Preporuka za izlazne cijevi u SE pojačalima

[Zmajz]

Već duže vrijeme želim ovdje prezentirati dio članka P. Turnera (http://www.turneraudio.com.au/index.html" target="_blank" target="_blank" target="_blank" target="_blank" target="_blank" target="_blank" target="_blank" target="_blank) vezano uz izlazne transformatore a vezano za opteretne otpore izlaznih elektronskih cijevi. Radi se o preporučenim vrijednostima najčešće korištenih cijevi u SE pojačalima, u pentodnom, tetrodnom, UL, Cathode Feedback načinu rada u jednoj tablici i triodnom načinu u drugoj. Zgodno je, ako ništa drugo, za informaciju kako se uobičajeno koriste date lampe.

SE Recomended Load.pdf

Ovdje je i autorovo pojašnjenje radi lakšeg razumijevanja, u originalu, nemam živaca za prevod:

"NOTE. Interpreting the tables above.
Tube Type. Includes those most commonly used plus a few which are
uncommon, like 13E1 which is no longer made.

Single Ended Mode.
"P" and "BT" = Pentode and Beam Tetrode, with fixed Eg2 between screen g2 and cathode k.
CFB = Cathode feedback windings are used on OPT. CFB windings have portion of total primary turns up to 50% of total primary turns. Screen g2 is taken to fixed Vdc supply often lower than anode B+ supply. Such a connection is known as Acoustical, as used in early Quad-II amps. Sometimes g2 is taken to taps on node winding for some screen feedback like the UL connection.
UL = Ultralinear, where g2 is taken to taps on anode winding where the portion of B+ to screen winding is not more than 66% of total anode turns.
Triode = Triode strapped multigrids where g2 and perhaps g3 is tied to anode or where the tube is a real triode like 300B.
Max Pda + Pg2 at idle, Watts = Total of product of ( Ea-k x Iadc ) +
( Eg2-k x Ig2dc ) at idle condition. The Pda is the maximum recommended and may be lower to allow longer tube life and reliability. The higher Pda, the higher the operating temperature and shorter the tube life. If Pda is from what is listed, all information in following table columns must be re-calculated.
Ea +Vdc a to k and Ia + Ig2 mAdc = Range of maximum and minimum Ea and Ia values which could be used. A graph may be made on an Ia / Ea graph to determine other values between those shown.
RL is calculated for all tubes except triode as RL = 0.9 x (Ea / Ia)
RL for triode is calculated as RL = (Ea / Ia) - (2 x Ra) where Ra is the straight line calculation for the first part of the Ra curve for where Eg1 bias = 0Vdc.
Max Audio Power Watts at Anode For pure class A1 at clipping and where
THD < 5% for the load value capable of producing the maximum possible PO for the Ea and Ia conditions at idle.
Beam Tetrodes and Pentodes,
POa = [ 0.5 x ( Iadc at idle - 5% )squared ) x anode RLa ] Watts. With applied NFB the THD may permit more PO with less THD and higher maximum anode efficiency.
Efficiency % Max = Anode efficiency, calculated as = ( 100 x maximum possible anode audio power / Pda at idle ) %

The tables are a GUIDE for OPT design. The Ea and Ia determine the load
value which gives the highest power at clipping. Raising Ea and lowering Ia
for the same Pda will allow a higher RL, and lowering Ea and raising Ia will
allow a lower RL. Thus the Ea and Ia may be adjusted to suit a given RL
or to suit an OPT which is available.

NOTE. For Parafeed connection where a high value choke inductance is used to
bring the Idc to the tubes, and the OPT primary is coupled to the anode with a
capacitance, the OPT may be designed using the method for PP OPT calcs.

Nažalost, nemam ništa slično za PP kombinaciju, pa ako je netko pri volji sastaviti nešto slično za PP topologiju, bilo bi dobro (u A, AB1, AB2" itd.)