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 (150; 150') is configured for applying a polynomial based on a form w = a + bx + c x 2 wherein w denotes an obtained corrected weighting factor, x denotes the spectral weighting factor and wherein a, b and c denote correction values. 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 (150; 150') is configured for applying a polynomial based on a form w = a + bx + c x 2 wherein w denotes an obtained corrected weighting factor, x denotes the spectral weighting factor and wherein a, b and c denote correction values.