Now you mention it, the 1st two tracks seem to lack minimal bass, (other than a bass drum hit just ahead of the fade away from Custard Pie). But then “In My Time of Dying” seems to have some extra bass… not sure what was occurring listed here, possibly https://goldrecordoutlet.com/shop/led-zeppelin-laser-cut-gold-record-with-poster-art-shadowbox-c3-3/