upper frequency bandwidth limiting

[Andy Le Blanc]

what are the pros and cons of limiting highs useing the following two approaches?

straping the plate resistor with a cap ala TW.

putting a cap between the plate a chathode ala ODS.

which is the most effective with the least harm to the amps responce?

[Andy Le Blanc]

Ive had a chance the gig out an amp with a cap from the plate to the cathode
simple amp, one pre stage, inverter, pair 6l6, 50ish watts, no global feed back.
the circuit design approach was based on 5c5\5d5 and was very brite in the shop without the mod....
both mods were applied to the input side of the inverter tube
a cap straping the plate resistor, as mentioned as part of the
universal gain stage in the train wreck pages, works but seemed to be less effective
than the same value capacitor, used between plate and cathode
it also didnt remove apparent briteness and overtones as well as the same value cap between the plate and cathode
the amp at volume performed nicely with sufficent briteness and clarity not being lost or losing character
but was not shrill or harshly overtoned as the sound developed further away from the amp