As an aside > If you use a Mullard GZ33 tube rectifier in your ST-70/ST-120, this tall tube at 5+ inches also won't fit under a tube cage.
Regarding tube cages for Dynaco amps ... They ARE useful if you have pets or young children who may have "access" to your amps. Those tubes themselves are 300+ degrees F and will cause an instant burn if you touch a tube while the amp is running. The down side of using a tube cage are that the amp will probably run a little warmer. Yep - I know that there are perforations in the tube cage for air flow but the amp has to run a few degrees warmer with the cage on. The other downside is that the cage must be removed to reset the bias. What some tube cage users do is place the cage on the amp but don't screw it down. I don't think your cat/dog or your toddler will know enough to raise the cage by paw/hand ? To reset the bias you can just quickly remove the cage. I personally do not use a cage because I just like the looks of the tubes glowing - especially in a dimly lit room. I don't have any toddlers around anymore but Chris and I do have a cat. The cat has access to the amps but has never expressed any interest in the amps nor have I ever seen the cat walk near the amps. I guess whether you use a tube cage or not has to be a personal decision.
If you do want a tube cage for your ST-70/ST-120 amp get in touch with Kevin at Dynakitparts. His reproduction ST-70 tube cages are extremely well made and are identical to the original ST-70 tube cages right down to the "Dynakit" label.
Last edited by Bob Latino on Fri Jul 22, 2011 2:09 pm; edited 1 time in total