Introduction
In a first approach, an equalizer is only an equalizer. Something simple that all the manufacturers should be able to design correctly.
But if you ask someone like Tom Scholz if the common commercial devices fit his requirements, the answer is less obvious.
The Rockman Instrument EQ is just different and better than what\'s available on the market. Let\'s see what makes its qualities and differences.
Objective and history
\"[...]a couple of years ago we designed a graphic equalizer. Now, how crazy is that?
There are dozens of them on the market, but there was not a single one that could be used with a guitar level signal, was footswitcheable, had a decent signal-to-noise ratio, and could give better than an octave resolution.
We tried to modify existing units, but finally gave up and designed the stupid thing so we would have what we needed.\"
(Tom Scholz in Guitar World, Feb. 90)
Inside the Module
The first thing that a tech will see inside the Instrument EQ is... no 4053/4066 chips! These J-FET IC\'s are everywhere in the other modules, and were not used in the EQ. As a matter of fact, SR&D designed it for the best signal-to-noise ratio, and selected a +/-12V power supply - instead of +/-8V - that prevented from using the integrated switches (the bypass circuit is therefore based on discrete J-FET\'s).
The higher the power-supply voltage is, the stronger the signal can be, and the better is the S/N ratio: with a total amplitude of 24V, the immediate improvement is 4dB compared to a 9V powered stompbox. The Rockman EQ can thus be used both with guitar level signals, as required by Tom Scholz, and strong line-level signals (up to 14dB): there is a switch on the Rockman EQ that selects the operating signal level (Normal: line level or Hot: instrument level).
Back to the features of the unit. The real difference between a classical EQ and the Rockman Instrument EQ is the presence of 3 additional bands in the mid-frequencies:
- 62,5 - 125 - 250 - 500 - 1000 - 2000 - 4000 - 8000 and 16000 Hz classical octave bands
- 700 - 1400 and 3000 Hz additional mid-frequency bands
The range of each band is +/-12dB: all in all, the Instrument EQ is extremely precise and efficient, and allows the best sound sculpture for the most demanding musicians.
This is not instrument gear any longer: the Instrument EQ is a genuine studio-quality device.
Usage and limitations
The Rockman EQ is truly mandatory for anyone who really wants to create and tweak his own sounds. When one starts building a Rockman rig with a Sustainor, it becomes rapidly obvious that two EQ\'s are necessary: one placed in the loop as a pre-distortion EQ, the second one being placed after the Sustainor.
The possibilities provided by a pair of EQ\'s are both subtle and endless. Changing a few dB\'s on a frequency band can alter significantly the sound and the position of the guitar in a mix, and using radical settings can also deliver specific sounds: fuzzy or metallish, fixed-wah effects, etc...
