PQ

Mastering Equalizer

The PQ Mastering Equalizer is a fully parametric, dual-channel five-band equalizer.

The PQ Mastering Equalizer – Model 1540/1544 is a new revised edition of the well-known SPL PQ Mastering Equalizer – Model 2050.

Both units are based on our 120V Rail Technology. The new PQ features the same high-quality characteristics as the previous model.

All five bands can each be activated or deactivated and you got the possibility (for every single band) to separately switch between Constant Q and Proportional Q. This kind of circuit has not yet been achieved in any other equalizer.

Each channel can completely be activated or deactivated, thanks to Auto-Bypass, even automated in a freely selectable time frame.

Bypass of each band and constant Q of the left side can be controlled by the right side in Link mode.

Thanks to the 1/4 Gain-Switch, you can reduce a maximum increase or attenuation of the amplitude by the factor 3/4, which regulates the potentiometer from max +/-20 dB to +/-5 dB cut. This gives you the possibility to perform small corrections, as common in Mastering or higher amplitudes in Proportional-Q mode.

Thanks to the detented potentiometers, a precise recall is very easy to realize. You can also adjust parameters Gain, Frequency and Q in 41 steps with the detented potentiometers

The Sound

120V Rail Technology is our reference technology developed and manufactured to run on an operating voltage of 120 volts, which corresponds to twice that of discrete operational amplifiers and four-times that of semiconductor operational amplifiers.

120V Rail Technology reaches outstanding technical and sonic performances. Technically especially in terms of dynamic range and headroom and sonically especially in reproducing the finest details and delivering a totally relaxed sounding audio experience. Music sounds absolutely natural and hearing fatigue is drastically reduced.

Even the best audio measuring equipment arrives at the boundaries. In same situations we ended up just measuring the Audio Precision Cascade 2 measuring device and we cannot say how good the 120V Rail Technology actually performs.

Comparisons

These diagrams show how our 120V Rail Technology compares to other circuits.

The direct relation between operating level and maximum level is fundamental for the classification: the higher the operating level, the higher the maximum level a circuit can handle. And since virtually all essential acoustic and musical parameters depend on this relation, a higher operating voltage also has a positive impact on the dynamic range, distortion limit and signal-to-noise ratio.

Do bear in mind that dB scales do not represent linear but rather exponential increases. A 3dB increase corresponds to doubling the acoustic power, +6dB correspond to twice the sound pressure level, and +10dB correspond to twice the perceived loudness.

When it comes to volume, the 120V Rail Technology exhibits a performance, in regard to maximum level and dynamic range, that is twice that of common components and circuits given that its values are approximately 10dB higher.

THD measurements of the 120V op-amp show a difference of more than 3dB compared to the OPA134 at 36V — in terms of sound pressure level, that corresponds to an improvement of more than 50%.

The operating level most commonly used for audio equipment is 30 volts

The 120V Rail Op-Amp Generations

Specification

- Frequency Range: 10Hz - 40kHz

- CMRR (1 kHz, +34 dBu, Band 1-5 ON, B/C = 0 : › -82dB

- Transmission Bandwidth: (3 dB, Band 1-5 ON, B/C = 0): 10 Hz-100 kHz

- THD & N (@ 24dBu, Constant-Q) › 107dB

- THD & N (@ 24dBu, Proportional-Q) › 106dB

- Noise (unweighted, at 24 dBu, Band 1-5 ON, B/C = 0) - 91dBu

- Noise (A-weighted, at 24 dBu, Band 1-5 ON, B/C = 0) - 94dBu

- Noise (CCIR, at 24 dBu, Band 1-5 ON, B/C = 0) - 86dBu

Harmonic Distortion:

•0,2% @ 1kHz/-30dBu

•0,05% @ 1kHz/-20 dBu

•0,01% @ 1kHz/0 dB

•0,002% @ 1kHz/+10 dBu

•0,0005% @ 1kHz/+30 dBu

- Input Inpedance: 20kOhm

- Max. Input Level: + 32,5dBu

- Output Inpedance: ‹ 600Ohm

- Max. Output Level: + 32,5dBu

- Power Consumption: max. 61W

Fuses

•230 V/50 Hz: 3,15 Amp

•115 V/60 Hz: 6,3 Amp

- Dimensions: 482 x 177 x 311,5 mm / approx. 19“ x 7“ x 12,25“

- Weight: 15,2 kg / 33,5 lb