Question: Can changing an amp’s OT create more clean headroom?
Answer: Changing out an OT with a tranny that has the same impedances as the one being replaced won’t deliver more power because volts-is-volts and watts-is-watts. Meaning: no extra power is delivered here for free.
You can force out more power from a tube by lowering the primary impedance of an OT. This usually does more harm than good, shortened tube life and harsher tone for starters. A player can get more out of his amp like extended clean tone headroom and a noticeable presence of a bigger soundstage effect by way of transformer solutions. By increasing an OT’s “tank capacity” with more of the right kind of iron and copper resulting in more inductance to the primary winding. It’s this inductance that has a more profound effect on tone and how large it sounds that goofing around with starving tubes with lowered impedances.
OTs that are physically larger in size do sound larger even if they may have the same impedance as their smaller counterpart. The reason for this is the energy carrying the guitar tone information through the tranny is seeing less power-robbing resistances and going through its magnetic field transformation with faster responding iron helps the tranny to have a larger window for tone to flow through.
The same holds true for the PT. While the OT benefits the player with extended headroom and frequency range, the PT supplies more energy and the quicker delivery of it to the amps circuit resulting better bottom end and improved note dynamics in the form of note attack and separation.
This is also why amps that run hotter than a bitch kitty usually don’t have good tone as well.
Source: https://mercurymagnetics.com/pages/_misc/FAQ.htm#Clean_headroom
