Sound Performance Lab EQ MAGIX User Manual

SOUND PERFORMANCE LABORATORY

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SOUND PERFORMANCE LABORATORY

EQ MAGIX Owner´s Manual
by Hermann Gier

Manual version 2.1/94

The information in this document has been carefully checked
and is assumed to be correct.
However Sound Performance Laboratory (SPL electronics
GmbH) reserves the right to modify the product described in
this manual at any time.
This document is the property of SPL electronics GmbH and
may not be copied or reproduced in any manner, in part or full
without the authorization of SPL electronics GmbH.

Construction and circuit layout are subject to constant improve­ment and development.

Changes will be made without notice.

©

1994 SPL electronics GmbH All rights reserved

® 1993 Vitalizer is a registered trademark of SPL electronics GmbH

SPL electronics GmbH
Sohlweg 55

D-41372 Niederkrüchten
Germany

Tel. [phone]
Fax [phone]

3

Contents

Foreword 4
Introduction 4

The concept of sound processing in the EQ MAGIX 7

Installation 9
Inputs & outputs 9
Power supply 10
Rear panel 11
Connection examples 11

Control elements

Input Mic /Line 12

Line -30dB 12
Peak 13
Phase reverse 13
48V phantom power supply 13
Insert 14

Parametric Active 15

Frequency 15
Boost/Cut (+/-) 16
Bandwidth Q 17
Q Fine 17
Notch 17
Deleting an interference frequeny 19

Introduction into the Vitalizer 20
The control elements of the Vitalizer

Active 22
+10dB 22
Peak 22
Bass 23
Deep 24
Mid-Hi Tune 24
Process 25
Harmonics 26
Combine 26

Output Pan 27

PPM Meter 27
Fader 27
Mute 27

Specifications 28
Block diagram 29
Circuit layout 30
Main board & top board 32

EQ MAGIX legend 33

Warranty 34

4

Dear customer,

Thank you for the confidence you have shown towards SPL electronics
GmbH by purchasing the SPL EQ MAGIX. The EQ MAGIX is a first-rate
Equalizer with exemplary specifications, excellent workmanship and unri­valled sound quality.

Please study this owner´s manual carefully so that you can make the
most of the wide range of possible applications offered by the EQ MAGIX
and to ensure ease of operation.

We have tried to write this manual in such a way that it is easy to under­stand, with as clear a layout as the complexity of such a sophisticated
product allows. The manual is divided into two columns throughout. The
main column contains a detailed description whilst the margin contains
headings and summarized information.

We wish you every success and unlimited enjoyment with your new EQ
MAGIX.

SOUND PERFORMANCE LABORATORY
SPL electronics GmbH

The EQ MAGIX is a single-channel equalizer system consisting of a para­metric and a psychoacoustic equalizer. Both are combined with a superior
microphone preamplifier and an active two-channel panorama output
stage.

People in MIDI hybrid studios or production studios often need a single
mixing desk channel with superior microphone preamplification and
perfect sound control to record different song tracks, saxophone or guitar
soli on R-Dat, hard disk or samplers. The EQ MAGIX is, so to speak, an
»all-in-one« tool for applications of this nature.

The EQ MAGIX is ideally suited for both a demanding instrumentalist's
or a singer's rack. Existing equipment can be looped into the signal path via
I

NSERT. The unit's outputs are either connected directly with the recording

medium or with one to four (2x balanced and 2x unbalanced) mixing desk
channels. From there, the signal is fed into the Insert Return after the EQ
section (provided that appropriate Insert points are available), so as to
bypass as much desk circuitry as possible. As you know, a signal is also
influenced if all the switches are on »off« and all controls are in the centre
position or on »0«. That is why it is advisable to feed the signal in after the
desk equalizer.

The technology in the microphone preamplifier is used in the very latest
generation of mixing desks made by Harrison and SSL. The P

ARAMETRIC

Foreword

Introduction

5

The

II

NNPPUUTT

section features a
microphone preamplifier with
48V phantom power supply,
P

HASEREVERSE

and L

INE

-30 dB

switch, P

EAK

indicator

II

NNSSEERRTT

jacks between

microphone preamplifier and

PARAMETRIC

equalizer.

