PASSEQ Red/Black
In the PASSEQ, SPL has revived the concept of the passive equalizer, which was used in the 50s and 60s. The charming sound of this vintage technology paired with modern 120V technology results in a very special equalizer.
Only one filter
All control functions are part of just one passive filter. There are three frequency ranges:
Low Freq / Mid Freq / High Freq
Each with a control on the left for cutting and a control on the right for boosting the set frequency. The output control is located in the middle.
The design
A passive filter has no gain stages. It can therefore only be attenuated. If one frequency is to be raised, all others must be lowered. There is then a stage behind the filter that makes up for the lowered overall level. Since low noise is particularly important here, as up to 20 dB is made up, the 120V technology comes into its own.
The entire passive filter (variable resistor, capacitor and coil) delivers a very nice sound characteristic. In addition to the choice of components, the charging behavior of the capacitors and the saturation behavior 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 suitable description for our perception.
During fine-tuning, through component selection, in countless listening sessions, the focus was on achieving the most musical sounding curves possible, which, for example, need not shy away from comparison with a Pultec EQ from the 1950/60s. But without all the disadvantages of a 60-year-old original, such as the very high noise floor, 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 won't want to switch it off.
The 120V technology
120V technology is SPL's reference technology. It is unique in the world of audio because it works with a DC voltage of 120 volts. This corresponds to four times the operating voltage of IC-based semiconductor operational amplifiers.
The highest possible audio quality requires the highest possible audio operating voltage.
The 120V technology works with +/-60 V. In order to handle such a high voltage, SPL has 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 advantages. Technically, in terms of dynamic range, signal-to-noise ratio and clipping resistance. In terms of sound, in terms of richness of detail and an absolutely relaxed listening experience.
Incidentally, the “120V” in the name of the technology has nothing to do with the local mains voltage from the socket. It refers to the operating voltage in the device with which the audio signals are processed.
The mains voltage from the socket is transformed to the required secondary voltage in the device's internal linear power supply unit with toroidal Transformer. Rectifiers convert this AC voltage into the DC voltages required in the audio device.
Technical data
Analog inputs and outputs; XLR (balanced)
- Maximum input and output level: 32.5 dBu
- Input impedance: 20 kΩ
- Output impedance: 75 Ω
- Common mode rejection: -60 dBu
- Frequency response (-3dB): 10 Hz - 200 kHz
- Crosstalk (1 kHz): -108 dBu
- THD + N (+30 dBu, 1 kHz): 0.0012 %
- Noise (A-weighted): -95.2 dBu
- Dynamic range: 134.5 dB
Internal power supply; linear power supply with shielded toroidal Transformer
- Operating voltage for analog audio electronics: +/- 60 V
- Operating voltage for relays and LEDs: + 12 V
Power supply unit
- Mains voltage (selectable, see fuse chamber): 230 V AC / 50; 115 V AC / 60 Hz
- Fuse for 230 V: T 500 mA
- Fuse for 115 V: T 1 A
- Power consumption: max. 15 VA
Dimensions & weight
- W x H x D (width x height x depth): 482 x 177 x 300 mm
- Weight of the device: 10.2 kg
- Shipping weight (incl. packaging): 11.9 kg