Now that you simply mention it, the main two tracks manage to lack low bass, (besides a bass drum strike just before the fade outside of Custard Pie). But then “In My Time of Dying” appears to have some more bass… unsure what was occurring here, likely recorded in https://ledzeppelinplatinumrecord44207.blogkoo.com/5-essential-elements-for-led-zeppelin-gold-records-46211734