Little Radiator

Little Radiator focuses on the saturation and harmonic behavior of the Altec 1566A preamp rather than the larger Radiator's two-band EQ and two-stage control layout. Heat determines how hard the modeled circuit is driven, producing more level and more coloration as it rises.

The Bias switch offers two related distortion responses based on different measured units, while Noise lets the modeled background noise remain part of the effect or be removed. Mix is the modern addition that makes the coloration easy to use in parallel: the untreated signal can remain underneath a strongly driven layer.

Use it when a track needs an intentionally colored front-end sound rather than transparent gain. Set Heat while listening to the actual source, compare the Bias options, then blend back some dry signal if the attack has become too rounded or the distortion too obvious. Match the final listening level in the host so increased loudness does not become the only reason the processed version seems preferable.

Manual, About Little Radiator, p. 4; The Little Radiator Control Panel, pp. 5–6.

Heat

Heat controls gain into the modeled tube circuit. Raising it increases saturation and output level together. Begin with modest drive and listen for changes in attack, sustain, and harmonic edge before pushing it further. This is not an output-only volume control or an automatically level-matched distortion amount.

Mix

Mix blends the original source with the processed path from dry to fully wet. Use a wet setting to hear the circuit clearly, then reduce the amount if the source needs more original transient detail. This provides parallel coloration without creating a separate bus. On an auxiliary return, keep the processor wet and use the return fader for the blend.

Bias

Bias On selects the more distorted of the two modeled responses. Bias Off uses the gentler response associated with a cleaner hardware unit. The change is described as subtle, so compare it with similar Heat and source levels instead of treating it as a second large gain boost.

Noise

Noise enables the modeled circuit-noise component. Switching it down removes that noise without turning off the saturation model. This is useful when applying the processor across multiple tracks or when quiet passages should stay clean; leave it enabled only when the noise contributes to the intended texture.

Little Radiator does not provide the full Radiator's Bass, Treble, separate Input/Output, or Mic/Line controls. Use host gain after it if Heat has raised the level too far, rather than looking for a nonexistent output-compensation knob.

Manual, Heat and Mix, p. 5; Bias and Noise Switch, p. 6.