Sound Performance Lab PQ Recording Equalizer - Manual (Page 5)

5
SPL High Gain Technology
SPL is constantly pushing analog signal processing to its limits by combining the best
possible components with perfectly optimized circuit design. As our latest achieve-
ment in this ongoing process, SPL‘s High Gain Series surpasses the hitherto accepted
limits of audio signal processing and combines truly unparalleled analog sound
quality with the control and convenience of digital units.
Together with the MMC1 multi-channel mastering console, the parametric equalizer
PQ, both as recording or mastering version, was the fi rst product of SPL’s new High
Gain Series. Further High Gain projects are in planning, including a microphone
preamplifi er and a compressor, although no availability projections can be made for
these currently.
The PQ is a fully parametric, dual-channel 5-band equalizer. As with all SPL High
Gain units, the PQ has an operating voltage of 120 V and is constructed with the best
analog components available.
Power for sound: SPL SUPRA components
The central component of the PQ is a fundamentally new amplifi cation design:
discrete, custom made Class A audio operational amplifi ers which run on a 120 V
operating voltage (+/- 60 V). This amounts to over three times the operating voltage
found in most high quality audio gear (+/- 15-20 V) and about twice as much as the
highest voltages used in the best units currently available.
This extremely high voltage allows the circuitry to process an astonishing dynamic
range of ca. 150 dB and an amazing +34 dB of headroom, virtually eliminating
overloading of individual fi lter stages—even when processing extremely high-level
signals.
For the fi rst time, transistor circuits with such an impressive degree of stability and
freedom from harmonic distortion can be realized. After the revival of tube units in
the early ‘90s, we feel that the time may be ripe for a revival of the „transistor sound“
in the near future.
Additional construction features
All crucial resistors in the I/O and fi lter circuits are subject to ultra-tight tolerances of
0.001% to ensure clean and accurate amplifi er stage performance. All circuit board
tracks are double-width (1 mm) and double-thickness (70 micrometers), guaranteeing
stable high-gain operation with minimum resistivity. A separate grounding track is
placed between signal track pairs, virtually eliminating crosstalk for maximum signal
separation.
The individually switchable fi lter bands are self-contained on separate circuit boards.
Contrary to most conventional equalizers, the bands are not summed via a central
stage, so that the signal passes only through those fi lter stages which are activated.
Technology