We present a new class of trellis-codes for partial-response channel. Our code configuration is based on the coded 1 - D scheme due to Wolf and Ungerboeck. However, no precoder between a convolutional encoder and the partialresponse channel is used. A new lower bound on the minimum free squared Euclidean distance of channel code is shown. The bound is available for any PR channel with a finite response. New codes for 1 - D and (1 - D) (1 + D)2 channels are found by computer code search using the lower bound. Some of the new codes have excellent properties: a significant d2free and a small decoding complexity.