PP

AARRAAMMEETTRRIICC

equalizer
with a frequency range from
14 Hz to 58 kHz, constant-Q,
Q-F

INE

switch,

+/-15dB B

OOST/CUT

,

N

OTCH

with R

OLL-OFF

equalizer of the EQ MAGIX is based on SVF design (state-variable-filter)
and provides a operation frequency range between 14 Hz and 58 kHz. The
integrated V

ITALIZER was developed by SPL and has achieved a significant

degree of popularity over the years. The filter concept works on the basis of
psychoacoustic sound principles and is therefore ideal to achieve creative
sound effects.

The combination of a flexible parametric EQ and V

ITALIZER means that

the EQ MAGIX is not only predestined to process the sounds of acoustic
instruments but also to post-process samples or poor quality Sync audio
tracks, ranging from the elimination of aliasing artefacts or other digital
interferences to the addition of sub basses or comprehensive sound impro­vements via the V

ITALIZER.

The EQ MAGIX provides you with equalizer technology which is unri­valled in comparable units. You will find that this equalizer can not only be
set quickly and accurately at the desired frequencies but, with the aid of
loudness sound control, can also form sound patterns which cannot be
achieved with conventional equalizers.

The section below contains a brief description of the EQ MAGIX's func­tion groups:

1.

II

NNPPUUTT

: Microphone and line level signals can be preamplified in the

I

NPUT section. Microphone signals can be preamplified up to 65 dB.

Activating the L

INE switch attenuates the preamplifiers stage by -30 dB.

There is a phantom power supply (48 V) for condensor microphones. The

P

HASE REVERSE switch is used to change the polarity of the microphone. The

P

EAK LED provides adequate warning of potential overdriving of the

output stages in the I

NPUT section.

2.

II

NNSSEERRTT

: Additional sound processing equipment such as a compressor,

de-esser or reverb can be looped into the EQ MAGIX via the I

NSERT jacks.

The I

NPUT section can be used separately for one signal, whilst the equa-

lizer sections are available for a second signal. Use the I

NSERT SEND as the

output for the I

NPUT section and the INSERT RETURN as the input for the

second signal.

3.

PP

AARRAAMMEETTRRIICC

: The PARAMETRIC equalizer is to boost or cut different
frequencies or to cut out specific interference noise signals. It is, in a
manner of speaking, a corrective instrument in the EQ MAGIX chain of
sound-processing tools. The P

ARAMETRIC works according to the constant-Q

principle. The frequency ranges between 14 Hz and 58 kHz. The control
characteristics of the bandwidth (Q) control ranges from Q0.6 to Q3.6 and
can be sensitized via the Q-F

INE switch to set more subtle Q values. The

boost or cut range is max. +/-15dB. The integrated N

OTCH filter can be

controlled in frequency, bandwidth and also in the filter slope (R

OLL-OFF)

from gentle decreasing or increasing (G

ENTLE) to steeply decreasing or

increasing (S

TEEP). This significantly increases the tonal flexibility of the

N

OTCH Filter.

Introduction

6

4. VITALIZER®®: The VITALIZER is an equalizer concept which makes use of
scientific psychoacoustic technology to process audio signals. The unique
combination of dynamic equalizers, amplitude-controlled phase correction
and harmonic filtering in the V

ITALIZER opens up a whole new listening

dimension by adapting the sound pattern to the non-linearities of the
human ear. The V

ITALIZER is thus the creative element amongst the EQ

MAGIX's sound processing tools.

The V

ITALIZER gives the mid frequencies accurate transparency with a

soft, unobtrusive sound. The treble and harmonics range is reworked with
broadband shelving filters of 2nd and 4th order, which focus on achieving a
smooth, silky sound pattern. High frequencies are livened up without them
sounding hard or agressive.

The V

ITALIZER uses a newly developed filter network to process the low

frequency range. The bass is accentuated without any risk of emphasizing
the lower mid frequencies unnaturally. You can choose between a dry,
percussive bass (T

IGHT) or a punchy, soft and very deep sound character

(S

OFT).

The result is a pleasanter and livelier sound pattern with an unrivalled
wealth of detail. You will be amazed by how transparent and powerful
almost every audio signal sounds after it has been processed with the
V

ITALIZER!

5.

