Tube amps known to have a low damping factor?

Which tubes amps are known to have a characteristically low damping factor, 20 or less? Which are known to have a characteristically high damping factor?
ralph noted...a *lot* depends on the speaker and the designer's intent!

AMEN. Look backwards from any driver after a crossover and let me know exactly how high (or low) DF can be a meaningful figure of merit.

Highly overrated spec? I hope so - my CAT JL2 and current amp have tiny little DFs, yet I had/have well controlled, tuneful bass. High DF might very well make my speaker sound constipated.