I figured out what the problem was. I had taken it into the shop right away when i first got it, because it had a 2 prong power chord as well as a 1/4" cable attatched to the back for the speaker it once came with, and plus it just needed a tune up and cap job to boot. So they removed the 1/4" cable but didn't replace it with another ext speaker jack, just covered the hole with a plastic cap, so that left one ext speaker jack to use.
So i hooked up my speaker cab to it (the cab was 16 ohms) and it sounded ok until i brought it out on the road for a few shows and it started sounding the way i described in my initial post. I brought it back to the same shop and thats when i learned that the original 1/4" speaker cable i had removed was for a 16ohm load, and the extra ext speaker jack i've been using is for an 8ohm load, ,,,,the power transformer in these b25's has some wierdness that lets you hook up either two 16ohm cabs,, or one 16ohm cab for the attatched 1/4" cable, or one 8ohm cab into the extra ext speaker jack. in other words, i was hooking up my 16ohm cab into the 8ohm ext speaker jack.
What i had the shop do was move the standby switch from the back of the amp up to the front face to replace the polarity switch (which wasn't hooked up since i had the 3prong ground plug installed), and in the place of the standby in the back, i had the 16ohm ext speaker jack installed to replace the 1/4" speaker cable that was removed before, so basically now i have 2 speaker inputs again (one is 16ohms, one is 8ohms), and now i'm hooking up two 16ohm cabs (1 is 2x15's and 1 is 2x12's) into this head and man what an awesome sounding amp! It has such a vintage crunch yet pretty clean and crisp tone and LOUD for a 55watt head. Also had the tube sockets tightened so the tubes won't get loose and fall out.
1977 Travis Bean Artist, Vintage 1969 Ampeg B25 50watt head, HiWatt LA4x12 cab
Pedals used; Boss tuner, Electro-harmonix microsynth, Fulltone Fat-Boost, Boss DD3.