OO

UUTTPPUUTT

: The OUTPUT section enables you to create a two-channel
output signal from a one-channel input signal. You can return the signal to
two desk channels or feed it directly into a multi-track recording medium or
effect unit. Balanced outputs available via XLR sockets and unbalanced
outputs available via jacks can be used in parallel. A signal can therefore be
recorded on two media simultaneously.

On the front panel, two bargraph meters each featuring 10 LEDs
provide information about the output level of each channel. The indication
of PPM values (peak values) provide more information than a VU display
(average values). The M

UTE switch can be used to mute the output signal

altogether. The P

ANORAMA control allows

active

panning between the two
output channels, compensating the loss in volume (- 3dB) which arises in
conjunction with panning to one channel. The F

ADER switch alters the

characteristics of the P

ANORAMA control, making it an output level control.

The output level can be reduced for both channels to compensate diffe­rences in the levels of the processed and the dry signal.

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IITTAALLIIZZEERR

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iinn tthhee EEQQ MMAAGGIIXX::
The new generation of psycho­acoustic equalizers for the first
time in a 19“ mixer channel
module, together with
microphone preamplifier,

PARAMETRIC

equalizer and

P

ANORAMA

output stage.

The

PP

AANNOORRAAMMAA

output stage
creates a double Mono output
signal from the Mono input signal
and enables active panning
between the two channels.

Two LED meters indicate the
PPM peak values.
M

UTE

and F

ADER

switch options.

Introduction

7

The concept of
sound processing
in the EQ MAGIX

The P

ARAMETRIC

section serves to
perfectly remove any interference
frequency or to accentuate a
frequency band as desired.

With its enormous range of
frequencies from 14 Hz to 58 kHz,
the EQ MAGIX provides a plat­form for experimentation as to
the extent signal portions affect
the tonal perception range beyond
the spectrum of the human
hearing.

The EQ MAGIX features a PARAMETRIC constant-Q equaliser combined

with the V

ITALIZER equaliser system.

This combination of filters is based on the assumption that after succes­sful microphoning, you only have one problem zone, if at all, that needs to
be equalized. The V

ITALIZER provides all the necessary circuitry for creative

sound post-processing.

The EQ MAGIX provides a total of five processing ranges: the PARAME­TRIC section provides an extremely variable and efficient filter for selective
intervention in a frequency band between 14Hz and 58kHz. The VITA­LIZER interferes in 4 frequency ranges, bass, mid and treble, along with the
harmonical frequencies pertaining to even and odd overtones.

The P

ARAMETRIC section is designed to clean up one »problem zone« in

the frequency spectrum of the recorded instrument or voice perfectly,
without prejudicing the sound and without being inhibited by technical
limitations of standardized filter circuits.

The equalizer used in the EQ MAGIX is based on the state-variable filter
type (SVF). Its function is phase-stable and neutral right down to 14 Hz in
the infra-sonic range. The frequency range extends right up to breath­taking 58 kHz! This initially provides a platform for experimentation as to
whether interspersing digital components affects into the tonal perception
range (16 Hz to 20 kHz) or whether the removal thereof can remedy sound
problems directly or indirectly.

We have visited sound engineers and producers in European and
American audio and video studios and they pointed out to us that inter­spersing the sample rate frequencies (44.1 kHz and 48 kHz) into the audio
path is a well-known phenomenon, whereby subharmonic elements can
be transposed right down into the audible frequency spectrum.
Furthermore, this can result in audible phase shifts and distortions. With
the EQ MAGIX, you can now influence these frequencies actively. The
sample rate frequencies are inscribed on the scale (44, 48).

All frequencies can be boosted or cut with 15dB throughout the entire

frequency range from 14 Hz to 58 kHz. The P

ARAMETRIC equalizer of the EQ

MAGIX is based on the constant-Q principle and provides an »inversible
Q«, i.e. when filtering out a interfering frequency, inverting the boost value
to a cut value results in precise inversion of the bandwidth (Q) values.

Notching is also possible with a variable R

OLL-OFF to select a STEEP or

GENTLE filter slope.

Extremely flexible bandwidth defintion allows Q values between 0.6
and 3.6.

8

The VITALIZER is the creative sound component in the EQ MAGIX. It works
»intelligently«, provided the appropriate parameters are preselected. This
means that it does not just raise or lower a certain frequency range but
analyses the signal and reacts to it, influencing the frequency and phase
response in a sophisticated fashion.

