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"PP tube OTs" for $20.13. (still good value) but I don't know why they have chosen to distinguish these from the 2W "matchers" @ 13$ ea - perhaps core material?
Transformers are like sausage: you pay by the pound, discount for large orders, plus any fancy wrapping you want.
I'm guessing you mean something like this pair:
XPP
15W, open framed push-pull tube output transformer for 10K Ohms to 16 Ohms.
$20.01
Weight 1.6 lbs.
Dimensions 3.67" (L) x 2.25" (W) x 2.25" (H)
XSM
2-1/2W 15K Ohms to 10K Ohms (1.2:1) line level matching transformer.
$12.97
Weight 0.75 lbs.
Dimensions 2.815" (L) x 1.79" (W) x 1.64" (H)
The "15W" is twice the weight, you expect twice the price. Looks like they have about $6 for per-each overhead, then metal for $9/pound.
You also see:
15Watts/1.6lb = 9 Watts per pound
2.5Watts/0.75lb = 3 watts per pound
The "15W" part only claims down to 70Hz. The "2.5W" part claims 20Hz but not the power at 20Hz. This is not unreasonable. A large system may have several matching transformers but usually only one OUTput transformer. You want the little ones a bit generous and perhaps shave a little on the one big one.
If I were paying $100 for either, I would want better specs. But the prices are indeed bare-bone and you can cheaply buy one from each series to test in YOUR particular apparatus. If you have heavy transistors, some transformer flaws can be overwhelmed. If you have a thin tube driving a transformer you may have to buy bigger than their general-use designations suggest. (Their "25W 20Hz" CXPP part is almost 5 pounds for under $50, so you could afford to work it WAY under the nominal rating for lower THD at deeper bass.)
What IS odd is that they sell XPP transformers rated "1W" at the same weight, same 70Hz, and $2 more than their "15W" part.
