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ROLL-OFF
The slope of the LOW PASS respectively HIGH PASS can be switched from 12 dB to 24 dB with the ROLL-OFF switch.
LOW CUT
In addition, there is also a low-cut filter. This filter frees both paths, the LOW PASS and HIGH PASS, from unwanted frequencies below 20 Hz. This means that the power amplifier does not have to amplify inaudible low frequencies and the loudspeaker is discharged.
PHASE
The three-position toggle switch PHASE can be used to activate phase control.The dedicated control is used to establish synchronization. If the toggle switch PHASE is in the top position (VAR 0°), a value between 0° and 180° can be set using the control. If the toggle switch PHASE is in the top position (VAR -180°), a value between 0° and -180° can be set via the control, thus allowing a control range of 360°. If the phase control is not required, it can be switched off (OFF) and thus disappears completely from the signal path.
The VOLTAiR Technology
The 120V technology is our reference technology. The 120V technology is unique in the world. It operates at a DC voltage of 120 volts. This is four times that of IC-based semiconductor op-amps. In our Professional Fidelity series, we refer to this unsurpassed technology as VOLTAiR technology. The highest possible audio quality requires the highest possible audio operating 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.
Comparison
Most audio devices work with an internal operating voltage of +/-15 volts and can thus process a maximum input level of +21.5 dBu. If a DAC, for example, has an output level of +22 dBu at 0 dBFS, level peaks of the music material would already cause overloads in the input stage of the device. All components in the audio device often operate at their limits. The result is an unsteady sound that causes stress and faster ear fatigue. SPL devices with VOLTAiR technology can handle input levels of +32.5 dBu thanks to the higher internal operating voltage of +/- 60 volts – thus offering 12 dB more headroom. All components consequently operate continuously in the optimum operating range. The result is a very pleasant, natural and relaxed sound experience. So you can enjoy your music in every detail. These diagrams clearly show the superiority of the VOLTAiR technology in comparison to other circuits with lower, common operating voltages.
