*posted with permission*
Sennheiser HD580 Open-back dynamic driver: Price varies, although allegedly priced at $349 in 1994
For those who care about baffles, this is a raised plate white paper variant of the hd580
For my personal compensation curve, I find "IEF neutral" to be most applicable in this day and age
The 580 has older plastics for hardware, while also feeling a bit sturdier compared to the modern Sennheisers (including the 2019 hd600 and hd650). The pair weighs in at 253g on a kitchen scale from the grocery store. Velour pads are direct from Sennheiser in the era of the HD660S pad revision, one revision before the currently available Sennheiser pads.
Bass (0-250 Hz):
On higher end systems, I find the HD580 (580) performs quite well for my perceived extension. It does not feel like it extends down to 20 Hz with the same strength of one of my favorite headphones for this category, that being the LCD4, but the extension into the sub-bass is quite good...