Another midnight mod project.
I picked up a pair of HST-11a's. These are unbranded, but are the same on the inside as (at least in the USA) the Apex 460.
I got pair of BV11 (5:1) transformers from AAmicrophones.
Mod will be:
Change tube to a 12AY7 (still need to order those from TubeDepot)
Swap out transformer and coupling cap (2.2uF)
swap in an edge terminated C12 inspired capsule,
eliminate some bypass capacitors.
Also, lower the B+ to 120v by swapping zeners in the PSU.
Credit for the mod goes to Dave Thomas.
The cathode follower (or apparently more precisely known as a constant current draw amplifier) will be maintained. This mod is slightly different than other mods I've seen which change to a plate follower circuit. (Also, there is a mod floating around which swaps out the stock 4:1? trafo for a 10:1 trafo, which to me doesn't make a lot of sense....)