Independently of the potentiometer settings on the front panel, the

V

ITALIZER filter system can correlate the phase and amplitude relations of

adjacent frequency bands in such a way that the increasing amplitude of a
frequency is given a growing phase drift which, however, can never
endanger the signal's mono compatibility. The maximum phase drift is +/­20° which equals a time difference of around 1 ms to 2.5 ms. This time
span is sufficient to trigger two hearing perceptions. Quiet frequencies
which are normally masked by louder ones are effectively demasked and
thus become audible.

The front panel also accommodates controls to define the bass sound

colour (S

OFT/TIGHT), the starting frequency of the MID-HI TUNE filter, the

P

ROCESS intensity and the addition of the harmonics.

The B

ASS control provides up to 20 dB gain, thus affecting the direction

of the phase drift by the bass sound colour selected. The fact that the phase
drift is controlled by the amplitude means that even high bass amplifica­tion remains free from negative sound colouration in the lower mid range.

The mid-high frequency filter (M

ID-HI TUNE) works with shelving filters

which provide »linear« broadband amplification. This rules out any comb
filter effects which create sound distortions similar to those produced by
graphic equalizers.

The P

ROCESS control determines the addition of the bass sound selected

and the M

ID-HI TUNE filter to the dry signal. In addition, dominant mid

frequencies are lowered by phase shifts which means that as the P

ROCESS

value increases, they are adapted automatically to curves of equal
loudness (Fletcher-Munson curves). The P

ROCESS is, in a manner of spea-

king, an »intelligent« loudness control which can be used to set the typical
»bath-tub« curves on graphic EQ's by turning one potentiometer.

The H

ARMONICS circuitry provides a silky sounding, refreshed version of

the original signal. This proves particularly beneficial for voices and acoustic
instruments. No distortions are added to the original as there is no Exciter
involved. The filters merely amplify the harmonic tones contained in the
original.

The EQ MAGIX is constructed like a mixing desk channel. Direct recor­dings can be made on to a recording medium (multi-track machine or hard
disk) which means that one less mixer channel is required.

The V

ITALIZER

is the creative sound

component in the EQ MAGIX.

The internal signal processing of
the V

ITALIZER

correlates the phase
with the amplitude in such a way
that masking effects in the original
signal are compensated.

The bass sound colours:
S

OFT

& T

IGHT

The MID-HIT

UNE

filter provides
shelving filtering with a broad
bandwidth which therefore sounds
very neutral.

The P

ROCESS

control adapts the
output signal to the curves of
equal loudness, thus realizing an
intelligent loudness concept.

The H

ARMONICS

filter stage accen-

tuates even and odd harmonics.

The concept of sound processing in the EQ MAGIX

9

The housing of the EQ MAGIX has the standard 19" EIA format and

occupies 1 height unit (1 U = 44 mm) in your rack.

When installing the unit in a 19" rack, the rear side of the unit needs

some support, especially in a Touring Case.

The EQ MAGIX should not be installed near units which produce strong
magnetic fields or extreme heat. Do not install the EQ MAGIX directly
above or below power amplifiers or digital processors. If possible, the EQ
MAGIX should be placed in an »analog rack« where the majority of (or all)
the equipment installed is analog. This eliminates problems which could
result from interfering high-frequency signals such as clock frequencies,
MIDI or SMPTE control signals.

Make sure that the correct mains voltage has been set on the mains

voltage selector located at the rear of the EQ MAGIX.

The EQ MAGIX is equipped with an electronically balanced, 3-pole
XLR socket to connect a microphone or a line signal.

The outputs of the EQ MAGIX are designed balanced on XLR sockets as
well as unbalanced on 1/4“ jacks. The outputs can be used parallel to each
other. This means that four output signals can be produced from one input
signal.

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In addition, the EQ MAGIX also has unbalanced I

NSERT jacks which inter-

rupt the signal flow between the microphone preamplifier and the

PARAME-

TRIC equalizer.

The I

NSERT SEND jack can also be used as an output of the microphone

preamplifier. The I

NSERT RETURN jack can then pick up an independent

signal which means that two signals can be processed in parallel to each
other. One signal uses the microphone preamplifier and another signal is
processed by the EQ MAGIX equalizer.

Fig. 1:
The diagram shows
how to unbalance
balanced wiring correctly

Installation

Inputs & Outputs