In looking I have found these two output transformers http://www.triodeelectronics.com/a451.html this one for a Dynaco audio amp so the low frequency response should be good. Here is the manual for the Dynaco amp http://www.dvq.com/hifi/images/dyna_mk6.pdf it has a schematic in it and the data sheet for the tubes http://www.mif.pg.gda.pl/homepages/f...168/8/8417.pdf Also this transformer http://angela.com/hammondoutputtransformer1650t.aspx a Hammond 1650T. For a bass amp you could consider wiring up the output as Ultra Linear http://www.ampbooks.com/home/amp-tec...y/ultralinear/

And this posting http://oestex.com/tubes/ulo.html