We present a novel method to adjust the perceived width of a phantom source by varying the deterministic inter channel time difference (ICT D) in a pair of signals over frequency. In contrast to given literature that focuses on random phase over frequency, our paper considers a deterministic approach that is open to a more systematic evaluation. Two allpass structures are described, finite impulse response (FIR) and infinite impulse response (IIR), for phase-based phantom source widening and evaluated in a formal listening test. Varying ICT D over frequency essentially alters the inter-aural cross correlation coefficient at the ears of a listener and in this way provides a robust way to control the auditory source width. The subjective evaluation results fully support our observations for both noise and speech signals.