Thiel Owners

If I may:
that’s the ear hieght
(+/-?) of the typical seated listening position.

Thanks jafant for finding and posting contact information for Rob Gillum's
Thiel speaker service company. My mint condition 1986 Thiel CS2's  continue to please to no end. Come the day they need attention I know who to call...:) 

38" ear height is design target.

I imagine there must also be a target distance to the listener, as well, that corresponds to the 38". In Soundstage’s measurements of the CS2.4, they measured at 2 m which is their standard. But the height was a manufacturer-specified 30" from the bottom of the speaker (presumably w/o spikes).

Thiel recommended a minimum of 8’, preferred 10’, extended to 12’. Measured at 3 meters.

The spikes add minimal consequence at the recommended seating distances. Much of the spike length was intended for carpet height piercing. 
For some the energy drain into more vibrant floor boards will negate the spikes advantages.