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 further comprises a linear prediction domain decoder for decoding the encoded downmix signal to obtain an encoded and decoded downmix signal; wherein the audio encoder (2") further comprises a multichannel residual coder for calculating an encoded multichannel residual signal using the encoded and decoded downmix signal, the encoded multichannel residual signal representing an error between a decoded multichannel representation obtained by using the multichannel information and the multichannel signal before the downmixing by the downmixer, and wherein the linear prediction domain decoder is configured to obtain, as the encoded and decoded downmix signal, only a low band signal representing the low band of the downmix signal, and wherein the encoded multichannel residual signal has only a band corresponding to the low band of the multichannel signal before the downmixing by the downmixer. 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 further comprises a linear prediction domain decoder for decoding the encoded downmix signal to obtain an encoded and decoded downmix signal; wherein the audio encoder (2") further comprises a multichannel residual coder for calculating an encoded multichannel residual signal using the encoded and decoded downmix signal, the encoded multichannel residual signal representing an error between a decoded multichannel representation obtained by using the multichannel information and the multichannel signal before the downmixing by the downmixer, and wherein the linear prediction domain decoder is configured to obtain, as the encoded and decoded downmix signal, only a low band signal representing the low band of the downmix signal, and wherein the encoded multichannel residual signal has only a band corresponding to the low band of the multichannel signal before the downmixing by the downmixer.