Audio encoder (2") for encoding a multichannel signal , comprising: a downmixer for downmixing the multichannel signal to obtain a downmix signal ; a linear prediction domain core encoder for encoding the downmix signal to obtain an encoded downmix signal , wherein the downmix signal has a low band and a high band, wherein the linear prediction domain core encoder is configured to apply a bandwidth extension processing for parametrically encoding the high band; a filterbank for generating a spectral representation of the multichannel signal ; and a joint multichannel encoder configured to process the spectral representation comprising the low band and the high band of the multichannel signal to generate multichannel information , wherein the linear prediction domain core encoder comprises an ACELP processor , wherein the ACELP processor is configured to operate on a downsampled downmix signal obtained from the downmix signal by a downsampler , and wherein a time domain bandwidth extension processor is configured to parametrically encode the high band of the downmix signal removed from the downmix signal by the downsampling using the downsampler , and wherein the linear prediction domain core encoder comprises a TCX processor , wherein the TCX processor is configured to operate on the downmix signal not downsampled or downsampled by a degree smaller than the downsampling for the ACELP processor performed by the downsampler , the TCX processor comprising a time-frequency converter , a parameter generator for generating a parametric representation of a first set of bands, and a quantizer encoder for generating a set of quantized encoded spectral lines for a second set of bands. a downmixer for downmixing the multichannel signal to obtain a downmix signal ; a linear prediction domain core encoder for encoding the downmix signal to obtain an encoded downmix signal , wherein the downmix signal has a low band and a high band, wherein the linear prediction domain core encoder is configured to apply a bandwidth extension processing for parametrically encoding the high band; a filterbank for generating a spectral representation of the multichannel signal ; and a joint multichannel encoder configured to process the spectral representation comprising the low band and the high band of the multichannel signal to generate multichannel information , wherein the linear prediction domain core encoder comprises an ACELP processor , wherein the ACELP processor is configured to operate on a downsampled downmix signal obtained from the downmix signal by a downsampler , and wherein a time domain bandwidth extension processor is configured to parametrically encode the high band of the downmix signal removed from the downmix signal by the downsampling using the downsampler , and wherein the linear prediction domain core encoder comprises a TCX processor , wherein the TCX processor is configured to operate on the downmix signal not downsampled or downsampled by a degree smaller than the downsampling for the ACELP processor performed by the downsampler , the TCX processor comprising a time-frequency converter , a parameter generator for generating a parametric representation of a first set of bands, and a quantizer encoder for generating a set of quantized encoded spectral lines for a second set of bands. <EOS>