If this helps, using a Fuji JPII C90 in my oldest Tascam 244 recording at 0dB on VU meter Track 1 with dbx I measured the following on replay (other tracks pretty much the same):
25 Hz -3dB
40 Hz 0dB
100Hz 0dB
400Hz 0dB
1000Hz -1dB
10000Hz 2dB
12500Hz 2dB
16000Hz...