Description
London Power’s VCK Voltage Clamp Kit stabilizes voltages in a tube preamp, helping to keep tone consistent with fluctuations of incoming power. This is particularly important in cathode-biased amplifiers fitted with Power Scaling but not using our SV2-Zh or SV2-Zp kits
- maximum input voltage: 550V (most preamps and cathode-biased amps are 400V or less)
- maximum input/output voltage difference: 200V
- maximum load current: 50mA depending on V-diff
- trimpot allows easy voltage setting
- modest hum reduction of 22dB typical
VCK can be used in situations where the incoming supply voltage varies due to, say, poor mains regulation in the locale. VCK should come after the main input filter capacitor, or cap-choke-cap pi-filter, and will provide a reduction in supply-borne noise for sensitive voltage amplifier circuits. VCK has a trimpot to set the output voltage
VCK has been designed to occupy as little space as possible in the amp chassis, requiring less than one-square-inch of space (1″x1″, 25x25mm)
If you have
VCK can be used in other situations where the incoming supply voltage varies due to, say, poor mains regulation in the locale.
VCK has been designed to occupy as little space as possible in the amp chassis, requiring less than one-square-inch of space (1″x1″, 25x25mm)
If you have Power Scaled a cathode-biased amplifier using our books as a guide, then VCK is a good addition. Cathode-biased amplifiers demand full power even at idle, which pulls the supply voltage down to a value that stays approximately the same, even when the amp is driven to full output. In a Power Scaled cathode-biased amp, as the Power Scale control is dialed down, the supply voltage will rise as it becomes “unloaded”. This will change the tonal contribution of the preamp at low power settings. Adding VCK to stabilize the preamp voltage to the stock “loaded” value will keep the tonal contribution of the preamp constant with any Power Scale setting.
The unloaded voltage in a cathode-biased amp can be 20% higher than the normal idle voltage. VCK is designed to minimize this rise of voltage and keep tone the same.
Note that London Power’s complete Power Scale solution for cathode-biased amplifiers is unitised as one module, SV2, which performs the actual Power Scale function and Voltage Clamp functions.
Available Kit Configurations:
VCK-COMP: includes PCB, components, notes; requires assembly; requires installation
VCK-BLT: includes pre-assembled PCB,notes; requires installation
If you require a high-voltage and higher-power version of the VCK, see VCK-HV.
PCB size: 1.4″ x 1″, 36mm x 25mm
See our Power Scaling FAQ.
