Encoder for encoding an audio signal, the encoder comprising: an analyzer configured for analyzing the audio signal and for determining analysis prediction coefficients from the audio signal; a converter configured for deriving converted prediction coefficients (122; 122') from the analysis prediction coefficients; a memory configured for storing a multitude of correction values; a calculator (130; 130') comprising: a processor (140; 140') configured for processing the converted prediction coefficients (122; 122') to obtain spectral weighting factors (142; 142'); a combiner (150; 150') configured for combining the spectral weighting factors (142; 142') and the multitude of correction values (162; a, b, c) to obtain corrected weighting factors (152; 152'); and a quantizer configured for quantizing the converted prediction coefficients (122; 122') using the corrected weighting factors (152; 152') to obtain a quantized representation of the converted prediction coefficients (122; 122'); and a bitstream former configured for forming an output signal based on the quantized representation of the converted prediction coefficients and based on the audio signal; wherein the combiner is configured for combining the spectral weighting factors (142; 142'), the multitude of correction values (162; a, b, c) and a further information related to the input signal to obtain the corrected weighting factors; wherein the further information related to the input signal comprises reflection coefficients obtained by the analyzer. an analyzer configured for analyzing the audio signal and for determining analysis prediction coefficients from the audio signal; a converter configured for deriving converted prediction coefficients (122; 122') from the analysis prediction coefficients; a memory configured for storing a multitude of correction values; a calculator (130; 130') comprising: a processor (140; 140') configured for processing the converted prediction coefficients (122; 122') to obtain spectral weighting factors (142; 142'); a combiner (150; 150') configured for combining the spectral weighting factors (142; 142') and the multitude of correction values (162; a, b, c) to obtain corrected weighting factors (152; 152'); and a quantizer configured for quantizing the converted prediction coefficients (122; 122') using the corrected weighting factors (152; 152') to obtain a quantized representation of the converted prediction coefficients (122; 122'); and a processor (140; 140') configured for processing the converted prediction coefficients (122; 122') to obtain spectral weighting factors (142; 142'); a combiner (150; 150') configured for combining the spectral weighting factors (142; 142') and the multitude of correction values (162; a, b, c) to obtain corrected weighting factors (152; 152'); and a quantizer configured for quantizing the converted prediction coefficients (122; 122') using the corrected weighting factors (152; 152') to obtain a quantized representation of the converted prediction coefficients (122; 122'); and a bitstream former configured for forming an output signal based on the quantized representation of the converted prediction coefficients and based on the audio signal; wherein the combiner is configured for combining the spectral weighting factors (142; 142'), the multitude of correction values (162; a, b, c) and a further information related to the input signal to obtain the corrected weighting factors; wherein the further information related to the input signal comprises reflection coefficients obtained by the analyzer.