2 Welcome
2
C Series C 88:4, C 68:4, C 48:4, C 28:4 and C 16:4 Operation Manual rev 2.2.3
2.2 Main Features
Your new C Series amplifier incorporates a number of sophisticated technologies – many of them proprietary to
Lab.gruppen – that are provided to ensure the best possible performance and many years of reliable operation.
Familiarizing yourself with these technologies will prove invaluable in setting up and optimizing your loudspeaker
system.
2.2.1 Class TD amplifier and Regulated Switch Mode Power Supply (R.SMPS)
Lab.gruppen’s patented Class TD technology combines the exceptional efficiency of a Class D amplifier with
the high sonic quality associated with Class B designs. Class TD also incorporates the same basic concepts
behind Class H designs, but here they are refined and pushed to a higher level to achieve much greater
efficiency.
The Class TD output sections work in concert with Lab.gruppen’s unique, regulated switch-mode power
supply (R.SMPS) to create a superior overall power amplifier topology. This ensures stable, full output power
over an extremely wide range of mains voltage levels. Sagging or fluctuating mains voltage will not affect the
power output delivered to the loudspeakers.
2.2.2 Amplifier gain
For greater flexibility in system integration, C Series amplifiers allow gain adjustment from +23 dB to +44 dB in
3 dB steps. This feature accommodates any combination of input device and loudspeaker type. For example,
if the input signal is weak, the gain can be boosted to maintain maximum power output while avoiding a poor
signal-to-noise ratio. This gain adjustment feature makes it easier to achieve an optimal balance between
headroom and noise floor.
2.2.3 Voltage Peak Limiter (VPL)
The Voltage Peak Limiter (VPL) feature allows user adjustments that determine maximum voltage output, thus
matching the amplifier to the connected speaker load. Whether the connected load is low impedance (2 to
16 ohms) or high impedance (70 V / 100 V), the VPL feature can be set to ensure that neither temperature nor
current limitations are exceeded before reaching the desired voltage threshold.
2.2.4 Protection and performance optimization
Appropriate and reliable power amplification is vital to any audio system. Inadequate or faulty power amplifica-
tion could cause damage to the loudspeakers, or in some cases to the power amplifiers themselves. To prevent
any damage or costly service interruptions, C Series amplifiers offer advanced features to protect both internal
circuits and any connected loads. These features even protect the mains fuse that, in extreme cases, could be
overloaded.
Following are short descriptions of standard built-in C Series protection features:
▸
CPL
, (Current Peak Limiter) ensures that the amplifier’s output does not exceed the safe current handling
parameters of amplifier components.
▸
Temperature protection
ensures that the amplifier will not be damaged by exceeding thermal limits.
▸
PAL
, (Power Average Limiter) limits the maximum average power consumption according to the power
supply and mains-breaker capabilities.
▸
VHF
, (Very High Frequency) protection circuits mute the output of the amplifier when non-dynamic continu-
ous signals above 10 kHz are detected.
