I have noticed a few threads previously regarding winding output transformers. I would like to point out an alternative suitable for DIYers. On page 888 of the Radio Designer's Handbook (Langford-Smith) there is mentioned a technique where the usual speaker crossover network is moved forward so as to be between the output tubes and transformers. This uses two trannies, one is used for low frequencies (say to 400 Hz) and the other covers the high freq. range. The low freq. trans. can be just a cheap 60 Hz power line xfmr. with the right turns ratio. (ie. need a center tapped high voltage xfmr) This is something that can often be found surplus. The high freq. trans. does not need nearly as many turns on it as the low freq. one, but needs the same turns ratio. This would be easier as the DIYer part. Use a big ferrite toroid core to wind it on yourself. Use small teflon wire or Kynar wire wrap for a low distributed capacitance primary. The toroid shape itself minimizes leakage inductance nicely if the windings cover 360 degrees of core. An additional advantage of this dual xfmr. scheme is that the bandwidth will extend up into the near megahertz range with a ferrite core, so one can use global feedback to much greater effect if desired. One would have to provide two feedback paths, one from each xfmr. secondary to get the full freq. range. The Handbook article references two articles in Electronics magazine, both by P. W. Klipsch: Vol. 21.11 (Nov. 1948) and Vol. 18.11 (Nov. 1945). I will try to get a copy of these and any subsequent references this winter at the library.
The Handbook (pg. 888) gives a diagram and parts values for a 12dB crossover version which requires two inductors. If one only wants a 6dB crossover then L2 and the two C1s can be eliminated as per fig. 4.53A (parallel) on page 185. It might be possible to use the high freq. xfmr. as the inductor itself (Lo) if it has an air gap and is connected per fig. 4.53A (series).
The Handbook (pg. 888) gives a diagram and parts values for a 12dB crossover version which requires two inductors. If one only wants a 6dB crossover then L2 and the two C1s can be eliminated as per fig. 4.53A (parallel) on page 185. It might be possible to use the high freq. xfmr. as the inductor itself (Lo) if it has an air gap and is connected per fig. 4.53A (series).