[Radioroslyn]

Another major consideration is the size or or the inductance of the output transformer. When manufacturers design inexpensive sets small speakers, output transformers, filter capacitors and coupling capacitors all go hand in hand. All of these parts can be used the limit the low frequency response thus making a set smaller and less expensive. The less lower frequency response the more 60cy hum can be on the hv but it's less less noticeable $$ savings for the manufacturers.

Another trick you can try to add some bass boost is to connect a small hv mica cap from the plate of the 12SQ7 to 50L6. Something around 25 to 100mmfd for starters. I've just read about and haven't tried it myself. I would suspect if the capacitance is too high it would break into oscillation.