor to be used with an external wall-wart!

    The Ultralight is very rare, and is praised for... its lack of reverb! It's actually the only way to have the straight sound of a Rockman without chorus nor reverb added.

    The Soloist is often underated: while its features are similar to those of an Ultralight, it is usually much cheaper.

    The homestudio trend makes the Rockman headphones amps more attractive today than what they were in the nineties. They are a wonderful DI box providing directly a fully processed guitar sound: as a matter of fact, we are back today to the original mission of the Rockman, the headphones function being a secundary feature.

    Copyright 2008