Τελικά δεν είναι κακή συνδεσμολογία η ultra linear από όσα διαβάζω....
ULTRA-LINEAR OPERATION, also known as DISTRIBUTED LOAD OPERATION, is a term when applied to push-pull audio amplifiers, that describes the particular output stage configuration whereby the Screen Grids (Grid 2) of Tetrodes, Pentodes or Beam Power Tubes are fed from a tapping in each half of the primary of the output transformer - typically 43% turns or 18.5% impedance when measured from the centre-tap, instead of from a DC supply either independent or common to the anodes.
The sonic properties of the ultra-linear output stage configuration - albeit single-ended or push-pull design - are midway between triode and tetrode/beam power tube "tone".
Some audio-engineers describe the sound of triodes as "smooth, sweet, mellow, natural" and tetrode/beam power tubes as "clean, bright, sharp, punchy".
Technically speaking, the ultra-linear configuration delivers the same power output as for pentode operation of the same tube under the same operating conditions and typically about twice the power output of triode operation of the same tube under the same operating conditions with the same applied DC voltages - but with substantially less harmonic distortion or intermodulation distortion (see comparative performance graph below).
The ultra-linear configuration also offers improved overload characteristics, resulting in more effective power output - ie what the listener actually hears at full power levels.
Output impedance is similar to triodes, allowing minimal or zero negative loop feedback to be used.
The ultra-linear amplifier concept is beautifully described by David Hafler and Herbert Keroes in their 1952 US Patent Application 2710312.