Lab.gruppen LUCIA Series - FAQ; Power Stage and Loading; Input Headroom for Clip; Latency and Delay

16. FAQ
LUCIA Operation Manual rev 1.0.0
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16. FAQ
Is the LUCIA power stage inherently bridged as on E Series, thereby allowing asymmetrical loading?
No, the power output limit per channel is xed on LUCIA. The amplier cannot be bridged and there is no way
to use power on one channel that is not being used on the other, as with Lab.gruppen’s E Series. However, the
channels are automatically optimized when it comes to peak voltage, enabling one channel to deliver the full
rated power into 2 ohms and the other channel into 8 ohms.
What is the meaning and importance of “Input headroom for clip” in the technical specications?
This is the level at which the input signal will reach full level on the input to the DSP. Above this level, the signal will
be severely compressed by an analog soft-clip circuit.
How many inputs can be driven by a LUCIA M line output?
Each LUCIA balanced line level output can drive up to 6 inputs in parallel; these can be any combination of LUCIA,
E Series, or C Series ampliers (or other 20 kOhm balanced inputs).
Why is there latency (delay) through LUCIA?
The latency through a LUCIA is 9.15 ms (acoustically equivalent of 10 ft or 3 m). This is primarily due to the look-
ahead limiters and to the multiband mastering compression used in our ADLC algorithm, which adjusts for the
nonlinearities of the ear (ISO226). The 9.15 ms of latency is below what is detectable as out-of-sync when used in
video sound applications. Nevertheless, in some applications, it is preferable to drive multiple LUCIA units in parallel
rather than in a series (‘daisy chain’) conguration, as this will result in incremental delays.
What limiter circuits are incorporated into LUCIA, and how do they operate?
Following is a simplied description of the LUCIA limiters:
• Short term (<60 ms), look-ahead voltage peak limiter - The threshold of this limiter is automatically trimmed by
an instantaneous impedance measurement when the amplier goes out of standby. This automatic adjustment
ensures that the threshold does not exceed the rated power or the maximum current that the amplier can
deliver. In LUCIA M models, alternate presets may be used that designed for a lower power output than the full
output allowed by the default preset.
• Medium term limiter - This limiter is inserted to avoid clipping if the power supply rail sags.
• Long term (>0.5 s) - This limiter is inserted to prevent thermal problems.