Mastering Equalizer

With the SPL PQ, the team around Wolfgang Neumann created and launched a Mastering EQ which outshines anything previously seen. It is hard to think of anything the SPL PQ does not perform or fulfill in perfection.


You can handle the PQ in a sovereign and natural manner. Just like having all the reserves of the world. And somehow this is true. (...) In case anyone still wonders – in my opinion the PQ belongs to the world-classics among all Mastering Equalizers.

Studio Magazin


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  • 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.

Right-click on image to download HiRes.

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


  • 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

0dBu = 0.775V. Specifications subject to change without notice.

Video instructions

Exchange defective fuses 115V

Exchange defective fuses 230V

Changing the mains voltage from 115V to 230V

Changing the mains voltage from 230V to 115V