The Passeq is a classic design with passive coil filters and perfectly fulfills the highest expectations in all areas of audio processing, from recording and mixing to mastering and playback.
The superior sound qualities and musical characteristics of passive filters ideally meet increasing demands in creating manifold sound colors full of character. In the HiFi domain, the Passeq is the high-end EQ beyond doubt – a perfect tool to solve room acoustical problems by the turn of a knob or improve the sound of old, or inferior, sources.
Design
A passive filter has no amplification stages. It can therefore only be lowered. If one frequency is to be boosted, all the others must be lowered. Behind the filter there is a stage that makes up for the lowered overall level. Since low noise is particularly important here, since up to 20 dB can be made up for, the 120V technology comes into its own.
The entire passive filter (variable resistor, capacitor and coil) provides a very nice sound characteristic. Besides the choice of components, the charging behaviour of the capacitors and the saturation behaviour of the coils play a major role in this. The resulting relative inertia compared to potentially very fast active filters is the reason for a pleasant, musically advantageous sound characteristic. We would choose smoothness and transparency as well as strikingly silky highs and pithy basses as a description that suits our perception.
During fine-tuning, through component selection, in countless listening sessions, the emphasis was on achieving the most musical sounding curves possible, which, for example, need fear no comparison with a Pultec EQ from the 1950/60s. Only without all the disadvantages of a 60 year old original, such as the very high background noise, but above all the very limited frequency selection.
Another highlight of the PASSEQ is the HF+ band, which has been extended by the frequencies 25 kHz and 35 kHz and sounds so incredibly good that you don’t want to switch it off.
Voltage
The 120V technology works with +/-60 V. To be able to handle such a high voltage, we have developed special proprietary operational amplifiers that can operate with a DC voltage of +/-60 V: the SPL 120V SUPRA operational amplifiers.
This high voltage would destroy conventional components and operational amplifiers.
The 120V technology achieves exceptional technical specifications and sonic benefits. Technically, in terms of dynamic range, signal-to-noise ratio and headroom. Sonically, in terms of richness of detail and an absolutely relaxed listening experience.
By the way, the “120V” in the name of the technology has nothing to do with the local mains voltage from the mains power socket. This is about the operating voltage inside the device with which the audio signals are processed.
The mains voltage from the mains power socket is transformed to the required secondary voltage in the device’s internal linear power supply with toroidal transformer. Rectifiers convert this AC voltage into DC voltage required in the audio device.
Specifications: