changing transformers in a fender frontman 15r

burnoutfun, for the speaker, check your other question. No, a bigger transformer will not work. You are dealing with a solid state amp, not a tube amp ;-). Your 15r is using a TDA2050 power amplifier which is capable of 32W. The input voltage to the TDA2050 should be at 23V, max being 25V. Any increase in voltage will most likely ruin your TDA2050. You could try to change your TDA2050 for a TDA2051 (40W) or a TD2052 (60W) and those would not require any change in wiring. Then, of course you would have to change the speaker to tolerate the higher wattage. I'd go with Jensen or Celestion (but that is personal preference. hope this helps, good luck.