When multiple microphones are available estimates of inter-channel delay, which characterise a speaker's location, can be used as features for speaker diarization. Background noise and reverberation can, however, lead to noisy features and poor performance. To ameliorate these problems, this paper presents a new approach to the discriminant analysis of delay features for speaker diarization. This novel and nonetheless unsupervised approach aims to increase speaker separability in delay-space. We assess the approach on subsets of four standard NIST RT datasets and demonstrate a relative improvement in diarization error rate of 25% on a separate evaluation set using delay features alone.