An air wound ring SE output transformer does not need an air gap

It may need too many turns of wire.


But in case of being an output transformer for a mic booster amplifier:


the large wire resistance


the low inductance


Will create a Pleiades (R,L) gentle slope high pass filter


The electron tube can operate at say 47μA with just 3.7 volts at anode and heater (see Pleiades V6). It would be very low noise.


By at the same time frequency response will be flat from producer's brain to listener's brain.


So no bass, mid heaviness.


If above reasoning is correct a sound of the league of:


When I fall in love - Nat King Cole


The Power of Love - FGTH


Into my Arms - Nick Cave and the Bad Seeds


Should be possible if too many turns won't cause too drop at HF.