Elysia museq Discrete class-A stereo equalizer

This analog EQ is a combination of premium sound shaping capabilities with optimally matched parameters and the highest quality components, enabling the user to find musical results quickly and easily. The five bands and their ample gain ranges as well as some special features make sure that the museq can be used flexibly in any tracking or mixing situation, and the stepped controllers are easily repeatable for mix bus or mastering applications.

Each of the two channels offers three parametric bands with a two-position switchable Q. The outer bands per side are low/high shelf designs which can be separately switched into a low/high cut mode. In the cut mode, a resonance peak keeps the knee frequency from sounding overly damped, reminiscent of inductor circuits in classic designs.

Each of the five gain controllers per side can be altered from boost to cut with a single switch, for easy location of problem frequencies and twice the number of available gain steps. Each channels has a switchable option for adding strong harmonic color of the signal, making two EQs in one. Many will prefer the color setting for mix use and the clean for tracking, but this is up to you to discover.

The circuit design of the museq is 100% discrete analog technology. All signal processing is realized with single transistors in permanent class-A mode, and even the power supply is composed of fully discrete circuits. An oversized transformer, selected capsuled conductive plastic potentiometers as well as special current feedback amplifiers are part of the technical refinement. The combination of these elements aims at maximum signal quality and guarantees clean and powerful sound characteristics even when extreme settings are used.

100% Discrete Class-A

As a true elysia specialty, the museq is completely based on discrete circuitry and does not use any integrated circuits at all.

To explain the advantages of discrete circuitry we’d like to present a comparison that might seem a little odd at first: audio technology vs. cooking! If somebody uses instant meals exclusively, he will have to accept whatever comes out of the box. A creative cook, however, focuses on his own special recipes and ingredients.

In this respect, integrated circuits (ICs) are pretty similar to packet soups: they are cheap, mainstream and they simply do not match haute cuisine. So if you want to design an analog audio device 100% according to your own demands and ideas without any compromise, there will be no way around a discrete design.

The museq follows this philosophy consequently. Not only all filter and gain stages, but also the complete power supply have specially been designed for this unit and they are built by the use of discrete components exclusively. A truly unique recipe!

In addition, our musical equalizer operates in permanent class-A mode. This means that the transistors are always conductive, resulting in the absence of crossover distortion and providing a pristine sonic base: the general sound character is always wide, open and punchy.

Active Bandpasses with FETs

The filter stages are completely active and benefit from a puristic design approach without coupling capacitors – the basis for a truly musical EQ.

All filter stages of the museq are active designs without any inductors. The actual layout of the bandpasses is where the magic happens: basically, they are composed of only six transistors, two capacitors and the resistor that determines the frequency.

This circuitry forms a bandpass that operates without any feedback, which results in a very musical sound. Especially regarding filters this puristic and compact design is of considerable acoustic benefit.

Resonance High & Low Pass Filters

The outer shelving filters can be switched into high and low pass filters which feature an additional resonance peak as a very useful specialty.

The outer bands of the museq show a great amount of flexibility. In their standard mode, they are set up as sweet sounding high and low shelf filters that can be used to tailor the airiness and fundamentals of your tracks fast and efficiently.

As a special feature, you can independently switch these to become high and low cut filters with 12 dB per octave and an additional resonance peak at the knee frequency. This allows some very interesting and useful filter curves.

Especially bass frequencies can benefit from a low cut with resonance by obtaining a clean and punchy character. But the resonance can also be used to stretch signals in the bass range, because the resonance filter causes a longer post-oscillation time.

In the high frequency range, you can use the resonance filter to put an accent on a selected frequency without boosting the complete HF spectrum at the same time, which can prevent harshness or an unwanted shift of the overall perception towards the treble.

Parallel Filter Design

A special circuit trick makes it possible to leave the high and middle frequencies completely untouched when using the high and low pass filters.

Another specialty is the design of the high and low pass filters: in actual fact, the high pass with resonance is a low pass with resonance which is flipped in its phase and then mixed with the original signal.

This has the great advantage that the mid and high frequencies are not affected by the filter and therefore do not change in sound at all. Only the bass frequency region is processed by the filter and the entire signal remains open and transparent.

Warm Mode

The museq offers a second, switchable sound flavor by altering its frequency spectrum, harmonics and transient response.

This function is basically a slew rate limiter that reduces the speed of the output amplifier stages. This affects the frequency spectrum, the harmonics and the transient response at the same time.

Fast transients are slowed down a bit and the overall sound appears more round and merged. As this function influences the behavior of the output stages, the effect it creates has an impact on the complete processing results of all EQ stages.

In this way the museq offers two different sound characters at the push of a button: The powerful transparency of the discrete class-A circuitry and the saturated richness of the Warm mode. 

Pure Transparency Path

The puristic design of the filter stages with current feedback amplifier stages and without any coupling capacitors results in an outstanding sound quality.

All active stages in the museq are based on current feedback amplifiers which have been optimized for a top notch impulse response. These amplifier stages operate completely without the use of additional capacitors.

These caps are usually inserted to eliminate high frequency oscillation (at the cost of affecting the frequency response). The result of consequently not using this kind of capacitors at all is an amplifier which sounds natural, open, dynamic and transparent.

Boost/Cut Mode

The boost/cut switch generates twice the number of values to be set with the 23 step potentiometers than the usual -/0/+ arrangement would offer.

Each band of the museq can be switched from boost into cut mode. The advantage is that the complete controller range is utilized for the desired action and the resolution of the stepped potentiometers is twice as large.

Another noteworthy fact is that the filters carry a signal permanently, which grants a superb signal to noise ratio and also produces a pleasant amount of harmonics.

Not until the gain controller is used, the specific frequency band will come into action. If the gain controller remains in its 0 position, the signal will not be affected at all – the band is virtually switched off. 

Switchable Filter Quality

The filter quality can be switched from a wide to a narrow Q factor which remains independent from the setting of the gain controller.

The filter quality of the three parametric bands can be switched between two characteristics: wide (Q 0.5) and narrow (Q 1.3). This does not have any effect on the maximum amplitude. The filters are based on the constant Q principle, which provides an ever constant filter quality that is independent from the gain controller.

Stepped & Matched Potentiometers

All potentiometers on the museq have 23 steps and are matched to build stereo pairs by a software routine that has been written just for this purpose.

The museq features stepped conductive plastic potentiometers for all its parameters throughout. The 23 steps make a precise recall very easy, which is very convenient not only for mastering purposes.

In order to keep the component tolerance as low as possible, we measure all potentiometers and match them as stereo pairs with a software routine we have written exactly for this purpose. The obvious benefit of this effort is that the left and the right channel behave exactly the same.