SPL Volume 2

Stereo Volume Controller

Volume 2 is an active DAW monitoring controller and a puristic high-end preamplifier.

Features:

• High-end volume potentiometer and illuminated mute switch from ALPS; the potentiometer controls directly (no VCA or DAC circuits)
• The mute switch allows a quick reaction when speakers or ears need to be protected (e.g. in case of a computer crash)
• In contrast to digital volume control, where the bit resolution is continuously reduced as the volume decreases, the signal does not deteriorate with analog volume control.
• In contrast to passive volume control, active volume control does not affect the phase and frequency response. The monitoring signal sounds reliably the same at any monitoring volume.
• Balanced XLR input and output connectors
• High-quality balancing stages with very high common-mode rejection (minimizing interference/interference in the signal paths)
• High-quality power supply unit with toroidal transformer
• Solid aluminium knob with 45mm diameter for smooth, sensitive operation
• Elegantly designed and compact housing for flexible desk positioning close to the screen.

Analog Volume Control

The monitoring volume is controlled analogously with an Alps-RK 27 potentiometer.

If the volume is controlled digitally, for example in the DA-converter, the bit resolution decreases with decreasing volume with one bit per -6dB. Usually we listen with about -30 dB at full volume, which decreases the bit resolution by 5 dB.

Active or Passive?

It is claimed that passive circuits are less signal influencing and more puristic and therefore better. Well, that is not so.

A passive control element such as a potentiometer in the signal path, which is not electronically buffered, influences the frequency response and phase position. Both change continuously as you change the volume.

This is exactly what does not happen with an active control.

Don't Panic

The Mute switch has two rights of existence. On the one hand, it allows the speakers to be muted without having to touch the volume control and thus leaving the set volume. 

Secondly, the Mute switch is a panic switch. Whenever the computer hangs or crashes, there is a risk that a full level signal will reach the speakers. This can be extremely loud and may damage the speakers.

The mute switch can be used to quickly turn off the signal and protect the speakers and your hearing.

Specifications:

Analog inputs & outputs:XLR (balanced)

• Maximum input & output gain: 21 dBu
• Input impedance: 22 kΩ
• Output impedance: 100 Ω
• Frequency range (-3 dB): 10 Hz – 100 kHz
• THD + N (10 Hz – 22 kHz, 15 dBu): -100 dBu
• Noise (A-weighted): -102 dBu
• Crosstalk (1 kHz): 80 dB
• Common mode rejection (1 kHz): 60 dB
• Dynamic range: 123 dB

Internal Linear Power Supply with Toroidal Transformer

• Operating voltage for analog audio: +/- 15 V
• Operating voltage for relays and LEDs: +12 V

Mains Power Supply

• Mains voltage (selectable): 230 V AC / 50; 115 V AC / 60 Hz
• Fuse for 230 V: T 250 mA
• Fuse for 115 V: T 500 mA
• Power consumption: max. 15 W

Dimensions & Weight

• W x H x D (width x height incl. feet x depth): 215 x 100 x 220 mm
• Unit weight: 1.6 kg
• Shipping weight (incl. packaging): 3.7 kg